Thursday, February 16, 2017


We know based on aural and/or visual detections that we have at least five species of owls on the Reserve; great horned owl, Northern pygmy owl, Northern saw-whet owl (NSWO, fall through spring?), California spotted owl (winter only), and Western screech owl (WESO). The screech owls are year-round residents and will sometimes come to investigate our NSWO caller, so they get caught in the nets. We have banded 25 WESO over 12 years of monitoring NSWO. Sometimes we are lucky to see them roosting in a cavity during the day, or perching at night. Banders Erika and Ken saw this owl perching in the barn, likely
Western screech owl in the barn at the Reserve
Possibly foraging on bats? He/she appears a little
perturbed at the disruption!
taking advantage of barn mammals. It may have been foraging on the bats that roost there! There happens to be a colony of wintering free-tailed bats, and potentially other bat species, living in the barn. I have seen great horned owls, peregrines, merlins, kestrels and red-tailed hawks capturing bats as they exit their roosts. It was quite an exciting flight dynamic as the predator bursts in a cloud of bats.  The success rate on capturing bats seemed pretty low. What we need to determine if this WESO has a palate for bats, is to find some pellets to identify prey remains.

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