The Annual Bat Count Report for 2023 is Ready!

The Annual Bat Count Report for 2023 is Ready! 1

Thanks to the effort of hundreds of volunteers and partners throughout BC, the BC Community Bat Program in partnership with the BC government has been able to successfully write our 7th Annual Bat Count Report.

White-nose syndrome (WNS) is an emerging fungal disease that results in high mortality of susceptible bat species. Not yet detected in British Columbia, it is spreading northwards in Washington State and is expected in BC in the near future. The BC Annual Bat Count is one potential method to assist with monitoring the spread of the disease, identify species-specific impacts, and track recovery of affected species.

The Annual Bat Count involves repeated emergence counts at bat roosts in anthropogenic structures including buildings, bridges, and bat boxes. Currently, it is the only long-term roost-monitoring program in the province. It covers much of BC and is cost-effective due to the large volunteer component and implementation through the BC Community Bat Program. The Annual Bat Count is also a valuable engagement tool that may lead to increased appreciation of bats and increased roost stewardship, and the project provides ecological data on bats species in anthropogenic structures. Begun in 2012, the Annual Bat Count has data on seven bat species at 946 anthropogenic roost sites. Species with the largest number of known roost sites are Little Brown Myotis and Yuma Myotis, both of which are susceptible to WNS.

Challenges in using the data for trend monitoring include that not all sites are monitored each year due to change in land ownership and/or availability of people to count sites, high variability observed in count data within and between years, movement of bats between different roost sites (roost switching), the small sample size of roosts for some species, and the occurrence of multi-species roosts, where a structure is used by two or more species.

Bat Count sites may provide valuable information on bat population declines without statistical analyses, if catastrophic declines occur such as those observed in bat populations of eastern North America. However, additional work is needed to address the complications in using statistics to detect lesser changes. This work is beyond the scope of the BC Community Bat Program and partnerships are needed to advance the utility of the monitoring program.  

Key successes of the Annual Bat Count in 2023 are:

  1. Contributions to White-nose Syndrome (WNS) surveillance and population monitoring, specifically: 
  2. 888 counts at 274 roost sites across the province in 2023; 198 of the sites are in the regions where WNS is first expected (Fraser Valley/ Vancouver, Sunshine Coast, Vancouver Island /Gulf Islands, Okanagan, Kootenay),
  3. Identification of species of bat by genetics or acoustics at 45 % of sites,   
  4. an increasing network of roost stewards who can monitor for spring mortality events associated with WNS.
  1. Ongoing stewardship and participation to engage roost stewards and volunteers in bat conservation actions.
  2. Contributions to knowledge of bat ecology across BC, specifically:
  3. Contribution to provincial knowledge of species that use anthropogenic structures. For example, the Bat Count has confirmed use of anthropogenic roosts by Californian Myotis in coastal BC and the Okanagan, and Long-legged Myotis in coastal BC and the Cariboo,
  4. Information on the timing of use of structures and dates of first pups across the province,
  5. Monitoring for and documenting impacts from unusual weather events (e.g., cold rainy June 2022, heat wave of late June/early July 2021, widespread fires and smoke in 2023), and
  6. Collection of carcasses from mortalities at roost sites for research into cause of death.

This report is a partnership between BC WLRS and the BC Community Bat Program. Data is collected entirely through the BC Community Bat Program, which is a joint venture of regional bat projects across the province. It is administered by the BC Conservation Foundation and funded by Habitat Conservation Trust Foundation, Forest Enhancement Society of BC, Habitat Stewardship Program, the Province of BC, and many regional funding partners. Thank you to all the Regional Coordinators who locate roost sites, identify candidate sites for the Annual Bat Count, and engage, organize, and train volunteers. BC Parks has done an exceptional job of ongoing counts at many sites over the years. Orville Dyer (retired from BC MoE) has provided valuable guidance and input to the program, as well as participating in bat counts. We especially thank Juliet Craig and the Kootenay Community Bat Project, who started the Annual Bat Count in BC. Finally, the Annual Bat Count could not occur without our many dedicated partners and volunteers (such as Peachland BEEPS, BC Nature clubs across BC, and many NGOs), who collect data for the program.