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• 1591. [Article] Patterns and mechanisms : postcopulatory sexual selection and sexual conflict in a novel mating system

  Postcopulatory sexual selection—sperm competition and cryptic female choice—has become a major area of research over the past 40 years. Within this field there are many outstanding questions at every level ...

  Citation × Citation Citation Abstract Copy Title: Patterns and mechanisms : postcopulatory sexual selection and sexual conflict in a novel mating system Author: Friesen, Christopher R. Postcopulatory sexual selection—sperm competition and cryptic female choice—has become a major area of research over the past 40 years. Within this field there are many outstanding questions at every level of analysis, from proximate to ultimate. The fitness consequences for both sexes in the period after copulation and before fertilization are considerable, but are obscured within the female reproductive tract. Our understanding of postcopulatory mechanisms is especially sparse in taxa other than birds and insects. Nearly nothing is known in reptiles except that multiple paternity is common and widespread, and often results from long-term sperm storage across breeding seasons. We present some of the very first data on the determinants of fertilization success in the context of sperm competition in reptiles, a group that accounts for 30% of terrestrial vertebrates. In the first chapter, "Asymmetric gametic isolation between two populations of red-sided garter snakes", we discuss the use of between-population crosses to reveal gametic isolation. The effect of population density and operational sex ratios on mating systems and the speciation process has fueled theoretical debate. We attempted to address these issues using two populations of red-sided garter snakes (Thamnophis sirtalis parietalis) from Manitoba, Canada. Our study populations differ markedly in their density mating aggregations, with a 10-fold difference between them. Using microsatellite markers for paternity analysis of litters produced from within and between population crosses. We found that the population with highest aggregation density, and presumably with the highest level of sexual conflict (i.e., when the evolutionary interests of the sexes differ) over mating, was also the population that exhibited homotypic sperm precedence. The less dense population showed a distinct postcopulatory male-size advantage. We also demonstrated that sperm stored within the female over hibernation can father 20-30% of offspring in a litter. In the second chapter, "Sperm competition and mate-order effects in red-sided garter snakes", we test whether females use mate-order effects to ensure that a larger (fitter) male will sire her offspring. Does that second male should have precedence in sperm competition? We tested for second-male precedence using singly-mated females that mated with a second male. Average proportion of paternity was shared equally among the first (P₁, i.e., proportion of offspring from a litter fathered by the first male to mate) and second males (P₂) to mate, and stored sperm (P[subscript ss]). This may be a case where last male precedence breaks down with more than two males. All females were spring virgins (they had not mated that spring, but may have stored sperm from fall matings); thus sperm stored presumably from fall matings is important in this system. As the interval between matings increased P₁ increased at the expense of P[subscript ss]. As the second male to mate's copulation duration increased, P₁ also increased at the expense of P₂. This last result may indicate female influence over sperm transfer during coerced matings. Copulatory plugs (CPs) are found in many taxa, but the functional significance is debated. Male garter snakes produce a gelatinous copulatory plug during mating that occludes the opening of the female reproductive tract for approximately two days. In chapter three, "Not just a chastity belt: the role of mating plugs in red-sided garter snakes revisited", we experimentally tested the role of the CPs. In snakes, sperm are produced in the testes and delivered through the ductus deferens, and the copulatory plug is thought to be produced by the sexual segment of the kidney and conveyed through the ureter. We manipulated the delivery of the two fluids separately by ligating the ducts. We confirmed that the CP is not formed in ureter-ligated males and that sperm leaks out immediately after copulation. The CP is analogous to a spermatophore. The protein matrix contains most of the sperm which are liberated as the plug dissolves within the female's vaginal pouch. One of the fundamental principles in sperm competition is that increased sperm numbers increase the odds of winning in competitions for fertilization success and males will adjust their ejaculate relative to competition and the quality of his mate. In chapter four, "Sperm depleted males and the unfortunate females who mate with them", we detect significant among-male variation in the number of sperm ejaculated, and that male mate-order reduces sperm numbers. Male sperm numbers drop significantly from one mating to the next, and this has implications for sperm competiveness, as Thamnophis sirtalis exhibits a disassociated reproductive tactic, in that sperm stores are produced outside the breeding season, and thus cannot be replenished after mating. Interestingly, however, the on average the mobility of the sperm increased for a male's second mating. Therefore, increased sperm quality may compensate for reduced numbers in a competitive context. Further, females increase their remating rate when mating with males that are unable to deliver sperm. In chapter five, "Sexual conflict during mating in red-sided garter snakes as evidenced by genital manipulation", we revisited the CP in the context of sexual conflict. Sex-differences in optimal copulation duration can be a source of conflict, as increased copulation duration may be advantageous for males as it delays female remating. Males of many species actively guard females to prevent them from remating, and in some cases males produce copulatory plugs to prevent remating. If precopulatory choice is limited at the time of her first mating, conflict may be especially onerous to a female. The size of the plug is influenced by the copulation duration. We experimentally tested the contribution of male and female control over copulation duration. We ablated the largest basal spine on the male's hemipene and found a reduction in copulation duration and an increase in the variation of plug mass. Further, we anesthetized the female's cloaca and found copulation duration increased, which suggests that males benefit from increased copulation duration while females actively try to reduce copulation duration. Therefore, sexual conflict is manifest in divergent copulation duration optima for males and females. Title: Patterns and mechanisms : postcopulatory sexual selection and sexual conflict in a novel mating system Author: Friesen, Christopher R. Postcopulatory sexual selection—sperm competition and cryptic female choice—has become a major area of research over the past 40 years. Within this field there are many outstanding questions at every level of analysis, from proximate to ultimate. The fitness consequences for both sexes in the period after copulation and before fertilization are considerable, but are obscured within the female reproductive tract. Our understanding of postcopulatory mechanisms is especially sparse in taxa other than birds and insects. Nearly nothing is known in reptiles except that multiple paternity is common and widespread, and often results from long-term sperm storage across breeding seasons. We present some of the very first data on the determinants of fertilization success in the context of sperm competition in reptiles, a group that accounts for 30% of terrestrial vertebrates. In the first chapter, "Asymmetric gametic isolation between two populations of red-sided garter snakes", we discuss the use of between-population crosses to reveal gametic isolation. The effect of population density and operational sex ratios on mating systems and the speciation process has fueled theoretical debate. We attempted to address these issues using two populations of red-sided garter snakes (Thamnophis sirtalis parietalis) from Manitoba, Canada. Our study populations differ markedly in their density mating aggregations, with a 10-fold difference between them. Using microsatellite markers for paternity analysis of litters produced from within and between population crosses. We found that the population with highest aggregation density, and presumably with the highest level of sexual conflict (i.e., when the evolutionary interests of the sexes differ) over mating, was also the population that exhibited homotypic sperm precedence. The less dense population showed a distinct postcopulatory male-size advantage. We also demonstrated that sperm stored within the female over hibernation can father 20-30% of offspring in a litter. In the second chapter, "Sperm competition and mate-order effects in red-sided garter snakes", we test whether females use mate-order effects to ensure