This US research may have some parallels on our side of the black stump.
U.S. Department of the Interior
U.S. Geological Survey
Release August 5, 2001
Grassland Birds and Habitat Fragmentation: The Role of Predators
North American grassland areas are increasingly fragmented, which may be
having an adverse impact on bird populations, according to biologists at
the U.S. Geological Survey.
Declines in North American grassland bird populations are largely due to
loss of habitat. As grassland areas are divided into smaller tracts of
land, there are more ?edges? and fewer large, open grassland areas for
birds to nest in. Biologists have suggested that predators looking for
food near these ?edges? might be more likely to prey on grassland bird
nests, making it more difficult for birds to successfully raise chicks.
>From 1998 through 2000, USGS biologist Rosalind Renfrew and her
colleagues Jamie Drossel and Christine Ribic from the Department of
Wildlife Ecology at the University of Wisconsin-Madison, placed
miniature cameras at 89 nests of five grassland bird species in
southwestern Wisconsin pastures. They found that most of the bird
predators were raccoons, thirteen-lined ground squirrels, and snakes.
About one-third of the nest failures were caused by species that prefer
the woody edges of grasslands, such as raccoons and opossums, and these
nests were usually closer to woody edges than other types of edges.
In 2000 and 2001, the scientists monitored sand track stations placed at
regular intervals along the edges of pastures and found that the same
species that preyed on nests near woody edges were predators that
frequented those edges.
The scientists conclude that the fragmentation of grasslands is making
it easier for ?edge? predators to find nests and that this may be
contributing to population declines among grassland birds.
Rosalind Renfrew may be reached at or
USGS Home page
Index of USGS News Releases
U.S. Geological Survey, MS119 National Center, Reston, VA 20192, USA
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