Utah’s open occurrence databases hold 30 records of the western little brown myotis, and only about a dozen of those are research-grade iNaturalist sightings; most of the rest come from GBIF. That’s a thin paper trail for a bat that spends its nights over ponds and slow water hunting insects and its days tucked into a crevice or rafter where nobody’s looking, not a sign of how many are actually out there.
Roosting from Wasatch rock to Uinta forest
This bat needs a warm, dark crevice for daytime cover and gathers in colonies from a handful of bats to several thousand wherever it finds one. Utah’s Wasatch Range and the Uinta-Wasatch-Cache National Forest supply that mix well: rocky fissures, hollow conifers, and old barns or cabins scattered along the Wasatch Front and Back. Because this species adapts to buildings about as readily as it does natural rock, a loose board on a Heber Valley shed can work as well as a crevice in the canyon wall above it.
Hunting the Provo River’s slow water
Nearly its whole diet is insects taken on the wing, mostly moths, mosquitoes, and midges snatched low over ponds and slow-moving water. Jordanelle Reservoir and the stretch of the Provo River that feeds it give this bat some of its best hunting ground in the Wasatch Back, and records cluster near that kind of water even in a state where most of the land stays dry.
A summer spike, then a long sleep
Utah records peak sharply in July and August, exactly when pregnant females crowd into warm nursery roosts to raise a single pup each and both mothers and young are out foraging most nights. A smaller rise shows again in October, likely bats still active before they head for a cave or old mine tunnel with steady, near-freezing air to sleep out the winter.
Status in Utah
NatureServe ranks the western little brown myotis S3, vulnerable, in Utah, and it’s native here, not introduced from anywhere else. The bigger picture is bleak almost everywhere the species has been checked: a cold-loving fungus called white-nose syndrome has wiped out huge hibernating colonies across the East since 2006, and the IUCN now lists the species as globally Endangered. The interior West, Utah included, hasn’t seen anything like that collapse yet, which is part of why every fresh record from here still counts.
Full species profile
