Northern Prairie Wildlife Research Center
Preceding sections of this report have dealt with summarizing research findings
on possible limiting factors and preferred habitat characteristics of prairie
chickens (and certain other galliforms) throughout the range and, in particular,
on the SNG. The primary assumption is that prairie chickens serve as a biological
indicator of ecosystem management at the SNG. There are 4 categories of monitoring
information needed: prairie grouse census data, livestock use data (how many,
when, where, how long), habitat characteristics (with a focus on prairie chicken
needs), and records of habitat management treatments (location and timing
of areas burned, mowed, trees cut down, weed control, etc.). Presumably climatological
data are collected by the National Weather Service which allows relating those
factors to cover conditions and prairie chicken population fluctuations.
The importance of good prairie grouse census data cannot be overemphasized
if prairie chickens are a featured species at the SNG. This is how management
effectiveness is measured. Three counts of males only on each ground should
be taken around the peak of the display period. Because of limited manpower
and time constraints, it is suggested that SNG managers chose an intensive
monitoring area where a good census is taken every year rather than
attempting to census the entire SNG and not have the resources to do a good
job. We suggest that the town of McLeod might be an approximate center for
this area (Figure 5). The size of this unit is 76 sections; is about 1/3 private
land; and contains most of the larger booming grounds (Figure 2), suggesting
that this is the best prairie chicken habitat at the SNG. The Ft. Pierre National
Grasslands uses the Cedar Creek Monitoring Unit (See Glen Moravek correspondence
in Appendix 6) as their intensive censusing block. Perhaps once every 5 years
the entire SNG could be censused. Currently, display grounds are numbered
at the SNG. This is fine for a general reference but it encourages observers
to go to a specific location and possibly miss new or relocated grounds. Display
grounds move in response to changing cover conditions.
In order to evaluate the effect of livestock use on the vegetation it is essential first, to have descriptive data on the vegetation at some point in time, but then to know the grazing history of a pasture. Presumably, with computer technology, it is possible to access this information for a given pasture in a given year as to number of animals and the period(s) grazed. Are animal units actually counted by Forest Service personnel or are approximate numbers turned in by graziers? Numbers in the files should be accurate if true effects of grazing are to be assessed.
Figure 5. Suggested prairie grouse intensive census block at the Sheyenne National Grasslands.
Currently nesting and winter roosting are monitored at SNG using
the visual obstruction method or the "Robel Pole" (Robel et al.
1970). Most literature and field workers use Visual Obstruction Readings (VOR)
instead of VOM and also use decimeters. For consistency of reporting
it is suggested that this convention be followed. Nesting cover and winter
roosting cover are not differentiated (Braun 1996), however prairie chickens
will roost in cover too rank for nesting such as dense growths in CRP fields
so they are not always the same. In current monitoring at the SNG, VOR's of
1.5 dm are used as minimum nesting values but we suggest that 2.0 dm be considered
the minimum value for good nesting cover as well as roosting cover.
Brooding cover is not currently monitored but, based on field studies, we
would suggest that a 100% VOR of 2.0 be an acceptable minimum but with no
litter and a minimum of 25% forbs, to increase the likelihood of adequate
insects for broods.
McCarthy et al. (1995) reported on the application of Prose's (1985) Habitat
Suitability Model to sample units delineated by a 1-mile radius of SNG booming
grounds. Many authors note that most nests are within 1 mile of a booming
ground and there is general agreement that display ground counts indicate
habitat suitability in the surrounding area. However, Svedarsky recorded 4
females nesting an average of 1.25 mile (2.0 km) from the booming ground on
which they copulated. If one considers the prehatching home range, the use
area of females extends beyond 1 mile (1.6 km). Rice and Carter (1982) and
Mechlin (1991) suggested a 2-mile radius to delineate habitat use area around
a booming ground. When McCarthy et al. (1995) applied the Habitat Suitability
Model, all of the Habitat Suitability Indices (HSI) were 0. This suggests
to us that the model needs refinement for application to the SNG. Perhaps
if the radius were extended to 2 miles, more habitat units would be included
and HSI values greater than 0 would be received. For example, if a food plot
were 1.5 miles from a booming ground, it would clearly be used by birds from
that ground yet would not be recorded using the Prose (1985) model. Also,
more habitat components could be added such as brood habitat and summer weather.
We have made the following critique of the Habitat Suitability Model but more
effort is needed to refine its application to the SNG:
Some suggested considerations for the revision and adaptation of the
Habitat Suitability Index Models: Greater Prairie Chicken (Prose 1985, in
Appendix 10) to the Sheyenne National Grassland.
