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• 1. [Article] The Impact of Weather on Kingbird Foraging Behavior

  Foraging data on Eastern Kingbirds (Tyrannus tyrannus) were collected during the early breeding season in eastern Kansas to test the hypothesis that foraging rate and other aspects of foraging behavior ...

  Citation × Citation Citation Abstract Copy Title: The Impact of Weather on Kingbird Foraging Behavior Author: Murphy, Michael T. Year: 1987 Foraging data on Eastern Kingbirds (Tyrannus tyrannus) were collected during the early breeding season in eastern Kansas to test the hypothesis that foraging rate and other aspects of foraging behavior vary with weather. Foraging characteristics of five additional kingbird species were also examined to assess Fitzpatrick's (1980) generalization that kingbirds (Tyrannus spp.) are aerial hawking specialists. In Eastern Kingbirds, total foraging rate was independent of air temperature, cloud cover, wind speed, and time of day, but the rate of aerial hawking varied directly with air temperature and inversely with cloud cover (both P < 0.05). Effects of the two variables were additive. The percentage of foraging movements that were aerial hawks also increased with temperature and declined with cloud cover, and, hover-gleaning and perch-to-ground sallying were observed mainly during cloudy weather. Sally (i.e., foraging flight) distance correlated directly with perch height and air temperature, and large insects were captured almost exclusively in long upward or horizontal flights. I interpret these data to indicate that foraging behavior and the capture of large, flying insects depends on weather because of how it affects the activity of insect prey. Foraging data on kingbirds support Fitzpatrick's generalization, but the relative use of aerial hawking varies considerably among species. Resident Tropical Kingbirds( T. melancholicus) are the most specialized foragers, whereas the migrant and widely distributed Eastern Kingbird appears to be the most generalized. Certain habitats also appear to favor the use of particular foraging methods (e.g., outward striking in grasslands and perch-to-ground sallying in drier, open habitats). Title: The Impact of Weather on Kingbird Foraging Behavior Author: Murphy, Michael T. Year: 1987 Foraging data on Eastern Kingbirds (Tyrannus tyrannus) were collected during the early breeding season in eastern Kansas to test the hypothesis that foraging rate and other aspects of foraging behavior vary with weather. Foraging characteristics of five additional kingbird species were also examined to assess Fitzpatrick's (1980) generalization that kingbirds (Tyrannus spp.) are aerial hawking specialists. In Eastern Kingbirds, total foraging rate was independent of air temperature, cloud cover, wind speed, and time of day, but the rate of aerial hawking varied directly with air temperature and inversely with cloud cover (both P < 0.05). Effects of the two variables were additive. The percentage of foraging movements that were aerial hawks also increased with temperature and declined with cloud cover, and, hover-gleaning and perch-to-ground sallying were observed mainly during cloudy weather. Sally (i.e., foraging flight) distance correlated directly with perch height and air temperature, and large insects were captured almost exclusively in long upward or horizontal flights. I interpret these data to indicate that foraging behavior and the capture of large, flying insects depends on weather because of how it affects the activity of insect prey. Foraging data on kingbirds support Fitzpatrick's generalization, but the relative use of aerial hawking varies considerably among species. Resident Tropical Kingbirds( T. melancholicus) are the most specialized foragers, whereas the migrant and widely distributed Eastern Kingbird appears to be the most generalized. Certain habitats also appear to favor the use of particular foraging methods (e.g., outward striking in grasslands and perch-to-ground sallying in drier, open habitats). Close

• 2. [Article] Body Size, Nest Predation, and Reproductive Patterns in Brown Thrashers and Other Mimids

  We describe the breeding biology of Brown Thrashers (Toxostoma rufum) in Kansas, and combine this with data from other temperate-zone breeding Mimidae to characterize reproductive patterns in this group. ...

  Citation × Citation Citation Abstract Copy Title: Body Size, Nest Predation, and Reproductive Patterns in Brown Thrashers and Other Mimids Author: Murphy, Michael T., Fleischer, Robert C. Year: 1986 We describe the breeding biology of Brown Thrashers (Toxostoma rufum) in Kansas, and combine this with data from other temperate-zone breeding Mimidae to characterize reproductive patterns in this group. Brown Thrashers produced clutches of 3 to 6 eggs, but clutches of 4 predominated. Most pairs raised 2 broods per year. Incubation required between 13 and 14 days, and hatching was usually asynchronous. Though sample size was small, asynchrony appeared to increase in frequency towards the end of the breeding season. Nestlings grew rapidly, and in 10 days or less most pre-fledgingg rowthw as completed. Young fledgedn ormallya t 11 days of age at 65% of aduli weight, but with the tarsi near adult size. Nestlings starved in 27% of nests, but predators were responsible for most nest failures. Overall nest success was 43%. Brown Thrashers are typical of other temperate-zone mimids. Modal clutch sizes are of either 3 or 4 eggs and all species are multi-brooded. Mimids from the southwestern United States and Mexico lay normally 3 egg clutches, but elsewhere 4 eggs are most common. Incubation length and nestling growth rate vary significantly with adult weight, but on average, incubation is 3 days shorter and nestlings grow 36% faster than predicted. Relative incubation length and relative fledging weight both declined significantly with adult weight, whereas daily nest mortality rate increased significantly with adult size. Although our data are consistent with the hypothesis that heavy nest predation has favored rapid nestling growth and completion of development outside of the nest, rapid growth may also function in brood reduction. Present data are insufficient to exclude conclusively either factor in the evolution of rapid development in mimids. Title: Body Size, Nest Predation, and Reproductive Patterns in Brown Thrashers and Other Mimids Author: Murphy, Michael T., Fleischer, Robert C. Year: 1986 We describe the breeding biology of Brown Thrashers (Toxostoma rufum) in Kansas, and combine this with data from other temperate-zone breeding Mimidae to characterize reproductive patterns in this group. Brown Thrashers produced clutches of 3 to 6 eggs, but clutches of 4 predominated. Most pairs raised 2 broods per year. Incubation required between 13 and 14 days, and hatching was usually asynchronous. Though sample size was small, asynchrony appeared to increase in frequency towards the end of the breeding season. Nestlings grew rapidly, and in 10 days or less most pre-fledgingg rowthw as completed. Young fledgedn ormallya t 11 days of age at 65% of aduli weight, but with the tarsi near adult size. Nestlings starved in 27% of nests, but predators were responsible for most nest failures. Overall nest success was 43%. Brown Thrashers are typical of other temperate-zone mimids. Modal clutch sizes are of either 3 or 4 eggs and all species are multi-brooded. Mimids from the southwestern United States and Mexico lay normally 3 egg clutches, but elsewhere 4 eggs are most common. Incubation length and nestling growth rate vary significantly with adult weight, but on average, incubation is 3 days shorter and nestlings grow 36% faster than predicted. Relative incubation length and relative fledging weight both declined significantly with adult weight, whereas daily nest mortality rate increased significantly with adult size. Although our data are consistent with the hypothesis that heavy nest predation has favored rapid nestling growth and completion of development outside of the nest, rapid growth may also function in brood reduction. Present data are insufficient to exclude conclusively either factor in the evolution of rapid development in mimids. Close