Northern Prairie Wildlife Research Center
Relationship to booming grounds
Movements of greater prairie chickens can best be described as occurring
within and/or on the periphery of a distribution of booming grounds. This
distribution of booming grounds and the area within 5 miles surrounding it
delineates a prairie chicken population and its habitat. In other words, prairie
chickens and their habitat will be found within sight of the booming grounds.
Perhaps the most striking aspect of the relationship of prairie chickens to
booming grounds can be seen during periods when individuals make major seasonal
shifts. Even when individual radio-marked birds have moved 5-30 miles, they
have always ended up within 2 miles and usually within 1 mile of a booming
In central Wisconsin all radio locations (n= 8,000) and observations of
prairie chickens (n=22,000) were within 4.5 miles of a booming ground, 92%
were within 1.2 miles and the average distance was 0.6 miles. Hamerstrom and
Hamerstrom (1973) stated, "With most of the known activities of birds
within a range of 2-3 miles and almost all within 5 miles it follows that
management practices should also be close together so that the annual requirements
of the birds can be met within small compass."
All locations of radio-marked prairie chicken cocks in central Wisconsin
were within 4 miles of their home booming ground and 75% were within 1.5 miles.
The home booming ground is the one a cock displays on and the one nearest
a hen's nest. Hens showed less of an association to their home booming ground
than cocks with all locations within 8 miles and only 47% located within 1.5
The distance to the nearest booming ground varies with the season, sex, age, and distribution of habitat types relative to disturbance patterns as they relate to the height of the vegetation and its ability to conceal a bird. The seasonal changes in the distribution of prairie chickens is one of shifting to and from the grassland areas within 1 mile of the booming grounds. Prairie chickens are closest to the booming ground during the breeding season and farthest during winter when snow cover reduces the amount of food and cover. The main factors that control daily movement patterns are the distance from the booming ground and/or food source to night roosting cover.
Night roosting cover is critical as prairie chickens spend more than half
their lives in this habitat. Toepfer (1988) and Toepfer and Eng (1988) found
that prairie chickens do not use the same night roosting area on successive
nights during the winter. The pattern of use was irregular and emphasizes
the need for a large amount and good distribution of roosting cover. Night
roosting and nesting cover are similar in form, hence many areas used for
night roosting will also provide habitat for nesting. Most booming grounds
are located within 0.25 miles of night roosting cover.
Booming grounds are not randomly located. Their location and habitat surrounding
them must meet the daily, seasonal and year round needs of the cocks. During
the period mid-September through April prairie chickens in the northern range
typically make at least 1 flight per day of 0.25 to 1.25 miles from night
roosting grassland cover to the booming ground or to agricultural fields to
feed. We know of no radio-marked birds anywhere that have existed solely in
the grassland habitat during the nonbreeding season.
Adult hens are rarely observed on or near the booming grounds and visit only to select a mate and/or breed. Hens have a loose bond to the area and habitat surrounding a specific booming ground, but not to the booming ground proper. Hens, unlike cocks, show no association to their nesting areas or home booming ground outside of the breeding season. This is in contrast with cocks that can be observed on the booming grounds on a regular basis every month of the year except during the peak of the flight feather molt during July and August. Cocks spend 10-15% of their lives on the booming grounds. This bond to the home booming ground is very strong especially in adults. Cocks have even been observed on the booming grounds on calm mornings in January and February when temperatures were 20-30 below zero.
Adult cocks will stay as close to their home booming ground as possible,
but immature cocks are more likely to abandon their home booming grounds during
winter and move to areas with better food conditions and/or less competition.
They will, however, return when conditions improve or the breeding drive becomes
Cocks start to abandon their booming grounds in mid-May. However, a majority
continue to visit and display until the last week of June. Once cocks abandon
the booming ground most spend the summer within 1-2 miles. It is at this time
that the prairie chickens begin to molt their flight and body feathers. The
replacement of flight feathers is not complete until October and the pinnae
and body molt are not complete until mid-November. Prairie chickens are never
flightless, but their ability to fly during summer becomes limited and their
movements reduced to short low flights of 0.1 to 0.2 miles.
Summer home ranges for cocks in Wisconsin averaged 425 acres. Movements
were limited with some individuals walking between feeding and night roosting
cover. Many birds spent the summer along the edges of agricultural fields
feeding in the crops and night roosting in the adjacent grassland cover.
