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Laiolo P.,Research Unit of Biodiversity
Revista Catalana d'Ornitologia | Year: 2011

Literature is increasingly reporting cases of animal species that change their behaviour when dwelling in towns. Common responses in passerines involve singing earlier in the day and varying the physical properties of their songs to reduce the impact of masking traffic noise on communication. In this paper I analyse the song of the Rufous-Collared Sparrow Zonotrichia capensis, a widespread passerine inhabiting Central and Southern America. I recorded the songs of 114 males along a rural-urban gradient encompassing open woodland, peripheral and inner garden suburbs in Bahía Blanca, Argentina. By considering the variation present in five frequency parameters, I found that Rufous-Collared Sparrows sang significantly higher pitched songs (with higher minimum frequencies) in suburbs than in rural habitats. This study provides further evidence of birds switching song frequency in urban habitats, as has previously been recorded in several Northern American and European passerines. Since anthropogenic noise is predominantly low in frequency, singing at higher pitches in cities is likely to reduce acoustic interference and maximize signal transmission over distance.

Blanco-Fontao B.,Research Unit of Biodiversity | Blanco-Fontao B.,University of Oviedo | Sandercock B.K.,Kansas State University | Obeso J.R.,Research Unit of Biodiversity | And 4 more authors.
PLoS ONE | Year: 2013

Partitioning of ecological niche is expected in lekking species that show marked sexual size dimorphism as a consequence of sex-specific ecological constraints. However, niche partitioning is uncertain in species with moderate sexual dimorphism. In addition, the ecological niche of a species may also be affected by landscape composition; particularly, agricultural fragmentation may greatly influence the trophic behavior of herbivores. We studied trophic niche variation in Greater Prairie-Chickens (Tympanuchus cupido), a grouse species that shows moderate sex-dimorphism. Greater Prairie-Chickens are native to tallgrass prairies of North America, although populations persist in less natural mosaics of cropland and native habitats. We used stable isotope analysis of carbon and nitrogen in blood, claws and feathers to assess seasonal differences in trophic niche breadth and individual specialization between male and female Greater Prairie-Chickens, and between birds living in continuous and fragmented landscapes. We found that females showed broader niches and higher individual specialization than males, especially in winter and autumn. However, differences between females and males were smaller in spring when birds converge at leks, suggesting that females and males may exhibit similar feeding behaviors during the lekking period. In addition, we found that birds living in native prairies showed greater annual trophic variability than conspecifics in agricultural mosaic landscapes. Native habitats may provide greater dietary diversity, resulting in greater diversity of feeding strategies. © 2013 Blanco-Fontao et al.

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