Differential responses of marsh predators to rainfall-induced habitat loss and subsequent variations in prey availability

Abstract

Rainfall has increased in many regions during recent decades, but most information is from dryland ecosystems, which precludes generalizations about its ecological consequences. We explored the effects of increased flooding on the Geoffroy’s cat, Leopardus geoffroyi (d’Orbigny and Gervais, 1844), and pampas fox, Pseudalopex gymnocercus (G. Fischer, 1814), exposed to an abnormally rainy period in marshes at Mar Chiquita, Argentina. In particular, we assessed the effects of flooding on (i) habitat use by L. geoffroyi and P. gymnocercus, (ii) abundance of their main prey, and (iii) functional responses of predators to variations in prey abundance. Overall, simple regression analysis identified negative effects of flooding on abundance of prey (rodents, waterbirds, and arthropods), but structural-equation modeling and logistic generalized linear models identified differential effects of rainfall on habitat use by and functional responses of predators, respectively. Habitat use by L. geoffroyi was more negatively affected by interannual variability in flooding-induced habitat loss, particularly through its effect on waterbirds. At the same time, habitat use by P. gymnocercus was less affected, likely because this species was less dependent on prey from flooded areas and used higher elevation habitats. Given that most native grasslands in elevated areas have been converted to agriculture, the more specialized L. geoffroyi faces a greater threat if current trends of climate change persist in this region.