I would like to take this opportunity to respond to a recent letter to the editor that characterizes bats as being a creepy nuisance.
All bats in Pennsylvania are insectivorous, meaning they eat only insects.
A single bat may consume up to one third of its body weight in insects each night. This could be as many as 3,000 insects per bat per night.
As the major biological consumer of night flying insects, bats are considered to be ecological keystone species just about everywhere they occur and play a vital role in controlling insects and maintaining the balance of nature.
Since bats are the major predators of nocturnal insects, one long-term impact of the reduction in bat populations will likely be an increase in insects.
Such increases could lead to greater crop damage and other economic impacts in PA.
Recent estimates by scientists show that the current level of activity of bats as an agent of insect control can be valued, on average, at about $74 per acre of agricultural land each year that we currently do not pay for, but which is provided free by our bats. This puts a value on bats, in their capacity of insect control for agriculture at over 4 million in Blair County alone, $292 million in the commonwealth of Pennsylvania, $22 trillion annually within the US.
Bat colonies are being decimated throughout the United States by land development (as trees are cleared), by wind turbines (which kill bats in enormous numbers each year) and most severely in northeastern U.S. by a disease called white-nose syndrome, which may have been accidentally imported to the U.S. by humans coming from Europe in 2005.
Federal and state agencies in the U.S. estimate that the continued die-off from these factors means that at least 1.1 million kilogram of insects (2.4 million pounds) will go uneaten and become a financial burden to farmers.
Having bats present to consume insects has a direct effect on the market value of all crops produced in the state.
The ongoing loss of large numbers of bats will likely have expensive impacts on agriculture and result in increased costs to the consumer. The increased cost of pest control, through the increase in use of pesticides as bats continue to decline, will be borne by the farmer and consumer, and will likely be reflected by elevated costs of food.
Moreover, the impact of increasing pesticide use on our environment and human health has yet to be fully evaluated.
In reality, there is probably little need to wait to remove the trees in question because of Indiana bats, which endangered. Indiana bats typically roost under the bark of trees such as shagbark hickory, or in dead trees where the bark is exfoliating, providing them with shelter underneath.
In my casual notice of the trees in question, I do not believe any of the ones I looked at would be capable of housing Indian bats.
An expert could be brought in and, in consultation with the Fish and Wildlife office in State College, could get clearance to remove the trees.
However, waiting until after the bats are gone for the season is much less cheaper and does not take the chance of further harming bat populations or violating Federal law.
Michael R. Gannon, Ph. D.
Bat Research Biologist
Professor of Biology and Ecology
Penn State Altoona