Local feeding specialization of the red fox (Vulpes vulpes) in response to eastern cottontail (Sylvilagus floridanus) introduction (NW Italy)

Alessandro Balestrieri, Luigi Remonti, Claudio Prigioni
2006 Hystrix, the Italian Journal of Mammalogy  
To appreciate the influence of the introduction of the Eastern cottontail (Sylvilagus floridanus) on the food habits of the red fox (Vulpes vulpes), between June 1998 and February 2000 fox diet was investigated by means of scat analysis (N=115) in a 250 ha wide Natural Reserve of NW Italy, and compared with data collected in the same area prior to cottontail colonization (1988-1989). Comparison included also the diet of badgers (Meles meles), considered as potential competitors for food
more » ... rs for food resources. Alien lagomorphs (mean percent volume, Vm% = 68%) represented by far the most exploited resource, only three other food items reaching values of mean percent volume barely higher than 5%. Cottontails frequency of occurrence did not vary according either to season or to their reproductive cycle (II-IX vs. X-I), whilst diet niche breadth varied inversely proportional to the use of this key-resource. Overall fox trophic niche breadth varied from 0.64 in 1988-89 to 0.31 in 1998-00 (B, Levin's index). These findings led us to consider the feeding habits of the fox in the study area as a result of local specialization of a typical generalist carnivore, according to the predictions of optimal foraging theory. No variation occurred in the badger niche breadth since cottontail introduction, whilst niche overlap between foxes and badgers decreased from 0.59 to 0.13 (O, Pianka's index), possibly reducing competition for food in summer. Riassunto Specializzazione alimentare a livello locale della Volpe Vulpes vulpes in risposta all'introduzione del Silvilago Sylvilagus floridanus (Italia nord occidentale). Per valutare gli effetti dell'introduzione del Silvilago (Sylvilagus floridanus) sul comportamento alimentare della volpe (Vulpes vulpes), nel periodo giugno 1998-febbraio 2000, la dieta del carnivoro è stata definita tramite l'analisi di 115 feci raccolte nella Riserva Naturale "Garzaia di Valenza" (Provincia di [...]
doi:10.4404/hystrix-16.2-4349 doaj:cc59af1132f34b85926a1810a22adefe fatcat:mpd5arkpfrhzfkam6olmsi42ia