Climate Change: Prime Time for Parasites
September 28, 2010
The latest symptom of climate change has wriggled onto the radar of a team of WCS researchers.
In northeastern Argentina, an increasingly muggy
climate is creating better conditions for fly larva
to infect baby birds. In a recent study, WCS field veterinarians and biologists
found an elevated number of parasitic maggots of Philornis torquans
the skin of more than 20 species of nesting chicks. Being large in comparison
to their unfortunate hosts, the parasites can sometimes kill the birds or cause them to grow abnormally.
“Although ours is a
short-term study looking at within-year variability, we clearly show that
higher temperature and precipitation result in greater parasitic fly loads.
This is a striking example of the kind of negative effects on wildlife that can
arise as a result of climate change,” said Dr. Pablo Beldomenico of WCS’s Global
Health Program. “The greater precipitation and warmer weather predicted for
some areas of South America could have a significant impact on native birds
because of a large increase in parasites like these.”
During two consecutive
austral summers, the scientists examined the prevalence of the fly among the
area’s bird community. They found a positive correlation between temperature
and rainfall levels and the amount of parasites affecting nestlings. Of the 41
bird species studies, 4 species—the great kiskadee, the greater thornbird, the
little thornbird, and the freckle-breasted thornbird—were the most prone to
having the telltale bulges on their heads, bodies, and wings of the underlying
The more parasites the
young birds had, the higher the chance the chick would die. The research found
that a bird with 10 larvae was twice as likely to die compared with a chick that was
parasite-free. More heavily parasite-laden chicks also grew at slower rates.
The scientists observed one poor chick that had 47 larvae on its body.
environmental factors influence the health of wildlife populations, and how
this is changing in response to climate change, will help inform strategies to
mitigate its deleterious effects,” said Dr. Paul Calle, WCS’s Director
of Zoological Health.