Geographic variations and temporal changes in songs of the Rufous-capped Babbler (Stachyris ruficeps praecognita) (original) (raw)
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The Evolution of Geographic Variation in Birdsong
Advances in the Study of Behavior, 2007
department of biology, graduate program in organismic and evolutionary biology, university of massachusetts amherst, massachusetts 01003 { department of natural resources conservation, graduate program in organismic and evolutionary biology, university of massachusetts amherst, massachusetts 01003
Geographic variation in the songs of the Common Yellowthroat
The Common Yellowthroat (Geothlypis trichas) exhibits widespread geographic variation in plumage, morphology, migratory behavior, and song. In addition, researchers recently found evidence that the Common Yellowthroat has three genetically distinct groups across its North American range: eastern, western, and southwestern. These groups are more genetically similar to other Geothlypis species than to each other, which suggests relatively long-term isolation. I hypothesized that geographic variation in song behavior should reflect these genetic differences. To test this hypothesis, I examined spatial patterns of variation in both note types and acoustic characteristics of song. Consistent with the hypothesis, I found significant differences among the three groups, particularly in frequency measures, internote duration, notes per phrase, and note elaborateness. Within the eastern and western groups, I also found significant song differences among historically recognized subspecies. When comparing western and eastern subspecies, I found different latitudinal trends, even though subspecies found at similar latitudes that exhibit similar migratory behavior might be expected to have similar song characteristics. Two possible explanations for this lack of convergence are (1) stochastic changes in song in isolated populations and (2) nonlatitudinal dissimilarities in habitat, including transmission properties or effects on morphological evolution, that drive song divergence. Without excluding other explanations, I found evidence of an effect of morphological divergence: Subspecies with larger bills sang songs with lower frequencies. Overall, the geographic variation in the songs of the Common Yellowthroat demonstrates that multiple evolutionary processes interact to shape birdsong, and that the importance of each of these processes and their interactions varies among populations.
Animal Behaviour, 2007
In this study, we investigated whether historical, refugial isolation may have caused current, large-scale geographical variation in the song frequency and structure in the chowchilla, Orthonyx spaldingii, or whether this variation can be better explained by the influence of isolation-by-distance, vegetation type and/or body size and mass. We recorded songs from 15 locations across the species' range, covering five historically isolated populations (Pleistocene refugia) and two areas of post-Pleistocene recolonization. We measured six spectrotemporal characteristics of 773 songs and used a multivariate approach to test for differences between refugia. Historically isolated populations could be clearly distinguished by their spectral characteristics, particularly bandwidth and peak frequency. In addition, we found striking song divergence across the Black Mountain Corridor, a known historical climatic barrier. Northern refugia showed significantly narrower bandwidths and higher peak frequencies than southern refugia. Spectral characteristics were not influenced by geographical distance, broad habitat differences or body size. This study shows that spectral song characteristics were at least in part influenced by historical isolation in refugia. Given the known history of population isolation in these refugia, cultural drift is the most likely explanation for the differences in spectral characteristics in chowchilla song.
Animal Behaviour, 2004
We studied the pattern of song variation in the rufous-collared sparrow, Zonotrichia capensis, in the 1987 and 2000 breeding seasons in a 7-km 2 area covering open and closed habitats. We measured 14 quantitative song variables over a total of 390 individuals and found consistent differences between habitats in both years. In particular, songs of individuals from closed habitat sites had trills with longer trill intervals and lower frequencies than those of individuals from open habitats. This pattern of variation is interpreted as a song cline that correlates with the environmental gradient. Although this cline was stable in location and shape, it also showed several differences between years. The songs recorded during 2000 had trills with longer trill intervals and lower minimum frequencies than those recorded during 1987. Thus, this study is the first to directly document temporal changes in song variables in a Z. capensis population. This change would be expected if all the habitats studied were more closed in 2000 than in 1987, but we did not find obvious differences in habitat features between seasons. However, this modification of song structure is compatible with alternative explanations, such as subtle differences in habitat characteristics, changes in climatic variables, a delayed effect of a past modification of the environment and neutrality of the change.
