Media Release May 4, 2016, Guelph, ON:
Captive breeding is well known as an effective last-ditch technique to prevent the extinction of endangered wildlife species, but a new study suggests it may be of little use in saving North American bats decimated by the recent outbreak of white-nose syndrome.
“In many ways, the spread of white-nose syndrome among bats parallels the spread of chytrid fungus among frogs and other amphibians,” says the study’s lead author, Dr. Christina Davy of Trent University. “Several amphibian species have been conserved by the establishment of captive assurance populations in zoos, and captive management has been proposed as a conservation tool for bats as well. Unfortunately, the hibernating, insect-eating bat species affected by white-nose syndrome have complex requirements that are challenging to meet in captivity.”
The Wildlife Preservation Canada study used a combination of simulation modeling, a survey of available infrastructure, literature reviews, and consultations with experts to determine the feasibility of bringing wild bats endangered by the fungus into captivity in order to preserve them. The results showed that, while there is considerable enthusiasm for the idea among conservation scientists, established husbandry methods are lacking, and little capacity is available.
The study focused on five bat species affected by the spread of the disease in eastern Canada: the little brown, northern long-eared, eastern small-footed, tricoloured, and big brown bat. Of these, eastern small-footed and tricoloured bats are so rare that it would likely be impossible to collect enough individuals to form a viable captive population. The big brown bat, meanwhile, appears to be resistant enough to the disease that bringing it into captivity isn’t warranted.
Only the little brown and northern long-eared bats were determined to be potential candidates for captive breeding in Canada. The survivorship of these species in captivity, however, was found to be low. Although experimental colonies have been kept for short times in the past, the researchers found no examples of colonies successfully maintained for longer than 3 years, or of any successful breeding in captivity.
The researchers also found no examples of reintroduction of insect-eating, hibernating bats into the wild following long-term captivity. Individual bats treated at wildlife rehabilitation facilities have been released after short-term captivity, but in those cases survivorship has not been assessed.
Finally, even if proven husbandry techniques did exist, none of the 13 zoos and 29 wildlife rehabilitation facilities surveyed currently have the infrastructure required to house and care for a long-term captive colony.
“The fungus that causes white-nose syndrome is now almost certainly a permanent resident in affected hibernacula,” notes Dr. Davy, ” so even if we could breed bats in captivity and release them into the wild, they’d face the same threat. The best hope appears to be an evolutionary response in which a resistant genetic profile emerges in the wild population.” In the meantime, Dr. Davy recommends studies of post-release survival of individual, rehabilitated bats, and possibly some small-scale captive colony experiments, to close key knowledge gaps and prepare for a possible future in which disease-resistant bats could be reintroduced to areas where they’ve been wiped out.
Although Wildlife Preservation Canada is known for its expertise in captive breeding and other “hands-on” species recovery techniques, its Executive Director, Randal Heide, notes that this doesn’t mean the organization advocates such intervention in all cases. “We’re passionate about preventing extinction,” says Heide, “but we are first and foremost science-driven. In this case, the science says we have a lot to learn before any large-scale captive breeding program should be attempted – and it may never be appropriate.”
The study was co-authored by Amelia Whitear of Wildlife Preservation Canada, and was funded through a grant from the K. M. Hunter Foundation. It was recently published in the Zoological Society of London’s journal Animal Conservation.
Read full study.
