Biologist says habitat shortage hurts grouse

By Tim Eisele Correspondent

Madison — Wisconsin’s grouse population has been in the dumps,
and hunters want to know why.

Grouse populations, especially in the north, normally vary on a
10-year cycle between peaks and valleys. The population in
southwestern Wisconsin has never seen that large cyclical variation
of a cycle and has been more consistent.

But, the northern population has not climbed out of its “low,”
and the southwestern population has been noticeably sparse.

Scott Walter, professor of biological sciences at UW-Richland,
is in his third year of studying grouse in Richland County to get
an idea of just what’s happening to southwestern ruffed grouse.

He started in August 2003 and expects that this will be the last
fall of the project. He and student assistants Jessica Haucke and
Jeremy Gudgeon put out wire traps to capture grouse. The birds are
aged and sexed, and a radio transmitter is placed on the back of
the birds to track their movement and examine the habitat they
use.

Walter has caught 46 grouse in three study areas during the
three trapping seasons, which is far fewer grouse than he
wanted.

“In the fall of 2003 we caught one grouse for every 37 traps we
checked,” Walter said. “Last year, it was about one grouse per 65
trap checks, and this year we’ve checked over 500 traps and caught
only two grouse. They continue to decline. We’re just not finding
the grouse.”

The study has monitored 28 males and 18 females, and the data
are not yet complete. So far the survival rate of males is about 56
percent, which is considered good. But, for females Walter is
finding survival of only 22 percent.

This year there were three females that nested and two
successfully hatched their nests, with an average clutch size of
11. However, both females were killed within two weeks of the
hatching date and the third female was killed on the nest, most
likely by a skunk.

“It’s hard to get a handle on what is going on with the
females,” Walter said. “Most female mortality occurs in late winter
or early spring from mid-March to early-April. I think what they
are doing is moving out of winter cover and looking for nesting
sites.”

He surmises that the females this spring were not using what is
considered to be good brood cover. Normally that’s the thickest
stands, such as the young aspen stands in northern counties, but
these females took the broods right after hatch into mature, open
forests.

Walter thinks they were looking for insects that the young
grouse need.

Why weren’t they in the young, dense forests?

“I think because it is not there,” he said. “The cut-over areas
such as where there was a blowdown or fire, would have berries,
sumac, and thick vegetation, but those types of thick areas are not
here today.”

Walter believes small pockets of disturbance in the forest
should be made to provide habitat for the birds to survive.

The big things that Walter has found so far is that female
survival is lower than male survival, the nesting season is
dangerous, and broods are not using typical brood cover and are
instead using mature cover where they get picked off.

The research has documented about 4,800 locations showing what
habitat grouse are using. At one area near Gotham, the habitat
assessment showed that about 75 percent of the forest is in the
pole or saw log sizes.

“This is mature timber, not the young stuff that grouse use,” he
said. “The young succession stuff, such as brush, only constitutes
about 7 percent of the study area, but that is where 82 percent of
the grouse locations have been.

“People are always asking why don’t we have grouse in southwest
Wisconsin and they always look at turkeys and predators,” Walter
said. “I think the primary reason grouse have declined in the south
is that we don’t have expansive areas of good grouse cover. From
our data, that is exactly what has happened.”

Walter said there is no evidence that turkeys have any impact on
grouse. He said predators are a factor, because grouse are prey for
many species big enough to eat them, but grouse prefer brushy areas
where they are safe.

People are convinced that predators are the problem, and people
think the countryside is covered by thick vegetation, but that’s
not true, Walter says.

“It is too simple to just say it is predators,” he said.
“Southwest Wisconsin 30 years ago had more high-quality grouse
cover, which made it safe to escape from hawks and owls, but that
cover is no longer extensive on the landscape. I think there is an
opportunity for management by intensive forest management.

“That requires intensive harvests to get that thick cover back
on the landscape. But, many landowners don’t want to cut trees,
even though it can be a part of good, sustainable management,” he
said.

Walter, who did extensive research on waterfowl and ruffed
grouse under the late Don Rusch at UW-Madison and today lives on
land near where he grew up in Richland County, recently did timber
stand work on 12 acres of his farm. He clear-cut ironwood and
bitternut hickory, and now has young oaks, blackberries, and is
seeing improved cover.

“Predators are always part of the equation when you talk about
ruffed grouse populations, but to say that predators alone have
driven grouse from abundance back in the 1970s down to their
current low level is a mistake,” he said. “There are more predators
today, but they have a bigger impact because the grouse don’t have
a place to escape. Where there is decent cover there are grouse,
but where there is not cover, there are no grouse.”

Walter said the population in southwest Wisconsin never really
cycles like it does in northern Wisconsin. Grouse populations in
the southwest are now down and he believes they’ll probably stay
down unless something happens to the forest.

Walter said people are beginning to recognize that
disturbance-dependent species need management, too. Species that
depend on young forests, species like ruffed grouse, buntings,
woodcock, eastern towhees, Indigo buntings, and blue-winged
warblers, need disturbances to create habitat.

“It all comes down to a lack of disturbance,” Walter said.
“Those who think that it is simply predation should realize that
predation is the proximate cause of grouse dying, but why numbers
have fallen in past decades is a result of the habitat.”

Walter said groups of landowners have to spearhead the effort
and talk to other landowners in their watershed to get them to
assess their land and realize the need to think about
clear-cuts.

“Small clear-cuts are not bad,” he said.

He is finding hillsides of elm, black locust, and bitternut
hickory, and the landowners aren’t doing anything to encourage
other species.

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