Adult cocks return to the booming grounds during the last week of September
and will visit every morning weather permitting. Fall display is sporadic
and if it is windy or raining the bird may not visit the booming ground proper
or if they do they will just sit and not display. After visiting the booming
ground cocks will fly to a feeding area then to a day roost or loafing area.
During late afternoon they fly to feed and then make a flight to a night roosting
area from where they return to the booming ground the next morning. This pattern
continues through the fall and into early winter.
Fall display appears to occur more frequently on larger booming grounds
(6 or more cocks) and less in populations of low density. In Illinois where
the populations declined from 250 to 10 cocks, fall display was observed less
and less and finally not at all (Westemeier personal commun.).
Adult hens without a brood follow a movement pattern similar to the cocks
during fall except they seldom visit booming grounds. Immature cocks and hens
will begin to visit booming grounds in mid-October. This coincides with the
break-up of broods from first nests. The young cocks visit in an effort to
obtain a territory. Young hens probably visit out of curiosity and/or due
to the urge to become part of a flock. Once young cocks recruit to a booming
ground they adopt the movement patterns of the local birds. Young hens localize
their movements with flocks consisting of other hens and immature cocks that
have not recruited to a booming ground. Fall home ranges in central Wisconsin
averaged 265 acres and 1,575 acres for cocks and hens, respectively. Flight
distances during the fall typically range from 0.25 to 0.5 miles.
Movements of both cocks and hens vary between areas and even between booming
grounds within areas (Toepfer 1988). The distance moved is directly related
to the distance between the different habitat types, especially the distance
between feeding and night roosting areas. Snow has the greatest influence
on daily movements as its presence and movement alters the form of cover and
reduces the availability of food. Winter home ranges in central Wisconsin
averaged 1,630 and 1,800 acres for cocks and hens respectively. On the SNG
winter home ranges averaged 1,900 and 2,175 acres for cocks and hens respectively.
Movements between feeding and night roosting areas during winter range from
0.5 to 1.0 miles.
Prairie chickens in Wisconsin, North Dakota and western Minnesota responded
to long periods of sub-zero temperatures by reducing activity; by feeding
only once a day and by remaining in snow burrows longer in the morning. Feeding
activities were limited to once a day followed by a return to a night roosting
area where the birds would make snow burrows earlier than at other times of
the year (as early as 11:00 AM). At times, birds would night roost (snow burrow)
in the fields they fed in during the day. Severe winter conditions, deep snow
and cold temperatures also cause cocks to abandon their booming grounds for
several days or for a month or more.
In winter, in both North Dakota and western Minnesota, prairie chickens
can typically be found feeding in grain, soybean or sunflower fields where
the wind has either reduced the amount of snow or blown it clear. In central
Wisconsin, standing corn food plots are planted specifically to provide winter
food for prairie chickens. Currently, the main agricultural crop in central
Wisconsin is potatoes and there is little waste grain available for winter
Burger (1988) found prairie chickens in Missouri moved farther and covered
larger areas in a grassland mosaic than in an area with large blocks of grassland
cover. Toepfer (1988) found that annual home ranges in central Wisconsin were
twice those of birds at Crex Meadows and reflected a closer juxtaposition
to agricultural food plots and undisturbed grasslands for night roosting.
Individual birds associated with booming grounds or areas with less undisturbed
cover have to fly farther between feeding/day and night roosting cover and
the booming ground to meet their daily and seasonal needs. However, smaller
ranges may not indicate better habitat. At Crex Meadows, habitat conditions
were ideal for adults but lacked enough upland grass habitat for nesting and
brood rearing necessary to sustain the population.
Prairie chickens are social birds. The exception is when hens often
move alone during nest site selection and egg laying. Of 30,000 prairie chickens
observed away from booming grounds in Wisconsin and North Dakota over 90%
were in groups of 2 or more. The large flocks or packs observed during the
winter in feeding areas are not social units but are concentrations of several
smaller flocks using a common feeding area. It may be redundant but prairie
chickens are attracted to prairie chickens. When immatures leave their brood
mates and mother the first thing they attempt to do is try to join a local
flock of prairie chickens. If they cannot recruit locally they will move until
they find a flock they can join.
