Habitat- and density-dependent demography of a colonial raptor in Mediterranean agro-ecosystems

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13 Citazioni (Scopus)

Abstract

Agricultural intensification is considered the major cause of decline in farmland bird populations, especially inthe Mediterranean region. Food shortage increased by the interaction between agricultural intensification anddensity-dependent mechanisms could influence the population dynamics of colonial birds. Weused demographicdata on lesser kestrels (Falco naumanni), a key species of Mediterranean pseudo-steppes, to understand the importanceof land-use changes and density-dependent mechanisms in the light of its fluctuating conservationstatus in the Western Palearctic. Our analysis indicated an important influence of land uses (artichokes, arableand grassland fields) and colony size on kestrel survival rates. The strong habitat effect revealed the unsuitabilityof intensive arable lands with respect to extensive grasslands for lesser kestrels. Notably, artichokes, a winterintensivecrop, proved to be a high-quality habitat as they were associated with survival values equal to thoseof grassland. This is likely due to prey availability and reveals that non-traditional crops may provide suitablehabitats for lesser kestrels. Information theory gave strong support to the negative influence of colony size on fecundity,albeit a small one, for its positive effect on survival probability. The estimated population growth ratewas negative for all three habitats, indicating a decline over time and urging conservation actions in all of theareas studied. This decline was much higher in colonies surrounded by arable fields. In sensitivity analyses, λ indicatedthat adult survival was the parameter with the greatest effect on population growth, followed by survivalof fledglings and fecundity. Our study showed howthe costs and benefits of group living interact with agriculturalintensification to drive species demography. In addition, we integrated significant information on one of thelargest lesser kestrel populations to fine tune the most effective conservation strategy to prevent the collapseof the species in a relevant part of its range.
Lingua originaleEnglish
pagine (da-a)116-123
Numero di pagine8
RivistaBiological Conservation
Volume193
Stato di pubblicazionePublished - 2016

All Science Journal Classification (ASJC) codes

  • Ecology, Evolution, Behavior and Systematics
  • Nature and Landscape Conservation

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