October 23, 2018 at 5:40 am
By MDIFW Biologists Sarah Boyden and Shevenell Webb
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Furbearer and small mammal biologists, Shevenell Webb, visits one of Maine’s bat hibernacula where bats hibernating during the winter.[/caption]
As Halloween approaches, bat decorations can be seen hanging from trees and spooky spider webs. At this time of year, most bats are already hibernating, but there’s a lot of mystery about where bats spend the winter. For a group of animals found throughout the state in the summer, we know very little about where they go in the colder months.
In Maine, we know of three winter roost locations, called hibernacula, where bats hibernate through the winter. Department biologists survey the hibernacula every 3 to 5 years to count the number and species of bats hibernating. The last survey of all the three hibernacula was conducted in 2016 and resulted in only 27 bats counted. We know that there are far more bats in Maine, so where do they go in the winter?
Eight species of bats live in Maine. Historic observations and acoustic surveys indicate that three species of bats migrate south in the winter. Unlike many bird species, bats are too small to carry tracking devices like those used in IFW’s Heron Observation Network. Instead, tiny tags weighing the same amount as a few paper clips are glued to the bat’s back. The tags look like buttons with a thin wire antenna that emit a signal detected by receiving towers called the Motus network. The battery of the tags only lasts 30 days, but it’s enough time to provide a snapshot of a bat’s migration.
[caption id="attachment_3178" align="alignleft" width="438"]
A migratory red bat with a nano tag glued on to it’s body. Note the antenna hanging off the back.[/caption]
Biologists from northeastern states and Canadian provinces are slowly expanding the network of towers to track tagged birds and bats migrating across the landscape. Data collected by the towers is providing insight into migratory movement of bats.
One project found that a species of bat did not appear to migrate along large river corridors, which debunked a long-held theory about how bats move across the landscape. With each new tower, we learn details about bat migration, something that was previously impossible because of the animals’ small size and nocturnal nature.
[caption id="attachment_3179" align="alignright" width="383"]
Motus towers (yellow dots) are used to track the migration of tagged bats, birds, and even butterflies.[/caption]
For the five remaining bat species, historic records tell us they likely spend the winter somewhere in Maine. Prior to white-nose syndrome, biologist had recorded over 500 bats at the three hibernacula. Given that biologists only counted 27 bats in the last survey, we’re trying to learn more about where these five species hibernate from November through April.
Biologists have found that some species of bats spend time in rocky, talus slopes during the summer, and bats may continue to use these refuge areas in winter. We suspect some species may hibernate in smaller groups in the large cracks and crevices found in talus slopes, instead of hibernating in larger groups in caves or mines.
Last winter, the Department began a project deploying acoustic recorders to listen for bat activity over rocky slopes across the state. During hibernation, bats will periodically wake up and echolocate as they fly around, which allows researchers the ability to detect them using the acoustic devices. The first season of surveys recorded bat calls in the middle of winter at many survey locations across the state. The project will give us insight into where bats are spending the winter and help biologists better understand and protect their winter habitat.
[caption id="attachment_3176" align="alignright" width="438"]
Regional Biologist, Mark Caron, investigates rocky habitat for signs of hibernating bats.[/caption]
Halloween decorations often include old houses with bats flying around and that’s not too far from the truth. Big brown bats are often found roosting in older homes in the summer and may find a suitable spot in your unheated attic or barn to hibernate through the winter too.
Unlike smaller species of bats, the larger big brown tolerates winter temperature fluctuations in an attic. They may even emerge during warm winter nights to get a drink of water or try to find something to eat, but go back into hibernation to survive the coldest part of winter. Most home owners never know the bats are there, as they peacefully hibernate through the winter.
October 24 to 31 is Bat Week. It’s a week devoted to appreciating a fascinating group of species that provide benefits like eating tons of insects and pollinating food crops like bananas, cocoa, peaches, cashews, and agave. For fun activities and to learn more about bats and celebrate Bat Week, visit: http://batweek.org/ .
