Thursday, October 15, 2009
Two nights ago I had the privilege of observing/assisting with part of a statewide bat inventory project at a cave less than 20 miles from my home. Keith Hudson, bat expert and one of ADCNR's Nongame Wildlife Program biologists, was directing (that's Keith's voice in this video), and other ADCNR and USFWS biologists were there as well. I'm not mentioning the cave by name because it's on private property, but it's one of the largest and most significant bat caves in Alabama's Coastal Plain. Keith was hoping to get four or five species, but we found just two. Southeastern myotis (Myotis austroriparius) is the most abundant, and was all we caught in the harp trap. We caught a few hundred, but there had to be many thousands of them in all, although we did not attempt even a ballpark estimate. Eastern pipistrelles (Pipistrellus subflavus) were also present in fair numbers, seen clinging to the cave wall well after most of the other bats had emerged.
The Austbat harp trap Keith uses is an amazing thing. Set up at the cave entrance (or exit, from the bats' perspective), it intercepts emerging bats after dusk, gently plopping them down into a collecting bag. Clear plastic flaps hang down on the inside of the bag, keeping them from crawling out. Incidentally, all bats were released following species ID and determination of sex and reproductive status.
This cave is in an area known as the Lime Hills, a physiographic province just south of and adjacent to the Red Hills. I've been there several times over the years, and it's really a special place. Not only is it perhaps the most important maternity cave in the state for southeastern myotis bats, it is the southernmost known occurrence for pickerel frogs (Rana palustris) in Alabama, and botanists recognize it as one of the southernmost localities for red columbine (Aquilegia canadensis).