Re: More Cave Closures and....
Posted: Dec 15, 2009 9:35 pm
Like many things semantics matters....In TN's case I believe (without speaking for him) that based on his statement his intention in saying "caves with no bats" was meant to mean caves not known as "bat caves" in the laymans sense.
it would indeed be incorrect to say "most caves" serve neither as hibernacula, maternity colonies, or summer roosts. However....
A "hibernaculum" for pipistrelles is quite different than one for Indiana Bats. A "maternity colony" for Gray Bats is quite different than one for Indianas or Red Bats. Then there is "roost". There are a multitude of types and usages of "roosts". A summer roost for Gray bats is different between the sexes and both differ from Indiana Bats, red bats, or pipistrelles. I have radio tracked summer roosting Indiana Bats to caves, shingles, old shaggy barked maples, and broom sticks hanging on an outside shed wall.It is my firm belief that summer male IN bats will virtually roost anywhere on anything that is vertical and resembles a rough surface out of direct sun whenever they decide to stop.
For the purposes of caves, a summer roost might mean 5,000 female gray bats who cant move without losing their young, 100 Northern myotis favoring 1 cave but who can move, 5 male Indianas who don't really care where they end up each day, or 1 Red Bat that only ends up in a cave if its lost...
To that end, yes many caves will host some number of bats some amount of time but only certain caves are important as summer (or especially, winter) refuges. Northerns in particular are known to squeeze up into tight crevices to dissappear, but I can also say that as a caver and biologist there are many caves that I believe never hold any bats beyond a transient occasional visitor who is "kicking the tires" for a night/day or 2 then moves on.
Context also matters. A cave holding 5 pipistrelles and one holding 5 rafenesque bats is quite a different story. In Michigan, a Hydro Dam is suitable as a winter hibernacula even though the same dam in KY might not get a second look.
so....building a "list" of "bat" caves does involve a lot of complexity. Mostly in defining what a "bat cave" is. But by the same token there are plenty of caves whos bat usage is small and not significant population-wide so as to render them of marginal value as refuges.
it would indeed be incorrect to say "most caves" serve neither as hibernacula, maternity colonies, or summer roosts. However....
A "hibernaculum" for pipistrelles is quite different than one for Indiana Bats. A "maternity colony" for Gray Bats is quite different than one for Indianas or Red Bats. Then there is "roost". There are a multitude of types and usages of "roosts". A summer roost for Gray bats is different between the sexes and both differ from Indiana Bats, red bats, or pipistrelles. I have radio tracked summer roosting Indiana Bats to caves, shingles, old shaggy barked maples, and broom sticks hanging on an outside shed wall.It is my firm belief that summer male IN bats will virtually roost anywhere on anything that is vertical and resembles a rough surface out of direct sun whenever they decide to stop.
For the purposes of caves, a summer roost might mean 5,000 female gray bats who cant move without losing their young, 100 Northern myotis favoring 1 cave but who can move, 5 male Indianas who don't really care where they end up each day, or 1 Red Bat that only ends up in a cave if its lost...
To that end, yes many caves will host some number of bats some amount of time but only certain caves are important as summer (or especially, winter) refuges. Northerns in particular are known to squeeze up into tight crevices to dissappear, but I can also say that as a caver and biologist there are many caves that I believe never hold any bats beyond a transient occasional visitor who is "kicking the tires" for a night/day or 2 then moves on.
Context also matters. A cave holding 5 pipistrelles and one holding 5 rafenesque bats is quite a different story. In Michigan, a Hydro Dam is suitable as a winter hibernacula even though the same dam in KY might not get a second look.
so....building a "list" of "bat" caves does involve a lot of complexity. Mostly in defining what a "bat cave" is. But by the same token there are plenty of caves whos bat usage is small and not significant population-wide so as to render them of marginal value as refuges.