As the sun would set, and dusk would inevitably approach and settle over the earth, the bats always took flight on those cool summer evenings on my aunt’s farm in Green Township, New Jersey. Launching with much gusto from the old farm house’s chimney and the eaves of the barn’s hay loft, they began their nocturnal search for food. In ephemeral fashion the winged mammals darted about the sky in daredevil display, catching gnats and mosquitoes as they flitted about the yard and the horse pastures. We humans were ever grateful to our bat friends, for they made evenings spent outdoors more enjoyable; they kept the otherwise incessant buzz and relentless stinging bite of the female mosquito – also in search for food – at bay.
There are nine species of bats that are in New Jersey; six species are here year round (little brown bat, big brown bat, Northern long-eared, Indiana , Eastern small-footed and Eastern pipistrelle bats) and three species are migratory (hoary, red and silver-haired bats). All nine species primarily feed on night flying insects, e.g. mosquitoes, amongst other pests. One little brown bat can consume approximately 3,000 mosquitoes in one night! However, eating 3,000 mosquitoes in one night is not a Fourth of July hot dog eating contest kind of event; for the six species that are non-migratory, winter is a time of hibernation, and hibernation means living off stored fat reserves. Therefore it is critical that bats consume as much as possible in the summer and early autumn months. Once winter begins bats will stop hunting, and typically hibernate in caves or abandoned mine shafts (CWFNJ, 2008). Unfortunately, another organism has been living in these same caves…Geomyces destructans.
Geomyces destructans, happens to be the fungus responsible for White Nose Syndrome (WNS) (NSS, 2011). The WNS is a topical, fungal disease, so-called due to the white fungus which grows on a bat’s nose, ears and wings. This genus of fungi is typically associated with soil, growing in an ideal temperature zone of approximately 40°F, or the average temperature of an over-wintering cave for bats. The first accounts of dead bats found with WNS occurred during the winter of 2006-2007. The first detected WNS case was in Schoharie County, NY and all subsequent cases have primarily occurred in northeastern America (USGS, 2009). Initially scientists began studying the fungus, trying to determine its physiological means of causing bat fatality, but never finding enough substantial or conclusive evidence. However, some scientists are now starting to believe that perhaps WNS is not the actual cause of death in bats, but rather the fungus may be an opportunistic pathogen which preys upon an already immune-compromised bat (NSS, 2011).
If the fungal infection is only the secondary cause of death, what then may be the primary cause? Scientists are still uncertain; stating possible chemical (pesticides), biological or environmental factors (loss of habitat) or some combination of all of these factors. What is interesting to note is that scientists have observed similarities in the behavioral changes of bats and that of the honeybees affected by colony collapse disorder (BCM, n.d.). Some signs and symptoms of WNS that you can look for include:
Bats flying outside during the day in near freezing weather, bats clustered in the winter in sections of caves or mines not normally used for winter roosts (especially near the entrance), dead or dying bats on the ground or on buildings, trees, or other structures during the winter, or bats not arousing after being disturbed (NSS, 2011).
Additionally, when the fungal infection invades a bat’s skin it can cause ulcer production, which in turn may alter a bat’s “hibernation arousal pattern” resulting in emaciation (abnormally thin body mass) (USGS, 2009). Imagine that: even after consuming an average of 3,000 mosquitoes per night all summer long – being well prepared for necessary winter fat reserves – a bat infected with WNS can still prematurely abandon hibernation completely emaciated. This is not normal.
So, what about those cool summer evenings? They are no longer as cool, and I no longer see as many bats as I used to, but I certainly notice more mosquitoes; without the bats around consuming nighttime insects, mosquito populations have been allowed to explode! This makes enjoying summer outside a little more difficult. Instead of reaching for a spray-on bug spray (another pesticide), perhaps we should find alternative ways to enjoy our time outdoors, for the sake of our bats.
For more information on bats and/or White Nose Syndrome, please check out the links below.
DID YOU KNOW: With Halloween just around the corner, many of you may be noticing decorative bats dangling out and about around town. Bats are one of the symbols synonymous with Halloween, but did you know that this tradition may have nothing to do with vampires? One source states that Halloween was a time of year for harvest feasts. Large bonfires would be built in celebration, drawing nighttime insects to the bright blaze. This would subsequently invite the insects’ main nocturnal predator, the bat, to dine amongst the jubilant harvesters and the fiery flames; the association between harvest time and bats forged (Venefica, n.d.).
- Bat Conservation and Management, Inc. (BCM). (n.d.).White Nose Syndrome: Could cave dwelling bat species in the eastern US become endangered in our lifetime? Retrieved from http://www.batmanagement.com/wns/wns.html
- Conserve Wildlife Foundation of New Jersey (CWFNJ). (2008, June).Bats of New Jersey. By John Braun and Maria Grace. Retrieved from http://www.state.nj.us/dep/fgw/ensp/pdf/bat_fact_sheet.pdf
- National Speleological Society (NSS). (2011, September 23).What is killing our bats?: The White-Nose Syndrome tragedy.Retrieved from http://www.caves.org/WNS/WNS%20Brochure.pdf
-  The Indiana bat is recognized federally and in several states (including New Jersey) as an endangered species (CWFNJ, 2008).