Trophic niche changes associated with habitat fragmentation in a Neotropical bat species

Abstract

Habitat fragmentation could alter ecological traits including species trophic habits.Here, we used carbon and nitrogen stable isotope ratios to establish differences in isotopic niche width and food resource use between forest fragments and the continuous forest for the phyllostomid frugivorous bat Artibeus lituratus. Using mist nests, we captured bats from two forest fragments and two sites in continuous forest, and sampled from each individual captured three body tissues with contrasting turnover rates (skin, muscle, and liver). Samples were collected between February and March (austral summer) and between August and September (austral winter). In addition, in each sampling site and season we collected potential food resources (fruits and insects) consumed by our A. lituratus. Our findings indicate that A. lituratus had a predominantly omnivorous diet, with high consumption of insects during summer in forest fragments. The increasing consumption of insects in these fragments seems to have led to a wider isotopic niche, in relation to the continuous forest. Because A. lituratus is typically a seed disperser, changes in trophic habits in the forest fragments from frugivory to insectivory may diminish their role in forest regeneration.Abstract in Portuguese is available with online material. K E Y W O R D SBrazilian Atlantic Forest, feeding habits, forest regeneration, phyllostomid bat, stable isotope analysis

Seasonal dietary niche changes in Neotropical bats

“…Stevens (2022b), in his study for the Atlantic Forest, warns that food seasonality together with habitat modification is the main driver of reduced specialisation and increased overlap of bat diets. We also expected higher values of niche breadth during the dry season, and our results show a niche expansion (see Figure 2), and this is in line with the optimal foraging theory, where individuals should specialise when resources are plentiful, but when faced with scarcity they tend to increase the number of items included in the diet (Muñoz-Lazo et al 2019; Stephens & Krebs, 1986).…”

“…Finally, we shall state that, however, faecal analysis is a widely employed technique; it may have disadvantages when compared with DNA metabarcoding and isotopic composition investigation (Oliveira et al . 2022; Munoz-Lazo et al 2019). These techniques show food items taken for long periods and not just those ingested during a unique consumption event (Schlautmann et al 2021, Vizentin-Bugoni et al 2021).…”

“…This may give them an advantage in exploiting these resources over other generalist species (Carvalho & Cardoso 2020, Muñoz-Lazo et al . 2019). Stevens (2022b), in his study for the Atlantic Forest, warns that food seasonality together with habitat modification is the main driver of reduced specialisation and increased overlap of bat diets.…”

“…This occasional specialisation in a smaller set of resources in seasonal times is important for the species because, in the face of more intense competition, bats restrict the use of a shared resource (Carvalho & Cardoso 2020). This may give them an advantage in exploiting these resources over other generalist species (Carvalho & Cardoso 2020, Muñoz-Lazo et al 2019. Stevens (2022b), in his study for the Atlantic Forest, warns that food seasonality together with habitat modification is the main driver of reduced specialisation and increased overlap of bat diets.…”

Variation in diet of frugivorous bats in fragments of Brazil’s Atlantic Forest associated with vegetation density

“…These suggest that, in denser fragments A. lituratus have a larger insect component in their diet than in more open forests, irrespective of fragment size or distance between fragments. A similar study examining differences in diet of A. lituratus found in fragments and in contiguous forest found an increase of insect consumption in fragments and in seasons when fruit resources were limited (Muñoz-Lazo et al 2019). Notably, in contrast to our study, Muñoz-Lazo et al (2019) found that this increased the niche breadth of A. lituratus, while we found no significant differences in niche breadth between different sampling 2019) did not characterize the locations they sampled beyond "fragment" and "continuous" forest, we found no significant effect of landscape metrics that are typically characterized as habitat fragmentation (i.e., AREA + ISOLATION, AREA, or PROX1000).…”