The Great Bat Decline: A Story of the White Nose Fungus

There’s nothing more pleasant at the conclusion of a summer day than to sit outside until dusk taking in the sights of nature, seeing the life around you change as the light grows dim and the surroundings take on a more melancholy and foreboding appearance. Such a time is perfect for contemplation of the day’s events, but also to witness the creatures of the night awaken, and realize how truly restless and robust this planet is—life is. As we turn in for the night, we hand over the baton to the next set of creatures that will continue this ceaseless relay race that isn’t set to the schedule of the sun, but rather has its outlines only nebulously bound in the depths of eternity. The hoot or screech of the owl, the mournful wails of the whip-poor-will, and the epileptic flutter of the bats in shadowy outline against the rapidly darkening sky always excited my imagination and was cause for inspiration, undoubtedly setting the stage for vivid dreams to come.

However of late, the composition of these nocturnal creatures has been swiftly changing. Though the owls and whip-poor-wills still hold in relatively the same numbers, the bats—the only mammal apart from humans that has truly mastered flight—are becoming increasingly absent from the skies, dying in the millions. Now when I sit outside at night trying to admire what I can that remains, I have to fend off vast swarms of mosquitoes, biting flies, and numerous other annoying insects that love to harass man and are no longer kept in check by those aerial predators. The time that I now devote to being outside at twilight is diminishing every year as bat numbers further plummet, insect levels spike, and my stress from both increases.

It’s hard to believe that all these interrelated problems are the result of a simple fungus— a dull and obscure one at that—but still the cause of the deadly White Nose Syndrome.

Pseudogymnoascus destructans, the white nose fungus responsible for the mass die offs, first appeared in the U.S. in upstate New York during the early months of 2006. Since then it has spread throughout the entirety of the northeast and has been detected south to Alabama. As of now it doesn’t appear to have crossed the Mississippi. While there is debate as to its origin, it appears as though the fungus was transported to the U.S. from Europe, as related bats there are also infected with it, although most seem to have built up a resistance.

The fungus receives its name from its tendency to grow on the snouts of bats, forming a small white patch that looks like a pinch of snow. It’s damaging in the fact that the pathogen rouses bats from their hibernation early, depleting their fat reserves, and ultimately causing them to starve to death.

Fungi, in many cases, can be just as detrimental as even the most virulent of viruses. Take, for example, the plight of the once ubiquitous American chestnut tree. At the start of the 20^th Century, this species was perhaps the most common tree in eastern North America, comprising a quarter of deciduous forests.  Some ancient specimens achieved truly gargantuan proportions, the trunks being nearly 10 feet thick and rising well over a hundred feet into the air. That is, until another non-native fungus was accidentally introduced into the country, also, as it happens, via New York.  Within several decades after its release into the wild, nearly every tree on the continent was eliminated—over 99% of the population felled by spores, a multitude of sizes smaller than a grain of sand. And so the same cycle has begun with our bats, and is only in the earliest of stages. Unlike viral or bacterial contagion that usually cannot survive outside its host for any significant length of time, fungi are perfectly suited to endure the harsh environment and be distributed vast distances on the wings of the wind, or perhaps, on the sole of a human boot.

The Palisades Interstate Park League of Naturalists (PIPLON) has seen firsthand how serious this decline has been. In early January members conduct an annual wildlife count within Bear Mountain and Harriman State Parks. These large and wild swaths of protected land on the western side of the Hudson Highlands, historically have been the most diverse habitat in southeastern New York, home to both rare and adrenaline inducing organisms. While still holding many unique species in its depths, every year that passes by, so too, does time drag away with it something of biological importance, leaving the land tamer and less productive.

During each wildlife count an inventory of bats is undertaken in an abandoned mine in Harriman State Park. Cranberry Mine, which actually wasn’t dug by those seeking ore deposits, was constructed in the early part of the last century to serve as a storage locale for dynamite that was being used in projects to help with park construction, such as the numerous roads that allow access to some of the more secreted lakes and other scenes of natural splendor that would otherwise be hidden from most of the public.  Burrowed into the rock, about a quarter of the way up a gently sloping mountain, the mine is hidden from a casual glance at a distance by a layer of oaks, that while aren’t overly dense, are exceedingly tall, so that the eye is drawn to them and must trace the outlines of each from the bottom to the topmost spire. It’s an ingenious cloaking device. Everything just seems to blend together and flow naturally, as water cascading down a waterfall. These ethereal looking trees, in conjunction with the rock of the mountain that bows at the base, forming an amphitheater-like enclosure, creates a wilderness cathedral. On a small knoll, a pew of this holy place, is where those of the past chose to sink their mine into the billion year old bedrock. Not until you reach the summit of this rise can you make out the entrance, which is cleverly hidden from sight by being behind the knoll and dug in perpendicular to the mountain, so that one on a head on approach to the amphitheater must shift to the left to get a full glimpse of the opening, once lined up to it.

