Oecologia

, Volume 172, Issue 3, pp 737–749

Anthropogenic subsidies mitigate environmental variability for insular rodents

Population ecology - Original research

DOI: 10.1007/s00442-012-2545-z

Cite this article as:
Ruffino, L., Russell, J. & Vidal, E. Oecologia (2013) 172: 737. doi:10.1007/s00442-012-2545-z

Abstract

The exogenous input of nutrients and energy into island systems fuels a large array of consumers and drives bottom-up trophic cascades in island communities. The input of anthropogenic resources has increased on islands and particularly supplemented non-native consumers with extra resources. We test the hypothesis that the anthropogenic establishments of super-abundant gulls and invasive iceplants Carpobrotus spp. have both altered the dynamics of an introduced black rat Rattus rattus population. On Bagaud Island, two habitats have been substantially modified by the anthropogenic subsidies of gulls and iceplants, in contrast to the native Mediterranean scrubland with no anthropogenic inputs. Rats were trapped in all three habitats over two contrasting years of rainfall patterns to investigate: (1) the effect of anthropogenic subsidies on rat density, age-ratio and growth rates, and (2) the role of rainfall variability in modulating the effects of subsidies between years. We found that the growth rates of rats dwelling in the non-subsidized habitat varied with environmental fluctuation, whereas rats dwelling in the gull colony maintained high growth rates during both dry and rainy years. The presence of anthropogenic subsidies apparently mitigated environmental stress. Age ratio and rat density varied significantly and predictably among years, seasons, and habitats. While rat densities always peaked higher in the gull colony, especially after rat breeding in spring, higher captures of immature rats were recorded during the second year in all habitats, associated with higher rainfall. The potential for non-native rats to benefit from anthropogenic resources has important implications for the management of similar species on islands.

Keywords

Anthropogenic resourcesMediterranean islandsPopulation dynamicsRattus rattusTrophic subsidies

Supplementary material

442_2012_2545_MOESM1_ESM.doc (93 kb)
Supplementary material 1 (DOC 93 kb)

Copyright information

© Springer-Verlag Berlin Heidelberg 2012

Authors and Affiliations

  1. 1.Department of Biology, Section of EcologyUniversity of TurkuTurkuFinland
  2. 2.IMBE, UMR CNRS7273/IRD237/Aix-Marseille UniversityAix-en-Provence Cédex 04France
  3. 3.School of Biological Sciences and Department of StatisticsUniversity of AucklandAucklandNew Zealand
  4. 4.IMBE, UMR CNRS 7263/IRD 237/AMU Centre IRD de NoumeaNoumea cedexFrance