Male songbirds of many species sing local song dialects that are restricted to defined geographic... more Male songbirds of many species sing local song dialects that are restricted to defined geographical areas. In most tests of responses to local versus foreign dialects, males respond more aggressively to songs from their own dialect, presumably because local males represent more of a threat to their success. We asked how hearing foreign songs during development and territory establishment affects discrimination of the local dialect in wild Savannah sparrows, Passerculus sandwichensis. After foreign songs had been heard from loudspeakers in the study area in at least two consecutive breeding seasons, males reduced the intensity of their responses to the local version of the population-specific buzz segment of the song. Four years after the foreign songs were last broadcast on the study area, males again responded more aggressively to the local version of the buzz. As for the basis of these responses, we found no evidence that birds discriminated among dialects by comparing them to their own songs. However, auditory experience with a foreign song, whether during song development (from speaker-simulated song tutors) or during the current breeding season (from neighbours' songs), reduced the intensity of birds' responses to the local buzz type. Both familiarity, in the form of auditory experience with a song type, and homogeneity, when a song type is sung by all or nearly all of the population, appear to contribute to heightened aggressive responses to a local song dialect.
Humans have dramatically altered ecosystem structure through landscape manipulation, often leavin... more Humans have dramatically altered ecosystem structure through landscape manipulation, often leaving refuge patches of suitable habitat for wildlife amidst inhospitable terrain. Large carnivores are especially vulnerable to such habitat modification because they tend to have low population densities and wide-ranging movements necessitated by their food requirements. Cougars (Puma concolor), unlike many other large carnivores, have demonstrated an ability to exploit resources in fragmented and managed landscapes. The influence of increasing landscape development on cougar foraging behavior, however, has yet to be fully elucidated. Accordingly, we investigated variation in cougar use of three prey types (synanthropes, ungulates, and rodents) along a wildland-urban gradient in western Washington to determine how urbanization affects the foraging ecology of this apex predator. We predicted that cougar diets would comprise more synanthropic prey (e.g., prolific urban species) and fewer deer as a function of increasing residential development. Generalized linear mixed model results showed that the odds of cougar predation on synanthropic prey did increase with urbanization. The odds of ungulate predation, however, remained relatively consistent across the wildland-urban gradient despite cougar use of black-tailed deer (Odocoileus hemionus columbianus) and elk (Cervus canadensis) increasing over time. These results suggest that cougar-ungulate predator-prey systems can persist in landscapes with substantial human presence. The odds of forest-associated rodent (Castor sp., Aplodontia sp.) predation decreased with increasing development, suggesting that urbanization may coincide with more intensive beaver management near residences and thereby reduce beaver and mountain beaver presence in exurban landscapes in western Washington. Most cougars exhibited similar diets, but certain individuals deviated significantly from the population averages characterizing use of all three major prey categories. This variation suggests that cougar population responses to urbanization are unlikely to be uniform and that cases of human-cougar conflict may be linked to individual cats, rather than the population as a whole.
Different components of learned birdsongs change at different rates across generations, and the r... more Different components of learned birdsongs change at different rates across generations, and the rate of change may correspond to the information carried by each component. To characterize the role of the buzz segment of Savannah sparrow songs, we examined recordings from southeastern Canada and the northeastern US and fully characterized buzz segments in songs recorded from two populations: one on Kent Island, NB, Canada and another in Williamstown, MA, USA. Buzzes varied geographically: Kent Island buzzes had higher mean frequencies and shorter pulse periods than Williamstown buzzes and the differences between the two populations persisted over time. Population-specific buzz characteristics also appeared to be resistant to change. Variants appeared on Kent Island in the late 1980s and were learned by some younger birds; however, these buzz variants disappeared by 2011. We conducted a playback experiment and found that males from both populations had longer responses to local buzzes. Therefore, buzz structure varies geographically; population characteristics of the buzz persist through time despite the introduction of variant forms; and territorial males discriminate between buzzes from different populations. The learned buzz segment of the song may thus serve as a population marker for Savannah sparrows.
