Do bigger bats need more time to forage?

Abstract

We test the hypothesis is that bats using the same area and at the same time would be using similar preys, but they would have different foraging times due to specific differences in biomass. A total of 730 captures was analyzed 13 species of Vespertilionidae and Molossidae bats netted over a small dam in southeastern Brazil from 1993 and 1999. The relationship between the average time of captures and the biomass of the species of Vespertilinidae and Molossidae most frequent (captures > 4) was positive and significant (r = 0.83, p = 0.022, N = 7). Two lines are discussed to answer the longer foraging time for bigger bats: 1) larger insectivorous bats don't consume proportionally larger preys and 2) larger insects are less available.Keywords: foraging time, insectivorous bats, feeding strategies, southeastern Brazil, Molossidae, Vespertilionidae. Maiores morcegos precisam de mais tempo de forrageamento? ResumoTestamos a hipótese de que morcegos insetívoros usando a mesma área podem estar usando as mesmas presas, mas têm diferentes tempos de forrageamento devido às diferenças de biomassa. De um total de 730 capturas, foram analisadas 13 espécies de Vespertilionidae e Molossidae capturadas em redes armadas sobre um pequeno açude no Sudeste do Brasil entre 1993 e 1999. A relação entre a média do horário de captura e a biomassa das espécies de Vespertilionidae e Molossidae mais freqüentes (capturas > 4) foi positiva e significante (r = 0,83, p = 0,022, N = 7). Duas linhas são discutidas para responder ao maior tempo de forrageamento pelos maiores morcegos: (1) morcegos insetívoros maiores não consomem presas proporcionalmente maiores; e (2) maiores insetos são menos disponíveis.Palavras-chave: horário de forrageamento, morcegos insetívoros, estratégias alimentares, sudeste do Brasil, Molossidae, Vespertilionidae.

Bat diversity of Ilha da Marambaia, Southern Rio de Janeiro State, Brazil (Chiroptera, Mammalia)

“…On Ilha da Marambaia an insectivorous species, M. molossus, predominated, since it was captured at the river delta, over water or at the dam. Only in Gávea Park (Parque da Gávea), Rio de Janeiro city (see Esbérard, 2003;Esbérard and Bergallo, 2008b), a similar result was obtained, in which M. molossus outnumbered a frugivorous species. Insectivorous bats can outnumber the frugivorous ones at least in some places, and nets opened over water collections are more productive in capturing insectivorous bats than nets in trails (Kunz and Kurta, 1988;Voss and Emmons, 1996).…”

Community structure of a Neotropical bat fauna as revealed by stable isotope analysis: Not all species fit neatly into predicted guilds

“…Community‐wide metrics of body size are likely less relevant to resource availability as many bats within the fauna vary significantly in feeding strategy. From an energetics perspective, larger bats may require more time to forage, though this may not reflect a larger niche breadth; some species may be specialists searching for ideal food sources (Esbérard & Bergallo, ; Peters, ). Barclay and Brigham () argued that body size does not limit prey type as much as does detection method, noting the high abundance of small generalist aerial insectivores that detect prey via echolocation, whereas bats that listen for prey‐generated sounds and glean their prey off the ground or vegetation tend to be larger and less common.…”

Relacionando dieta e horários de captura entre duas espécies de morcegos frugívoros (Chiroptera, Phyllostomidae, Stenodermatinae)

“…Essa correlação na dieta, juntamente com informações sobre os padrões horários e sazonais de atividades, proporcionam o entendimento da ocupação do nicho e do estabelecimento e manutenção das comunidades nos ecossistemas (PIANKA, 1969;SCHOENER, 1974). Esses padrões de atividades devem ajustar-se às variações de alguns fatores, como: disponibilidade de alimento, possibilidade de serem predados (ESBÉRARD; BERGALLO, 2008;RYDELL, 1994;KUNZ;ANTHONY, 1996) e competição com espécies de hábitos alimentares similares (KUNZ;ANTHONY, 1996).…”