Immature hens may initially try to join up with the flock of adult cocks
on a nearby booming ground but they probably remain only temporarily because
adult cocks almost always dominate hens. Hence young hens will continue to
move until they can join a flock of adult hens/or immature cocks and hens.
This is probably why young hens are so much more mobile than young cocks.
Where an individual bird is born, its sex and age, not necessarily habitat
will play a dominant role in why, when and where individuals move. A young
bird cannot go wherever it wants but has to work its way into an already existing
social structure of cocks and hens. Therefore all habitats and areas are not
available to young birds. Hence they tend to wander, especially the young
hens, until they can establish themselves in a specific area and develop a
familiar area. Habitat plays a role in these early movements but only as it
relates to the presence and density of birds already in a given area. Once
established these young inexperienced birds tend to adopt the movement patterns
of the local birds they associate with. The establishment on a booming ground
(cocks) or to a local area (hens) occurs for some in the fall and early winter
but a portion do not become completely established until the following spring.
Relationship to booming ground - nests
All past and current studies indicate that the area immediately surrounding
the booming grounds contains the habitat that is critical to reproduction
and year round survival of prairie chickens. All nesting studies over the
past 75 years indicate that most if not all nests are located within 2 miles
of a booming ground with at least 75% located within 1 mile (Buhnerkempe et
al. 1984, Newell 1987, Toepfer 1988, Toepfer unpub. data, Burger 1988, Schroeder
and Braun 1992). There is little doubt that the area within 1-2 miles around
the booming grounds should be the focal point of management activities for
Average annual home ranges for 21 radio-marked prairie chickens in
central Wisconsin were 6.6 square miles and were larger for hens (11.1 sq.
miles) than cocks (3.3 sq. miles). In northern Wisconsin at Crex Meadows average
annual ranges for 9 radio-marked prairie chickens were approximately half
those in central Wisconsin at 3.8 sq. miles and larger for hens (6.0 sq. miles)
than cocks (2.1 sq. miles). Burger (1988) reported that the distribution of
habitat also influenced annual home ranges of prairie chicken hens in Missouri
where they were approximately 9.9 and 3.3 sq. miles, respectively for mosaic
and large block grasslands. The smaller home ranges at Crex and Missouri reflect
the close proximity of feeding and night roosting areas. However, all of these
annual ranges are for adult birds and do not include the first 8 months of
a birds' life or for birds followed for 3-5 years.
Recent work in western Minnesota indicated that the inclusion of movements
during the first year of life results in much larger annual home ranges. Analysis
is only beginning but some immature hens have first year ranges of 20-50 sq.
miles and hens followed for 3-5 years have large lifetime ranges that exceed
70 sq. miles yet others have ranges of only 5-10 sq. miles in size. Our present
concept of how large an area prairie chickens need and what constitutes a
prairie chicken management area is too small.
Movements of prairie chickens are closest to booming grounds during
the spring. Cocks display on the booming grounds every day during both the
morning and evening, and feed and night roost nearby. Adult hens shift from
their wintering areas to their nesting areas (1-15 miles) during the last
week of March or first week of April. Immatures shift from their wintering
areas to nesting areas (1-30 miles) 1 to 3 weeks later than adults. Hens eventually
localize their movements in the grasslands within 1-2 miles of the booming
grounds where they will establish their egg laying ranges. Flight distances
during this time range from 0.25 to 0.5 miles and decrease as the breeding
season progresses. Breeding season home ranges averaged 650 acres for cocks
and 1,400 acres for hens.
During egg laying hens move alone or in small groups. The initial
movement during this period is from the night roost to a feeding area by walking
or flying 0.15 to 0.25 miles then walking to the nest site to lay an egg usually
between 11: 00 AM and 1:30 PM with 1 egg laid per day. They fly or walk from
the nest to a feeding area, then fly to a night roosting area. As egg laying
progresses, the hen spends more and more time at the nest eventually remaining
for the night, starting incubation. Hens often have an egg laying range that
consists of a mix of agricultural fields and grassland cover. Hens utilize
the former for feeding, but some hens do not visit agricultural fields to
feed during this period and spend all of their time during egg laying in grassland
cover. Average egg laying ranges vary in size from 77 to 160 acres and appear
to be directly related to the amount of undisturbed grassland cover.