In the following publications,
McCarthy, C., L. Potts, and B. Braun. 1995. 1994 Prairie chicken habitat monitoring report on the Sheyenne National Grasslands. U.S. Forest Service, Lisbon, ND, andthey each recommend that the Prose model needs to be adapted and validated for the SNG. Prose endeavored to develop a model with range-wide application in 1985. We offer the following suggestions with reference to his report based on recent findings and with particular reference to the SNG:
Braun, B. 1996. 1995 Prairie chicken monitor report on the Sheyenne National Grassland. U.S. Forest Service, Lisbon, ND,
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|p-1, para. 3, l-9:||Mast and buds never have been nor have they become important winter foods in the northern part of the range. The evidence is that they merely supplement agricultural foods, the really important foods.|
|p-2, para. 1, l-1:||Insects are not abundant in the spring in the North; often they (those eaten by chickens) do not occur in any amount until June.|
|p-3, para. 1, l-1:
||Yes, corn is still very important but sunflowers are apparently more highly preferred where they occur. They are not mentioned in the report.|
|p-3, para. 2, l-2:||Cultivated grains are apparently important in Missouri as well as other areas. They may not have sufficient "high quality native tall grass prairie" remaining in Missouri; also on page 2, para. 6, line 1, it is stated that Missouri chicken "fed almost exclusively in cultivated fields throughout the late winter and early spring".|
|p-4:||In the "Reproduction" section, nesting cover and brood cover are discussed together as if they are the same. In most cases, optimum cover for each function is not the same as recent research documents. Some reference is made to the use of disturbed sites by broods on page 7, para. 1, line 4.|
|p-10, para. 1, l-4:||Winter food and nesting cover are obviously essential but the brood period/cover may be as important as nesting cover. Also, winter roosting cover goes hand-in-hand with winter food; both are required and it is best if they are in close proximity.|
|p-10, para. 2, l-4||I believe we can say that from at least Nebraska, north, prairie chickens depend a lot on cultivated grains.|
|p-14, para. 4:||Broods don't necessarily need residual cover as such, they can do fine on new growth cover, providing it is sufficiently tall, provides insects, etc. when the broods hatch. Also, it must be close to nesting cover since chicks have to walk there.|
|p-15:||The discussion here on minimum VOR for nesting cover justifies, to us at least, that 2.0 dm is a reasonable minimum for good nesting cover, yet 1.5 has been used in the SNG reports (McCarthy et al. 1995, Braun 1996).|
|p-16, para. 4, l-4:||Why the big concern about the proximity of winter food and nesting cover? Obviously they must be within reasonable proximity, but of greater concern should be the proximity of nesting cover and brooding cover, and winter food and roosting cover. The proximity of winter food plots and nesting cover could be of importance but not because of the winter food per se but of the use of these plots as spring food for nesting females (and displaying males) and as summer brooding areas if they are left partially untilled.|
|p-22, para. 6, l-7:||The VOR value of 2.0 dm is mentioned here and we believe it should be applied to the SNG.|
|p-26, para. 5, l-2:||We agree that open space must be addressed, particularly as it concerns trees. Most states which have a fair amount of trees in their prairie chicken range now have a cut the trees down when you can philosophy, particularly in nesting and brooding habitats. The key factor is their use as nesting and hunting perches by raptors, especially red-tailed hawks and great horned owls.|
|Other:||Litter cover/depth could be a useful index in evaluating nesting cover and/or brood cover. McKee (1995) found when litter cover exceeded 25%, nesting success went down substantially. She found it to be the best single predictor of nesting success in Missouri.|
We suggest that the following working definitions be used for prairie chicken cover types at the SNG:
Nesting cover: About 16 in. (40 cm) tall and relatively dense close
to the ground having a 100% VOR of 2.0 dm. (1.5 dm = poor, 2.0 = good, 2.5
= optimum). Undisturbed for at least 1 growing season with light litter (about
2 in. or 5 cm deep) and <25% litter cover.
Brood cover: Cover with 2.0 dm VOR but having an open understory
with no litter, resulting from disturbance the year before. Minimum of 25%
forb composition to promote insects.
Roosting cover: Can be the same as nesting cover except that it
can be more rank and lowlands seem especially favored. Cover of at least 2.0
dm VOR. Optimum winter roosting cover should have a mixture of stout forbs,
like goldenrods and perhaps light shrubs, to promote accumulation of snow
adequate for snow burrowing.