Seasonality and relationships of food resource use of Martes martes, Genetta genetta and Felis catus in the Balearic Islands

Abstract

Year-round diet characteristics of pine martens (Martes martes), spotted genets (Genetta genetta), and feral cats (Felis catus) were studied on Mallorca, Ibiza, and Cabrera in the Balearic archipelago, Spain. Analysis of 2531 scats were used to describes seasonal food habits and its variation. Mallorcan pine marten diets varied least of all between seasons. Plant material (mainly fruit) was the dominant pine marten food followed by mammals which appeared in half of the seasonal samples. Mallorcan and Ibizan genet diets were most alike, while Cabreran genet diets were markedly different from the two. Mammals were the dominant year-round diet component on Mallorca and Ibiza, whereas mammals and birds were of equal importance on Cabrera. Genets preyed heavily on wood mice (Apodemus sylvaticus) on Mallorca and Ibiza, and rats (Rattus) on Cabrera. Avian predation was highest on Cabrera and Ibiza during autumn and winter. Mammals and reptiles were major year-round diet components of Cabreran feral cats. Human refuse and birds were seasonally important cat foods and were consumed when most abundant on the island. Trophic niche breadth values were greatest for Cabreran genets and lowest for Mallorcan genets. On Mallorca and Cabrera, coexisting carnivores had similar niche breadth values but exploited the available foods differently. Mallorcan and Ibizan genet diets were most similar while on Cabrera genets were opportunistic predators. The methodological limitations of genet diet descriptions from faecal mass analysis are presented. A method for determining correction factors for diet meaures of faecal mass food items from scats is proposed.