that a larger (fitter) male will sire her offspring. Does that second male should have precedence in sperm competition? We tested for second-male precedence using singly-mated females that mated with a second male. Average proportion of paternity was shared equally among the first (P₁, i.e., proportion of offspring from a litter fathered by the first male to mate) and second males (P₂) to mate, and stored sperm (P[subscript ss]). This may be a case where last male precedence breaks down with more than two males. All females were spring virgins (they had not mated that spring, but may have stored sperm from fall matings); thus sperm stored presumably from fall matings is important in this system. As the interval between matings increased P₁ increased at the expense of P[subscript ss]. As the second male to mate's copulation duration increased, P₁ also increased at the expense of P₂. This last result may indicate female influence over sperm transfer during coerced matings. Copulatory plugs (CPs) are found in many taxa, but the functional significance is debated. Male garter snakes produce a gelatinous copulatory plug during mating that occludes the opening of the female reproductive tract for approximately two days. In chapter three, "Not just a chastity belt: the role of mating plugs in red-sided garter snakes revisited", we experimentally tested the role of the CPs. In snakes, sperm are produced in the testes and delivered through the ductus deferens, and the copulatory plug is thought to be produced by the sexual segment of the kidney and conveyed through the ureter. We manipulated the delivery of the two fluids separately by ligating the ducts. We confirmed that the CP is not formed in ureter-ligated males and that sperm leaks out immediately after copulation. The CP is analogous to a spermatophore. The protein matrix contains most of the sperm which are liberated as the plug dissolves within the female's vaginal pouch. One of the fundamental principles in sperm competition is that increased sperm numbers increase the odds of winning in competitions for fertilization success and males will adjust their ejaculate relative to competition and the quality of his mate. In chapter four, "Sperm depleted males and the unfortunate females who mate with them", we detect significant among-male variation in the number of sperm ejaculated, and that male mate-order reduces sperm numbers. Male sperm numbers drop significantly from one mating to the next, and this has implications for sperm competiveness, as Thamnophis sirtalis exhibits a disassociated reproductive tactic, in that sperm stores are produced outside the breeding season, and thus cannot be replenished after mating. Interestingly, however, the on average the mobility of the sperm increased for a male's second mating. Therefore, increased sperm quality may compensate for reduced numbers in a competitive context. Further, females increase their remating rate when mating with males that are unable to deliver sperm. In chapter five, "Sexual conflict during mating in red-sided garter snakes as evidenced by genital manipulation", we revisited the CP in the context of sexual conflict. Sex-differences in optimal copulation duration can be a source of conflict, as increased copulation duration may be advantageous for males as it delays female remating. Males of many species actively guard females to prevent them from remating, and in some cases males produce copulatory plugs to prevent remating. If precopulatory choice is limited at the time of her first mating, conflict may be especially onerous to a female. The size of the plug is influenced by the copulation duration. We experimentally tested the contribution of male and female control over copulation duration. We ablated the largest basal spine on the male's hemipene and found a reduction in copulation duration and an increase in the variation of plug mass. Further, we anesthetized the female's cloaca and found copulation duration increased, which suggests that males benefit from increased copulation duration while females actively try to reduce copulation duration. Therefore, sexual conflict is manifest in divergent copulation duration optima for males and females. Close

• 1592. [Article] Food habits and diet quality of deer and cattle and herbage production of a sagebrush-grassland range

  Research was conducted on the Keating rangelands in north-eastern Oregon to determine the food habits of deer and cattle and similarity of their diets, and to estimate deer and cattle months of grazing ...

  Citation × Citation Citation Abstract Copy Title: Food habits and diet quality of deer and cattle and herbage production of a sagebrush-grassland range Author: Hilken, Thomas O. Research was conducted on the Keating rangelands in north-eastern Oregon to determine the food habits of deer and cattle and similarity of their diets, and to estimate deer and cattle months of grazing on both a quantitative and nutritional basis. Data were collected during the winters of 1978-1979, 1979-1980 and during the spring and fall of 1979 and 1980. In the Crystal Palace, Tucker Creek and Spring Creek study areas, field fecal collections were made and the microhistological method was used in the laboratory to determine the food habits of both deer and cattle. Similarity indices were calculated comparing food habits of both deer and cattle. In delineated plant communities, available herbaceous forage was estimated within 0.5m² circular plots employing a double sampling technique, and available browse was estimated employing a multiple linear regression technique. Subsamples of available forage were analyzed for in vitro dry matter digestibility and crude protein. An extensive literature review was conducted to determine nitrogen (N) and metabolizable energy (ME) requirements of both deer and cattle. Cattle and deer months of grazing were calculated for each plant community on a quantitative (i.e., forage biomass) and nutritional (i.e., metabolizable energy and nitrogen) basis employing the resources available following relationships: number supported = resources available/resources required. Management recommendations were made based on data collected in this study. Grass was the most dominant forage consumed by cattle, while deer consumed both grass and browse. Forbs were not an important dietary constituent for either cattle or deer. During the early winter period of 1978-1979, browse and grass averaged 57.4 percent and 1.6 percent of the deer diets, respectively. However, during the late winter period of 1978-1979, browse and grass averaged 40.2 percent and 31.5 percent of the deer diets, respectively. During the 1979-1980 winter, browse and grass averaged 35.4 percent and 51.9 percent of the deer diets, respectively. The predominant grass and browse consumed by deer was Sandberg's bluegrass and big sagebrush, respectively. During the spring period, crested wheatgrass, cheatgrass and Sandberg's bluegrass averaged 21.8, 29.1 and 19.5 percent of cattle diets, respectively. During the fall period,.cheatgrass and Sandberg's bluegrass averaged 30.4 and 24.9 percent of cattle diets, respectively. Diet similarity ranged from 27.1 percent to 52.8 percent while the average spring overlap for both years was 37 percent and the average fall overlap was 50 percent. Most of the dietary overlap occurred on Sandberg's bluegrass. The literature review revealed that on a forage biomass basis a cow-calf pair in spring required 14 kg/day, while a dry pregnant cow in the fall required 10 kg/day. On an energy and nitrogen basis, a nursing cow required 26.6 Meal/day of ME and 206 g of N, while a dry pregnant cow required 10.0 Meal/day of ME and 94.5 g of N. On a forage biomass basis, a wintering adult deer required .9 kg of forage per day while a fawn required .6 kg per day. Considering the length of the winter period, the energy obtained by catabolism of fat, and the energy and nitrogen required in gesta tion, I determined that during the early and late winter periods of 1978-1979 deer required 1.81 and 1.80 Meal/day of ME and during the 1979-1980 winter, they required 1.73 Meal/day of ME. The literature also revealed that a wintering deer required 12.9 g of N per day. Quantitative forage analysis showed that depending upon study area and pasture on a kg/ha basis the predominant grasses available to cattle were crested wheatgrass, Sandberg's bluegrass and cheatgrass. Determination of available browse biomass was made employing a multiple linear regression model for mountain big sagebrush (log y = -6.37 + .9337 log H + 1.49 log W₂), and a simple linear regression model for gray rabbitbrush (log y = -3.70 + 1.81 log W) and basin big sagebrush (log y = -3.84 + .9870 log A). Depending upon study area and plant community, quantitative analysis of the forage showed that big sagebrush and Sandberg's bluegrass were the dominant species available to deer. Early spring grazed pastures could carry more AUMS on a nutritional basis than on a quantitative basis. Pastures sampled in late spring showed that total AUMS on a forage quantity basis exceeded those on a nutritional basis. During the fall on an old-growth (i.e., previous year's growth) and fall growth basis, total AUMS based on N generally