Winged Defense In Trouble

Winged Defense In Trouble

Follow the F&WS link below to enlarge!

How does nature solve its overpopulation problems?

Predators.

What happens when we have a decline in predators? Overpopulation of the prey species.

What if the prey species of concern is insects? Because, I don't know, you farm or you eat? And the insects are eating your livelihood/lunch?And what if the predator you need is bats? And between 5.7 and 6.7 million of them have died in the Northeastern United States since 2006 from White-Nose Fungus*?

Yeah, I'm not much liking the sound of those numbers, either. I talked about how this fungus does in bats back in

2010

, but today I'd like to address the impact on the ecosystem at large.

From the 2009 article from Scientific American, "because bats are essential to the control of nocturnal flying insects, the outbreak could upset local ecologies, weaken the health of forests and even affect crop yields." Bats are the predators of small, winged things that can carry diseases that impact humans and other mammals. Three of the big diseases you don't want-- West Nile virus, dengue fever and malaria--are carried by a favored bat delicacy (mosquitoes). We are already seeing an increase in these diseases in the areas that have lost the most bats. 

It appears that the fungus is of European origin, where it is found in the presence of cave-dwelling bats without impacting them. So this is yet another example of how our global, traveling community--either through shipping or tourism--has likely brought a species to our shores that is invasive both by definition and by practice. 

The mortality rate of bats infected with

Geomyces destructans

, the fungus we call "white-nose fungus," approaches, if not achieves, 95%. It is not airborne, but is spread through touch. Bat colonies, depending on roosting spaces, range from the hundreds to the thousands, and the little critters crawl all over each other as they squeeze together for warmth during hibernation. What will happen if 95% of all hibernating bats in the U.S. succumb to the fungus? What happens when only 5% of our hibernating bats are available to patrol our night skies and eat the little buggers who have the potential to plague us?

From Wild Things Sanctuary (a truly excellent article):

Why are bats important to humans?
     Bats may be the most under-appreciated mammal on the planet. As a top predator of flying insects and as pollinators, bats serve an important role in the ecosystem. These little animals are voracious predators, consuming up to their body weight a night in flying insects. These insects include many human, agricultural and forest pests such as mosquitoes, moths and beetles. By reducing the numbers of pests, bats help reduce crop damage and the use of insecticides. Bats also serve as pollinators and seed disseminators for our crops. Without bats we face significant environmental and economic consequences.
     As bats numbers dwindle towards extinction, farmers may start finding themselves without a major ally in the war against pests. Several species of bats can eat up to 1,200 insects an hour, or about 3000-7000 insects a night. One researcher compares this to a human eating 50 pizzas a day! The loss of the one million bats in the Northeast over the last 5 years means that there are between 660 and 1320 metric tons of insects that are no longer being eaten each year by bats in this region. 
     This appetite for insects may make bats the most overlooked non-domestic economically important animal in North America. Bats enable organic farmers to grow food successfully without chemicals. But even non-organic farmers save millions of dollars every year by the bats' pest control services. In the U.S. alone it has been estimated that the pest control service provided by bats to agriculture range from a low of $3.7 billion to a high of $53 billion a year. As increasing numbers of bats succumb to WNS, scientists have predicted that within 4 to 5 years noticeable economic losses could occur to North American agriculture.

Not working in our favor is the fact that bats typically give birth to only a single pup at a time. Were bats more prolific, a 5%-the-original-size population would have much better recovery chances. So even if enough bats survive with enough immunity to continue the species, it will be years before they will recover to levels sufficient to deal with the booming insect population.

I recommend that you investigate the source links for images and further information--there are now a number of people contributing to the science on this issue. Even so, we may see the extinction of one of our most common predators, the little brown bat, within only a few short years. If you need a research project--I'd like to suggest this one.  And please--put up a bat house. At least when you put it up, it will be free of fungus.

*

While it is clear that

Geomyces destructans

is present in all of the infected and dead bats, "cause" has yet to be proven.

Sources:

U. S. Fish & Wildlife Service

,

Wikipedia

,

Scientific American

,

Wild Things Sanctuary

,

USGS Fort Collins Science Center

,

Tom's Fungi

,

Little Brown Bat

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