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791. [Article] Hawaiian duck (Anas wyvilliana) behavior and response to wetland habitat management at Hanalei National Wildlife Refuge on Kaua'i
The endangered Hawaiian Duck (koloa maoli; Anas wyvilliana), a non-migratory and island-endemic species, experienced a significant population decline during the twentieth century due to factors such as ...Citation Citation
- Title:
- Hawaiian duck (Anas wyvilliana) behavior and response to wetland habitat management at Hanalei National Wildlife Refuge on Kaua'i
- Author:
- Malachowski, Christopher P.
The endangered Hawaiian Duck (koloa maoli; Anas wyvilliana), a non-migratory and island-endemic species, experienced a significant population decline during the twentieth century due to factors such as habitat loss, overharvest, introduced mammalian predators, and hybridization with introduced feral Mallards (A. platyrhynchos). A key objective for Hawaiian Duck recovery is to establish a protected and managed network of wetland habitats; however, development of effective habitat management plans is stymied by the lack of information on patterns of habitat use in relation to fundamental resource requirements. Furthermore, many generalizations regarding dabbling duck behavior and resource requirements that guide seasonal wetland management objectives in North America may not apply to tropical regions and island systems. In this thesis, I compare the behavioral repertoire of the Hawaiian Duck with closely related island-endemic waterfowl and migratory North American Anas, I investigate the behavioral response of Hawaiian Ducks to wetland habitat management and taro cultivation, and I examine the effects of environmental, climatic, temporal, and social factors on the activity budgets of Hawaiian Ducks. I conducted instantaneous focal sampling (n = 984 observation sessions; 328.8 hr) throughout the annual cycle from September 2010 to August 2011 at managed wetlands and taro lo'i within Hanalei National Wildlife Refuge (NWR), Kaua'i. I documented 73 specific Hawaiian Duck behaviors in eight broad behavior categories including foraging, maintenance, resting, locomotion, alert, courtship, and intraspecific and interspecific agonistic interactions. I found that the behavioral repertoire of the Hawaiian Duck was similar to that of the Mallard; however, subtle variations in the form and linkage of certain courtship displays, such as nod-swimming, were observed. Additionally, male Hawaiian Ducks were occasionally associated with brood-rearing females (11% of brood observations), and this behavior appeared to be a male strategy whereby females received little perceived benefit , but males may have potentially garnered additional breeding attempts or maintained pair-bonds for subsequent breeding seasons. After accounting for sex, pair status, month, and time of day, the diurnal behavioral activities of Hawaiian Ducks differed between managed wetlands and taro habitats (F₆,₉₆₀ = 30.3, P < 0.001). Hawaiian Ducks utilized taro predominantly for resting (44%), maintenance (21%), and foraging (15%), while birds used managed wetlands for a variety of activities, including foraging (11%), maintenance (28%), resting (27%), and locomotion (22%). Social activities, particularly courtship, occurred more frequently in managed wetlands than in taro (H₁ = 11.9, P < 0.001). In managed wetlands, birds foraged slightly more with increasing cover of Cyperus spp. (r = 0.18, P < 0.001) and Fimbristylis littoralis (r = 0.17, P < 0.01) and decreasing cover of Urochloa mutica (r = -0.15, P < 0.01) and wetland vegetation height (r = -0.22, P < 0.001). Within taro habitat, the behavioral activities of Hawaiian Ducks differed significantly between birds in lo'i and on dikes (F₆,₄₆₈ = 142.8, P < 0.001); birds utilized lo‘i dikes for resting (60%) and maintenance activities (21%), whereas birds entered lo‘i primarily to forage (45%). The activity budget of Hawaiian Ducks was strongly influenced by time of day (F₁₈,₂₇₁₅.