exceeded those based on ME or forage quantity, except in the crested wheatgrass-dominated pasture where more AUMS were calculated on a quantity basis than on a nutritional basis. On a fall-growth-only basis, more AUMS were calculated on a nutritional basis than on a quantity basis. Generally, the least number of AUMS could be carried on the medusahead communities while the most AUMS could be carried on the crested wheatgrass seedings. Deer months calculated for the two winters across the three study areas showed more deer months per plant community were calculated on a forage quantity basis than on an ME or N basis. However, an exception to this trend occurred in the grassland com munities where more deer months were calculated on an N basis than on an ME or forage quantity basis. Generally, the most deer months were calculated for the basin big sagebrush communities while the least number of deer months were calculated on the medusahead communities. Title: Food habits and diet quality of deer and cattle and herbage production of a sagebrush-grassland range Author: Hilken, Thomas O. Research was conducted on the Keating rangelands in north-eastern Oregon to determine the food habits of deer and cattle and similarity of their diets, and to estimate deer and cattle months of grazing on both a quantitative and nutritional basis. Data were collected during the winters of 1978-1979, 1979-1980 and during the spring and fall of 1979 and 1980. In the Crystal Palace, Tucker Creek and Spring Creek study areas, field fecal collections were made and the microhistological method was used in the laboratory to determine the food habits of both deer and cattle. Similarity indices were calculated comparing food habits of both deer and cattle. In delineated plant communities, available herbaceous forage was estimated within 0.5m² circular plots employing a double sampling technique, and available browse was estimated employing a multiple linear regression technique. Subsamples of available forage were analyzed for in vitro dry matter digestibility and crude protein. An extensive literature review was conducted to determine nitrogen (N) and metabolizable energy (ME) requirements of both deer and cattle. Cattle and deer months of grazing were calculated for each plant community on a quantitative (i.e., forage biomass) and nutritional (i.e., metabolizable energy and nitrogen) basis employing the resources available following relationships: number supported = resources available/resources required. Management recommendations were made based on data collected in this study. Grass was the most dominant forage consumed by cattle, while deer consumed both grass and browse. Forbs were not an important dietary constituent for either cattle or deer. During the early winter period of 1978-1979, browse and grass averaged 57.4 percent and 1.6 percent of the deer diets, respectively. However, during the late winter period of 1978-1979, browse and grass averaged 40.2 percent and 31.5 percent of the deer diets, respectively. During the 1979-1980 winter, browse and grass averaged 35.4 percent and 51.9 percent of the deer diets, respectively. The predominant grass and browse consumed by deer was Sandberg's bluegrass and big sagebrush, respectively. During the spring period, crested wheatgrass, cheatgrass and Sandberg's bluegrass averaged 21.8, 29.1 and 19.5 percent of cattle diets, respectively. During the fall period,.cheatgrass and Sandberg's bluegrass averaged 30.4 and 24.9 percent of cattle diets, respectively. Diet similarity ranged from 27.1 percent to 52.8 percent while the average spring overlap for both years was 37 percent and the average fall overlap was 50 percent. Most of the dietary overlap occurred on Sandberg's bluegrass. The literature review revealed that on a forage biomass basis a cow-calf pair in spring required 14 kg/day, while a dry pregnant cow in the fall required 10 kg/day. On an energy and nitrogen basis, a nursing cow required 26.6 Meal/day of ME and 206 g of N, while a dry pregnant cow required 10.0 Meal/day of ME and 94.5 g of N. On a forage biomass basis, a wintering adult deer required .9 kg of forage per day while a fawn required .6 kg per day. Considering the length of the winter period, the energy obtained by catabolism of fat, and the energy and nitrogen required in gesta tion, I determined that during the early and late winter periods of 1978-1979 deer required 1.81 and 1.80 Meal/day of ME and during the 1979-1980 winter, they required 1.73 Meal/day of ME. The literature also revealed that a wintering deer required 12.9 g of N per day. Quantitative forage analysis showed that depending upon study area and pasture on a kg/ha basis the predominant grasses available to cattle were crested wheatgrass, Sandberg's bluegrass and cheatgrass. Determination of available browse biomass was made employing a multiple linear regression model for mountain big sagebrush (log y = -6.37 + .9337 log H + 1.49 log W₂), and a simple linear regression model for gray rabbitbrush (log y = -3.70 + 1.81 log W) and basin big sagebrush (log y = -3.84 + .9870 log A). Depending upon study area and plant community, quantitative analysis of the forage showed that big sagebrush and Sandberg's bluegrass were the dominant species available to deer. Early spring grazed pastures could carry more AUMS on a nutritional basis than on a quantitative basis. Pastures sampled in late spring showed that total AUMS on a forage quantity basis exceeded those on a nutritional basis. During the fall on an old-growth (i.e., previous year's growth) and fall growth basis, total AUMS based on N generally exceeded those based on ME or forage quantity, except in the crested wheatgrass-dominated pasture where more AUMS were calculated on a quantity basis than on a nutritional basis. On a fall-growth-only basis, more AUMS were calculated on a nutritional basis than on a quantity basis. Generally, the least number of AUMS could be carried on the medusahead communities while the most AUMS could be carried on the crested wheatgrass seedings. Deer months calculated for the two winters across the three study areas showed more deer months per plant community were calculated on a forage quantity basis than on an ME or N basis. However, an exception to this trend occurred in the grassland com munities where more deer months were calculated on an N basis than on an ME or forage quantity basis. Generally, the most deer months were calculated for the basin big sagebrush communities while the least number of deer months were calculated on the medusahead communities. Close

• 1593. [Article] Investigation of the structural influence on the properties of functional inorganic oxides

  While properties are extremely important from an application point of view, it is crucial to have a detailed understanding of the underlying structural influence. Once a concrete correlation between the ...

  Citation × Citation Citation Abstract Copy Title: Investigation of the structural influence on the properties of functional inorganic oxides Author: Laurita-Plankis, Geneva While properties are extremely important from an application point of view, it is crucial to have a detailed understanding of the underlying structural influence. Once a concrete correlation between the structure and the observed property is established, rational design of novel materials with optimized properties can be realized. These optimized materials lead to advancements in technology in a variety of applications, including new building materials, faster electronic devices, and more efficient catalysts. This dissertation examines the structural influence on the observed properties in a series of metal oxide materials for electronic and energy applications. A series of pyrochlores Ag[subscript 1-nx]M[superscript n][subscript x]SbO₃ (M = Na⁺, K⁺, Tl⁺, and Cd²⁺) has been studied to evaluate the structural influence on the samples' photocatalytic activity. A complete solid solution between the anion-deficient pyrochlore Ag₂Sb₂O₆ and the ideal pyrochlore Cd₂Sb₂O₇ has been synthesized through the standard solid state ceramic method. Each composition has been characterized by various different techniques, including powder X-ray diffraction, optical spectroscopy, electron paramagnetic resonance and ¹²¹Sb Mössbauer spectroscopy. Computational methods based on density functional theory complement this investigation. Photocatalytic activity has been studied, and transport properties have been measured on pellets densified by spark plasma sintering. The analysis of the data collected from these various techniques enables a comprehensive characterization of the complete solid solution and revealed an anomalous behavior in the Cd-rich end of the solid solution, which has been proposed to arise from a possible radical O⁻ species in small concentrations. Polycrystalline samples of the pyrochlore series Ag[subscript 1-nx]M[superscript n][subscript x]SbO₃ (M = Na⁺, K⁺ and Tl[superscript +/3+]) have been structurally analyzed through total scattering techniques and evaluated for photocatalytic activity. The upper limits of x obtained are 0.08 for Na, 0.16 for K, and 0.17 for Tl. The Ag⁺ cation occupies a site with inversion symmetry on a 3-fold axis. When the smaller Na⁺ cation substitutes for Ag⁺, it is displaced by about 0.6 Å perpendicular to the 3-fold axis to achieve shorter Na-O bond distances. When the larger Tl⁺ cation substitutes for Ag⁺, it is displaced by about 1.14 Å along the 3-fold axis and achieves an environment typical of a lone pair cation. Some of the Tl³⁺ from the precursor remains unreduced, leading to a formula of Ag₀.