Ruffed Grouse Decline in Southwest WI

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Ruffed Grouse Decline in Southwest WI
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• Dr. Scott Walter
• University of Wisconsin-Richland

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Population Decline Drums/Stop in SW
WI 1973-1978 2.82 2000-2006 0.48
The last 40 years
-Clear cycles in N WI
-Dramatic decline in SW
(Brian Dhuey, WI DNR)
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The goal of this project was to assess the
current SW WI grouse population
-Survival
-Habitat use
-Reproductive success
-Home range size/movements
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3 broad ideas persist
1) Predation has caused the decline
2) Habitat change has caused the decline
3) Competition with turkeys has caused the
decline
No evidence for 3, from this or other studies
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• 4 study areas selected in Richland County

Viola
Sylvan
Ash Creek
Gotham
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• 56 grouse captured from 2003-2006

• Aged sexed via examination of feathers

• Transmitter attached, with mortality switch

• Grouse released monitored 3x per week

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• Intensive habitat surveys also conducted

Habitat Types -Cropland -Old Field -Developed
Area -Pasture -Young Pine Plantation -Old Pine
Plantation -Fencerow -Early Successional
forest -Aspen Sapling -Aspen Poletimber -Aspen
Sawtimber -Lowland Forest -Hardwood
Plantation -Oak Poletimber -Oak Sawtimber -Oak
Converting to Maple -Maple Poletimber -Maple
Sawtimber -Orchard -Red Cedar -Red Maple
Pole -Red Maple Sawtimber
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Findings

• Sex ratio biased (36 Males, 20 Females)
• suggestive of poor female survival?

• Few juveniles captured (only 1.5 per adult
  female)
• suggestive of poor reproductive success?

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Findings

• Habitat use

• As expected, grouse select dense stands
• (early successional forest)

Early successional forest
Grouse locations
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Male Survival 41 annually (good)
Findings
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-Most males die in late Winter/early Spring...
... or in early Fall

• Survival

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Findings
Female survival 18 (poor)
-Relatively heavy female mortality from late
Winter late Spring

• Survival

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• Reproductive success
• -Poor female survival limited our ability to
• assess reproduction.

• 5 nests located

• Average clutch size 11 eggs

• 2 nests (40) hatched 23 chicks

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Interestingly, 2 females with broods tended not
to utilize dense brush for cover they
instead moved to mature forest habitats.
It may be that much of our dense cover has
developed a closed canopy shading out the
ground vegetation no insects for chicks. Hens
may then move into areas of poor cover in
search of invertebrates.
Bare ground
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So, whats behind the grouse decline?
Predation?
-Avian predators have increased slightly in
number
Data from the Breeding Bird Survey from
1966-2005 for 3 grouse predators
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However, little long-term data exist regarding
trends in mammalian predators (fur harvest
totals are biased by fluctuating fur prices).
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However, its clear that most mammalian predators
have always been present in Southwest
Wisconsin.
From 1930-1959, Southwest counties were
often listed in the top 5 harvest counties
for -Raccoon -Red Fox -Gray Fox -Opossum
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and at least red fox and opossum were
occasionally numerous
Boscobel Dial, Oct. 27th, 1966
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Summer observations coordinated by the DNR
suggest coyotes have increased statewide since
the 80s, and fox have declined concurrently.
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Interestingly, research on waterfowl in North
Dakota suggests coyotes can IMPROVE nesting
success among ducks, by displacing red fox and
reducing densities of raccoons (Sovada et al.
1995).
food for thought.
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Suffice it to say, the predator community has
likely increased and changed in composition over
the last half century. but predators have
always been a part of the landscape in
Southwestern Wisconsin..
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Habitat maturation

• The structure of Southwestern Wisconsin forests
• has changed INCREDIBLY in the last half
• century or so.

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On a regional scale, U.S. Forest Service forest
inventory data show declines in young forest
types throughout the Eastern and Central U.S.
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More locally, I examined this by comparing the
current forest with that evident in historic
aerial photos
Gotham area, 1992 Gotham area, 1940
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• Here is a nice example of how the forest has
• changed on a portion of the Viola study
  area

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1937 Open Forest
2003 Mature, closed Forest
In between Brush
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Of 1,563 forested acres we surveyed at Gotham,
only 9.1 could be considered quality grouse
habitat (early-successional forest) in 2005
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-As well, 93 of these brushy areas were
less than 2 acres in size
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using a GIS, I digitized forested areas (1940)
with lt50 canopy closure -This
accounted for 42 of the forested area this
entire area would have succeeded through a
brushy stage over the ensuing few decades.
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On the Viola study area, the story is largely the
same
In 2005, only 12.8 of 1340 acres of forest
surveyed was in a brushy, early-successional
phase
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and, again, 78 of the brushy patches were
lt2 acres in size.
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On this study area, a full 59.5 of the forested
area had an open canopy in 1937. In other
words, 60 of the forest would have
developed a brushy understory over the ensuing
few decades..
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But again, only 12.8 of the current forest at
Viola is in this state.
so, most of our quality grouse cover came and
went between 1937 and 2005.
We rode a peak in grouse cover- and grouse
numbers- as grazed woodlands succeeded to
brush from the 40s through the 80s.and saw
our grouse population decline as these areas
matured to older forest types.
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All aspen stands inventoried are pole- or
sawlog-size no sapling aspen present
We can also see the aging nature of our forests
by looking at aspen (a disturbance-dependent
species)
Aspen Sapling Pole Sawtimber
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The small patch size and fragmented nature of
our current brushy cover makes movements
dangerous for grouse. Greater movement by
females in late Winter may, in part, explain
their lower survival.
Locations of Male M9714 from 11/1/2004 3/1/2005
Locations of Female F9942 from 11/1/2004
3/1/2005
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The upshot? -Habitat for grouse in Southwest
Wisconsin is marginal consisting primarily of
narrow brushy field woodland edges, and small
pockets of cover. This lack of expansive
protective cover..
combined with a diverse and relatively abundant
predator community is keeping grouse numbers low
in Southwest Wisconsin.
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What can we do?

• Increase the area and connectivity of early-
• successional cover by integrating intensive
  timber
• harvests into our forest management
  activities

Timber Stand Improvement (TSI)
Removal of poor quality/species often opens the
canopy sufficiently to allow a dense understory
to develop. This 3-4 acre improved stand on
the Viola area regularly held grouse.
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Regenerate mature aspen stands
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Consider small (1-5 acre) patch cuts as part of
your timber management plan.
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Planting of shrubs conifers
-Especially as a means of connecting blocks of
brushy cover
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Without the development of more quality cover,
grouse in our area will remain low, and
disappear locally as forests continue to
mature.