White-Nose Syndrome Research
A deadly fungus shifts the focus of bat conservation work.
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 New Jersey - like everywhere else the fungus has reached - bats that overwinter in caves have nearly disappeared. Hibernia Mine (Morris Co., New Jersey) went from a hibernating population of around 27,000 bats to fewer than 600 in just four years. The threat is so serious that the little brown bat and the eastern small-footed bat, are now candidates for the federal endangered species list. The northern long-eared bat was listed at federally threatened in April 2015.
Stephanie Feigin with the Conserve Wildlife Foundation provides support to MacKenzie Hall of the New Jersey Endangered and Nongame Species Program, who oversees bat research in NJ.
Winter is the time of year when the White-nose fungus (Pseudogymnoascus destructans, or Pd for short) takes its toll on bats that hibernate in caves and mines. During their delicate hibernation, the bats' metabolic activity is low, their immune systems are suppressed, and their body temperatures drop to match the 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 undertand how it emerges and at what stage the bats become imperiled.
A majority of the remaining bats inside Hibernia Mine and many from nearby Mount Hope Mine are now outfitted with their own uniquely numbered band. Noting which survive the winter and which return the following fall is helping us understand survivability after the initial (and most severe) WNS exposure.
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 Pd 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 have thus been conducted at increments throughout the winter in Hibernia Mine to track the disease. John Gumbs of BATS Research Center, in PA, pioneered this research technique here in NJ and is sharing his observations with biologists across the country.
Maternity Colony Surveys
Thanks to our long-running Summer Bat Count, we have a host of maternity colony locations on record across NJ. We monitor any remaining little brown bat colonies (which are difficult to find in a post-WNS world), as well as a few big brown bat colonies, which are still common. We appreciate all of the people who allow 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.
As of summer 2013, the wing scars we had seen in so many bats after their first exposure to White-nose Syndrome were almost completely gone. It's encouraging to see that some bats are surviving multiple winters without showing the same detrimental symptoms from year to year. Female bats are also successfully rearing young. But summer counts have not yet shown an up-tick in little brown bat numbers; in fact, they have continued to go down. In addition, very few adult bats have been recaptured from one year to the next, making it difficult to measure survivorship within maternity colonies. We have been able to tie at least three maternity colonies to three different hibernation sites in NJ and PA, though, through banding efforts.
This past summer 2015 we surveyed 6 maternity colonies to assess bat survivorship and recruitment (4 little brown bat roosts and 2 big brown bat roosts) with great success, taking measurements and banding over 150 bats. We also confirmed a new colony of nearly 50 little brown bats roosting in bat houses in Morris County, containing some individuals banded at Hibernia Mine over the past few years (one had been banded as a juvenile in 2011).
The team also participated in studies on natural impediments (i.e bacteria and yeast byproducts) to the White-nose fungus. We collected swabs and tissue samples for a lab research study of skin immune proteins as possible agents of resistance against the White-nose Syndrome fungus.
The wing scars we had seen in so many bats after their first exposure to White-nose Syndrome were almost completely gone. Though we are still seeing continued survivorship, we continue to see a slow decline of little brown bat populations.
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