Decreasing dietary diversity following habitat loss: the case of the thin-spined porcupine in the Atlantic forest

Abstract

The thin-spined porcupine (Chaetomys subspinosus Olfers, 1818) is an endemic and threatened rodent from the Atlantic Forest biological hotspot. Previous studies have demonstrated it follows a strictly leaf-based diet, limited to a few tree species, although such information is derived from few individuals (n = 7) resident in small forest fragments. We aimed to evaluate whether such dietary specialization persists when animals inhabit larger forest fragments. For this, we assessed the diet composition of 19 radiotracked individuals inhabiting small ( 500 ha; n = 9) forest fragments in southern Bahia state. We compared the composition and diversity of the diet in terms of tree parts and species consumed in these contrasting fragment size environments. Secondly, we aimed to evaluate the influence of leaf chemical composition on the consumption of plant species. Our findings show that the thin-spined porcupine is a strict folivore, with individuals responding to the reduction in forest size by reducing the diversity of plant species consumed, but not by feeding on new plant parts. Although the diet was richer in larger forest fragments, certain tree species were the most consumed in both fragment-size categories and the unique item consumed were leaves. Fiber influenced positively the leaf consumption of the plant species, while there was no effect of other chemical characteristics. The influence of the habitat size reduction on food diversity may be a risk factor for the species.