|
TRENDS BY HABITAT:
(1997-2004 Trends)
|
The species
classifications listed here are based on designations
assigned by Chicago Wilderness. For our purposes,
shrubland birds have also been further separated out and
placed into their own category. Indicator species
(species that well represent a designated habitat type)
are denoted in the "IND" column. The
"TREND" column lists the average yearly rate of change
of a species based on 1997-2004 point count data.
* Click on a species
below to pull up graphs and detailed information about
its trend. *
Grasslands |
Shrublands | Woodlands |
Wetlands
|
|
Nationally,
grassland birds are facing the most significant declines
according to the Audubon 2004 State of the Birds report.
In the Chicago Wilderness region where tallgrass prairie
was one of the predominant habitat types, results are similar and
many species are decreasing as urban expansion continues
to spread through the Chicago area. At the same
time, results from the BCN Census show that some
species like the state threat-ened Henslow's Sparrow are
doing very well in preserved areas despite declining trends on Breeding Bird Survey routes
in Illinois and the Midwest. In addition to
the protection of habitat, active restoration of grasslands
by land managers and volunteers has also had a very
noticeable and in many cases almost immediate beneficial impact.
|
|
"U.B." & "L.B." represent
the upper and lower bounds of the 95% Confidence
interval.
|
|
This habitat
is often under managed and under researched due to its
vague identity as an often transitional habitat between
grasslands and woodlands and its relatively less
important role for plants and other animals.
Nonetheless, this habitat distinction is very important
to birds. The Audubon State of the Birds report shows that many shrubland
species are facing serious declines, second only to
grasslands. As a successional habitat, the long
term management of fragmented shrublands in the Chicago
Wilderness region is a difficult task that often
requires sensitive care.
* Shrublands include
any grasslands or open canopy woodlands with at least moderate understory.
|
|
"U.B." & "L.B." represent
the upper and lower bounds of the 95% Confidence
interval.
|
|
Trends for
woodland birds are fairly equally mixed. Many
species are declining, but many others are increasing.
Woodlands have received a lot of attention due to their
degradation by many nonnative, invasive species
including buckthorn and garlic mustard that have
impacted woodlands at almost every level. Active
buckthorn removal and restoration of woodlands in the
Chicago Wilderness region has had beneficial results for
many species of birds in preserved areas. A number
of species are negatively impacted by the removal of
buckthorn and other shrubs. Restoration in areas
where these birds nest requires additional care;
however, these species will likely increase again as
native understory is reintroduced and allowed to take
hold in areas that were formerly dominated by buckthorn.
|
|
"U.B." & "L.B." represent
the upper and lower bounds of the 95% Confidence
interval.
|
|
Wetland birds
have the fewest declining trends of the four categories
outlined here. Although collectively wetland
species are on the increase, there are still many
species of concern. Many species have adapted to
urban and suburban environments, but others are very
sensitive to environmental changes. The
depredation of nests by predators, changes in water
levels, and invasion of nonnative plant species continue
to be problematic. Furthermore, trends for wetland
species are the least well know. Wetland species
are often very elusive and breed in remote, difficult to
access areas. Continued preservation of marshes in
the Chicago Wilderness region has helped many wetland
species.
|
|