Population Ecology

, Volume 53, Issue 4, pp 535–548

Low individual-level dietary plasticity in an island-invasive generalist forager

  • Lise Ruffino
  • James C. Russell
  • Benoît Pisanu
  • Stéphane Caut
  • Eric Vidal
Original Article

DOI: 10.1007/s10144-011-0265-6

Cite this article as:
Ruffino, L., Russell, J.C., Pisanu, B. et al. Popul Ecol (2011) 53: 535. doi:10.1007/s10144-011-0265-6

Abstract

The ability of invasive mammals to adjust their diet in response to new or variable resources is often proposed to explain their invasion success on islands with differing environmental conditions, especially islands with strong spatiotemporal changes in the nature and abundance of their resources. In this study, we investigated how habitat heterogeneity and seasonal fluctuation in resource quality affect dietary breadth and plasticity in an island-invasive rodent, the black rat Rattus rattus, on a small Mediterranean island. We tested for dietary plasticity of rats at both the individual and population levels by using traditional dietary and stable isotope analyses at successively increasing time scales, coupled with a long-term study of individual rats in three habitats of close proximity. Dietary and movement analyses both indicated that R. rattus is able to exploit a wide range of resources and habitats. However, dietary plasticity and habitat breadth were far narrower at the individual level. Results revealed that rats exclusively used resources found in their local habitat, and very few individuals moved among adjacent habitats in pursuit of higher-quality resources, despite those resources being abundant in their immediate environment. This counterintuitive finding suggests that intraspecific interactions must restrict rat mobility. Our results suggest that even on small islands, accessibility of patchy and high-quality resources to individuals from the entire population is not systematic. This result has important implications when quantifying invasive rodent impacts on patchily distributed species, especially when studies use indirect methods such as dietary analyses as a substitute for direct observations of predatory behavior.

Keywords

Alien invasive rodentsCapture–mark–recaptureDietary shiftInvasion successResource use

Copyright information

© The Society of Population Ecology and Springer 2011

Authors and Affiliations

  • Lise Ruffino
    • 1
  • James C. Russell
    • 2
  • Benoît Pisanu
    • 3
  • Stéphane Caut
    • 4
  • Eric Vidal
    • 1
  1. 1.IMEP, CNRS-UMR 6116 & IRD 193, Université Paul CézanneAix-en-Provence Cedex 04France
  2. 2.Department of Environmental Science, Policy, and ManagementUniversity of California-BerkeleyBerkeleyUSA
  3. 3.Département Ecologie et Gestion de la Biodiversité Conservation des espèces, restauration et suivi des populations, UMR 7204 MNHN-CNRS-P6Muséum National d’Histoire NaturelleParis Cedex 05France
  4. 4.Estación Biológica de DoñanaConsejo Superior de Investigationes Científicas (CSIC)SevilleSpain