The Condor, 2008
The populations of many species are declining worldwide, and conservation efforts struggle to keep pace with extinction rates. Conservation biologists commonly employ strategies such as translocation and reintroduction, which move individuals of endangered species from one part of their range to another. Because individuals from endangered populations are nonexpendable, identifying any potential barriers to the establishment of viable populations prior to release of individuals should be a priority. This study evaluates the potential for learned communication signals to constrain conservation strategies such as reintroduction in an endangered species, the Thick-billed Parrot (Rhynchopsitta pachyrhyncha). We conducted vocal surveys at three geographically distinct breeding populations in the Sierra Madre Occidental of Chihuahua, Mexico. Acoustic analyses utilizing both spectrogram cross-correlations and parameter measurements from spectrograms revealed no significant differences among the three sites in two common call types. Calls did vary among individuals within a site. The apparent lack of significant geographic variation across sampled sites suggests that differences in learned communication signals are unlikely to pose a barrier to the integration of translocated individuals from different populations into newly established populations. The use of hand-raised psittacines for reintroduction: a case study of Scarlet Macaws (Ara macao) in Peru and Costa Rica. Biological Conservation. 2005; 121:465-472. Briskie JV. Song variation and the structure of local song dialects in the polygynandrous Smith's Longspur. Canandian Journal of Zoology. 1999; 77:1587-1594. Casgrain, P.; Legendre, P. The R package for multivariate and spatial analysis, version 4.0.d3-user's manual. Département de sciences biologiques, Université de Montréal; Montréal: 2001. Catchpole, CK.; Slater, PJB. Bird song: biological themes and variations. Cambridge University Press; Cambridge, UK: 1995. Charif, RA.; Clark, CW.; Fristrup, KM. Raven 1.2 user's manual. Cornell Lab of Ornithology; Ithaca, NY: 2004. Enkerlin-Hoeflich, EC.; Macias-Caballero, C.; Monterrubio-Rico, T.; Cruz-Nieto, MA.; Snyder, NFR.; Venegas-Holguin, D.; Cruz-Nieto, J.; Ortiz-Maciel, G.; Gonzalez-Elizondo, J.; Stone, E. Status, distribucion, ecologia y conservacion de las cotorras serranas (Rhynchopsitta pachyrhyncha y R. terrisi) en el Norte
Singing in the sky: song variation in an endemic bird on the sky islands of southern India
Birdsong structure is known to vary across different scales of geographical separation, from differences between neighbours in a habitat to populations across continents. The high-elevation regions of the Western Ghats mountains in southern India form sky islands containing the unique Shola habitat. Bird species on such sky islands are often specically adapted to habitats typical of these islands while populations on different islands may have been geographically isolated over varying periods of time. Forest fragmentation can intensify the effects of such isolation by affecting species dispersal processes. We examined the effects of genetic differentiation across populations on the song of a threatened, endemic bird, the white-bellied shortwing, Brachypteryx major, on different islands of this sky island system. We compared songs from three populations, one of which on one island was genetically distinct from the other two populations on another island. These two populations were genetically similar but separated by recent deforestation. We recorded songs from 23 individuals and characterized 572 songs by 13 parameters. Multivariate analyses revealed signi cant differences in song between the three populations, with the genetically distinct populations across the two islands being the most differentiated. This was supported by a visual and aural examination of spectrograms that revealed characteristic qualitative differences in songs across these populations. Finally, this study corroborates accepted patterns of congruence between song and genetic divergence across islands and also highlights the difference in song between anthropogenically fragmented, but genetically similar populations, possibly owing to cultural drift.
