Introduced black rats Rattus rattus on Ile de la Possession (Iles Crozet, Subantarctic): diet and trophic position in food webs.

• Published in: Polar Biology
• Main Authors: Pisanu, Benoit, Caut, Stephane, Gutjahr, Sylvain, Vernon, Philippe, Chapuis, Jean Louis
• Other Authors: Centre d'Ecologie et des Sciences de la COnservation (CESCO), Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN), Centro de Investigaciones Biológicas (CSIC), Consejo Superior de Investigaciones Científicas Madrid (CSIC), Ecosystèmes, biodiversité, évolution Rennes (ECOBIO), Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR)-Institut Ecologie et Environnement (INEE), Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES), IPEV 136 Ecobio CNRS ZA Antarctique et Subantarctique CSIC, ANR-05-BDIV-0003,ALIENS,Assessment and Limitation of the Impacts of Exotic species in Nationwide insular Systems(2005)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2011
• Subjects: Introduced rodent; Rattus rattus; Diet; Stable isotopes; Food web; Subantarctic island; envir; anthro-se; Polar Biology
• Online Access: https://doi.org/10.1007/s00300-010-0867-z; https://hal.archives-ouvertes.fr/hal-00597309

International audience Rats introduced on islands can affect ecosystem structure and function by feeding on terrestrial plants and both marine and terrestrial animals. The diet and trophic position of Rattus rattus introduced on Ile de la Possession (Iles Crozet) was assessed from two sites, according to the presence or absence of a king penguin colony. We used three complementary assays: macroanalyses of the stomach, faecal microhistology, and stable isotope analyses of d15N/d13C in liver. Near the rookery, spermatophytes contributed on average 50% (confidential interval: 23-75) to the diet based on isotopes, mainly consisting in reproductive parts of Poa spp., Agrostis magellanica, and Cerastium fontanum identified in faeces. Terrestrial animal preys were represented by insects that contributed 25% (0-56) in isotopes, dominated in faeces by caterpillars of Pringleophaga spp. and adult weevils. Bird remains were found in faeces, forming 18% (6-30) of isotopes. Terrestrial earthworms contributed to 7% (0-21), with chaetae observed in faeces. On the other site, spermatophytes represented 62% (51-73) of assimilated food in rats' livers, mainly formed by Poaceae and Acaena magellanica, insects by caterpillars [24% (10-39)], and terrestrial earthworms [13% (2-23)]. Our results suggest that rats, which were found at the top of terrestrial food chains, may have a direct role on a such simplified ecosystem, by preying on the most abundant and largest body-sized terrestrial invertebrates,--e.g. the keystone species Pringleophaga spp.--, and by feeding on both reproductive and vegetative parts of autochthonous and introduced plants. The discrepancies and usefulness of employing both isotopes and faecal analyses are discussed.