₇₇Tl⁺₀.₁₃Tl³⁺₀.₀₄SbO₃.₀₄. The position of the K⁺ dopant was effectively modeled assuming that K⁺ occupied the same site as Ag⁺. The expansion of the lattice caused by substitution of the larger K⁺ and Tl⁺ cations results in longer Ag-O bond lengths, which would reduce the overlap of the Ag 4d and O 2p orbitals that compose the valence band maximum. Substitution of the smaller Na⁺ results in a decrease in the Ag-O bond distance, thus increasing the overlap of the Ag 4d and O 2p orbitals. An increase in the photocatalytic activity has been observed for the nominal composition Ag₀.₈Na₀.₂SbO₃ made through solid state synthesis, and this is attributed to both the slight decrease in the band gap and the increase in pore dimensions compared to the parent compound AgSbO₃. The structural transitions in Cd₂Nb₂O[subscript 7-x]S[subscript x] (x = 0, 0.25, 0.5, and 0.7) have been studied to determine the origin of ferroelectricity in pyrochlore oxides. For x = 0, 0.25, and 0.5 peak splitting indicative of a transition to orthorhombic symmetry is observed below the transition temperature. In the x = 0.7 sample, the evolution of new peaks suggest a cubic space group is retained below the phase transition accompanied by a loss of the face-centering symmetry. The observed lowering of symmetry may be responsible for the transition into a ferroelectric phase, and may be driven by a strong displacement of both the Nb and Cd from the high- to low-symmetry structures. The S content may drive the stability if different ferroelectric phases, as no trend was observed with increasing content in the ferroelectric Curie temperatures of the samples. The structure of the hollandites A[subscript x]Ru₄O₈ (A = K⁺, Rb⁺) has been studied through total scattering techniques upon cation exchange with Na⁺ on the A-site to evaluate the effect on the quasi-one dimensional (Q1D) nature of these materials. It is observed that the A-site of the hollandite structure is not fully occupied when A = K⁺, Rb⁺, and full A-site occupancy is achieved after ion exchange with NaNO₃. All samples exhibit Pauli paramagnetism, and this is primarily due to a large low temperature range of metallic conduction. The double chains of edge-shared RuO₆ octahedra and corner shared double chains found in the channel of the hollandite structure promotes two conduction mechanisms: ρ∥ (intra-chain metallic) and ρ⊥ (inter-chain hopping). The coexistence of ρ∥ and ρ⊥ gives rise to metallic conductivity below T[subscript max] (suppressed hopping at lower temperature) and semiconductivity above T[subscript max] (intra-chain mean free path becomes smaller than the inter-chain hopping distance), exhibiting the Q1D conduction at lower temperatures. The inter-chain distance is larger in the Rb-containing samples, and consequently the region dominated by intra-chain metallic conduction increases, along with an increase in T[subscript max]. Title: Investigation of the structural influence on the properties of functional inorganic oxides Author: Laurita-Plankis, Geneva While properties are extremely important from an application point of view, it is crucial to have a detailed understanding of the underlying structural influence. Once a concrete correlation between the structure and the observed property is established, rational design of novel materials with optimized properties can be realized. These optimized materials lead to advancements in technology in a variety of applications, including new building materials, faster electronic devices, and more efficient catalysts. This dissertation examines the structural influence on the observed properties in a series of metal oxide materials for electronic and energy applications. A series of pyrochlores Ag[subscript 1-nx]M[superscript n][subscript x]SbO₃ (M = Na⁺, K⁺, Tl⁺, and Cd²⁺) has been studied to evaluate the structural influence on the samples' photocatalytic activity. A complete solid solution between the anion-deficient pyrochlore Ag₂Sb₂O₆ and the ideal pyrochlore Cd₂Sb₂O₇ has been synthesized through the standard solid state ceramic method. Each composition has been characterized by various different techniques, including powder X-ray diffraction, optical spectroscopy, electron paramagnetic resonance and ¹²¹Sb Mössbauer spectroscopy. Computational methods based on density functional theory complement this investigation. Photocatalytic activity has been studied, and transport properties have been measured on pellets densified by spark plasma sintering. The analysis of the data collected from these various techniques enables a comprehensive characterization of the complete solid solution and revealed an anomalous behavior in the Cd-rich end of the solid solution, which has been proposed to arise from a possible radical O⁻ species in small concentrations. Polycrystalline samples of the pyrochlore series Ag[subscript 1-nx]M[superscript n][subscript x]SbO₃ (M = Na⁺, K⁺ and Tl[superscript +/3+]) have been structurally analyzed through total scattering techniques and evaluated for photocatalytic activity. The upper limits of x obtained are 0.08 for Na, 0.16 for K, and 0.17 for Tl. The Ag⁺ cation occupies a site with inversion symmetry on a 3-fold axis. When the smaller Na⁺ cation substitutes for Ag⁺, it is displaced by about 0.6 Å perpendicular to the 3-fold axis to achieve shorter Na-O bond distances. When the larger Tl⁺ cation substitutes for Ag⁺, it is displaced by about 1.14 Å along the 3-fold axis and achieves an environment typical of a lone pair cation. Some of the Tl³⁺ from the precursor remains unreduced, leading to a formula of Ag₀.₇₇Tl⁺₀.₁₃Tl³⁺₀.₀₄SbO₃.₀₄. The position of the K⁺ dopant was effectively modeled assuming that K⁺ occupied the same site as Ag⁺. The expansion of the lattice caused by substitution of the larger K⁺ and Tl⁺ cations results in longer Ag-O bond lengths, which would reduce the overlap of the Ag 4d and O 2p orbitals that compose the valence band maximum. Substitution of the smaller Na⁺ results in a decrease in the Ag-O bond distance, thus increasing the overlap of the Ag 4d and O 2p orbitals. An increase in the photocatalytic activity has been observed for the nominal composition Ag₀.₈Na₀.₂SbO₃ made through solid state synthesis, and this is attributed to both the slight decrease in the band gap and the increase in pore dimensions compared to the parent compound AgSbO₃. The structural transitions in Cd₂Nb₂O[subscript 7-x]S[subscript x] (x = 0, 0.25, 0.5, and 0.7) have been studied to determine the origin of ferroelectricity in pyrochlore oxides. For x = 0, 0.25, and 0.5 peak splitting indicative of a transition to orthorhombic symmetry is observed below the transition temperature. In the x = 0.7 sample, the evolution of new peaks suggest a cubic space group is retained below the phase transition accompanied by a loss of the face-centering symmetry. The observed lowering of symmetry may be responsible for the transition into a ferroelectric phase, and may be driven by a strong displacement of both the Nb and Cd from the high- to low-symmetry structures. The S content may drive the stability if different ferroelectric phases, as no trend was observed with increasing content in the ferroelectric Curie temperatures of the samples. The structure of the hollandites A[subscript x]Ru₄O₈ (A = K⁺, Rb⁺) has been studied through total scattering techniques upon cation exchange with Na⁺ on the A-site to evaluate the effect on the quasi-one dimensional (Q1D) nature of these materials. It is observed that the A-site of the hollandite structure is not fully occupied when A = K⁺, Rb⁺, and full A-site occupancy is achieved after ion exchange with NaNO₃. All samples exhibit Pauli paramagnetism, and this is primarily due to a large low temperature range of metallic conduction. The double chains of edge-shared RuO₆ octahedra and corner shared double chains found in the channel of the hollandite structure promotes two conduction mechanisms: ρ∥ (intra-chain metallic) and ρ⊥ (inter-chain hopping). The coexistence of ρ∥ and ρ⊥ gives rise to metallic conductivity below T[subscript max] (suppressed hopping at lower temperature) and semiconductivity above T[subscript max] (intra-chain mean free path becomes smaller than the inter-chain hopping distance), exhibiting the Q1D conduction at lower temperatures. The inter-chain distance is larger in the Rb-containing samples, and consequently the region dominated by intra-chain metallic conduction increases, along with an increase in T[subscript max]. Close

• 1594. [Article] Comparative wintering ecology of two subspecies of sandhill crane : informing conservation planning in the Sacramento-San Joaquin River Delta region of California

  California's Central Valley agricultural landscapes provide several important wintering regions for Pacific Flyway sandhill crane (Grus canadensis) populations; however, the value of those regions is being ...

