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Pakanen V.-M.,University of Oulu | Orell M.,University of Oulu | Vatka E.,University of Oulu | Rytkonen S.,University of Oulu | And 2 more authors.
PLoS ONE | Year: 2016

Correct reproductive timing is crucial for fitness. Breeding phenology even in similar species can differ due to different selective pressures on the timing of reproduction. These selection pressures define species' responses to warming springs. The temporal match-mismatch hypothesis suggests that timing of breeding in animals is selected to match with food availability (synchrony). Alternatively, time-dependent breeding success (the date hypothesis) can result from other seasonally deteriorating ecological conditions such as intra- or interspecific competition or predation.We studied the effects of two ultimate factors on the timing of breeding, synchrony and other time-dependent factors (time-dependence), in sympatric populations of two related forest-dwelling passerine species, the great tit (Parus major) and the willow tit (Poecile montanus) by modelling recruitment with long-termcapture-recapture data.We hypothesized that these two factors have different relevance for fitness in these species.We found that local recruitment in both species showed quadratic relationships with both time-dependence and synchrony. However, the importance of these factors was markedly different between the studied species. Caterpillar food played a predominant role in predicting the timing of breeding of the great tit. In contrast, for the willow tit time-dependence modelled as timing in relation to conspecifics was more important for local recruitment than synchrony. High caterpillar biomass experienced during the pre- and postfledging periods increased local recruitment of both species. These contrasting results confirmthat these species experience different selective pressures upon the timing of breeding, and hence responses to climate change may differ. Detailed information about life-history strategies is required to understand the effects of climate change, even in closely related taxa. The temporal match-mismatch hypothesis should be extended to consider subsequent critical periods when food needs to be abundantly available. © 2016 Pakanen et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

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.

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.

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