New threats call for new partnerships in wildlife conservation
Note: This piece ran in the Sunday, June 3, News-Gazette, but I haven't figured out a way to fit it into a radio spot so there's no audio version of it. -rk
Last spring, some mushroom hunters made a strange and
unsettling discovery at Forest Glen Preserve in Vermilion County, a group of
about 50 dead box turtles. Or, to be more precise, the closed, empty shells of
the deceased turtles.
According to Chris Phillips, who is a herpetologist with the
Illinois Natural History Survey, a division of the Prairie Research Institute
at the University of Illinois, a total of 65 shells were ultimately found in
the area. They were dispersed in a way suggesting they had died where they
lived--that is, they had not become infected elsewhere and been dumped there.
What killed them? Phillips says the shells yielded few
clues. Unlike the shells of turtles that have died under normal circumstances,
they were devoid of any soft tissue, but the bones of the pelvic and shoulder
girdle were inside. This was odd since it meant that the animals were in their
shells when they died and nothing scavenged them enough to get the bones out.
Sealing themselves off from enemies is, in most cases, an
excellent defense for eastern box turtles, which may live to an age of 50 years
or more, even in the wild. But the turtles involved in last year’s die-off at
Forest Glen obviously met up with an out-of-the-ordinary foe.
[Photos: above, a healthy eastern box turtle (Chris Phillips); below, Matt Allendar draws blood from a turtle with its shell propped open (Rob Kanter).]
Fortunately, it was possible to identify a culprit through an
examination of living turtles discovered in the same area. Phillips and others
collected 12 of them. Of those 12, five were missing all or part of a leg, the result
of an aggressive bacterial infection that subsequently killed them, too.
If Phillips had been the only researcher to handle the living
turtles found at Forest Glen, he might never have even witnessed the grisly
effect the infection had on them. That’s because the ecological and genetic
data he collects can be taken while a turtle’s shell is closed, with the head
and legs out of view.
But Phillips was examining the turtles together with Matt
Allender, who is a wildlife veterinarian and instructor in comparative
biosciences at the UI. Allender’s assessment of the turtles required waiting
until they opened their shells, and at that point their affliction was
apparent.
Phillips and Allender, who have known each other since
Allender was a student in Phillips’ UI herpetology class in 2000, are
collaborating in a one-of-a-kind effort to combine long-term ecological data about
box turtles with periodic health assessments.
Phillips and his students from the UI Department of Natural
Resources and Environmental Sciences seek to understand how certain populations
of box turtles in east central Illinois are faring over time. Toward that end,
they’ve been capturing and marking turtles at three sites in the Vermilion
Valley since 2009. Such work allows for an assessment of the status of the
population now, and provides data to predict the likelihood the population will
survive 50 or 100 years into the future. This is the classic wildlife ecology
approach that has been practiced for decades.
Allender and his students from the College of Veterinary
Medicine seek to profile the health of turtle populations at a given time by
analyzing the physical condition of individual animals.
Much of their analysis is done through blood work. They monitor the immune system by checking
for anemia or elevated white blood cell counts. They test for the presence of
ranavirus, a pathogen that has been linked to mass deaths of a variety of
reptiles and amphibians worldwide. And they look for evidence of exposure to
environmental toxins, such as lead and zinc, which compromise health by
suppressing the immune system, even at low levels.
Such work has not typically been integrated with wildlife
ecology in the past, but Allender thinks it could play an important role in future
conservation decisions. For example, he says it could provide evidence of
whether or not turtles experience health effects from living in habitats
dominated by invasive species, or how the extent of habitat available affects a
population’s capacity to withstand disease.
There was a time in the not too distant past when the threat
of disease scarcely entered the calculations of people who were concerned with
the welfare of wildlife, and habitat seemed to be everything. It was widely
assumed that if people could just preserve or reconstruct the right amount of
the right kind of habitat, they could ensure the continued existence of many species,
especially ones facing no immediate threats of overexploitation or exposure to
obvious toxins.
Such thinking caused Phillips to assume that he and Allender
were parting ways for good back in 2000. “Knowing
that Matt was going to vet school, I thought, that's too bad, I'll never run
into this bright kid again. He's going to treat cats and dogs, or end up
at a zoo. It didn't dawn on me at that time that there was even a remote
chance that I would ever need to collaborate with a vet.
Even when he approached me about doing a Master’s degree on the health of massasauga
rattlesnakes at our study site near Carlyle (Illinois), I thought, well, as
long as he doesn't get in our way.”
More recently, however, the emergence of devastating
pathogens in a variety of species around the world has caused Phillips and
others who have spent their careers doing traditional wildlife ecology to
reconsider. As Phillips puts it, “Habitat does little good when entire
populations are destroyed by disease.”
Perhaps the most well known of these is the notorious white-nose
syndrome, which has killed North American bats by the millions since its
emergence in 2006, wiping out entire colonies of some species as it spreads.
Among reptiles and amphibians, two diseases have had
dramatic impacts around the world. A chytrid fungus, B. dendrobatidis, has led to the extinction of localized frog
and toad populations in many places, and possibly entire species in some cases.
Ranaviruses have killed numbers of amphibians ranging from one to 1,500 in
populations where they have struck across the Unites States, Canada, and
western Europe. Ranaviruses have been proposed as a major threat to
biodiversity in North America.
Close to home, Allender recently identified a fungus,
Chrysosporium, as the cause of death for four of the eastern massasauga
rattlesnakes from the already dwindling population near Carlyle. (Massassaugas
are already classified as endangered in the state, and they appear to be headed
for federal listing soon, too.) According to Allender, the genus Chrysosporium infection has long been a
problem among captive reptiles, but this species of Chysosporium has not previously been identified as a problem in captive
or wild animals.
At the same time Chrysosporium has become a problem for
massasaugas in Illinois, it has also caused significant losses among struggling
populations of timber rattlesnakes in New Hampshire and Massachusetts, where it
was also not previously known as a problem. In fact, since the December 2011
publication of a paper about the infection in Illinois, Allender has received nearly
a dozen reports of similar infections from five states east of the Mississippi.
The turtles involved in last year’s die-off at Forest Glen
were afflicted by none of the above maladies, but rather a bacterial infection.
According to Allender, the bacterium responsible for it
occurs in many environments. While it’s capable of infecting a wide range of
hosts, including birds and mammals, it is also commonly present without causing
infection. He suspects that the health of the afflicted turtles had already been
compromised in some other way, and hopes that further study will reveal how.
Allender says he has never seen such an infection in his
previous work with box turtles, and he knows of no other reports of it
elsewhere. He’s certain it’s not a one-time occurrence, though, since five of
the turtles he and Phillips captured for study at another site this year exhibited
lesions similar to those on the turtles from Forest Glen.
Whether or not this bacterial infection turns out to be a
large-scale, ongoing problem for box turtles, Phillips and Allender both see it
as a clear indicator of the need for biologists and veterinarians to cooperate in
the cause of wildlife conservation.