Furbearer and small mammal biologists, Shevenell Webb, visits one of Maine’s bat hibernacula where bats hibernating during the winter.[/caption]
As Halloween approaches, bat decorations can be seen hanging from trees and spooky spider webs. At this time of year, most bats are already hibernating, but there’s a lot of mystery about where bats spend the winter. For a group of animals found throughout the state in the summer, we know very little about where they go in the colder months.
In Maine, we know of three winter roost locations, called hibernacula, where bats hibernate through the winter. Department biologists survey the hibernacula every 3 to 5 years to count the number and species of bats hibernating. The last survey of all the three hibernacula was conducted in 2016 and resulted in only 27 bats counted. We know that there are far more bats in Maine, so where do they go in the winter?
Eight species of bats live in Maine. Historic observations and acoustic surveys indicate that three species of bats migrate south in the winter. Unlike many bird species, bats are too small to carry tracking devices like those used in IFW’s Heron Observation Network. Instead, tiny tags weighing the same amount as a few paper clips are glued to the bat’s back. The tags look like buttons with a thin wire antenna that emit a signal detected by receiving towers called the Motus network. The battery of the tags only lasts 30 days, but it’s enough time to provide a snapshot of a bat’s migration.
[caption id="attachment_3178" align="alignleft" width="438"] A migratory red bat with a nano tag glued on to it’s body. Note the antenna hanging off the back.[/caption]
Biologists from northeastern states and Canadian provinces are slowly expanding the network of towers to track tagged birds and bats migrating across the landscape. Data collected by the towers is providing insight into migratory movement of bats.
One project found that a species of bat did not appear to migrate along large river corridors, which debunked a long-held theory about how bats move across the landscape. With each new tower, we learn details about bat migration, something that was previously impossible because of the animals’ small size and nocturnal nature.
[caption id="attachment_3179" align="alignright" width="383"] Motus towers (yellow dots) are used to track the migration of tagged bats, birds, and even butterflies.[/caption]
For the five remaining bat species, historic records tell us they likely spend the winter somewhere in Maine. Prior to white-nose syndrome, biologist had recorded over 500 bats at the three hibernacula. Given that biologists only counted 27 bats in the last survey, we’re trying to learn more about where these five species hibernate from November through April.
Biologists have found that some species of bats spend time in rocky, talus slopes during the summer, and bats may continue to use these refuge areas in winter. We suspect some species may hibernate in smaller groups in the large cracks and crevices found in talus slopes, instead of hibernating in larger groups in caves or mines.
Last winter, the Department began a project deploying acoustic recorders to listen for bat activity over rocky slopes across the state. During hibernation, bats will periodically wake up and echolocate as they fly around, which allows researchers the ability to detect them using the acoustic devices. The first season of surveys recorded bat calls in the middle of winter at many survey locations across the state. The project will give us insight into where bats are spending the winter and help biologists better understand and protect their winter habitat.
[caption id="attachment_3176" align="alignright" width="438"] Regional Biologist, Mark Caron, investigates rocky habitat for signs of hibernating bats.[/caption]
Halloween decorations often include old houses with bats flying around and that’s not too far from the truth. Big brown bats are often found roosting in older homes in the summer and may find a suitable spot in your unheated attic or barn to hibernate through the winter too.
Unlike smaller species of bats, the larger big brown tolerates winter temperature fluctuations in an attic. They may even emerge during warm winter nights to get a drink of water or try to find something to eat, but go back into hibernation to survive the coldest part of winter. Most home owners never know the bats are there, as they peacefully hibernate through the winter.
October 24 to 31 is Bat Week. It’s a week devoted to appreciating a fascinating group of species that provide benefits like eating tons of insects and pollinating food crops like bananas, cocoa, peaches, cashews, and agave. For fun activities and to learn more about bats and celebrate Bat Week, visit: http://batweek.org/ .Categories