Seasonal variation in the diet of two predators in an agroecosystem in southern–central Chile

Abstract

In ecosystems, seasonal fluctuations in the availability of resources can promote effects on species with similar trophic requirements, increasing the probability of interspecific competition. This scenario becomes more evident in human–dominated landscapes where homogenization of space can contribute to the shortage of resources, modifying species feeding behavior to an uncertain degree. Understanding how these species modify their feeding habits within the context of habitat transformation is of special interest. We evaluated the diversity of prey and overlap for two predators, the chilla fox Lycalopex griseus and the barn owl Tyto alba, during three seasons in 2018 (winter, spring and summer). The study was based on the analysis of feces and pellets in a landscape with agricultural predominance in Southern–central Chile. We found the chilla fox had a generalist dietary profile, feeding on a broad spectrum of prey, with predominance of lagomorphs and, to a lesser extent, rodents. In contrast, the diet of the barn owl mainly consisted of small rodents, with little variation across seasons. Analyses of dietary overlap showed fluctuations during the periods surveyed, with a maximum value in winter and a minimum value in spring. Variations in the consumption of prey based on their size could facilitate their coexistence in the study area.

Landscape use and food habits of the chilla fox (Lycalopex griseus, Gray) and domestic dog (Canis lupus familiaris) in a peri-urban environment of south-central Chile

“…This shows the importance that this item occupied in dietary terms. This fi nding is consistent with what was observed in agroecosystems (ZÚÑIGA et al, 2018;ZÚÑIGA et al, 2021), which suggests that this prey is acquiring more relevance as the environment is transforming (SIMONETTI, 1986). The incorporation of murids in the intermediate position of the isoclines is consistent with the aforementioned study of agroecosystems, which indicating that this group also presents importance in the diet of chilla fox, with a decrease of native prey (NOVARO et al, 2000).…”

“…The incorporation of murids in the intermediate position of the isoclines is consistent with the aforementioned study of agroecosystems, which indicating that this group also presents importance in the diet of chilla fox, with a decrease of native prey (NOVARO et al, 2000). On the other hand, the geometric mean values of prey in general terms are lower than those reported in agroecosystems (ZÚÑIGA et al, 2021), which suggests a low availability of prey in peri-urban habitats, with limitations to obtain their energetic requirements (SILVA et al, 2005).…”

“…This means that the effect the urban mosaic would affect the availability of preys, and therefore their spatial patterns. In a similar way, recordings of chilla foxes in agroecosystems were low in all seasons sampled (ZÚÑIGA et al, 2021), which was explained by the homogenization of resources present in this environment (BENTON et al, 2003).…”

“…To avoid the incidence of type-I errors as a consequence of multiple comparisons, Bonferroni correction was performed (HOLM, 1979). The proportion in the consumption of each item was compared across seasons to determine if there were variations among these periods, for which the arithmetic mean of the frequencies obtained for each case was considered as the expected value (ZÚÑIGA et al, 2021). The biomass calculation of the prey consumed by chilla fox was carried out through geometric mean (JAKSIC and BRAKER, 1983), an indicator that was estimated for the four sampling seasons.…”