The contraction of the spring home range into a small egg laying range in
the vicinity of the nest suggests that this area is a critical aspect of nesting
behavior and habitat use in prairie chickens. A hen must maintain herself
in good physical condition for egg production, incubation and rearing of young
chicks - a period of 70 days; much longer for renesting hens. Hence, a quality
egg laying range may be as important to successful reproduction as the nest
site itself and is an indicator of habitat quality. The small size of these
ranges in several different study areas supports this hypothesis.
A comparison of egg laying ranges show they averaged 86, 91, 77 and 160
acres, respectively for central Wisconsin, Crex Meadows, western Minnesota
and the Sheyenne National Grasslands study areas (Svedarsky 1979, Toepfer
1988, Newell 1987). The much larger egg laying ranges on the Sheyenne National
Grasslands are thought to be the result of extensive areas of heavily grazed
grasslands with short cover. The other areas have larger blocks of undisturbed
grassland cover, consequently egg laying requirements of individual hens can
be met in a smaller area.
Incubating hens leave their nests twice a day to feed, once in the
morning and once in the evening for 30-45 minutes. Some hens will walk from
the nest and feed nearby, however, most make a flight of 0.1 to 0.25 miles
to and from the nest. Many hens feed in agricultural fields on waste grain
while off the nest, however there are hens that feed solely in native grassland
cover. In 4 years of study in northwestern Minnesota we have documented no
incubating hens feeding in CRP grasslands which are dominated by brome and
Most adult hens renest but some immatures do not. This may be related
to the condition of the hens as immatures are usually smaller than adults.
The distance between first and second nest varies and appears to be related
to the amount of nesting cover available. Where the quantity of nesting cover
is limited, adult hens will remain relatively close to their first nest. This
contrasts with immatures in that, if they renest, will nest farther away from
the first nest. In areas with abundant nesting cover the distance between
first and second nests is greater. This is probably because there are more
potential nesting sites.
Hens with chicks move away from the nest right after the eggs hatch.
Hens with broods move by walking until the chicks are 6-8 weeks old when some
begin to make short flights between night roosting and feeding areas. Hens
with chicks will remain within grassland cover until they are at least 6 weeks
old at which time they may begin to feed in agricultural fields and return
to night roost in grassland cover. Chicks from first nests remain with the
hens until mid-October while chicks from renests stay until late October or
early November. In the northern range chicks hatched after 15 July will have
a difficult time surviving unless warm weather extends into November.
Brood ranges from nesting to fledging in Wisconsin averaged 625 acres and
varied from 140 to 1,140 acres. Brood ranges on the Sheyenne National Grasslands
ranges were 2-3 times larger than those in Wisconsin. This is thought to reflect
the larger portion of that area which is heavily grazed or mowed during the
summer. Grazing and mowing leave less taller cover making hens with broods
cover larger areas to meet the needs of their chicks.
Hens that have lost their brood or last nest exhibit movement patterns
similar to that of cocks. However, their molt chronology can be 2-3 weeks
behind that of cocks. Some hens will make major moves of 5-15 miles after
they lose their last nest or young brood. Schroeder and Braun (1992) reported
similar moves for prairie chickens in Colorado. Hens that lose older chicks
probably cannot make such moves because they are in poorer condition and further
into the molt. Hens and cocks, once into the primary molt, are probably not
physically capable of making long sustained flights.
Preliminary information on dispersal of chicks from western Minnesota
indicates that young of the year prairie chickens move farther and cover larger
areas than previously thought. Hens captured as chicks that have been followed
to their subsequent breeding areas ended up an average of 8 miles (n=11, range
3-30 miles) from where they were fledged. One hen nested 27 miles from where
she was fledged, lost her nest and then returned the 27 miles to renest. Three
sibling hens followed during the course of 1 year covered an area of over
1,000 square miles. Of 14 cocks followed from their fledging areas to booming
grounds, all remained within 3 miles.
At this time there seem to be 2 strategies of dispersal and establishment
in prairie chickens; hens wander away from their fledging area while cocks
remain near their fledging sites. This means that the most of the cocks on
a particular booming ground are coming from the habitat immediately surrounding
the booming grounds.
