Among the wildlife species that have received very little attention among wildlife biologists here on Long Island are one of the most interesting and usual groups of mammals: the bats.Despite being warm and furry, bats are one of the most-feared and least-liked members of the animal kingdom. Most people’s knowledge of bats is limited to the fact that they fly and are nocturnal. Many consider them dangerous, rabies-ridden varmints that should be exterminated.
Over the last 15 years, Bats Conservation International (www.batcon.org) and other conservation organizations have waged their own public relations campaign in an effort to turn the tide on the public perception of bats. They point out that bats are an amazing group of animals with some fascinating adaptations, and they play an important role in the ecosystem.
Of the 5,000 species of mammals in the world, more than 1,000 are bats. In some Neotropical areas, there are actually more species of bats than all other species of mammals combined. The two major adaptations that have allowed bats to flourish are echolocation and flight. Some biologists claim that bats have achieved a degree of maneuverability in flight that surpasses that of any bird. Echolocation is a means of perceiving the environment and locating prey in total darkness. Combined, these adaptations enable bats to occupy many of the niches at night that are filled by birds during the day.
The vast majority of bats, including the seven or eight species found here on Long Island, are insectivores. Their ability to sense their surroundings by emitting ultrasonic pulses produced in the larynx (200 pulses per second), and hearing the pulses echo back from objects, is truly astonishing. Although they are nocturnal and rely on this form of echolocation to hunt, bats have eyes and can see.
Bats have remarkable longevity for such a tiny animal. One of our bat species, the Little Brown Bat that tops the scales at a mere third of an ounce, may reach 24 years of age!
The low reproductive rates of bats, combined with their longevity and their insect prey base, means that the use of harmful pesticides can have drastic impacts on local populations. The use of DDT during the 1940s through the 1960s may have caused a sharp decline in Long Island’s bat population, just as it impacted another long-lived, slow-reproducing member of our fauna, the osprey.
About five years ago I wrote in this column, “Unfortunately, no studies were done to determine the impact of DDT spraying on bats, and the most recent comprehensive survey of bats on Long Island was done in the 1960s. Their longevity makes them a useful candidate for monitoring the health of our environment, and updating the 40-year-old survey of these fascinating creatures would be a very worthwhile endeavor.”
Both of those comments are no longer true. Wildlife biologists Tim Green and Mike Fishman began surveying for bats here on Long Island in 2011. Fishman gave an excellent presentation on his work at last April’s Northeast Natural History conference, and he is scheduled to present that again at the Long Island Natural History conference on December 6 at Brookhaven National Lab.
In 1902, Arthur Helme reported that the eastern red bat (Lasiurus borealis) was the most abundant bat on Long Island. Robert Cushman Murphy and John T. Nichols agreed in their 1913 publication on the bats of Long Island.
Paul Connor’s field surveys, undertaken in the 1960s, found that was no longer the case. While the eastern red bat was not rare here, the most abundant species encountered in the 1960s was the little brown bat (Myotis lucifugus), with big browns (Eptesicus fuscus) and the Keen’s or long-eared bat (Myotis septentrionalis) the most commonly encountered at specific locations, such as Fresh Pond in Hither Woods. Connor also noted, “in some apparently favorable situations, such as certain ponds and fields on still summer nights when insects were abundant, we failed to detect any bats at all.”
Forty years later, Fishman’s 2011-2012 survey found the big brown bat to be the most numerous on his Long Island survey sites. It’s possible that these different results can be attributed to surveying locations and techniques. I wondered if the deadly fungal disease called white nose syndrome (WNS) might be playing a role in the species abundance shifts, but WNS is spread among bats at their hibernation sites, so it should be impacting the cave dwelling big browns as much as other species.
What about the impacts of DDT and other pesticides? Recent studies have found that bats are very sensitive to DDT even at very low levels of exposure. During migration, bats rely on their fat reserves where the DDT is stored. Bound up in the fat, the DDT does not harm the bats, but as they metabolize it, the DDT is released into their system in relatively high concentrations and the results are toxic.
You might wonder where they are being exposed to DDT, which was banned in the United States in 1972. We still manufacture it, and export it to other countries where the pros and cons of its use are still being debated.
While we’re on the subject of pesticides, remember that there is no such thing as a contact chemical that only kills mosquitoes or ticks. Anvil is sprayed by Suffolk County to control mosquitoes; it is also toxic to bees, butterflies and fish. Your local mosquito and tick eradicator most likely sprays a pyrethroid insecticide. Look it up.
Atrazine is the most widely used herbicide in the United States. It is an endocrine disruptor, and banned in the European Union. Take responsibility for what you are doing on your property, even if you are hiring someone else to do the spraying.