₇₈ = 6.4, P < 0.001), and birds spent more time engaged in active behaviors (i.e., foraging, locomotion, and alert) and less time resting during early morning and evening than during late morning and afternoon. While strong seasonal shifts in most behavioral patterns were not detected, males allocated more time to courting (1.1 vs. 0.3%; H1 = 6.92, P = 0.009) and mate-guarding (0.5 vs. <0.1%; H₁ = 9.83, P = 0.002) in managed wetlands between November and March than the remainder of the year. The effects of sex (F₆,₉₆₀ = 6.06, P < 0.001) and social status (F₆,₆₈₂ = 6.69, P < 0.001) on activity budgets were also significant. Females spent more time foraging (18 vs. 12%) and less time in alert, locomotor, and social behaviors than males. Paired birds allocated more time to aggression towards conspecifics, mate-guarding, and courtship, and within taro lo‘i, paired birds foraged more and rested less than unpaired birds. Overall, Hawaiian Duck allocated diurnal activity budgets differently in managed and cultivated wetland habitat at Hanalei NWR, suggesting that both systems may play an important role in fulfilling fundamental daily and seasonal resource requirements. The increased range of activities and foraging tactics used in managed wetlands may indicate the greater habitat diversity (e.g., vegetation structure, patchiness, plant species richness, range of water depths) provided by seasonal wetlands. In general, Hawaiian Duck allocated less time to diurnal foraging than North American Anas, such Mallard and Mottled Duck (A. fulvigula), suggesting that Hawaiian Duck may have lower daily and seasonal energy demands, have access to higher quality diet, or allot more time to nocturnal foraging activities. Also, unlike many North American migratory waterfowl that demonstrate significant behavioral plasticity in adjusting activity budgets to meet seasonal energy demands associated with breeding, molting, wintering, and migration, Hawaiian Duck did not exhibit a strong seasonal shift in most behaviors which may reflect their non-migratory nature and asynchronous life history cycle.
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792. [Article] Carbon Nanodots as Biolabels for Fluorescence Immunoassays
There has been a tremendous growth in interest in carbon nanodots (C-dots) in the past several years. As a nascent nanomaterial, C-dots have shown great promise in applications that benefit from their ...Citation Citation
- Title:
- Carbon Nanodots as Biolabels for Fluorescence Immunoassays
- Author:
- Wu, Yuanyuan
There has been a tremendous growth in interest in carbon nanodots (C-dots) in the past several years. As a nascent nanomaterial, C-dots have shown great promise in applications that benefit from their superior water dispersibility, low toxicity, non-blinking fluorescent output, chemical and biological compatibility, ease of functionalization and resistance to photobleaching. With this positive outlook, however, challenges remain for the practical application of these fluorophores in specific biolabeling processes and bioassays. The goal of this effort has been to combine C-dots with biorecognition units for quantitative biomolecule determinations; specifically, the development of novel fluorescent immunoassays is presented here. These studies largely focused on the use of C-dot-labeled antibodies to target a protein disease biomarker, human alpha-fetoprotein (AFP). The research effort began with C-dot synthesis, followed by the application of capillary electrophoresis (CE) as an analysis tool for C-dot characterization and synthesis optimization. In addition, the CE work facilitated optimization of ensuing C-dot biolabeling reactions. C-dots were hydrothermally synthesized from citric acid (CA) and ethylene diamine (EDA) with a quantum yield as high as 99%. A novel CE method utilizing an alkaline working buffer was developed for rapid and reliable analysis of C-dots. A calibration curve was established over a broad concentration range (0.5-10 mg/mL) with excellent linearity (R²=0.9989). Then, the C-dots were used to label antibodies via amine-amine coupling using glutaraldehyde. All of the components in the conjugation reaction were baseline separated using the newly developed CE method. One peak in the electropherogram, having a migration time between that of the unlabeled antibody and that for the unmodified C-dots, was identified as representing the C-dot labeled antibodies. In summary, a novel, simple and rapid CE method was developed for: (1) quantitation of C-dots and (2) analysis of a C-dot-antibody bioconjugate, thus providing a method for optimization of conditions for acquiring the desired C-dot bioconjugate. The research continued with the development of a sensitive, selective, environmentally-friendly, high throughput, well plate based immunosorbent assay for human AFP using C-dots. The