 

Apart from it being situated to exclude discovery by accident, its perpendicular setting was probably created to provide a buffer to the nearby Seven Lakes Drive. If, for some reason, the stored dynamite was ever to detonate, instead of debris being hurled directly at the road, it would instead fly parallel to it. Older dynamite could be a highly volatile substance. Many brands of the time were essentially constituted of nitroglycerin mixed with some type of absorbent material such as diatomaceous earth or sawdust to make the product more stable. As the dynamite ages, the sticks may “sweat” and crystals of pure nitroglycerin may form on the outside. Even a minor jolt or shock to these crystals can result in a massive explosion. Today in some cases, the nitroglycerin is being substituted by more stable explosive elements for safer handling.

Cranberry Mine at its lengthiest point is around 200 feet long. At a distance of about 50-60 feet in, the mine bifurcates, each leading section then becoming much more rugged, no longer having an even floor, and the ceiling contracts, so that you now must be conscious of every move to ensure you don’t accidentally hit your head on the jagged rock above. The passage on the left-hand side is the smallest of the two in all respects, and resembles much more a natural cave than it does a man-made structure. On the floor, at the end of the tunnel, are hundreds of dried fecal pellets of the Alleghany woodrat that are at a bare minimum 30 years old. This species has been extirpated from this part of the state for many years, dying off as a result from infection by raccoon pathogens. The sole population that still resides within the state can be found in the Palisades near the New Jersey border. The only visible traces here of the bats that have succumbed to the fungus is the occasional slender wing bone, each narrower than a toothpick, more resembling fish bones than anything else. The bats which drop to the floor are quickly removed from the mine by roving scavengers, such as the aforementioned raccoons.

The longer passage to the right, once you make it past the bifurcation, quickly begins ascending, with a small rivulet running down the floor, making the trek up somewhat slippery and dangerous. The farther you penetrate into the earth, the wetter and steamier it becomes so that staying here for any length of time will result in a thorough soaking from the omnipotent drops of water plunging from the ceiling. It’s hard to imagine any bats wanting to hibernate in this portion of the mine, and yet, in a very moist segment of the ceiling we find a single little brown bat (Myotis lucifugus) clenching tightly to the rock, visibly covered in water droplets. The wings surrounding the body seem to act as a rudimentary rain coat. Perhaps this tiny bat resides here for the warmth, regardless of the dampness. It must be noted that mines provide a much more equable environment than in the open and capricious air outside. Year round the temperatures remain about the same. In the winter it stays well above freezing, while in summer provides refreshing relief from the oft-times overbearing heat.

Scattered in various clusters throughout the entirety of the mine we discover isolated pockets of the big brown bat (Eptesicus fuscus). In certain nooks there are 2 or perhaps 3 bats nestled together, grouped so closely it’s difficult to determine where one ends and another begins. It’s simple to see how the fungus spreads easily with the bats so compacted. The occasional loner is also present, unable to find a compatriot in this roomy cavern. Prior to the fungus’ entry here, every survey turned up hundreds of individuals comprising several species. On this January day 7 big brown bats and a single little brown bat were recorded, giving us a grand total of 2 species and a mere 8 individuals. This precipitous decline is depressing to witness as you walk around where there were once a multitude of slumbering mammals overhead forming furry, brown blankets— now all you see is the cold, damp, and dismal rock, with the addition of the occasional cave cricket hiding in the crevices of the lower ledges, adding to the sense of loneliness and desolation.

This is just one cave of many that has experienced the punch that the white nose fungus delivers indiscriminately.

To help lessen the spread to the few locales not yet contaminated, it’s important to stay out of sites that bats like to frequent, such as their favored caves and mines. As mentioned earlier the spores of the fungus can easily hitch a ride on clothing and shoes. While bat numbers will undoubtedly continue to fall for quite some time and certain previously rare species may unfortunately pass into the history pages, unable to recoup their losses, it is hoped that like their European counterparts, many will develop a resistance to the fungus and make a rebound. We haven’t lost them entirely just yet.