Food processing does not affect energy intake in the nectar-feeding bat Anoura geoffroyi

Food processing affects the way animals behave with important implications in their ecology and community structure. Despite numerous studies of food processing by nectar-feeding bats have been done, these have been focused on species living in tropical climates, whereas the information about species inhabiting high altitude environments is scarce. Here, we investigated food processing of the nectar-feeding bat Anoura geoffroyi, a species that can be found in places above 2, 500 m a.s.l. To do this, we evaluated the capacity of bats to assimilate the energy content in seven sucrose solutions ranging from 5 to 35%. We measured: 1) nightly food/energy intake, and 2) changes in body mass of seven captive individuals feeding from the different experimental solutions. Bats increased food intake nearly seven times (from 16.9 ± 4.7 to 111.6 ± 18.7 g) when sucrose concentration decreased from 35 to 5% (wt/vol). By doing this, animals were able to obtain a constant energy intake of 101.07 kJ ± 5.4 (mean ± SD) and a mean body mass gain of 1.31 g ± 0.1 (mean ± SD). Both values were independent of sugar concentration. This response (known as compensatory feeding) may enable bats the access to many feeding sources present in their environment, increasing their feeding niche-breadth and their ability to live in cold environments.