Back To Previous Page
Grassland
Management
|
Cool Season
Grasses
|
Warm Season
Grasses
Prairie
Restoration
|
Old Fields | Grass
Planting | Prescribed
Burning
Meadows | Grassland
Birds
| Upland
Grasslands State Birds and
Flowers
|
Butterflies | Wildflowers | Grain Plots
GRASSLAND BIRDS
Grassland habitats support a large
variety of birds. Before European settlement, grasslands were
largely dry prairies, oak savannas, and wet meadows.
During settlement, expansive, open prairies disappeared quickly
as they were converted to farmland due to their rich soils. Wet
meadows were drained and also made into productive agriculture
lands.
Over the past
25 years, grassland bird populations have declined in
North America more than any other group of birds. This decline
is due to fragmentation and loss of habitat. Habitat
fragmentation occurs when large blocks of habitat are broken up by human development
such as roads, trails, powerlines, homes, farms, and other
disturbances.
Succession
Large grasslands support more bird species than
small grasslands. Because of the massive decline of native grasslands, it is
critical to grassland bird survival that large blocks of this
habitat be maintained and managed. Before management begins, it is
necessary to understand the natural progressions that occur on the
landscape over time.
"Succession" is the word used to describe
these natural progressions. Over time, an area changes from annual plants to perennial plants to shrubs to forests. Succession can be set
back or moved forward naturally (wildfire, windthrow, flooding,
disease) or through human disturbance (prescribed burning, mechanical and chemical
treatments).
As habitats change, different types of wildlife are attracted to
them. For example, a large meadow will provide nesting cover for
bobolinks, but when woody plants begin to emerge the bobolinks will
no longer use it. However, now American goldfinches will appear.
Therefore, to manage for grassland birds you will need to prevent
succession from proceeding too far into the shrub stage by
maintaining a mix of annual and/or perennial grasses and plants include weeds such as lamb's
quarters, ragweed, mare's tail, and foxtail, and grasses such as
quack grass and switchgrass. Perennial plants include goldenrod,
asters, daisy fleabane, brome, timothy, switchgrass, Indiangrass,
and big bluestem.
Warm season grasses are the most productive
of cover types for grassland birds. Big and little bluestem,
Indiangrass, and switchgrass are examples of warm season prairie
grasses, which grow most rapidly during summer's peak when warm
nights follow hot days. Because these prairie grasses stand up well to snow, they
provide thermal cover for roosting birds and other wildlife.
Consider mixing the grasses with forbs (native, flowering herbaceous
plants such as wildflowers) to provide wildlife food and perches for
songbirds. Black-eyed Susan, blazing star, coreopsis, wild bergamot,
and coneflower are some examples of these forbs. Big bluestem,
Indiangrass, and switchgrass are examples of tall prairie grasses.
Short prairie grasses include little bluestem and prairie
dropseed.
Cool season grasses, such as timothy grass,
orchardgrass, and Canada wild-rye, and legumes such as medium-red
clover and alfalfa grow most rapidly during spring and early summer
and again at the end of summer when cool nights follow warm days.
These grasses provide a variety of cover and food for grassland
birds, and are considered short to intermediate grasses. Cool season
grasses are best planted in conjunction with adjacent warm season
prairie grasses.
Species
Preferences
Depending on the grassland bird, each species may prefer a
certain type of grass or grass/forb mix. Many species prefer around
75% grasses and 25% forbs, such as the dickcissel, song sparrow,
horned lark, and upland sandpiper. Northern bobwhite quail prefer
half and half. Whereas the Henslow's sparrow, and common
yellowthroat prefer a minimum amount of forbs.
In addition, certain grassland birds
are attracted to specific grass heights. This refers not only to the
natural height of the grasses themselves, but also the height of the
grasses due to human or natural disturbance. For instance, killdeer
prefer very short grasses and sparse open areas. These usually
include plowed agricultural and early stage old fields. The upland
sandpiper, and horned lark are found in short grasses such as newly
planted row crops and grasses, recently mowed hayfields, and old
fields. Grasses intermediate to tall in height such as late stage
old fields, uncut hayfields, and established prairies attract the
eastern meadowlark, dickcissel, bobolink, and field and savannah
sparrows.
We characterize grassland birds as species that
utilize grasses at some point throughout the year. These species can
also be distinguished into two groups: grassland dependent and
independent. Dependent species use grasslands for all of their
habitat needs. Independent species use grasses for one or two
habitat components while also utilizing other areas, such as forests
or wetlands, for their habitat needs. For
example, the American goldfinch prefers shrubs and small trees along
with intermediate grasses to fulfill its habitat needs. The grasses
are used for food and nesting materials. An example of a grassland
dependent species is the eastern meadowlark. It only utilizes
grasslands for all of its habitat needs.
Edge-sensitivity
Grassland birds also have a preference for the amount of
unfragmented habitat available. Edge-sensitive grassland birds are those
with the lowest tolerance for fragmented habitat. These are also
usually the species that prefer only grasslands (grassland dependent
species). Conversely, species that live in more than one habitat
usually have low sensitivity to edge.