capture anti-AFP (Ab₁) was coated onto polystyrene well plates and bovine serum albumin (BSA) was used to block unsaturated binding sites. The C-dots were used to label the other member of the anti-AFP pair (Ab₂) via amine-amine coupling using glutaraldehyde. AFP was incubated to form a sandwich immunocomplex between Ab₁ and Ab₂ in the well plates, with unbound AFP and Ab₂ washed away with Tween-20. The fluorescence intensities detected from the C-dots in these immunocomplexes positively correlated to the concentrations of AFP antigen. A 5-parameter logistic regression curve was established between fluorescence and clinically important AFP concentrations (range: 0-350 ng/mL with an R-squared value of 0.995). The results were in agreement with those from two more traditional immunoassays which used horseradish peroxidase (HRP, R²=0.964) and fluorescein isothiocyanate (FITC, R²=0.973) as biolabels. This demonstration was the first example of a C-dot linked immunosorbent (solid phase) assay. To enable convenient separation by centrifugation and straightforward surface chemistry, in the next stage of the research described here, C-dots were encapsulated into a stable suspension of 45 nm silica nanoparticles through a reverse microemulsion method. A novel ratiometric immunoassay was developed to target human AFP, based on C-dot doped silica nanoparticles (CD-SNPs) and fluorescein isothiocyanate (FITC). CD-SNPs (Ab₁-CD-SNPs) capped with capture antibodies together with FITC labeled secondary antibodies (Ab₂-FITC) constituted a ratiometric immunoassay pair, in which CD-SNPs functioned as both a solid support enabling separation and washing, and as a built-in source of correction to account for inconsistent environmental effects and experimental errors. A linear calibration curve was established between ratio of FITC to C-dot fluorescent signals ("F/C") and a broad range of AFP concentrations (0-280 μg/dL with an R-squared value of 0.9977) with a low detection limit (0.317 μg/dL or 3.17 ng/mL) and acceptable recoveries. This is the first application of carbon nanodot doped silica nanoparticles to quantitative immunoassays for protein disease biomarkers. Moreover, the demonstration that these low-cost, simply-obtained and highly- fluorescent C-dots can be simply encapsulated into silica nanoparticles for specific biolabeling may expand future applications of C-dots into areas of in-vivo cellular imaging, drug delivery, and in-vitro cell labeling and biomolecule sensing. In the last part of the research effort described here, an alternative colorimetric detection platform, where an Apple iPhone 4 camera equipped with a color analysis application (ColorAssist) was combined with Vitros® blood urea nitrogen (BUN) colorimetric assays, was examined as a model for rapid and inexpensive clinical diagnostic testing. Color images of assay slides at various concentrations of urea were collected with the smartphone camera and quantified in three spectral ranges (red/green/blue or RGB) using the color analysis application. Absorbance values were converted from these diffuse reflectance data to quantitate BUN over its clinically important concentration range (2-190 mg/dL) with good linearity (R² = 0.9996 [n = 5]). This method was also applied to canine serum samples, the urea concentrations obtained were in good agreement with those from the instrumental "gold standard" (Beckman Coulter AU480) and a commercial colorimetric dry slide analyzer (HeskaTM Element DC)). This effort demonstrated that smart phones have the potential to be used as simple, effective colorimetric detectors for quantitative diagnostic tests. Furthermore, many additional demonstrations of the use of C-dots for sensitive detection of ions showed discernible color changes as well. This in turn suggests a valuable direction for future research: to explore combinations of these simple and effective colorimetric C-dot assays for both point-of-care applications in the developed world and field deployment in developing nations.
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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
- 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.
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Humpback whales (Megaptera novaeangliae, Borowski 1781) in the North Pacific migrate from mid- to high- latitude summer feeding grounds along the Pacific Rim, including areas off the coasts of the U.S., ...
