@article {48147, title = {Trophic niche flexibility in Glossophaga soricina: how a nectar seeker sneaks an insect snack}, journal = {Functional Ecology}, volume = {28}, year = {2014}, month = {Jan-06-2014}, pages = {632 - 641}, abstract = {

Omnivory enables animals to fill more than one trophic niche, providing access to a wider variety of food resources with potentially higher nutrient value, particularly when resources become scarce. Animals can achieve omnivory using different strategies, for example opportunistic foraging, or switching between multiple trophic niches.

The Neotropical bat Glossophaga soricina (Pallas, 1766) is a common and widespread species known for nectar feeding, but it also eats fruit and insects. Approaching stationary objects (flowers and fruits) or moving objects (insects) poses different sensory tasks and should require different echolocation behaviours. Here we tested the contrasting hypothesis that G. soricina can approach both stationary and moving objects using the same echolocation behaviour, thus feeding at different trophic levels by a single sensory mechanism.

Using DNA barcoding, we demonstrate that G. soricina eats beetles (Coleoptera), flies (Diptera) and noctuid moths with bat-detecting ears. Laboratory observations show that G. soricina actively hunts for prey so insect consumption does not appear to be opportunistic. After capture, individuals consumed prey while perched and manipulated them with jaw, thumb, wrist and wing movements, but food handling was longer and chewing rate slower than in obligate insectivores.

In contrast to most insectivorous bats, the echolocation calls of G. soricina are of high frequency and low intensity, and G. soricina did not produce feeding buzzes when approaching insects. An acoustic model of detection distances shows that its low-intensity calls fail to trigger the auditory neurons of eared moths, allowing G. soricina to overcome auditory prey defences.

Individuals achieved niche flexibility using a unique but generalist behavioural approach rather than employing two different specialist methods. Our findings provide a novel insight into the functional mechanisms of insect capture in G. soricina and highlight the importance of considering niche flexibility in classifying trophic links in ecological communities.

}, keywords = {acoustic modelling, bats, molecular scatology, predator{\textendash}prey, stealth echolocation}, doi = {10.1111/fec.2014.28.issue-310.1111/1365-2435.12192}, url = {http://doi.wiley.com/10.1111/fec.2014.28.issue-3}, author = {Clare, Elizabeth L. and Goerlitz, Holger R. and Drapeau, Violaine A. and Adams, Amanda M. and Nagel, Juliet and Dumont, Elizabeth R. and Hebert, Paul D. N. and Brock Fenton, M.}, editor = {Konarzewski, Marek} } @article {48144, title = {Sensory ecology of prey rustling sounds: acoustical features and their classification by wild Grey Mouse Lemurs}, journal = {Functional Ecology}, volume = {21}, year = {2007}, month = {Jan-02-2007}, abstract = {

1. Predatory mammals and birds from several phylogenetic lineages use prey rustling sounds to detect and locate prey. However, it is not known whether these rustling sounds convey information about the prey, such as its size or profitability, and whether predators use them to classify prey accordingly.

2. We recorded rustling sounds of insects in Madagascar walking on natural substrate and show a clear correlation between insect mass and several acoustic parameters.

3. In subsequent behavioural experiments in the field, we determined whether nocturnal animals, when foraging for insects, evaluate these parameters to classify their prey. We used field-experienced Grey Mouse Lemurs Microcebus murinus in short-term captivity. Mouse Lemurs are generally regarded as a good model for the most ancestral primate condition. They use multimodal sensorial information to find food (mainly fruit, gum, insect secretions and arthropods) in nightly forest. Acoustic cues play a role in detection of insect prey.

4. When presented with two simultaneous playbacks of rustling sounds, lemurs spontaneously chose the one higher above their hearing threshold, i.e. they used the rustling sound\&$\#$39;s amplitude for classification. We were not able, despite attempts in a reinforced paradigm, to persuade lemurs to use cues other than amplitude, e.g. frequency cues, for prey discrimination.

5. Our data suggests that Mouse Lemurs, when foraging for insects, use the mass\–amplitude correlation of prey-generated rustling sounds to evaluate the average mass of insects and to guide their foraging decisions.

}, keywords = {foraging, prey choice, prey selection, primates, size selection}, issn = {0269-8463}, doi = {10.1111/fec.2007.21.issue-110.1111/j.1365-2435.2006.01212.x}, url = {http://www.blackwell-synergy.com/toc/fec/21/1}, author = {Goerlitz, H. R. and Siemers, B. M.} }