Our good neighbors: Understanding ecosystem services provided by insectivorous bats in Rwanda

Bats are prodigious consumers of agricultural and forest pests, and are, therefore, a natural asset for agricultural productivity, suppressing populations of such pests. This study provides baseline information of diet of 143 bats belonging to eight insectivorous bat species from agricultural areas of Rwanda while evaluating the effectiveness of bats as pest suppressors. Using DNA metabarcoding to analyze bat fecal pellets, 85 different insect species were detected, with 60% (n = 65), 64% (n = 11) and 78% (n = 9) found to be agricultural pests from eastern, northern and western regions, respectively. Given the high percentages of agricultural pests detected, we submit that Rwandan insectivorous bats have the capacity for biocontrol of agricultural pests. Rwandan bat populations should be protected and promoted since they may foster higher crop yields and sustainable livelihoods.

Compromises: sound frequencies used in echolocation by aerial-feeding bats

Hunting aerial-feeding bats, species that take airborne prey (usually flying insects), use echolocation to detect, track,and assess targets. The echolocation calls of aerial-feeding bats at sites in Canada (British Columbia and Ontario), Mexico,Brazil, and Zimbabwe were significantly dominated by frequencies between 20 and 60 kHz, although at the more tropicallocations some aerial-feeding bats used echolocation calls with most energy <20 or >60 kHz. The impact of frequency-specificattenuation, perhaps combined with frequency-specific, hearing-based defenses of some insects, suggests that by usingecholocation calls <20 kHz, bats could both extend the effective range of echolocation and make their calls less conspicuous toinsect ears. Bats using calls >60 kHz would be less conspicuous to the insects. We found two patterns of echolocation-callbehaviour. Most adjacent echolocation calls, and all that were dominated by sounds >20 kHz, showed large (80%) overlap inbandwidth. The other pattern involved much less overlap in bandwidth (0–30%) between adjacent calls and was evident in thecalls of the molossid Tadarida midas, which used echolocation calls dominated by sounds <20 kHz. This behaviour wouldallow the echolocating bat to extend its effective range of perception by separating in frequency the echoes returning fromadjacent calls.