Fungal disease is wiping out bat species in North America
Numbers of the Northern myotis, little brown bat and tri-coloured bat have been decimated by the spread of the fungal pathogen, Pseudogymnoascus destructans, which causes white-nose syndrome in bats.
The disease manifests as a fungus which grows over the bats face, wings and/or ears (see figures) while it is hibernating through the harsh winter months when food is scarce. To gain a presumptive diagnosis in the field, bats are examined for this white fungal growth but this is not definitive; to confirm the diagnosis scientists examine the individual for the characteristic pattern of skin erosion caused by this fungus. It is not entirely clear how it causes mortality as it does not infect the blood or the organs but appears to destroy the tissue in the affected areas, leading to fat loss and therefore increasing the bat’s susceptibility to the cold.
It is believed to have been introduced to North America from Europe where this particular fungus has been present for a much longer time, though it appears that European bat species have immunity to the disease. The greatest cause for concern is also the rate at which it is spreading, with the disease progressing at a rate of roughly 200-250 Km per year. Biologists tracking the disease in Canada have also recorded an unprecedented decline in bat numbers; 99% of little brown bats have been wiped out by the disease since it was first documented in 2006, and a rough estimated decline of 80% overall in the effected species. These mammals are long lived and only have one pup per year, making it a long and tenuous recovery process for those which survive.
There is, as of yet, no cure and no method of containment. It is estimated that within 12-18 years, all bat populations in Canada will have been hit by this disease. Research into the disease itself has been hindered by the lack of knowledge about the true activities of the bats in the winter, and where their hibernicula are located. Information is continuing to be gathered and assessed and pressure is being placed on the Canadian Government to upgrade the bats status to ‘Endangered’.
www.natureworldnews.com, www.whitenosesyndrome.org, www.cbc.ca, www.scientificamerican.com
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