Citation Citation
- Title:
- The influence of local fidelity and recruitment on population dynamics and specialized foraging of humpback whales in Glacier Bay and Icy Strait, Alaska
- Author:
- Pierszalowski, Sophie Penny
Humpback whales (Megaptera novaeangliae, Borowski 1781) in the North Pacific migrate from mid- to high- latitude summer feeding grounds along the Pacific Rim, including areas off the coasts of the U.S., Canada, Russia and eastern Asia, to tropical breeding grounds each winter along Pacific coasts of Mexico and Central America as well as the offshore islands of Mexico, Hawaii, and Japan. Humpback whales in the North Pacific and elsewhere were reduced to very low numbers during a period of intense commercial exploitation that ended in 1965. As the population recovers in abundance, the range of cultural and genetic diversity that survived the exploitation-driven bottleneck is able to adapt, endure and evolve. My work uses genetic tools and photo identification data to investigate the population dynamics, mitochondrial (mt) DNA control region evolution and potential drivers of a specialized feeding behavior in a recovering subpopulation of humpback whales in the Glacier Bay and Icy Strait (GBIS) sub-region of the southeastern Alaska (SEAK) feeding ground. I first collated and reconciled available DNA profiles (mtDNA control region, 10 microsatellite loci and sex) from 556 individuals using tissue samples collected from 1987 to 2012. Photo identification records associated with 692 of 1,026 total genetic samples collected in SEAK (now archived within the SEAK DNA Register and Tissue Database) corresponded to extensive life-history information, extending back to the early 1970s, as archived within the SEAK Regional Database, curated by the National Park Service (NPS) and University of Alaska, Southeast (UAS). Changes in population structure in GBIS over 32 years (1973-2005) were investigated in order to determine whether the increase in local abundance was attributable to local fidelity and recruitment or immigration from outside of SEAK. Two temporal strata were defined: 'Founder' individuals identified between 1973-1985 (n = 74, n = 46 with DNA profiles) and 'Contemporary' individuals identified between 2004-2005 (n = 171, n = 114 with DNA profiles). There was no significant genetic differentiation between the strata, indicating that it is unlikely that the population increase within GBIS was due largely to immigration of whales from elsewhere in the North Pacific. However, two additional haplotypes were documented in the Contemporary stratum at low frequency, one of which was previously unreported in the North Pacific (haplotype A8, see below). This relative stability in haplotype frequencies over time argues for strong regional fidelity of the maternal lineages represented in GBIS between 1973 and 1985. After excluding the 42 Contemporary whales with no photo ID record of a mother or genotype available for maternity inference, at least 73.6% (n = 95) of the Contemporary stratum was either a returning Founder or a recruited descendant of a Founder female. Of all genetically confirmed females with genotypes in the Founder stratum, 96% (n = 24) were either represented in the Contemporary stratum, had at least one confirmed descendant in the Contemporary stratum, or both. This high proportion, in addition to the large proportion of the verifiable Contemporary stratum that were either returning Founders or a descendant of a Founder female, provides clear evidence for local fidelity and recruitment to GBIS. The discovery of the A8 haplotype, which differs by one base pair from a common haplotype referred to as A-, represents an increase in mtDNA diversity for the North Pacific humpback whale from 28 to 29 haplotypes. To investigate the origin of this new haplotype, we re-evaluated n = 1089 electropherograms of n = 710 individuals with A- haplotypes from both the SEAK DNA Register and Tissue Database and the ocean-wide program, SPLASH (Baker et al. 2013). From this review, we identified two individuals with the A8 haplotype (a cow and calf, both sampled in GBIS) and n = 20 individuals with clear