  Citation × Citation Citation Abstract Copy Title: Comparative wintering ecology of two subspecies of sandhill crane : informing conservation planning in the Sacramento-San Joaquin River Delta region of California Author: Ivey, Gary L. California's Central Valley agricultural landscapes provide several important wintering regions for Pacific Flyway sandhill crane (Grus canadensis) populations; however, the value of those regions is being compromised by urban expansion, other developments, and conversions to incompatible crop types. Greater (G. c. tabida) and lesser sandhill cranes (G. c. canadensis) both have special conservation status in California; the greater is listed as threatened and the lesser as a bird species of conservation concern by the state. However, basic information about their wintering ecology has been lacking to design biologically sound conservation strategies to maintain their wintering habitats. My study of sandhill cranes focused on one major Central Valley wintering region, the Sacramento-San Joaquin River Delta (Delta). I compared daily movements and winter site fidelity between the two sandhill crane subspecies, evaluated the timing of crane arrival and departure from the region, assessed foraging habitat choices, measured abundance and distribution in the Delta, documented the characteristics of roost sites, and developed habitat conservation models and decision tools for managers to facilitate habitat conservation and management. Both crane subspecies showed strong fidelity to my Delta study area. Foraging flights from roost sites were shorter for greaters than lesser (1.2 ± 0.4 km vs. 3.1 ± 0.1 km, respectively) and consequently, mean size of 95% fixed kernel winter home ranges was an order of magnitude smaller for greaters (1.9 ± 0.4 km² vs.21.9 ± 1.9 km², respectively). The strong site fidelity of greaters to roost complexes within landscapes in the Delta indicates that conservation planning targeted at maintaining and managing for adequate food resources around traditional roost sites can be effective for meeting sandhill crane habitat needs, while the scale of conservation differs by subspecies. I recommend that conservation planning actions consider all habitats within 5 km of a crane roost as a sandhill crane conservation "ecosystem unit." This radius encompasses 95% and 69% of the flights from roosts to foraging location (commuting flights) made by greaters and lessers, respectively. For lessers, a conservation radius of 10 km would encompass 90% of the commuting flights. Management, mitigation, acquisition, easement, planning, and farm subsidy programs intended to benefit cranes will be most effective when applied at these scales. Within these radii, conservation and management of wintering habitats should include creating both new roost and feeding areas to ensure high chances of successful use. Sandhill cranes used major crops and habitat types available in the landscapes surrounding their roost sites and focused most of their foraging in grain crops. They generally avoided dry corn stubble, selected dry rice stubble early in the season, and rarely used dry wild rice stubble. Tilled fields were also usually avoided but were occasionally used shortly after tillage. Mulched corn ranked high in comparison to other corn treatments while mulched rice use was used similarly to dry rice stubble. Both subspecies often highly favored cropland habitats when they were initially flooded. Cranes were attracted to new plantings of pasture and winter wheat. One important difference between the subspecies was that lessers used alfalfa which was generally avoided by greaters. Dry corn stubble was avoided while dry rice stubble was favored early in winter. If wildlife managers want to encourage winter field use by cranes they could provide incentives for favorable practices such as production of grain crops, reduction or delaying tillage and flooding of grain fields, provision of irrigations to some crop types, and increasing the practice of mulching of corn stubble. Of the 69 crane night roosts I identified, 35 were flooded cropland sites and 34 were wetland sites. I found that both larger individual roost sites and larger complexes of roost sites supported larger peak numbers of cranes. Water depth used by roosting cranes averaged 10 cm (range 3-21 cm, mode 7 cm) and was similar between subspecies. Roosting cranes avoided sites that were regularly hunted or had high densities (i.e., > 1 blind/5 ha) of hunting blinds. Roost site design and management should consider providing and maintaining large roost complexes (100 - 1000 ha) ideally in close proximity (< 5 km) to other roost sites, with large individual sites (> 5 ha) of mostly level topography, dominated by shallow water (5-10 cm depths). The fact that cranes readily use undisturbed flooded cropland sites makes this a viable option for creation of roost habitat. Because hunting disturbance can limit crane use of roost sites I suggest these two uses should not be considered compatible. However, if the management objective of an area includes waterfowl hunting, limiting hunting at low blind densities (i.e., < 1 blind/60 ha) and restricting hunting to early morning may be viable options for creating a crane-compatible waterfowl hunt program. Radio-marked sandhill cranes arrived in the Delta beginning 3 October, most arrived in mid-October, and the last radio-marked sandhill crane arrived on 10 December. Departure dates ranged from 15 January to 13 March. Mean arrival and departure dates were similar between subspecies. From mid-December through early-February in 2007-2008, the Delta population ranged from 20,000 to 27,000 sandhill cranes. Abundance varied at the main roost sites during winter, likely because sandhill cranes responded to changes in water and foraging habitat conditions. Sandhill cranes used an area of approximately 1,500 km² for foraging. Estimated peak abundance in the Delta was more than half the total number counted on recent Pacific Flyway midwinter surveys, indicating the Delta region is a key area for efforts in conservation and recovery of wintering sandhill cranes in California. Based on arrival dates, flooding of sandhill crane roost sites should be staggered with some sites flooded in early September and most sites flooded by early October. Maintaining flooding of at least some roost sites through mid-March would provide essential roosting habitat until most birds have departed the Delta region on spring migration. Not all 5-km radius ecosystem units are equal in their value to greater sandhill cranes, and the relative foraging value of a particular parcel within an ecosystem unit depends on the numbers of cranes using the focal roost site, the habitat choices they make, and the probability that they will fly to a particular parcel. Additionally, some ecosystem units overlap, and in these overlap zones, the probability of crane use is higher, because of additive effects. To provide a tool to allow managers to further refine management plans, I developed a model which allows more specific focus of crane conservation, mitigation and habitat management, using what my study revealed about greater sandhill cranes. This model considers the abundance of greaters at individual roost sites and the probability that they would fly to a given location. Sites closer to roosts had a higher probability of crane use. I calculated the probability that greaters would fly to a parcel within concentric 1-km intervals as a product of the proportion of commuting flights of individuals that reached that interval, and the proportion of all commuting flights that reached that interval. Within crane ecosystem units, it is important to protect the existing habitat from further loss and optimize foraging conditions for cranes. I provide a decision matrix to assist with plans to enhance existing crane landscapes, create new crane habitat areas or mitigate habitat losses. This matrix provides a framework for decision-making regarding enhancing sandhill crane foraging and roost site habitats. Wildlife managers could employ a variety of tools to conserve and manage crane habitats, including fee title acquisitions, private conservation easements, and specific cropland management actions to maintain crane-compatible conditions and high food values for cranes (possibly including providing unharvested food plots). My study has demonstrated that most cranes use a relatively small landscape surrounding their traditional roost sites and that they favor certain crops and post-harvest crop management practices for foraging. However, we need a better understanding of the actual carrying capacity for cranes in these crane management zones to ensure that managers can maintain these sites for cranes in the future. Title: Comparative wintering ecology of two subspecies of sandhill crane : informing conservation planning in the Sacramento-San Joaquin River Delta region of California Author: Ivey, Gary L. California's Central Valley agricultural landscapes provide several important wintering regions for Pacific Flyway sandhill crane (Grus canadensis) populations; however, the value of those regions is being compromised by urban expansion, other developments, and conversions to incompatible crop types. Greater (G. c. tabida) and lesser sandhill cranes (G. c. canadensis) both have special conservation status in California; the greater is listed as threatened and the lesser as a bird species of conservation concern by the state. However, basic information about their wintering ecology has been lacking to design biologically sound conservation strategies to maintain their wintering habitats. My study of sandhill cranes focused on one major Central Valley wintering region, the Sacramento-San Joaquin River Delta (Delta). I compared daily movements and winter site fidelity between the two sandhill crane subspecies, evaluated the timing of crane arrival and departure from the region, assessed foraging habitat choices, measured abundance and distribution in the Delta, documented the characteristics of roost sites, and developed habitat conservation models and decision tools for managers to facilitate habitat conservation and management. Both crane subspecies showed strong fidelity to my Delta study area. Foraging flights from roost sites were shorter for greaters than lesser (1.2 ± 0.4 km vs. 3.1 ± 0.1 km, respectively) and consequently, mean size of 95% fixed kernel winter home ranges was an order of magnitude smaller for greaters (1.9 ± 0.4 km² vs.21.9 ± 1.9 km², respectively). The strong site fidelity of greaters to roost complexes within landscapes in the Delta indicates that