Colony size and foraging range in seabirds

Autor: Jovani, Roger, Lascelles, Ben G., Garamszegi, László Z., Mavor, R., Oro, Daniel
Rok vydání: 2015
Předmět:
Zdroj: Digital.CSIC. Repositorio Institucional del CSIC
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Popis: Trabajo presentado en el 4º Congreso Ibérico de Ecología, celebrado en coimbra, Portugal, del 16 al 19 de junio de 2015
Understanding why group size varies among animals species is an open question in evolutionary ecology. Seabird colonies range from some few breeding pairs up to hundreds of thousands of nests. We have previously reported high colony size variation within species, but consistent median and maximum colony sizes when studying same species in different populations. Seabirds are central place foragers with species-specific foraging distances ranging from some few hundred meters from the colony to hundreds of kilometers to find food for their nestlings. Here we predicted that the foraging range of species imposes a ceiling on their maximum colony sizes; according to the mathematical equation of the area of the circle, we predicted a second-order relationship between (foraging) radius and (foraging) area. Accordingly, on a log-scale, maximum colony size would scale with slope 2 with foraging range. We performed a phylogenetic comparative study of 43 species. Foraging range showed weak relationships with the low percentiles of colony size, but the strength of the association increased for larger percentiles, peaking at the maximum colony sizes. In order to model constraints on the functional relationship between the focal traits, we applied a quantile regression based on maximum colony size, which showed that the slope of the correlation was around 2 for species that have the higher colony sizes given their foraging ranges. Our results provide a mechanistic explanation to seabird colony sizes, and pose strong support to the hypothesis that food availability is an important regulator of seabird populations.
Databáze: OpenAIRE
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