heteroplasmy for haplotypes A-/A8. The majority of A-/A8 individuals (n = 15) were sampled in SEAK. Genotype exclusion and likelihood were used to identify one of the heteroplasmic females, #196 (first sighted in SEAK in 1982), as the likely mother of the A8 cow and grandmother of the A8 calf, establishing the inheritance and germ-line fixation of the new haplotype from the parental heteroplasmy. Based on life history records and estimates of pairwise relatedness from microsatellite genotypes, it appears likely that the A-/A8 and the A8 individuals are descendants from a common maternal ancestor one or more generations prior to the three generations documented here. Humpback whale sociality takes a distinct form in Icy Strait, where whales form large, coordinated groups with repeated membership across several decades. Twenty-one years of group association records (1985-2005, n = 2,204 groups) were used to investigate the hypothesis that kin selection influences membership in large, stable groups. Of the 2204 groups recorded, 113 consisted of 6 or more individuals; a size considered unexpectedly large assuming a Poisson distribution of group size with a mean of 1.7. A total of n = 71 individuals (n = 48 with DNA profiles) were encountered in a large group in at least one year, n = 38 individuals (n = 34 with DNA profiles) were encountered in a large group in at least two years, n = 29 individuals (n = 27 with DNA profiles) were encountered in a large group in at least three years, decreasing to n = 2 individuals (n = 2 with DNA profiles) that were encountered in a large group in at least 20 years. There were no significant differences in mtDNA frequencies between large group feeders and the Founder and Contemporary strata or when compared to whales never encountered in large groups in Icy Strait, indicating that group membership is not predominately passed through one maternal lineage. Sex ratios did not deviate significantly from 1:1 for those feeding in large groups over an increasing number of years, as would be expected if females were actively recruiting offspring into large groups. The average pairwise relatedness for large group feeders was not significantly greater than expected by chance and did not increase for those feeding in large groups over an increasing number of years. Of the 179 known offspring of females encountered in a large group, only 6% were also encountered in a large group in Icy Strait as an adult and only 2.2% in the same large group as their mother. These results indicate that kin selection is not the primary driver of membership in large, stable groups and pose an interesting dynamic in local habitat use: individuals are recruited to GBIS through local maternal fidelity but do not usually associate closely with direct maternal kin. The extensive collection of DNA profiles now archived with the individual-based data within the SEAK Regional Database allowed us to integrate genetics and photo ID to answer ecologically relevant questions regarding the whales in GBIS. Together, these results demonstrate that GBIS provide habitat for a distinct collection of individuals that exhibit strong fidelity and local recruitment, some of which engage in a highly specialized feeding behavior. Further, GBIS is a local feeding habitat for two individuals with a newly arising North Pacific mtDNA haplotype. These findings reveal local genotypic and cultural variation and highlight the importance of habitat protection for species with fine-scale habitat use and strong fidelity to local migratory destinations.
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795. [Article] Students as pro-social bystanders : opportunities, past behaviors, and intentions to intervene in sexual assault risk situations
Sexual assault is a major public health concern in the U.S, and college students are particularly vulnerable to victimization. A health issue that affects nearly one in four women (Fisher, Cullen, & Turner, ...Citation Citation
- Title:
- Students as pro-social bystanders : opportunities, past behaviors, and intentions to intervene in sexual assault risk situations
- Author:
- Hoxmeier, Jill C.
