NEW YORK (September 28, 2010)—A Wildlife Conservation Society (WCS) study on
nesting birds in Argentina finds that increasing temperatures and rainfall—both
side effects of climate change in some parts of the world—could be bad for
birds of South America, but great for some of their parasites which thrive in
warmer and wetter conditions.
study, which looked at nesting forest birds in Santa Fe, Argentina, found that increases
in temperature and precipitation produce a bumper crop of parasitic fly larvae of
the species Philornis torquans,
parasites that burrow into the skin of baby birds to feed. The researchers also
found that these greater parasite burdens result in higher probability of mortality
and impaired growth for the parasitized chicks.
study now appears in the online edition of the Journal of Zoology—published by the Zoological Society of London. The
authors of the study are: Pablo Beldomenico of the Wildlife Conservation
Society’s Global Health Program; and Leandro Antoniazzi, Darío Manzoli, David
Rohrmann, María José Saravia, Leonardo Silvestri of Universidad Nacional de
Litoral in Argentina.
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
the Wildlife Conservation Society’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.”
Carried out by field
veterinarians and biologists between September and March of 2006-7 and 2007-8,
the study focused on both the prevalence and abundance of parasitic larvae in
the study area’s bird community and the impact of parasites on the growth and
survival of bird nestlings.
also examined the influence of environmental factors on parasite prevalence and
abundance, noting a positive correlation between variations in climatic
variables (temperature and precipitation levels) and parasite loads on
nestlings. They found that increases in temperature and rainfall resulted in
During the course
of the study, researchers examined the nests of 41 bird species (715 chicks)
within a 30-hectare area (74 acres) of forest, gathering data on nest height,
brood size, body mass of chicks, and the number of parasites on each bird. The
fly larvae—large in relation to the size of the chick—were easily identified by
the bulges on the heads, bodies and wings of the baby birds. The parasites were found on half (20) of
the bird species studied, with the majority found on only four passerine species:
the great kiskadee, the greater thornbird, the little thornbird, and the
freckle-breasted thornbird. These species were monitored every three days for
data on the impact of parasites on survival and growth.
researchers found that the more larvae the baby birds carried, the higher the
chance of mortality; chicks with 10 larvae were twice as likely to die as chicks
without parasites. One chick had as many as 47 larvae on its body. The fly
larvae also impacted the growth rates of the baby birds; in five days, chicks
that hosted 10 larvae grew 1.85 fewer grams than chicks that were parasite-free.
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, Director of Zoological
Health for the Wildlife Conservation Society’s Global Health Program.
funded by Morris Animal Foundation will shed new light on the ecology of Philornis
and their impact on chicks in the realm of
Contact:John Delaney (1-718-220-3275; firstname.lastname@example.org)Stephen Sautner (1-718-220-3682;
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