|
 Researchers studied migratory birds and their foraging habitats
to determine which environmental factors affect bird-tick
encounters and the dispersal of ticks in Illinois. Birds are
known to move ticks long distances and play a role in spreading
the black-legged tick (Ixodes scapularis), a primary vector of
Lyme disease.
Along with her colleagues, Parker (who conducted this study for
her master’s research in the Department of Natural Resources and
Environmental Sciences at the University of Illinois) set up
mist nets in 22 forested areas in Champaign, McLean, Piatt,
Putnam, and Vermilion Counties. They trapped birds twice in fall
and again in spring over three years.
Researchers examined the birds’ heads and necks where ticks are
most likely to be found because birds are unable to effectively
groom these areas. During the study, the scientists captured and
released 1,077 birds of 83 species.
Of the species studied, 42 percent were infested with at least
one tick. Nearly 370 ticks were found on 136 (13 percent) of the
birds captured.
“These numbers are fairly typical of what we would expect to see
on birds in forested areas in central Illinois,” Parker said.
“None of the birds had a large infestation.”
Birds with the largest number of ticks included the
white-throated sparrow, Northern Cardinal, and gray catbird.
About 20 percent of ticks found were the black-legged tick.
The most important factor influencing bird infestation by ticks
was the height above the forest floor at which birds forage,
Parker said. Birds that forage closest to the ground were most
likely to have ticks, since ticks live on the ground and in low
vegetation, surviving on moisture from the underbrush.
The researchers expected higher infestation rates in patches
where invasive shrub cover was relatively high. Invasive species
such as honeysuckle and multiflora rose form a dense understory
with abundant fruit and cover for wildlife, and also suitable
conditions for the black-legged and other tick species. Instead,
the researchers found that as the vegetation cover increased,
tick infestation among captured birds declined. Parker suggested
that the fruit grows across the crown of these shrubs, which may
reduce tick-bird interactions if ticks are searching for hosts
at lower levels below shrub crowns.
Tick infestations were also more prevalent among birds captured
in large forest plots compared with smaller plots, likely
because tick populations tend to flourish where there are
abundant deer and other large animals available for blood meals.
[to top of second column] |
“It is important for people to be aware that migratory birds
move ticks, and thereby pathogens, into areas where ticks were
previously not established,” Parker said. “Just because Lyme
disease isn’t a problem in one area doesn’t mean that
disease-carrying ticks won’t inhabit that area in the future.”
The study was published in the Journal of Medical Entomology.
About the Prairie Research Institute: The Prairie Research
Institute (PRI) at the University of Illinois at
Urbana-Champaign comprises the Illinois Natural History Survey,
Illinois State Archaeological Survey, Illinois State Geological
Survey, Illinois State Water Survey, and Illinois Sustainable
Technology Center. PRI provides objective natural and cultural
resource expertise, data, research, service, and solutions for
decision making, the stewardship of Illinois’ resources, and the
public good. www.prairie.illinois.edu
[© 2017 Thomson Reuters. All rights
reserved.] Copyright
2017 Reuters. All rights reserved. This material may not be
published, broadcast, rewritten or redistributed.
 |