Different components of learned birdsongs change at different rates across generations, and the r... more Different components of learned birdsongs change at different rates across generations, and the rate of change may correspond to the information carried by each component. To characterize the role of the buzz segment of Savannah sparrow songs, we examined recordings from southeastern Canada and the northeastern US and fully characterized buzz segments in songs recorded from two populations: one on Kent Island, NB, Canada and another in Williamstown, MA, USA. Buzzes varied geographically: Kent Island buzzes had higher mean frequencies and shorter pulse periods than Williamstown buzzes and the differences between the two populations persisted over time. Population-specific buzz characteristics also appeared to be resistant to change. Variants appeared on Kent Island in the late 1980s and were learned by some younger birds; however, these buzz variants disappeared by 2011. We conducted a playback experiment and found that males from both populations had longer responses to local buzzes. Therefore, buzz structure varies geographically; population characteristics of the buzz persist through time despite the introduction of variant forms; and territorial males discriminate between buzzes from different populations. The learned buzz segment of the song may thus serve as a population marker for Savannah sparrows.
Humans have dramatically altered ecosystem structure through landscape manipulation, often leavin... more Humans have dramatically altered ecosystem structure through landscape manipulation, often leaving refuge patches of suitable habitat for wildlife amidst inhospitable terrain. Large carnivores are especially vulnerable to such habitat modification because they tend to have low population densities and wide‐ranging movements necessitated by their food requirements. Cougars (Puma concolor), unlike many other large carnivores, have demonstrated an ability to exploit resources in fragmented and managed landscapes. The influence of increasing landscape development on cougar foraging behavior, however, has yet to be fully elucidated. Accordingly, we investigated variation in cougar use of three prey types (synanthropes, ungulates, and rodents) along a wildland–urban gradient in western Washington to determine how urbanization affects the foraging ecology of this apex predator. We predicted that cougar diets would comprise more synanthropic prey (e.g., prolific urban species) and fewer dee...
Male songbirds of many species sing local song dialects that are restricted to defined geographic... more Male songbirds of many species sing local song dialects that are restricted to defined geographical areas. In most tests of responses to local versus foreign dialects, males respond more aggressively to songs from their own dialect, presumably because local males represent more of a threat to their success. We asked how hearing foreign songs during development and territory establishment affects discrimination of the local dialect in wild Savannah sparrows, Passerculus sandwichensis. After foreign songs had been heard from loudspeakers in the study area in at least two consecutive breeding seasons, males reduced the intensity of their responses to the local version of the population-specific buzz segment of the song. Four years after the foreign songs were last broadcast on the study area, males again responded more aggressively to the local version of the buzz. As for the basis of these responses, we found no evidence that birds discriminated among dialects by comparing them to their own songs. However, auditory experience with a foreign song, whether during song development (from speaker-simulated song tutors) or during the current breeding season (from neighbours' songs), reduced the intensity of birds' responses to the local buzz type. Both familiarity, in the form of auditory experience with a song type, and homogeneity, when a song type is sung by all or nearly all of the population, appear to contribute to heightened aggressive responses to a local song dialect.
