Bat monitoring

Allie Perrin

Our recent outing took us to the southwestern corner of Chautauqua County to conduct a bat population survey on a Little brown bat (Myotis lucifugus) colony that at one time, had approximately 1,700 bats. However, once the dreaded disease White-Nose Syndrome hit the population, it hit hard. White-Nose Syndrome is a fungal disease that affects bats during hibernation. This terrible disease makes the bats wake up more times during hibernation which causes the bats to use more energy thus using up all of their fat reserves so they technically starve before spring even arrives.  The bat population was reduced to extremely low numbers due to this horrible disease. It specifically targets the little brown bats and other similar species that hibernate, as opposed to migrate. The location of the colony we visited was on a couples property. The Little browns use to congregate in the barn they had on their land. When the couple decided that the guano and pee from the bats was too much for them to stay in the barn, the couple decided to put up 6 bat houses on the outside of the barn. Thus, allowing the bats to have somewhere to sleep and keeping them out of the barn. Another house was added by the Chautauqua Institution to the couple’s property, making the total of their bat houses to be 7.  To do the population survey, we went to the property and sat in lawn chairs and waited till the bats came out. The Little browns started to emerge around 9:15 p.m.. We sat and counted until around 10:15. We watched closely and counted every bat that came out of the houses. By the end of the night, we came to a conclusion that there was around 120 bats in the colony. We personally had counted 112 bats. We also looked directly into the bat houses after and could see there was still some left, as well as even a few pups inside. We also did acoustic surveying at the same time. This is when you record and analyze the echolocation calls of the bats. You have to use specific equipment to pick up the calls because the human ear cannot detect it. We ended up with some Little brown calls and even some Big brown bat calls.

Bat monitoring programs are important because they allow us to see how the bat colony are growing and how much they got affected from the White-Nose Syndrome. It gives us the information that we need to take conservation efforts and try and help out these little creatures. It helps us understand their behavior and breeding habits. We can closely monitor the populations sizes and hopefully document the rise in numbers of the Little brown bats.

This experience was very surreal. Being up close and personal with the bats as they come out of there houses and fly around was amazing. Some bats flew right at you and you could feel the power they had in there wings as they flew over you. Overall, I learned a lot about the different bats and calls and how they were affected by White-Nose Syndrome. I can’t wait to do it again.


Brandon Nielsen:

Continuing with our first two weeks of training as new PWA crew leaders, Allie and I got to take part in a bat survey earlier this week. We drove to the southwestern region of Chautauqua County to visit a couple that had a growing bat colony of Little Brown Bats (Myotis lucifigus) and Big Brown Bats (Eptesicus fuscus). The bats are currently using bat boxes on the property to roost in and raise their young in. We had to wait until a little after sunset, around 9:15 PM, for the bats to begin to be active. Around this time the bats started to wake up from sleeping all day and began leaving the bat boxes to go out hunting for insects to eat. As the bats left their roosting sites, we were able to conduct our survey by noting the numbers of bats coming out of each bat box during the night and getting a rough estimate of the number of bats currently in the colony. That night we recorded seeing 120 bats based on the bats leaving the boxes, and from the bats, we could see still hanging out in the boxes later in the night. Along with this, we could also use ultrasonic recording software to record the bat’s use of echolocation to navigate in the dark and find their food sources. We could then use these recorded calls to help us in the identification of the bats we saw in the boxes. Based on these recordings we could say with a greater certainty that these were Little Brown Bats and Big Brown Bats in the colonies.

It is exciting to be finding these bats, especially the Little Brown Bats, as they were mostly killed off in recent years due to White-Nose Syndrome. This fungal disease has had a significant impact on many bat populations, as it causes the bats not be able to maintain a constant state of hibernation in the winter. This, in turn, will cause the bats to use more energy in the winter being awake and causes them to burn through their built up food stores before the end of the winter, and the bats will end up dying from starvation.

So these surveys are essential as they allow us to monitor the current state of these bat populations.  Before White-Nose Syndrome came into the area this colony numbered around 1,700 and was down to under 40 by 2016. In NY, 90% of Little Brown Bats have vanished. These surveys also provide us with valuable information on what food sources the bats are eating and the kinds of habitat they can utilize to be able to rear successful pups based on where the bats are feeding. Even though sadly, this large scale die-off occurred, it is encouraging to be seeing a rebound in these local bat populations. We look forward to being able to conduct more of these surveys in the summer with the full PWA crew and the continued growth and success of these local bat colonies.

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