Bat Colony Monitoring

Why do bat colonies matter?

Bats are important for pest control, seed dispersal, and pollination world-wide. A disease discovered in New York in 2006 threatens their long term survival. White-nose syndrome, caused by a fungus, is responsible for more than 6 million bat deaths in United States since 2006.

Since initial detection more than 10 years ago, WNS has been confirmed in 33 states and 7 Canadian provinces. The fungus has been confirmed in three states but the disease has not been detected in bats. WNS has been confirmed in Arkansas, Pd has been detected in Mississippi and Texas, increasing the potential of spread into our state.

To date, the fungus has not been detected in Louisiana. In Louisiana bats will roost in man-made structures due to a lack of caves.

Knowing colony locations and sizes allows us to more effectively monitor the potential for disease spread into Louisiana.

Who can participate?

Anyone interested can participate, no special skills are required. Many bat colonies are on private lands, we really need landowners and volunteers to report colonies and conduct emergence surveys.

When can I help?

Emergence counts are conducted when bats leave the roost at night to feed.

  • Winter count: one count conducted between the second week of December and the last week of February
  • Maternity count: one or two counts conducted within the pre- or post-volant season, or both
    • Pre-volant count: period before pups fly, count the last week of May through the third week of June
    • Post-volant count: period when pups begin to fly, the month of July.

How do I conduct a colony count?

Determine where bats are exiting the roost. If possible, have enough people to cover all exits. Arrive about 20 minutes prior to sunset with the bat count data sheet, pencil and paper. Count bats as they exit the roost, this should last 30-45 minutes. In a five minute period if you don’t see bats exit or it is too dark to see, you have completed your survey.

Some Tips:

  • It’s easier to count bats if you’re looking along the side of a structure rather than straight on. Bats silhouetted against the sky are easier to see.
  • A tally app or sheet of scratch paper maybe useful.  
  • Not all bats will exist the roost so you won’t be able to count all of them, but that’s okay, just count as many as you can.
  • Please do not shine lights to see the bats and try to minimize disturbance. Too much disturbance may cause bats to abandon the roost.  
  • If you don’t know what species of bat you have, snap a picture and send it along with your data sheet. Cell phone photos work great. Please remember do not handle bats or disturb them. If you are unable to get a photo or identify the species that’s okay.
  • Please remember to ask permission of the landowner and have a great time!

Where do I send my information?

Please return data sheets via email or standard mail to Nikki Anderson. Always feel free to contact us with any questions or concerns.

Contact Information:

Nikki Anderson
Wildlife Disease Biologist
Louisiana Department of Wildlife and Fisheries
2000 Quail Drive
Baton Rouge, LA 70803


Citizen scientists and volunteers are critical to colony monitoring in Louisiana. This project is not possible without your help.