Humans have dramatically altered ecosystem structure through landscape manipulation, often leavin... more Humans have dramatically altered ecosystem structure through landscape manipulation, often leaving refuge patches of suitable habitat for wildlife amidst inhospitable terrain. Large carnivores are especially vulnerable to such habitat modification because they tend to have low population densities and wide-ranging movements necessitated by their food requirements. Cougars (Puma concolor), unlike many other large carnivores, have demonstrated an ability to exploit resources in fragmented and managed landscapes. The influence of increasing landscape development on cougar foraging behavior, however, has yet to be fully elucidated. Accordingly, we investigated variation in cougar use of three prey types (synanthropes, ungulates, and rodents) along a wildland-urban gradient in western Washington to determine how urbanization affects the foraging ecology of this apex predator. We predicted that cougar diets would comprise more synanthropic prey (e.g., prolific urban species) and fewer deer as a function of increasing residential development. Generalized linear mixed model results showed that the odds of cougar predation on synanthropic prey did increase with urbanization. The odds of ungulate predation, however, remained relatively consistent across the wildland-urban gradient despite cougar use of black-tailed deer (Odocoileus hemionus columbianus) and elk (Cervus canadensis) increasing over time. These results suggest that cougar-ungulate predator-prey systems can persist in landscapes with substantial human presence. The odds of forest-associated rodent (Castor sp., Aplodontia sp.) predation decreased with increasing development, suggesting that urbanization may coincide with more intensive beaver management near residences and thereby reduce beaver and mountain beaver presence in exurban landscapes in western Washington. Most cougars exhibited similar diets, but certain individuals deviated significantly from the population averages characterizing use of all three major prey categories. This variation suggests that cougar population responses to urbanization are unlikely to be uniform and that cases of human-cougar conflict may be linked to individual cats, rather than the population as a whole.
Different components of learned birdsongs change at different rates across generations, and the r... more Different components of learned birdsongs change at different rates across generations, and the rate of change may correspond to the information carried by each component. To characterize the role of the buzz segment of Savannah sparrow songs, we examined recordings from southeastern Canada and the northeastern US and fully characterized buzz segments in songs recorded from two populations: one on Kent Island, NB, Canada and another in Williamstown, MA, USA. Buzzes varied geographically: Kent Island buzzes had higher mean frequencies and shorter pulse periods than Williamstown buzzes and the differences between the two populations persisted over time. Population-specific buzz characteristics also appeared to be resistant to change. Variants appeared on Kent Island in the late 1980s and were learned by some younger birds; however, these buzz variants disappeared by 2011. We conducted a playback experiment and found that males from both populations had longer responses to local buzzes. Therefore, buzz structure varies geographically; population characteristics of the buzz persist through time despite the introduction of variant forms; and territorial males discriminate between buzzes from different populations. The learned buzz segment of the song may thus serve as a population marker for Savannah sparrows.
Different components of learned birdsongs change at different rates across generations, and the r... more Different components of learned birdsongs change at different rates across generations, and the rate of change may correspond to the information carried by each component. To characterize the role of the buzz segment of Savannah sparrow songs, we examined recordings from southeastern Canada and the northeastern US and fully characterized buzz segments in songs recorded from two populations: one on Kent Island, NB, Canada and another in Williamstown, MA, USA. Buzzes varied geographically: Kent Island buzzes had higher mean frequencies and shorter pulse periods than Williamstown buzzes and the differences between the two populations persisted over time. Population-specific buzz characteristics also appeared to be resistant to change. Variants appeared on Kent Island in the late 1980s and were learned by some younger birds; however, these buzz variants disappeared by 2011. We conducted a playback experiment and found that males from both populations had longer responses to local buzzes. Therefore, buzz structure varies geographically; population characteristics of the buzz persist through time despite the introduction of variant forms; and territorial males discriminate between buzzes from different populations. The learned buzz segment of the song may thus serve as a population marker for Savannah sparrows.
Humans have dramatically altered ecosystem structure through landscape manipulation, often leavin... more Humans have dramatically altered ecosystem structure through landscape manipulation, often leaving refuge patches of suitable habitat for wildlife amidst inhospitable terrain. Large carnivores are especially vulnerable to such habitat modification because they tend to have low population densities and wide‐ranging movements necessitated by their food requirements. Cougars (Puma concolor), unlike many other large carnivores, have demonstrated an ability to exploit resources in fragmented and managed landscapes. The influence of increasing landscape development on cougar foraging behavior, however, has yet to be fully elucidated. Accordingly, we investigated variation in cougar use of three prey types (synanthropes, ungulates, and rodents) along a wildland–urban gradient in western Washington to determine how urbanization affects the foraging ecology of this apex predator. We predicted that cougar diets would comprise more synanthropic prey (e.g., prolific urban species) and fewer dee...
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