Sexual assault is a major public health concern in the U.S, and college students are particularly vulnerable to victimization. A health issue that affects nearly one in four women (Fisher, Cullen, & Turner, 2000; Karjane, Cullen, & Turner, 2005) and that is associated with severe negative health outcomes, including depression substance abuse, suicide ideation, and risky sexual behaviors (CDC, 2012), warrants effective prevention programs. Moving away from traditional prevention efforts, which target females as potential victims in risk reduction programs and males as potential perpetrators in attitudinal-shifting programs, bystander engagement programs have become increasingly more widespread. These programs aim to engage all students on the college campus as potential bystanders who can intervene to prevent a sexual assault or reduce the harm of an assault that has already occurred (Banyard, Moynihan & Plante, 2007). Burn (2009) investigated potential barriers to pro-social bystander intervention using the Situational Model of Bystander Intervention, a model based on the original research of bystander behavior of Latanè and Darley (1970). The model outlines five barriers that influence students' intent to intervene as witnesses to sexual assault: failure to notice the situation, failure to identify the situation as high risk, failure to take intervention responsibility, failure to intervene due to skills deficit, and failure to intervene due to audience inhibition (Burn, 2009). She found that students' perception of barriers negatively correlated with intervention behaviors as bystanders to sexual assault (Burn, 2009). Although bystander engagement programs have shown initial promise in increasing students' intent to intervene, more needs to be known about the opportunities students have to intervene, their past intervention actions, and their intent to intervene in the future across the wide range of situations that encompass sexual assault risk. In addition, to develop effective programs that aim to increase pro-social behavior, understanding the salient influences of students' intent is critical. This study uses the Theory of Planned Behavior (TPB; Ajzen & Fishbein, 1991) to examine the influences of students’ intent to perform 12 different pro-social bystander behaviors. The TPB asserts that individuals' behavior is most proximally influenced by their behavioral intentions, and intentions are influences by their perceived behavioral control to perform the behavior, subjective norms that support performing the behavior, and attitudes toward the behavior (Ajzen & Fishbein, 1991). The four primary aims of this study were: 1) to examine the demographic correlates of students' opportunities, past intervention actions, and reported intent to intervene; 2) to examine any differences in students' intent to intervene based on the level of intervention (pre-, mid-, and post-assault) and type of intervention (with the potential or actual victim compared to the potential or actual perpetrator); 3) to examine the influences of perceived behavioral control, subjective norms, and attitudes on students' intent to intervene as bystanders; and 4) to compare the TPB-based model to the Situational Model of Bystander Intervention (Burn, 2009) in its ability to explain students' intent to intervene as bystanders. In the Fall of 2014, a sample of 815 undergraduate students at Oregon State University completed the Sexual Assault Bystander Behavior Questionnaire (SABB-Q), a tool comprised of items to measure students' opportunities, past behaviors, and future intent, in addition to measures assessing the influences of students' intent in line with the Theory of Planned Behavior and Burn's (2009) Situational Model of Bystander Intervention. Students who participate in Greek communities (fraternities and sororities) reported significantly greater odds of having the opportunity to perform four of the 12 intervention behaviors compared to non-Greek students, while student-athletes reported significantly greater odds of having the opportunity to perform two of the 12 intervention behaviors. Females reported significantly more past pro-social intervention behaviors (x̄ = 0.87) compared to males (x̄ = 0.79; p = 0.007). Regarding intent to intervene in the future, females reported significantly greater intent to intervene compared to males (x̄ = 6.07 vs. 5.68; p = 0.007). Students with friends who have been victims of sexual assault reported greater intent to intervene compared those without friends who have been victims (x̄ = 6.04 vs. 5.89; p = 0.02). Students with a personal history of victimization reported significantly greater intent compared to those without a personal history (x̄ =6.13 vs 5.93; p = 0.03). Students reported significantly greater intent to intervene with the potential or actual victim compared to the potential or actual perpetrator (x̄ = 6.19 vs. 5.74, p < 0.001). Females reported significantly greater intent to intervene with both the potential or actual victims and perpetrators (x̄ = 6.31 and 5.84, respectively) compared to males (x̄ = 5.88 and 5.49, respectively). Both males and females reported the greatest intent to perform post-assault intervention behavior (x̄ = 6.23), followed by pre-assault (x̄ = 6.08) and mid-assault behaviors (x̄ = 5.57). Females reported significantly greater intent to perform nine of the 12 pro-social intervention behaviors compared to males. A multiple regression analysis revealed that perceived behavioral control, subjective norms, and attitudes explained a significant proportion of the variance in intent to intervene (R² = 0.55, F(3, 771) = 315.68, p < 0.000). Perceived