Darkness falls as two people wearing headlamps secure one end of a nearly-invisible mist net to a supporting pole
Mist nets set up at night in bat habitat are being used to survey bats in Marin County and examine them for signs of White Nose Syndrome. Starting in late July, bats captured via mist netting on state and federal park lands will also be fitted with radio telemetry devices.

Courtesy Sue Gardner / Golden Gate National Parks Conservancy

June 2018 - The US Geological Survey Western Ecological Research Center, Point Reyes National Seashore, and One Tam partners are embarking on their second year of bat surveys in Marin County. The collaborative effort aims to shed light on local bat species diversity, distribution, roosting sites, and disease.

Acoustic monitoring to help measure bat diversity is already underway and will cover 31 different sites. Starting at the end of July, bats caught on state and national park lands will be fitted with radio telemetry tags and then tracked to their roosting sites. The number of bats that then emerge from the roost in the evening will be counted, and surveys of the vegetation and other features will help reveal what kinds of roosting habitats the bats prefer.

Head-on view of a hoary bat held in a gloved hand
Hoary bat captured during mist netting.

Courtesy Sue Gardner / Golden Gate National Parks Conservancy

Last year’s surveys provided baseline data about species composition and foraging habitats of 13 species, with some sites recording the calls of 7 or 8 different kinds of bats. In addition to adding roost site surveys this year, the team is also expanding the geographic scope of their acoustic monitoring efforts to learn more about bat diversity and distribution across Marin County. This research may also help inform how bats in Marin County respond to White Nose Syndrome, a deadly fungal disease that impacts bats as they hibernate, but has not yet been detected in the area.

In addition to helping local managers understand what species of bats live where in Marin, this information will also be shared with the North American Bat Monitoring Program, which tracks the status and trends of bat species nationwide. To learn more about this project contact Gabe Reyes.