Risk Research on Bat Survival

Research on Beavers reintroduced into Poland’s forests suggests that their logging and dams help bats find insects:

We aimed to test the hypothesis that beaver activity promotes new foraging sites for insectivorous bats. The beaver’s influence can be especially significant on aerial hawkers that prefer moderate structural clutter, like the Pipistrellus species (by creating new canopy gaps), and on water-surface foragers, like Myotis daubentonii (by creating ponds with smooth water surface). The study was conducted on small streams in forest areas of northern Poland, which were colonized by the European beaver (Castor fiber). Bat activity was recorded with a Pettersson D-980 ultrasound detector on line transects. The number of bat passes was significantly higher in the stream sections modified by beavers (flooded and subjected to intensive tree cutting) than in the unmodified sections (for Pipistrellus nathusii, Pipistrellus pipistrellus, Pipistrellus pygmaeus, Nyctalus noctula, and all species lumped together).

On the other hand, research on wind turbines and wind farms shows that they disturb insect patterns and kill bats:

We suggest that mortality of bats at wind turbines may be linked to high-altitude feeding on migrating insects that accumulate at the turbine towers. Modern wind turbines seem to reach high enough into the airspace to interfere with the migratory movements of insects. The hypothesis is consistent with recent observations of bats at wind turbines. It is supported by the observation that mortality of bats at wind turbines is highly seasonal (August–September) and typically peaks during nights with weather conditions known to trigger large-scale migratory movements of insects (and songbirds).

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