conservation planning targeted at maintaining and managing for adequate food resources around traditional roost sites can be effective for meeting sandhill crane habitat needs, while the scale of conservation differs by subspecies. I recommend that conservation planning actions consider all habitats within 5 km of a crane roost as a sandhill crane conservation "ecosystem unit." This radius encompasses 95% and 69% of the flights from roosts to foraging location (commuting flights) made by greaters and lessers, respectively. For lessers, a conservation radius of 10 km would encompass 90% of the commuting flights. Management, mitigation, acquisition, easement, planning, and farm subsidy programs intended to benefit cranes will be most effective when applied at these scales. Within these radii, conservation and management of wintering habitats should include creating both new roost and feeding areas to ensure high chances of successful use. Sandhill cranes used major crops and habitat types available in the landscapes surrounding their roost sites and focused most of their foraging in grain crops. They generally avoided dry corn stubble, selected dry rice stubble early in the season, and rarely used dry wild rice stubble. Tilled fields were also usually avoided but were occasionally used shortly after tillage. Mulched corn ranked high in comparison to other corn treatments while mulched rice use was used similarly to dry rice stubble. Both subspecies often highly favored cropland habitats when they were initially flooded. Cranes were attracted to new plantings of pasture and winter wheat. One important difference between the subspecies was that lessers used alfalfa which was generally avoided by greaters. Dry corn stubble was avoided while dry rice stubble was favored early in winter. If wildlife managers want to encourage winter field use by cranes they could provide incentives for favorable practices such as production of grain crops, reduction or delaying tillage and flooding of grain fields, provision of irrigations to some crop types, and increasing the practice of mulching of corn stubble. Of the 69 crane night roosts I identified, 35 were flooded cropland sites and 34 were wetland sites. I found that both larger individual roost sites and larger complexes of roost sites supported larger peak numbers of cranes. Water depth used by roosting cranes averaged 10 cm (range 3-21 cm, mode 7 cm) and was similar between subspecies. Roosting cranes avoided sites that were regularly hunted or had high densities (i.e., > 1 blind/5 ha) of hunting blinds. Roost site design and management should consider providing and maintaining large roost complexes (100 - 1000 ha) ideally in close proximity (< 5 km) to other roost sites, with large individual sites (> 5 ha) of mostly level topography, dominated by shallow water (5-10 cm depths). The fact that cranes readily use undisturbed flooded cropland sites makes this a viable option for creation of roost habitat. Because hunting disturbance can limit crane use of roost sites I suggest these two uses should not be considered compatible. However, if the management objective of an area includes waterfowl hunting, limiting hunting at low blind densities (i.e., < 1 blind/60 ha) and restricting hunting to early morning may be viable options for creating a crane-compatible waterfowl hunt program. Radio-marked sandhill cranes arrived in the Delta beginning 3 October, most arrived in mid-October, and the last radio-marked sandhill crane arrived on 10 December. Departure dates ranged from 15 January to 13 March. Mean arrival and departure dates were similar between subspecies. From mid-December through early-February in 2007-2008, the Delta population ranged from 20,000 to 27,000 sandhill cranes. Abundance varied at the main roost sites during winter, likely because sandhill cranes responded to changes in water and foraging habitat conditions. Sandhill cranes used an area of approximately 1,500 km² for foraging. Estimated peak abundance in the Delta was more than half the total number counted on recent Pacific Flyway midwinter surveys, indicating the Delta region is a key area for efforts in conservation and recovery of wintering sandhill cranes in California. Based on arrival dates, flooding of sandhill crane roost sites should be staggered with some sites flooded in early September and most sites flooded by early October. Maintaining flooding of at least some roost sites through mid-March would provide essential roosting habitat until most birds have departed the Delta region on spring migration. Not all 5-km radius ecosystem units are equal in their value to greater sandhill cranes, and the relative foraging value of a particular parcel within an ecosystem unit depends on the numbers of cranes using the focal roost site, the habitat choices they make, and the probability that they will fly to a particular parcel. Additionally, some ecosystem units overlap, and in these overlap zones, the probability of crane use is higher, because of additive effects. To provide a tool to allow managers to further refine management plans, I developed a model which allows more specific focus of crane conservation, mitigation and habitat management, using what my study revealed about greater sandhill cranes. This model considers the abundance of greaters at individual roost sites and the probability that they would fly to a given location. Sites closer to roosts had a higher probability of crane use. I calculated the probability that greaters would fly to a parcel within concentric 1-km intervals as a product of the proportion of commuting flights of individuals that reached that interval, and the proportion of all commuting flights that reached that interval. Within crane ecosystem units, it is important to protect the existing habitat from further loss and optimize foraging conditions for cranes. I provide a decision matrix to assist with plans to enhance existing crane landscapes, create new crane habitat areas or mitigate habitat losses. This matrix provides a framework for decision-making regarding enhancing sandhill crane foraging and roost site habitats. Wildlife managers could employ a variety of tools to conserve and manage crane habitats, including fee title acquisitions, private conservation easements, and specific cropland management actions to maintain crane-compatible conditions and high food values for cranes (possibly including providing unharvested food plots). My study has demonstrated that most cranes use a relatively small landscape surrounding their traditional roost sites and that they favor certain crops and post-harvest crop management practices for foraging. However, we need a better understanding of the actual carrying capacity for cranes in these crane management zones to ensure that managers can maintain these sites for cranes in the future. Close

• 1595. [Article] Distribution and movements of Chinook salmon, Oncorhynchus tshawytscha, returning to the Yukon River basin

  Chinook salmon, Oncorhynchus tshawytscha, returning to the Yukon River basin and other large river systems in western Alaska have declined dramatically since the late 1990s. This continuing trend has ...

  Citation × Citation Citation Abstract Copy Title: Distribution and movements of Chinook salmon, Oncorhynchus tshawytscha, returning to the Yukon River basin Author: Eiler, John H. Chinook salmon, Oncorhynchus tshawytscha, returning to the Yukon River basin and other large river systems in western Alaska have declined dramatically since the late 1990s. This continuing trend has raised concerns over the future status of the returns, and severely impacted commercial and subsistence fisheries within the drainage. Management is further complicated by the mixed-stock composition of the run, the presence of other temporally similar salmon species, and the need to equitably allocate harvests between the numerous fisheries and user groups scattered throughout the basin. Detailed information is needed on Chinook salmon run characteristics to better understand and manage the returns, and facilitate conservation efforts. However, this goal is exacerbated by the massive size and remote nature of the basin, the large number of highly mobile fish, and the compressed timing of the run. To address these challenges, radio telemetry was used to determine the stock composition and spawning distribution of the returns, and the migratory characteristics of the fish. The migratory patterns exhibited by returning salmon provide a number of insights into the status of the run. Since the Yukon River is essentially free-flowing (i.e., not regulated), this study also presented an opportunity to document the distribution and upriver movements of large returns of wild Chinook salmon under natural conditions. During 2002-2004, returning adult Chinook salmon were captured in the lower Yukon River (approximately 300 km upriver from the river mouth), tagged with radio transmitters, and tracked upriver using remote tracking stations located on important migratory routes and major spawning tributaries. Aerial tracking surveys were used to locate fish in spawning areas and between stations. The fish responded well to the capture and handling procedures, with most (2,790, 98%) resuming upriver movements. Although the fish initially displayed a negative tagging response, with slower migration rates observed immediately after release, the duration of this response was relatively short (several days) and less severe as the fish moved upriver. Independent measures indicated that the swimming speeds and timing of the fish upriver from the tagging area were comparable to untagged fish, suggesting that the tagging methods used were relatively benign. Fish returned to spawning areas throughout the basin, ranging from several hundred to over 3,000 km from the tagging area. Distribution patterns were similar across years, suggesting that the principal components of the run were identified. Most spawning fish were clustered in a number of key tributaries, with smaller numbers of fish located in other spatially isolated areas. The fish typically returned to clear water tributaries that were relatively entrenched, had moderate gradients, and were associated with upland areas. Fish were largely absent in lowland reaches characterized by meandering, low gradient, highly alluvial channels often associated with main river floodplains. There was suggestive evidence of mainstem spawning in reaches of the Upper Yukon. The status of fish remaining in other mainstem areas was less certain, and may represent local spawning activity or fish that died while in-transit to upriver