Saturday, December 10, 2011

Migratory bats

I wanted to bring up the subject of bats after some sightings that I have had in the past few weeks. On November 26, I noticed a unique flying creature swirling around through my neighborhood around sunset. It was quickly obvious that it was not a swallow or a swift. I was able to determine that it was a Red Bat (Lasiurus borealis), a species of Special Concern on the Connecticut Endangered Species Act, before it flew off to the south continuing its migration as darkness overtook the area. Red Bats are forest dwellers, and while it was certainly not out of place in my neighborhood, it did seem late in the season for a sighting.

Little is known about the migratory routes and timing of departure from Connecticut or points north for the various bat species we can expect to see in our state, but November and December can be brutally cold months for insectivores. Even October was a perilous month this year. Stratford Point is actually a good place to spot Red Bats in the fall, and we are starting to think the site may be on a migration route with bats following either the Housatonic River to the south or the Long Island Sound coastline to the west. An extreme example occurred on the morning after Tropical Storm Irene. I arrived at Stratford Point well before sunrise, and around 6 a.m. I spotted a Red Bat coming in from Long Island Sound and heading towards our main building, likely roosting there, possibly in the vents along the roof, for the day. I believe it was returning to land after finding itself over water as the sun came up, as many birds do.

Again, the Red Bat is a forest dwelling species, and the mouth of the Housatonic River, sands of Long Island Sound, and Stratford Point's coastal grasslands are well out of place for it. Inclement weather likely pushes some of the others to stay here and hunt the area, once again just like some bird species that are out of habitat on the property do. Another notable sighting was of a bat species flying into the gable vent on the main building of Stratford Point on Tuesday afternoon, December 6, as the rain poured down and fog continued to cover the area. Twan believes what I saw was an Eastern Pipistrelle (Pipistrellus subflavus) as we have already encountered the species on the property in December before, with a single Eastern Pipistrelle seen roosting in a building during an extreme cold snap a couple years ago. We do not know if it was a migrant or a resident.

I also had a recent report via an at-reply to our Twitter account of what an observer believes to be multiple Little Brown Bats every night in their yard. Clearly, there is a lot to learn about bats in Connecticut, and we would always appreciate hearing about any sightings you have, especially during the fall and winter months.

Scott Kruitbosch
Conservation Technician

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