White-Nose Syndrome Research
A deadly fungus shifts the focus of bat conservation work.
A little brown bat is checked for wing scars, age, and reproductive status. She also gets a band (see her left wrist). MacKenzie Hall
In response to White-nose Syndrome (WNS), the US Fish and Wildlife Service and many states have stepped-up efforts to study bat colonies in both summer and winter, trying to understand the causes and consequences of this unprecedented die-off. In NJ - like everywhere else the fungus has reached - overwintering cave bats have all but disappeared. Hibernia Mine (Morris Co., NJ) went from a hibernating population of around 27,000 bats to fewer than 1,000 in just three years. The common little brown bat and its close relatives, the northern long-eared bat and eastern small-footed bat, are now being considered for federal endangered species listing.
The Conserve Wildlife Foundation provides support to Mick Valent of the NJ Endangered and Nongame Species Program, which oversees bat research in NJ.
Maternity Colony Surveys
Zoom+ Mick Valent and the team set up a harp trap to catch bats as they exit the barn loft at dusk. MacKenzie Hall
Thanks to our long-running Summer Bat Count, we have a host of maternity colony locations on record across NJ. We chose about a dozen of the largest (or historically largest) colonies for more intensive summer surveys. We appreciate all of the people who allowed us into their attics, barns, bat houses, and churches to study the bats. Our goals are to:
- Assess bats for signs of WNS exposure - like wing scars, rips, or holes caused by the fungus;
- Record their weight, sex, and age status;
- Determine whether adult females have been nursing young (showing reproductive success);
- Band bats for future observation;
- Collect fur, blood, and fecal samples for genetic analysis.
Bats have to be physically captured in order for us to do these things. Sometimes bats can be scooped or persuaded into a simple butterfly net, or even grabbed by hand (gloved hand, that is). At other locations, bats are unreachable by day and have to be trapped as they exit their roosts at dusk. This is done with a harp trap, which gets its name from the two parallel rows of offset strings that are pulled tight through a metal frame. A harp trap is set up across a roost exit - such as an open window, door, or hole that the bats travel in and out of. Bats are able to detect and maneuver through the first line of parallel strings using echolocation, but most are not quick enough to avoid the second set. They hit the strings and fall into a plastic receiving bag where they can be picked up and handled.
Hibernation Surveys
Zoom+ John Gumbs (BATS Research Center) and Mick Valent (NJ ENSP) photograph a bat's wings backlit by Ultraviolet light. Brooke Maslo, PhD.
Winter is the time of year when the White-nose fungus (Geomyces destructans, or Gd for short) takes its toll on bats that hibernate in caves and mines. The bats' metabolic activity is low, their immune systems are suppressed, and their body temperatures drop to that of their underground environment. They rely on stored energy to get them through roughly 6 months without food. White-nose Syndrome invades their tissues, disrupting normal hibernation patterns as it eats away at their wings and causes life-threatening physiological changes. Tracking the progression of WNS over winter is necessary to understanding how it emerges and at what stage the bats become imperiled.
As of fall 2011, a majority of the remaining bats inside Hibernia Mine have been banded with their own uniquely engraved bracelet. Noting which survive the winter and which return the following fall is helping us understand survivability after the initial (and most severe) WNS hit.
Zoom+ A little brown bat's wing shows significant fungal involvement under UV light (January 2, 2011). The damage is not yet visible to the unaided eye. John Gumbs, BAT Research Center
Ultraviolet light is also being used as a tool to monitor the onset and development of WNS in hibernating bats. Many minerals, bacteria, and fungi "glow" under UV light - and it turns out that Gd does, too. Scanning a bat's wings under long-wave UV light can reveal the early stages of fungal infection months before the unaided eye would notice anything wrong. Photographic Ultraviolet light surveys are thus being conducted at increments throughout the winter in Hibernia Mine to track the disease. John Gumbs of BATS Research Center, in PA, is pioneering this research in NJ.
Already some valuable observations have been made. For example, we found 3 big brown bats hibernating inside Hibernia Mine last winter. Big brown bats do not commonly hibernate in caves or mines; their hibernation habits are actually quite poorly known. All three big brown bats were startlingly "clean" under the UV light, showing that even those exposed to the White-nose fungus have an inherent resistance to it. This helps explain why big brown bat numbers appear to be stable or even increasing despite the carnage that surrounds them.
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