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<DIV><STRONG>New Study May Help in Reducing Bird Collision Mortality at
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<P><STRONG></STRONG></P><STRONG>MEDIA RELEASE</STRONG><BR>Contact: Robert Johns,
202-234-7181 ext.210, <A href="mailto:bjohns@abcbirds.org">Email click here</A>
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<TD width=376><IMG alt="Virginia opossum by Cody Pope, Wikimedia Commons"
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<TD class=note-text height=29>Virginia Opossum by Cody Pope, Wikimedia
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<P>(Washington, D.C., June 8, 2012) A new study published in the June issue of
the <EM>Journal of Field Ornithology</EM> should prove helpful to
conservationists attempting to better understand, quantify, and mitigate one of
the largest killers of birds in the world – collisions with glass on
buildings.</P>
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<P>The study, titled: “Scavenging Affects Persistence of Avian Carcasses
Resulting from Window Collisions in an Urban Landscape,”was produced by Stephen
B. Hager from Augustana College,IL, Bradley J. Cosentino, from the University of
Illinois, and Kelly J. McKay from the BioEco Research and Monitoring Center,
IL.</P>
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<P>“One of the more difficult aspects of understanding and ultimately reducing
bird collision mortality at the millions of buildings in the U.S. and around the
world is accounting for predator scavenging of killed bird carcasses. Our study
is the first to show that scavengers remove bird carcasses at buildings at
different rates and locations depending on the presence of suitable habitat for
predators and if seasonal temperatures allow predators to be active. This
information is useful because it can inform researchers about where and when
scavengers might be a problem and how to best monitor buildings in problem
areas. We also offer advice to researchers about how to approach studying
scavengers at buildings in other locations since scavenger populations may vary
from region to region,” said Stephen Hager, the study’s lead researcher.</P>
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<P>“From 300 million up to one billion birds are killed in collisions with
buildings in the U.S. each year. More accurate measurement of mortality at
individual buildings leads to a better understanding of causal factors, which
can lead to better solutions. Carcass persistence studies have typically been
conducted along with monitoring of collisions at communication towers and in
wind turbine fields. Monitoring of collisions with buildings is more difficult
because buildings are numerous, unevenly dispersed and variable in size and
design, even in a small town. A few studies have tried to monitor representative
samples of buildings but generalizing is difficult and most city monitoring
programs focus on documenting the problem and rescuing injured birds where
possible. The study by Hager et al is especially interesting because it shows
scavengers are able to target areas where carcasses are most likely to occur,”
said Dr. Christine Sheppard, Bird Collisions Campaign Manager at American Bird
Conservancy.</P>
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<P>The study suggests that (1) times between a bird being killed by a window and
being scavenged (carcass persistence) will be shorter at locations with
preferred habitats for known scavengers, such as raccoons and foxes, and
predictable sources of food, and (2) knowledge of scavenger distribution and
activity can be useful in predicting duration of carcass persistence at any
given site. Intervals between searches for dead birds at buildings that will
minimize the number of carcasses lost to scavengers can then be inferred.</P>
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<DIV align=right>Surveillance footage of a raccoon scavenging a
carcass.<BR>Photo by Kelly J. McKay </DIV></TD></TR></TBODY></TABLE>
<P>The study tested the hypothesis that carcass persistence depends on local
habitat factors known to influence scavenger behavior. Scavenger activity on
bird carcasses was documented at 20 buildings in an urban landscape in
northwestern Illinois for one week during each season of one year. The study
also documented species of scavengers and the timing of scavenging using
motion-triggered cameras.</P>
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<P>The study found that carcass persistence decreased as canopy cover (trees and
shrubs within a 50-meter buffer) increased. This is likely because a denser
canopy provides more preferred habitat for scavengers. Carcass persistence also
decreased as window area on the building increased. This is because increase in
window surface increases the number of bird collisions, providing a more
predictable source of food for scavengers – a relationship scavengers seem to
learn</P>
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<P>On the other hand, carcass persistence increases as pavement cover increases,
reflecting diminished preferred habitat for scavengers and consistent with a
well-documented hesitancy on the part of some scavengers to attempt to gather
readily available prey from paved surfaces.</P>
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<P>The study also looked at carcass persistence as a function of season.
Researchers monitored 20 bird carcasses in each season. Estimated mean time of
persistence of carcasses was 82.9 ± 11.7 days for winter and 11.8 ± 7.2 days for
other seasons. For example, at one building, carcasses were estimated to persist
for an average of 23.7 days in the winter, but just 3.5 days during other
seasons. Longer carcass persistence in winter may be explained by the diminished
response of raccoons to unpredictable food sources; i.e., in winter, mortality
due to window strikes is relatively low, and, as a result, scavengers may focus
foraging activities elsewhere. Carcass persistence in winter may also be
affected by reduced activity by vertebrate scavengers when temperatures are
below freezing.</P><!-- InstanceEndEditable -->
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