The evolution of birdsong on islands
Ecology and Evolution, 2013
Islands are simplified, isolated ecosystems, providing an ideal set-up to study evolution. Among several traits that are expected to change on islands, an interesting but poorly understood example concerns signals used in animal communication. Islands are typified by reduced species diversity, increased population density, and reduced mate competition, all of which could affect communication signals. We used birdsong to investigate whether there are systematic changes in communication signals on islands, by undertaking a broad comparison based on pairs of closely related island-mainland species across the globe. We studied song traits related to complexity (number of different syllables, frequency bandwidth), to vocal performance (syllable delivery rate, song duration), and also three particular song elements (rattles, buzzes, and trills) generally implicated in aggressive communication. We also investigated whether song complexity was related to the number of similar sympatric species. We found that island species were less likely to produce broadband and likely aggressive song elements (rattles and buzzes). By contrast, various aspects of song complexity and performance did not differ between island and mainland species. Species with fewer same-family sympatric species used wider frequency bandwidths, as predicted by the character release hypothesis, both on continents and on islands. Our study supports the hypothesis of a reduction in aggressive behavior on islands and suggests that discrimination against closely related species is an important factor influencing birdsong evolution.
Dominant frequency of songs in tropical bird species is higher in sites with high noise pollution
Environmental Pollution, 2018
The structure and organization of acoustic signals arise through evolutionary processes and adaptive pressures on each species. During learning, natural or anthropogenic factors, such as high noise levels in urban areas, pose challenges to acoustic communication in birds. Many species adjust their acoustic signals to higher noise levels by increasing the frequency of vocalizations. The objectives of this study were to compare the dominant frequency of songs among birds dwelling in forest fragments distant from and near to urban areas, establish correlations between the dominant frequency of song and noise levels in these environments and verified the difference of response between oscines, suboscines and nonpasserines. We recorded vocalizations of birds between July/2013 and November/2014 in four forest fragments, two of them near and two distant from urban areas. We used Audacity software to measure the dominant frequency. We measured the ambient noise by a calibrated sound pressure level meter in decibels (dBA) in each of the forest fragments. We analyzed 3740 vocalizations of nine tropical bird species. Forest fragments near to urban areas have higher noise levels than more distant forest fragments. Eight of nine studied species presented higher dominant frequencies of songs in forest fragments near to urban areas. Only one species, Myiothlypis flaveola, did not change the dominant frequency of song between the four analyzed forest fragments. The difference in dominant frequency between the forest fragments distant and closer to the urban areas did not vary between oscines, suboscines and nonpasserines. Eight tropical birds exhibited higher dominant frequencies of song in forest fragments near urban areas with high level of ambient noise. Oscine, suboscine and non-passerine showed song variations. Bird species that have differences in the vocalization dominant frequency can be used in environmental monitoring and in ethological studies, as they are sensitive to high noise levels. Noise pollution caused by the vehicular traffic and urbanization are correlates with changes in the vocalization of tropical birds in forest fragments.
Behaviour, 2013
ABSTRACT In songbirds, male song is an acoustic signal used to attract mates and defend territories. Typically, song is an acoustically complex signal; however, the fee-bee song of the black-capped chickadee is relatively simple. Despite this relative simplicity, two previous studies (Christie et al., 2004b; Hoeschele et al., 2010) found acoustic features within the fee-bee song that contain information regarding an individual’s dominance rank; however each of these studies reported a different dominance-related acoustic cue. Specifically, the relative amplitude of the two notes differed between the songs of dominant and subordinate males from northern British Columbia, while the interval pitch ratio differed between the songs of dominant and subordinate males from eastern Ontario. In the current study, we examined six acoustic features within songs from both of the chickadee populations (northern British Columbia and eastern Ontario) examined in these previous studies and used bioacoustic analyses and discriminant function analyses to determine whether there is a consistent dominance-related acoustic cue across both, or in each of these populations. Consistent with the previous findings, the current results indicate that relative amplitude differs based on dominance status in the songs from British Columbia; however, our results failed to reach significance with songs from Ontario. These results suggest that acoustic cues that signal a male’s dominance in this species vary with geographic location. Furthermore, examining songs from these two locations and one additional location in northern British Columbia, we found that discriminant function analyses could correctly classify songs based on geographic location. Considering the broad extent of the species’ range, black-capped chickadee song is considered relatively invariant; however, our results suggest that there is geographic variation in songs, although the differences are subtle compared to geographic song variation in other species.