behavioral control was highly significant (β = 0.48, p < 0.001), as were subjective norms (β = 0.15, p < 0.001) and attitudes (β = 0.30, p < 0.001). Gender differences were also observed. For females, perceived behavioral control was highly significant (β = 0.49, p < 0.001), as were subjective norms (β = 0.15, p < 0.001) and attitudes (β = 0.29, p < 0.001). For males, perceived behavioral control was highly significant (β = 0.49, p < 0.001), as were attitudes (β = 0.29, p < 0.001). However, males' subjective norms were not significantly related (β = 0.07, p = 0.199) to their intent to intervene. Further analysis revealed a significant interaction between gender and subjective norms (β = -0.28; p = 0.039). The TPB-based model including this moderation effect explained a significant proportion of the variance in students' intent to intervene (R² = 0.57, F(6, 766) = 168.46, p < 0.000). Interveners reported significantly greater perceived behavioral control than non-interveners for seven of the 12 intervention behaviors; more supportive subjective norms than non-interveners for six of the 12 intervention behaviors; more positive attitudes than non-interveners for only one of the 12 intervention behaviors; and greater intent to intervene in the future for six of the 12 intervention behaviors. However, differences in the three TPB variables between interveners and non-interveners were not consistent for the 12 intervention behaviors. Regarding Burn's (2009) Situational Model of Bystander Intervention, a multiple regression analysis revealed two of the five barriers were significantly related to students’ intent to intervene: the failure to take intervention responsibility barrier (β = -0.29, p < 0.001) and the failure to intervene due to audience inhibition barrier (β = -0.22, p < 0.001). The model in whole explained a large proportion of the variance (R2 = 0.25, F(5, 768) = 50.14, p < 0.000). Gender differences were also observed. For females, failure to take intervention responsibility (β = -0.23; p < 0.000) and failure to intervene due to audience inhibition (β = -0.23; p < 0.001) both had a significant, negative influence on their intent to intervene. For males, failure to take intervention responsibility (β = -0.21; p < 0.014) had a significant, negative influence on intent to intervene. Additional analysis revealed no significant interactions between gender and any of the five barriers. The TPB-based model explained a greater proportion of the variance (R2 = 0.55) compared to Situational Model of Bystander Intervention (R² = 0.25) in the multiple regression analysis using all 12 intervention behaviors. All three variables in the TPB-based model were significantly related to students’ intent, whereas only two of the five barriers were significantly related. A final multiple regression analysis was conducted using all three significant TPB variables and the two significant barriers to explain students' intent to intervene. The combined model explained a significant proportion of variance in students' intent (R² = 0.58 F(5, 756) = 206.19, p < 0.000) and significantly improved upon the TPB-based model (Δ R² = 0.03; p < 0.000). The results of this study have several implications for future research and public health practice. First, it is important to ask students about their opportunities to intervene in addition to their actual intervention behaviors because this information helps paint a clearer picture of bystander engagement. This assessment could also help identify high-risk groups: students who have greater opportunities to intervene as bystanders and/or report fewer intervention behaviors compared to their reported opportunities. Second, students may conceptualize intervention behaviors differently depending on the phase of the assault and with whom the intervention behavior requires intervening. Accordingly, programs aimed at encouraging students to intervene should take these differences into consideration. Third, the Theory of Planned Behavior, used to explain and change other health-related behaviors, can effectively be applied to help uncover determinants of pro-social bystander behaviors. Perceived behavioral control, subjective norms, and attitudes appear to be salient influences in students' intent to intervene. Therefore, bystander engagement programs should incorporate activities to heighten students' skills to intervene, change social norms that support bystander intervention, and shift attitudes toward the benefits of intervening. This study demonstrates the importance of using an established, evidenced-based theoretical framework to explain behavioral influences and strengthens the argument for continued use of theory to identify, and potentially change, salient influences in behavioral performance. Students as pro-social bystanders have the potential to make a positive impact on the reduction of sexual assault on the college campus. Although the responsibility for sexual assault rests on those who perpetrate such acts, and primary prevention strategies aimed at those demonstrating a risk for perpetration are imperative, sexual assault is a public health issue that warrants a multi-pronged approach to reduce its incidence and migrate its associated harms. Programs that engage students as pro-social bystanders have the potential to make a positive impact on the reduction of sexual assault incidence in the absence of effective primary prevention strategies. The findings of this study make a contribution to the literature examining influences of students' pro-social bystander intervention to sexual assault situations and provide suggestions for strategies to increase bystander engagement.