Fungal growth: A white substance can be seen growing on the noses of these hibernating bats, experts believe it may be unchecked fungal growth.
Credit: Al Hicks, New York Dept. of Environmental Conservation
SYDNEY: Thousands of hibernating bats in the U.S. have been found dead or dying due to an unknown disease. Experts have noted similarities to the colony collapse disorder, which has ripped through North American bee populations.
Since March 2008, the bat malady has spread to afflict colonies in at least 25 caves and mines across the north-eastern states, says the U.S. Geological Survey (USGS). The agency has issued a call for wildlife workers to keep a careful watch for 'white-nose syndrome' as the killer has been dubbed.
"Major and imminent threat"
"Hibernating bats are dying by the tens of thousands in the north-eastern United States and a growing circle of top scientists is anxiously trying to figure out why," said a statement from Bat Conservation International (BCI) a NGO based in Austin, Texas.
"The syndrome clearly is a major and imminent threat to North American bats, and until the cause is identified, we can do little to counter it," the conservation group said.
Most of the affected bats are found with a mysterious white substance on the nose and in patches over their bodies.
However, experts say that the white substance may not be the cause of the disease, but a symptom. Some believe it is an overgrowth of a normal skin fungus indicating poor health. Sick bats have been emaciated and dehydrated, and some showed an unusual pathology of the lungs never seen before.
Race against time
"Anyone finding sick or dead bats should avoid handling them and should contact their state wildlife conservation agency," said USGS disease specialist Kimberli Miller at the National Wildlife Health Centre in Madison, Wisconsin.
That centre has already examined over 100 dead bats from as far as New York, Connecticut, Vermont and Massachusetts.
The syndrome has been seen in species including the little brown (Myotis lucifugus), big brown (Eptesicus fuscus), northern long-eared (Nyctophilus arnhemensis) and eastern pipistrelle (Pipistrellus subflavus) bats.
It is now a race against time for scientists to find the cause of the sickness and attempt to halt its progress.
Several suspects
BCI said that the main suspects are: an unknown viral, bacterial or fungal pathogen; the effect of climate change on food supply or hibernation; or an environmental pollutant (such as a pesticide) which has impaired the bats' ability to build fat reserves for the winter.
At present, scientists can't be sure whether the disease is just transmitted between bats or if humans are helping the spread.
Wildlife biologist Al Hicks of New York's State Department of Environmental Conservation is heading up the scientific effort to find the culprit. He says that the first cases were reported in Albany, New York, over a year ago and this year has rapidly spread over a wide area – potentially supporting the idea that a disease is behind the deaths.
Carole Copeyon of the U.S. Fish and Wildlife Service's Pennsylvania Field Office noted an uncanny similarity in the epidemiology of the disease to the deadly bee disease colony collapse disorder (CCD), which has swept across the U.S. since 2004. In both bats and bees, sick animals were found to leave their colonies during winter, she said, which is highly unusual.
Maladaptive behaviour
"There may be no association with what we are seeing in bats … but some of the similarities including the timing of the bee and bat colony collapses and the incidences of highly unusual, maladaptive behaviour raise questions," said Copeyon in an email.
Whatever the cause, bat numbers are dropping fast, with losses of around 90 per cent reported in some colonies. This is of major concern in species where the female only produces one pup a year, said a statement from the U.S. Fish and Wildlife Service. The loss of bats from the ecosystem could also cause an ecological upheaval, since the mammals each eat many thousands of flying insects in the summer.
BCI has arranged an academic meeting in June for scientists to compare notes and identify the most important avenues for investigation.
