Friday, August 29, 2014

Bats on Radar

Grey Bat - Wikimedia
Bats on radar - click to enlarge
Drew Albert of our Master Naturalist chapter has been involved in discovering a new and previously unknown colony of grey bats.  And he did it from work at the National Weather Service.  As reported on KSMU, forecasters at the National Weather Service Office in Springfield noticed a mysterious radar signal over Dallas county every evening beginning in June of last year.  This lasted all summer, and then recurred again this year.

Being a naturalist, he thought biologically of birds and bats as they are known to show up on radar in some circumstances.  "We made some assumptions initially.  We do know that National Weather Service radar can pick up what we call biological scatterers, and that can include birds, insects and of course bats, and it was assumed they were bats just because of the time of day," he told KSMU.

High-flying Mexican free-tail bats show up on Texas radar because of their large numbers and high flight patterns.  Missouri bats fly lower and in smaller numbers, under the radar.  He explained these signals were much closer to the ground, showing up on radar because of our weather conditions.
"During the evening, the beam does get bent downward a little bit towards the ground as what meteorologists call a night time temperature emergence sets up, and that inversion sets up as the ground cools, so the beam does get bent downward just a little bit, and also the beam will spread out with distance from the radar, too."
The echoes were 20 to 30 miles from the radar.  What do you do in our modern technological world to find the answers.  Facebook!  They sent out the following posting.
"We think there might be bats flying out of these two locations in Dallas County... and near Windyville.  Notice the two echo radar sampling something near these two locations.   Radar has been sampling this over the last several evenings.  We suspected it is bats... but wanted to see if any local Dallas County folks could confirm that.  Let us know if you have information.  Thanks!

After they posted their findings on social media, they were connected with the Missouri Department of Conservation (MDC).  The signals were found to be coming from an endangered species, gray bats emerging at night to eat insects.  Tony Elliot, a bat biologist with MDC was excited to discover a colony of the grey bats that wasn't known.  There are only three main hibernation caves for gray bats known in Missouri, "but in the summer they disperse to a larger number of what are called maternity and bachelor caves. "

Missouri grey bat in a cave - MDC
There are an estimated 700,000 gray bats in Missouri, so how can they possibly be endangered?  The answer is that they are clustered in only a few populations which all huddle together over the winter.  Like humans who are pushed together in large numbers, the bats' close proximity to one another increases the risk of the spread of an infectious disease.  In this case, the disease is White Nose Syndrome that has killed over 5 million bats in the US.

An additional risk to the bat population is us.  Humans have used caves over hundreds of thousands of years, first for shelter, and now as an interesting place to explore.  In addition to the risk of spreading disease, we disturb their summer "nests" causing the young who are just "hanging around" to drop to the ground.  Further more, in their winter hibernation they have just enough energy stored to make it until spring.  Waking up and moving around because of human activity requires the use of stored energy and they may run out fuel before their spring wake-up occurs.

Needless to say, the site is being protected by the local landowner in conjunction with the MDC.  Like any other endangered species, the location is confidential to protect it from the curious public, i.e. you and me.

Meanwhile, Drew Albert's Master Naturalist juices are still flowing.  "My loose plan is to maybe more systematically follow these signatures with time to see maybe how the populations are shifting around, how things are changing with time." Who knows, he may even find another populations of bats.  Citizen Science strikes again!

Learn more about radar's use in monitoring bird, bats and insects in this Youtube video and this from Science Magazine
Bats of Missouri discussed here.

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