Mammal Research

, Volume 64, Issue 1, pp 121–125 | Cite as

Stable isotope analyses suggest Mus musculus occupies the place of the “possibly extinct” Peromyscus guardia in Angel de la Guarda Island, (Mexico)

  • Ma Carmen Blázquez
  • Gustavo Arnaud
  • Víctor Ortiz-Avila
  • Alfredo Ortega-Rubio
  • Miguel Delibes
Short Communication


According the IUCN Red List criteria, species must be tagged as “possibly extinct” when there is a small chance that they may be extant. This means that the formal acceptance of the extinction is very dependent on search effort. Here, we report two unsuccessful attempts to detect the critically endangered (possibly extinct) Peromyscus guardia on Angel de la Guarda Island (Gulf of California, Mexico). Instead, we found that invader house mice seem to be very abundant just at the same habitat (beaches) where P. guardia were lastly reported. We analyzed the isotopic niche of the house mice, confirming that the species is currently occupying the presumed trophic niche (common use of marine resources: stranded remains and littoral invertebrates) of the last known populations of P. guardia. The apparent replacement of the specialized endemic species by the ubiquitous house mouse is a new evidence of the current trend towards global biodiversity homogenization.


Conservation Insular fauna Invasive species Marine subsidies Threatened species 



We thank Mr. C. Swann for field assistance and for the review of the English of the manuscript; Herbarium (Drs. R. Cadenas and A. Medel), Macroalgae Laboratory (M.C A. Mazariegos), and Animal Ecology Laboratory (A. Cota) of CIBNOR for identification of plants, algae, and cat’s preys; S. Carrasco, J. Navarro, and the Laboratory of Stable Isotopes of EBD (CSIC) for isotopic analyses and explanations; and Dr. Lacher and two anonymous reviewers for their useful comments in improving the manuscript.

Funding information

Research was supported by a sabbatical grant (number 454959) to M.C. Blázquez, Projects CONACYT 251919 and CONACYT 269540.


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Copyright information

© Mammal Research Institute, Polish Academy of Sciences, Białowieża, Poland 2018

Authors and Affiliations

  1. 1.Centro de Investigaciones Biológicas del Noroeste CIBNOR, Dpto. Planeación Ambiental y ConservaciónLa PazMexico
  2. 2.Estación Biológica de Doñana-CSICSevillaSpain

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