areas. Although Chinook salmon spawned throughout the basin, the run was dominated by two regional components (Tanana and Upper Yukon), which annually comprised over 70% of the return. Substantially fewer fish returned to other areas ranging from 2-9% of the return, although the collective contribution of these stocks was appreciable. Most regional returns consisted of several principal stocks and a number of small, spatially isolated populations. Regional and stock composition estimates were similar across years even though differences in run abundance were reported, suggesting that these abundance differences were not related to regional or stock-specific differences. Run timing was relatively compressed compared to rivers in the southern portion of the range, with most stocks passing through the lower river over a 6-week period, ranging from 16 to 38 d. Run timing was generally earlier for stocks traveling farther upriver, although exceptions were noted. Lower basin stocks were primarily later run fish. Pronounced differences were observed in the migration rates (km/d) exhibited by regional stocks. Substantially slower swimming speeds were observed for fish returning to terminal tributaries in the lower basin ranging from 28-40 km/d compared to 52-62 km/d for upper basin stocks. The migratory patterns (migration rates in sequential reaches) of the fish also showed distinct regional differences. Average migration rates through the lower river were remarkably similar for the different stocks, ranging from 57-62 km/d, with most stocks exhibiting a general decline as the fish moved farther upriver. Tanana River stocks displayed a pronounced reduction in swimming speed after leaving the Yukon River main stem, with migration rates declining to 24 km/d on average as the fish approached their terminal tributaries. Conversely, upper basin stocks exhibited a relatively gradual (but variable) overall decline in migration rate even though these fish were traveling substantially greater distances upriver. Average migration rates for upper basin stocks ranged from 43-61 km/d as the fish approached their terminal tributaries. There was substantial variation in the migratory patterns exhibited by individual fish, although these patterns tended to be similar to the patterns exhibited by the regional stocks, particularly as the fish moved farther upriver from the tagging area. The dominant source of variation among fish reflected the average migration rate, with individual fish traveling slower in the lower basin exhibiting consistently slower migration rates as they moved upriver compared to their faster moving counterparts. This migratory pattern was consistent across stocks, and on average explained 74% of the within-stock variation in migration rate represented by the multivariate data. The second source of variation in migration rate reflected a shift in the relative swimming speeds of the individual fish as they progressed upriver. Although movement rates declined for nearly all of the fish during the migration, differences were observed in the pattern of the decline. Fish with faster migration rates in the lower river exhibited a pronounced decline in swimming speed as they moved upriver, whereas fish moving slower in the lower river displayed a more gradual decline in migration rate. On average, this migratory pattern explained 22% of the within-stock variation in migration rate represented by the multivariate data. Most fish (98%) exhibited continuous upriver movements and strong fidelity to the rivers they entered. However a small number of fish (n = 66) deviated from this pattern. Some of these individuals initially passed their final destination and continued upriver for varying distances before reversing direction, swimming back downstream, and entering their terminal tributary. Although most of these excursions were relatively short (< 30 km), there were several instances where fish traveled hundreds of kilometers out of their way. Thirty-four fish tracked to terminal tributaries subsequently left these rivers, and traveled to other terminal tributaries within the basin (n = 31) or were harvested in upriver fisheries (n = 3). Although most of these incidents involved nearby tributaries, major diversions were also observed, with several fish traveling over 300 km to natal rivers after leaving the initial tributary. Chinook salmon returns to the Yukon River typically consisted of a series of distinct and sizable increases in the number fish entering the river over the course of the run, commonly referred to as pulses. A large number of fish (n = 251) were radio tagged over a 4-day period during a pulse in 2003 to provide information on the progression of the pulse as it moved upriver. The time taken by the pulse to move past subsequent upriver locations increased as the fish moved farther upriver from the tagging area, with the fish passing sites located 580 and 800 km upriver over a span of 14 and 21 d, respectively. Although not surprising considering the extensive variation in migration rates observed among individual fish, this finding does suggest that these pulses do not represent cohesive aggregates of fish moving upriver. Unlike the well established methods used to estimate other life history characteristics, the development of quantitative methods for analyzing and modeling fish movements has lagged noticeably behind, due in part to the complexity associated with movement data and (prior to the advent of telemetry) the difficulty of collecting this type of information on free-ranging individuals. Two fundamentally different analytical approaches, hierarchical linear regression models and multivariate ordination, were used during this study to evaluate factors thought to influence the upriver movements of the fish. In spite of the inherent differences, both methods provided strikingly similar results, indicating that the study findings were not dependent on the approach used, and suggesting that the results were plausible based on the information available and the weight of evidence. Both analytical methods had advantages, and provided complementary information. With hierarchical linear models, it was possible to simultaneously evaluate a wide range of explanatory variables (in our case, both biological and environmental), which provided standardized comparisons and simplified the interpretation of the results. Since both fixed and random effects were incorporated in the models, it was possible to account for sources of variation when insufficient information was available to identify the underlining factors – an important consideration since few field studies provide comprehensive data. With multivariate ordination, separate analyzes were needed to examine the relationships between the migration rates and the biotic and physical variables. In addition to being cumbersome, this limitation made it more difficult to compare the relative influence of the different factors and interactions between factors. However, ordination was very useful as an exploratory tool. Although compartmentalized by stock, across fish comparisons were simple and relatively straightforward. Because the explanatory variables were evaluated separately in relation to the ordination score assigned to the fish, it was possible to examine and compare highly correlated variables. Ordination was also able to identify overall patterns within the data and assess the relative importance. While this can be accomplished within the framework of linear regression using mixture models to determine whether multiple distributions exist within the data, the process is much simpler with ordination. The migratory patterns of the fish were influenced by a wide range of factors, with evidentiary support for complex, multi-faceted relationships. Physical features of the basin demonstrated stronger explanatory power, accounting for over 70% of the observed variation in migration rate compared to 18% for the biological characteristics of the fish. Parameter estimates associated with the steepness of the migratory route and remaining distance the fish had to travel to reach their natal rivers were most strongly correlated with migration rate, with consistent relationships observed across stocks. Migration rates were also noticeably slower in extensively braided reaches of the basin. The weaker relationships between migration rate and biotic factors may reflect stabilizing selection on long-distance migrants. Smaller fish exhibited minimally faster swimming speeds on average than larger individuals. This relationship was stronger in highly braided reaches. Run timing was positively related to migration rate for most stocks. Surprisingly, upper basin stocks traveling farther upriver displayed progressively negative relationships, suggesting that late-run fish were moving slower. Ancillary information suggests that this decline may relate to deteriorating fish condition later in the season. Title: Distribution and movements of Chinook salmon, Oncorhynchus tshawytscha, returning to the Yukon River basin Author: Eiler, John H. Chinook salmon, Oncorhynchus tshawytscha, returning to the Yukon River basin and other large river systems in western Alaska have declined dramatically since the late 1990s. This continuing trend has raised concerns over the future status of the returns, and severely impacted commercial and subsistence fisheries within the drainage. Management is further complicated by the mixed-stock composition of the run, the presence of other temporally similar salmon species, and the need to equitably allocate harvests between the numerous fisheries and user groups scattered throughout the basin. Detailed information is needed on Chinook salmon run characteristics to better understand and manage the returns, and facilitate conservation efforts. However, this goal is exacerbated by the massive size and remote nature of the basin, the large number of highly mobile fish, and the compressed timing of the run. To address these challenges, radio telemetry was used to determine the stock composition and spawning distribution of the returns, and the migratory characteristics of the fish. The migratory patterns exhibited by returning salmon provide a number of insights into the status of the run. Since the Yukon River is essentially free-flowing (i.e., not regulated), this study also presented an opportunity to document the distribution and upriver movements of large returns of wild Chinook salmon under natural conditions. During 2002-2004, returning adult Chinook salmon were captured in the lower Yukon River (approximately 300 km upriver from the river mouth), tagged with radio