A summary of 847 dispersal movements from winter to first spring for banded birds in central Wisconsin showed that only 60% of adult and 26% of immature hens moved 3 miles or less from winter to spring while 87% and 76% of the adult and immature cocks respectively, moved less than 3 miles or less from winter to spring; 28% of the immature hens moved from 6 to 15 miles from winter to spring. They also found that when birds moved long distances they moved to areas where birds were known to be present. On the SNG, radio-marked hens moved an average of 4 miles from winter to spring while cocks moved an average of only 2 miles (Toepfer and Eng 1988). These movements do not appear to be related to food or habitat. Based on data collected in western Minnesota these movements appear to be a return to a familiar area (adults) or in immatures an effort to establish a nesting area or recruit to a booming ground.
Historically, greater prairie chickens were thought to be migratory
(Hamerstrom et al. 1973, Amman 1957, Grange 1948, Gross 1930). Cooke (1888)
said they migrated as regularly as Canada geese. The distance of the migration
south was believed to vary depending upon the severity of the winter. It was
thought that hens were more migratory and left the cocks behind (Gross 1930).
The need for migratory movements were thought to have been reduced with the
introduction of agriculture especially standing corn (Leopold 1931).
In western Minnesota, radio-marked birds have moved up to 30 miles as have
banded prairie chickens in Wisconsin (Hamerstrom and Hamerstrom 1973). In
western Minnesota we have had birds move 3-15 miles to winter and then return
for the breeding season. Fredrickson (1987) in South Dakota had 4 radio-marked
birds abandon their grassland areas during the winter and move 4-27 miles
to areas with standing corn along the Missouri river. All 4 returned ("migrated")
back to the areas they used the previous fall.
The question of whether prairie chicken migrate or not is moot as they do
move large distances, especially young hens during dispersal. They also make
relatively large moves from fall to winter and winter to spring (Hamerstrom
and Hamerstrom 1973). The dispersal movements probably cannot be limited nor
should they because they are probably necessary for the exchange of genes
to prevent inbreeding.
All agree that the seasonal shifts appear to be movements to winter food.
In an agriculture community there are usually great quantities of waste grain
in fields during the fall. However, there are 2 major factors that influence
the availability of food and hence movements and survival of prairie chickens.
One is snow cover but in most years the wind blows sizable portions of fields
open allowing access to waste grains. The second factor is fall plowing. This
practice greatly reduces the quantity of food available to birds. The placement
of windbreaks can prevent wind from exposing waste grain. If it is deemed
necessary to reduce these long moves from fall to winter and to spring it
could best be accomplished by providing winter food plots or scraping snow
from agricultural fields to expose waste grain.
In western Minnesota we are beginning to accumulate data that suggest that
winter food may not be as limiting as previously thought. In the winter of
1995-96 in western Minnesota, one of the toughest winters on record, only
2 birds moved distances of 6-8 miles. Yet during the winter of 1993-94 at
least 10 birds, mostly hens, moved 10-15 miles between their fall and winter
areas. One hen moved 27 miles in less than 10 days. This suggests that what
we may perceive as difficult winter conditions may not be as hard on the birds
as we think. Winter survival in western Minnesota the past 4 winters has averaged
76% for 209 radio-marked birds and ranged from 58% to 90%.
Birds translocated to the Bry area in North Dakota (west of Grand Forks)
have for the past 4 winters, shifted 5-13 miles to find winter food. However,
the areas used 1 year have not been the same as those used in previous years,
and appear related to the presence of standing corn or sunflowers in proximity
to winter night roosting habitat. Standing corn or winter food may not be
available to the birds if it is not within flying distance (1-2 miles) of
night roosting cover.
Prairie chickens are mobile birds with large home ranges and this aspect
of their ecology needs to be addressed in any management scenario. Long migratory
movements do not appear to be a regular occurrence today but birds do make
seasonal shifts of several miles and up to 35 miles.
Tradition is important in prairie chickens as indicated by the use
of certain booming grounds for over 50 years. Hens show fidelity to nesting
areas at least for the first 2 years. However, evidence currently being collected
suggests that fidelity to previous nest sites may not be as strong in 3-year-old
or older hens. Booming ground locations shift or move generally because the
cover on the booming ground proper changes (i.e. gets too high or rank so
birds cannot be seen) or not enough young birds are recruited to the area
to maintain numbers. Once established, cock prairie chickens maintain a strong
fidelity to a particular booming ground; 84% of the banded cocks in central
Wisconsin remained on the booming ground on which they displayed the previous