[TN-Bird] Fw:West Nile Impacts on Chickadees and other Songbirds

Since there was interest in our study of the impacts of West Nile Virus on
crows, I'm sending to this list the results of our study of its effect on
chickadees...

Study Finds Chickadees Gone in Large Areas
West Nile Threats to People and Wildlife

A study of results gathered by 74 trained monitors throughout the 6-county
Chicago region found that the black-capped chickadee, a common bird of our
woods and towns, appears to have been completely extirpated in large areas.
This is the first study that focuses attention on the effect of West Nile
disease on songbirds, and it raises questions about the effects of chemicals
used to control mosquitoes.

The map of the survey results tells a dramatic story. In three areas of our
region - parts of eastern Lake County, some south suburbs, and a large area of
northern Chicago and nearby suburbs - chickadees were almost completely gone.
Thirty trained volunteer monitors spent 101 hours searching 31 sites with good
chickadee habitat and found only two chickadees. Judging from previous October
data, more than 120 chickadee sightings would be expected for this level of
effort at these sites. The findings in these three areas are in marked
contrast
to the rest of our region. In all other areas surveyed, chickadee numbers were
reported as low or average (ranging between one and 23 per survey); in these
areas very few observers found no chickadees.

The mosquito season is now waning. West Nile concerns will not be in the
forefront until spring 2003. Audubon recommends carefully weighing the
needs of
birds in developing next year's pest control strategies.

The map of the area where chickadees are missing in the north suburbs
coincides
with the map of the highest incidence of human West Nile Virus cases.
Twenty-two chickadee searches totaling 81 hours turned up only two birds in an
area of approximately 120 square miles extending from northwest Chicago
through
Des Plaines to Northbrook, and east to the lakefront from Winnetka south to
the
northernmost neighborhoods in Chicago.  Many observers reported having seen
dead or ill chickadees in early August, when thousands of dead crows were
being
picked up by municipalities in this area. Early August was also the date many
gave of their last sightings of chickadees in the area.

A second area where no chickadees were found is in the south suburbs,
encompassing Calumet City, Park Forest and Crete. Finally, no chickadees were
found in five surveys in Zion and Lake Forest. For the rest of the region,
chickadees were reduced in numbers but present; only three of 42 surveys
outside these areas failed to turn up chickadees. Numbers were low at the
points surveyed in DuPage and Northwestern Cook County, and average to low in
points in southwest Cook, western Will, Kane, McHenry and western and southern
Lake County.

The study results cannot be ascribed to habitat differences: the older, wooded
neighborhoods, forest preserves, and parks of these areas are optimal
chickadee
habitat. Nor can they be ascribed to time of year: comparisons were made to
previous years' October data to determine expected numbers.

Study participants commented on low numbers of many other bird species.
According to Scott Wright, Branch Chief, Disease Investigations, USGS National
Wildlife Health Center, "From this study, it appears that we should take a
close look at the survival rate of chickadees and some of our other songbirds.
We have much more to learn about the impact of this disease on wild birds."

Both West Nile disease and some mosquito control methods are threats to humans
and many other mammal and bird species. Audubon supports wise mosquito-control
and encourages that the planning for 2003 start now.

Trained and experienced bird monitors of the Bird Conservation Network Census
conducted the study. This is the second study of the impact of West Nile Virus
by this group. The first study documented that crows had entirely disappeared
from the north suburban area, and found reduced numbers in some other areas.

Material from various sources
about the study and West Nile virus

"Communities can greatly enhance their ability to eliminate the threat of
disease-carrying mosquitoes by replacing chemical larvicides with
bacteria-based products, which kill mosquitoes, but not beneficial insects,
such as dragonflies; amphibians; and fish that prey upon mosquitoes. By
eliminating pools of stagnant water in parks and at dumps, and by allowing
some
drainage of dammed areas, communities also decrease the available breeding
ponds for mosquitoes. Homeowners can help; cleaning out gutters and removing
tarps, tires, and other objects where water can collect also prevents
mosquitoes from reproducing. Aerial spraying of pesticides has been shown
to be
less effective than targeted, localized spraying. If pesticides are to be
employed, a focused, limited, and timely response works best."
Frank Gill, Senior Vice President for Science
Audubon (National Audubon Society)

"Several species of Culex mosquitoes are suspected as the main vectors of this
disease. One, Culex restuans, feeds only on birds. Another, Culex pipiens,
feeds primarily on birds but may also bite mammals. This mosquito is very
adaptable, breeding in catch-basins, gutters, and other urban stagnant water
all around the world. You might wonder how mosquitoes get to birds through all
those feathers - they bite birds around the eyes and feet."
Robert Novak
Professional Scientist
Center for Economic Entomology, Illinois Natural History Survey

"West Nile Virus has patchy distribution in its effects humans and wildlife.
Within those patches, bird mortality can be extremely high."
Scott Wright
Branch Chief, Disease Investigations
USGS National Wildlife Health Center

Observers were asked to look for chickadees on October 10, 11, 12 and 13 in
their yards or in woods where they would expect to find them, and to record
the
number of chickadees they found and the amount of time spent looking. They
were
also asked send data from the same spot in previous Octobers, if available,
and
if not, to estimate whether the number of chickadees they found was high,
average or low. Finally, respondents who found no chickadees in a location
were
asked when they last saw them.

Judy



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Judy Pollock
Bird Conservation Projects Manager
Audubon - Chicago Region
5225 Old Orchard Rd.  Suite 37
Skokie, IL 60077
(847) 965-1150
fax (847) 965-9282
jpollock@xxxxxxxxxxx

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