transmitters, and tracked upriver using remote tracking stations located on important migratory routes and major spawning tributaries. Aerial tracking surveys were used to locate fish in spawning areas and between stations. The fish responded well to the capture and handling procedures, with most (2,790, 98%) resuming upriver movements. Although the fish initially displayed a negative tagging response, with slower migration rates observed immediately after release, the duration of this response was relatively short (several days) and less severe as the fish moved upriver. Independent measures indicated that the swimming speeds and timing of the fish upriver from the tagging area were comparable to untagged fish, suggesting that the tagging methods used were relatively benign. Fish returned to spawning areas throughout the basin, ranging from several hundred to over 3,000 km from the tagging area. Distribution patterns were similar across years, suggesting that the principal components of the run were identified. Most spawning fish were clustered in a number of key tributaries, with smaller numbers of fish located in other spatially isolated areas. The fish typically returned to clear water tributaries that were relatively entrenched, had moderate gradients, and were associated with upland areas. Fish were largely absent in lowland reaches characterized by meandering, low gradient, highly alluvial channels often associated with main river floodplains. There was suggestive evidence of mainstem spawning in reaches of the Upper Yukon. The status of fish remaining in other mainstem areas was less certain, and may represent local spawning activity or fish that died while in-transit to upriver areas. Although Chinook salmon spawned throughout the basin, the run was dominated by two regional components (Tanana and Upper Yukon), which annually comprised over 70% of the return. Substantially fewer fish returned to other areas ranging from 2-9% of the return, although the collective contribution of these stocks was appreciable. Most regional returns consisted of several principal stocks and a number of small, spatially isolated populations. Regional and stock composition estimates were similar across years even though differences in run abundance were reported, suggesting that these abundance differences were not related to regional or stock-specific differences. Run timing was relatively compressed compared to rivers in the southern portion of the range, with most stocks passing through the lower river over a 6-week period, ranging from 16 to 38 d. Run timing was generally earlier for stocks traveling farther upriver, although exceptions were noted. Lower basin stocks were primarily later run fish. Pronounced differences were observed in the migration rates (km/d) exhibited by regional stocks. Substantially slower swimming speeds were observed for fish returning to terminal tributaries in the lower basin ranging from 28-40 km/d compared to 52-62 km/d for upper basin stocks. The migratory patterns (migration rates in sequential reaches) of the fish also showed distinct regional differences. Average migration rates through the lower river were remarkably similar for the different stocks, ranging from 57-62 km/d, with most stocks exhibiting a general decline as the fish moved farther upriver. Tanana River stocks displayed a pronounced reduction in swimming speed after leaving the Yukon River main stem, with migration rates declining to 24 km/d on average as the fish approached their terminal tributaries. Conversely, upper basin stocks exhibited a relatively gradual (but variable) overall decline in migration rate even though these fish were traveling substantially greater distances upriver. Average migration rates for upper basin stocks ranged from 43-61 km/d as the fish approached their terminal tributaries. There was substantial variation in the migratory patterns exhibited by individual fish, although these patterns tended to be similar to the patterns exhibited by the regional stocks, particularly as the fish moved farther upriver from the tagging area. The dominant source of variation among fish reflected the average migration rate, with individual fish traveling slower in the lower basin exhibiting consistently slower migration rates as they moved upriver compared to their faster moving counterparts. This migratory pattern was consistent across stocks, and on average explained 74% of the within-stock variation in migration rate represented by the multivariate data. The second source of variation in migration rate reflected a shift in the relative swimming speeds of the individual fish as they progressed upriver. Although movement rates declined for nearly all of the fish during the migration, differences were observed in the pattern of the decline. Fish with faster migration rates in the lower river exhibited a pronounced decline in swimming speed as they moved upriver, whereas fish moving slower in the lower river displayed a more gradual decline in migration rate. On average, this migratory pattern explained 22% of the within-stock variation in migration rate represented by the multivariate data. Most fish (98%) exhibited continuous upriver movements and strong fidelity to the rivers they entered. However a small number of fish (n = 66) deviated from this pattern. Some of these individuals initially passed their final destination and continued upriver for varying distances before reversing direction, swimming back downstream, and entering their terminal tributary. Although most of these excursions were relatively short (< 30 km), there were several instances where fish traveled hundreds of kilometers out of their way. Thirty-four fish tracked to terminal tributaries subsequently left these rivers, and traveled to other terminal tributaries within the basin (n = 31) or were harvested in upriver fisheries (n = 3). Although most of these incidents involved nearby tributaries, major diversions were also observed, with several fish traveling over 300 km to natal rivers after leaving the initial tributary. Chinook salmon returns to the Yukon River typically consisted of a series of distinct and sizable increases in the number fish entering the river over the course of the run, commonly referred to as pulses. A large number of fish (n = 251) were radio tagged over a 4-day period during a pulse in 2003 to provide information on the progression of the pulse as it moved upriver. The time taken by the pulse to move past subsequent upriver locations increased as the fish moved farther upriver from the tagging area, with the fish passing sites located 580 and 800 km upriver over a span of 14 and 21 d, respectively. Although not surprising considering the extensive variation in migration rates observed among individual fish, this finding does suggest that these pulses do not represent cohesive aggregates of fish moving upriver. Unlike the well established methods used to estimate other life history characteristics, the development of quantitative methods for analyzing and modeling fish movements has lagged noticeably behind, due in part to the complexity associated with movement data and (prior to the advent of telemetry) the difficulty of collecting this type of information on free-ranging individuals. Two fundamentally different analytical approaches, hierarchical linear regression models and multivariate ordination, were used during this study to evaluate factors thought to influence the upriver movements of the fish. In spite of the inherent differences, both methods provided strikingly similar results, indicating that the study findings were not dependent on the approach used, and suggesting that the results were plausible based on the information available and the weight of evidence. Both analytical methods had advantages, and provided complementary information. With hierarchical linear models, it was possible to simultaneously evaluate a wide range of explanatory variables (in our case, both biological and environmental), which provided standardized comparisons and simplified the interpretation of the results. Since both fixed and random effects were incorporated in the models, it was possible to account for sources of variation when insufficient information was available to identify the underlining factors – an important consideration since few field studies provide comprehensive data. With multivariate ordination, separate analyzes were needed to examine the relationships between the migration rates and the biotic and physical variables. In addition to being cumbersome, this limitation made it more difficult to compare the relative influence of the different factors and interactions between factors. However, ordination was very useful as an exploratory tool. Although compartmentalized by stock, across fish comparisons were simple and relatively straightforward. Because the explanatory variables were evaluated separately in relation to the ordination score assigned to the fish, it was possible to examine and compare highly correlated variables. Ordination was also able to identify overall patterns within the data and assess the relative importance. While this can be accomplished within the framework of linear regression using mixture models to determine whether multiple distributions exist within the data, the process is much simpler with ordination. The migratory patterns of the fish were influenced by a wide range of factors, with evidentiary support for complex, multi-faceted relationships. Physical features of the basin demonstrated stronger explanatory power, accounting for over 70% of the observed variation in migration rate compared to 18% for the biological characteristics of the fish. Parameter estimates associated with the steepness of the migratory route and remaining distance the fish had to travel to reach their natal rivers were most strongly correlated with migration rate, with consistent relationships observed across stocks. Migration rates were also noticeably slower in extensively braided reaches of the basin. The weaker relationships between migration rate and biotic factors may reflect stabilizing selection on long-distance migrants. Smaller fish exhibited minimally faster swimming speeds on average than larger individuals. This relationship was stronger in highly braided reaches. Run timing was positively related to migration rate for most stocks. Surprisingly, upper basin stocks traveling farther upriver displayed progressively negative relationships, suggesting that late-run fish were moving slower. Ancillary information suggests that this decline may relate to deteriorating fish condition later in the season. Close