The Problem with Cave Gates and Bat Biolgy

[wyandottecaver]

I was trained as a wildlife biologist and have worked professionally with bat hibernacula. The MYTH is that gating caves always protects bats. Gating caves does not magically change the laws of nature. There are only so many bats and they can only breed so fast and the surface environment in almost every case plays a far far greater role in their overall survival and abundance.

In rare locations where high population declines coincide with high visitation, gates may well be needed. Also in rare cases there may simply only be very few viable caves in a region (what constitutes viable is often hotly debated). What gating caves mostly does biologically is either nothing, or creates a concentration point whereby over time the scattered local bat populations that presumambly had resorted to "poor" areas of a cave or other "poor" caves to escape distubance now concentrate in the "good" gated and undisturbed cave. Large, rapid population increases are often simply local re-allocation of bats that were already there. Does providing these undisturbed hibernacula prevent some stress and direct injury bat deaths from human activity? Absolutely, but how many? And at what cost biologically? As more and more bats gather in fewer and fewer places the risks get higher and higher. The Wyandotte Cave area in Indiana is a prime example of how gating caves "for bats" created more bats in fewer caves with a mostly unchanged total population growth by region.

Concentrated populations WILL ALWAYS be vulnerable to disease or disaster. WNS has reminded everyone of that. EVERY concentrated population is prone to disease outbreaks, bats are no different in that than wildebeests. Moreover, by getting more and more bats into more and more "ideal" hibernacula conditions we keep lowering the bar on how fit or healthy a bat needs to be in order to make it through the winter. Thus come spring, you have more bats with worse overall fitness competing for dwindling food resources and mating opportunities. That means even fewer bats overall go into the next winter in their best possible condition and/or weaker members pass on those traits by breeding and thus all of them are more vulnerable to a long winter, or other stresses like WNS.For a while you might have more total bats, but as a population they are weaker and more vulnerable and thus the long term negative impacts for the survival of the population increase.

In the olden days you had these great caves stuffed with bats and lots of other caves with some bats...and a entire non-urbanized, non-pesticided, continent to feed from. Just because a cave used to have a million bats doesn't mean it should have a million bats today. While undisturbed, ideal hibernacula might be limited, suitable hibernacula sites are simply almost never a limiting factor. Also keep in mind that human disturbance of caves, particularly big, nice caves has been going on a LOOONG time. One might argue that while human disturbance of primary hibernacula is a negative impact at the individual level, moderate levels of disturbance might have biological benefits at the population level long term.

The simple fact is that in many cases (not all) gating caves for "bat protection" is usually driven by 1) a money making venture by gate builders using funds from State or Federal sources (see 2) 2) A State or Federal agency that has legal obligations and/or an agenda to pursue every whimsical scheme dreamed up that might benefit some bat, somewhere, somehow, sometime and uses your tax money to do it. 3) a means by which land managers can eliminate or simplify burdensome ongoing access issues or perceived liability by eliminating or severely restricting access by people to caves "for the bats".

Left largely unmentioned are the primary causes of most declines which include loss of surface habitat, loss of food density, and direct killers like cars, windmills, and environmental toxins.

[jbirdweb]

Thank You!
You have confirmed my suspicions that most gates on caves do very little to protect bats from humans!
When you consider the sheer number of caves, and the number of caves that humans simply can't enter due to the entrance size
I have always felt that the hibernacula issue just did not hold much validity.
But sadly as long as certain individuals see themselves as the Cave Gods or Protectors of an otherwise naturally occurring Karst feature
gates will continue to be installed. I have always maintained that one form of vandalism to protect against another is simply bad policy!
I just sent Dave Bunnell an open letter to the members concerning this and other issues.
I feel it is the need for ego stroking by telling people how wonderful we are for caving thus increasing the interest of thrill-seekers and a lack of discernment about who we take caving with us that creates the greatest negative impact on the cave, not simply human visitation on it's own!

Jerry Sparrow
NSS 25234

[plicpriest1]

Interesting, bats are neat little guys. I would love to know how a bat family (Papa bat, momma bat, and baby bat ) new to the area can find an enterance to a cave.

Concerning the would be CAVE GODS who love to control the situations: Lets stop giving them the power to control the situation. I do what I want, when I want, for as long as I want. Why? Because I have good sense to realize that protecting an ecosystem is important, It does take a long time to create cave features, and I know how not to be an idiot (you know common sense). With that said I do realize there are those dummies out there that are idiots. Sadly it is tough to mitigate the dangers thy pose. Since you really cant, why place a blanket policy that includes the REST OF US? It makes no sense, since the dumies wont follow policy anyways. Thats all I will say about that.

Lastly I feel that if a person owns there own land with a cave on it... If they gate it that is there buisiness. I really cant tell them what to do since I dont pay the property tax.

[wyandottecaver]

well there really isnt much in the way of a bat family. papa does the deed in the fall and runs off, in many cases he does the deed over and over with lots of mamas, burning fat, and meaning he is less likely to survive a bad winter. Mama gives birth the next spring (after storing the sperm all winter). After a summer of fattening up they return to the area they started from and often the same cave. They do however do a lot of scouting around to find other bats to mate with and also in some cases finding temporary roosts for a night or two.

This is probably how new roosts (including buildings) are found. bats can try them out and if they like them, return later when they get ready to hibernate.

[plicpriest1]

papa does the deed in the fall and runs off, in many cases he does the deed over and over with lots of mamas

Sounds like alot of folks in the big cities .