Increasing edge for a certain wildlife species will also
detrimentally impact other wildlife species. When grasslands are
fragmented, many grassland birds are subjected to nest predation
from crows, jays, skunks, raccoons, opossums, foxes, and cats. This
problem reiterates the importance of expansive grasslands for the
survival of declining grassland bird species.
Grassland birds that are
edge-sensitive include the upland sandpiper, bobolink, and savannah
and Henslow's sparrows. The eastern meadowlark and grasshopper
sparrow are moderately sensitive to habitat fragmentation. Due to
their sensitivity and the increase in fragmentation, many of these
species are declining or no longer exist in specific
areas.
Grassland birds that are tolerant to an abundance of edge include
the northern bobwhite quail, red-winged
blackbird, American goldfinch, vesper, field, and song sparrows,
dickcissel, and common yellowthroat.
Management
Considerations
It is important to take a community or
landscape approach to your management. If you own only a small
grassland, it may help to determine what the surrounding landscape
looks like. If other grasslands or agricultural lands are present,
then it may be feasible for you to manage for grassland birds.
However, if your grassland is surrounded by forest, you may want to
consider other goals.
Although most of our original grasslands no longer exist,
there are opportunities available to help grassland birds. Federal
and State conservation programs are helping to increase grasslands
by setting aside land that had been actively farmed. Some good ways
to maintain grasslands in agricultural landscapes is through
pastures, old fields left idle, and protecting vast, open meadows.
Also, for those within smaller, parcels, prairie plantings in your
yard may be beneficial to those tolerant species that do not only
need grasslands.
The following management guidelines will not necessarily
guarantee the presence or absence of certain species. Restoring and
enhancing existing grasslands, and reducing fragmentation are the
best management options for grassland birds. Whenever you increase
the size of a grassland, you will increase the likelihood that
grassland birds will benefit. Therefore, the larger the grassland,
the more species it will support.
The
following are options to consider when managing for grassland
birds:
- To manage for edge-sensitive species, you will need a minimum
of 20 acres. Moderately sensitive species need between 10 and 20
acres, and tolerant species need less than 10 acres. These
estimates are the minimum amounts these species need to survive.
Again, the larger the grassland, the better.
- Avoid fragmenting existing grassland areas. If hiking trails
are to be developed, restrict activities to the edges of the area.
Avoid maintaining hedgerows that may serve as predator perches.
- Minimize the amount of linear edge by avoiding irregular
borders. Circular tracts are ideal.
If large tracts of grassland restorations are not possible, establish
several patches. Try to incorporate adjacent grassy habitats such
as pastures, hayfields, and grassy waterways as
connections between the grassland patches or as non-wooded, open
edges.
Maintain succession in its earliest stages by managing for
grasses and sparse shrubs. Manipulations such as burning and
mowing are required to maintain grass productivity typically
within three to five year intervals.
- Manipulate your grasslands in 1/3 to 1/4 annual rotations. If
several fields are maintained, it is better to manipulate one
entire field, rather than a portion of each field per rotation.
This will reduce fragmentation of your grasslands. However, if you
have only one field, do not manipulate the entire field at once as
it will displace the grassland birds. If possible, allow some
subunits to lie idle each year.
- Use prescribed burns to increase the
productivity of warm season grasses in particular. Conduct burns
in early spring (March or April) or late fall (October or
November).
- Mow grasslands, including cool season grasses and hayfields,
between July 15 and August 31. This will reduce the chance of
destroying bird nests, and discourages the invasion of problem
grass species that move in after late season mowing. Cutting
height should be about 6 inches.
- If you use the grassland for grazing, permit only light
activity by livestock, and leave some areas ungrazed each year by
rotating. Do not graze below 6 inches. Moderate grazing may
actually benefit some wildlife species.
Plant or maintain several types of
grasslands in your area. A mosaic of tall and short grass fields
will provide habitat diversity. If you can plant only one area
to grass, a mixture of warm season grasses with forbs is best.
Cool season grasses mixed with legumes is a second
choice.
- Create 100 ft shrub buffers next to forest edges and human
habitations to reduce the harsh edge. An alternative to planting
shrubs along the edge of a forest is to allow the fire to burn
slowly into the woods so as to create a "feathered" edge. Local
fire authorities should always be contacted prior to the burn to
discuss permits and/or restrictions.
Chemical treatments of grasslands can also be
used to control woody plants. This
should be used only as a last resort!
Herbicides can be used to control any type of undesirable plants
in your grassland, from wood plants to grasses and weeds. Correct
application is most important. Damage of non-target vegetation or
to wildlife is possible if you do not follow the herbicides label
instructions.
- Reducing or eliminating the use of insecticides will provide more valuable
insect food for birds.
In summary, to attract grassland birds you need to provide the
most grassland possible in your area. Reducing fragmentation, and
restoring and enhancing existing grasslands will greatly benefit
grassland birds. Working with your neighbors to maintain larger
tracts of grasslands in your area will likely increase your
success.
|