Transcript Population Management - University of Minnesota

Population Management
Minnesota DNR divides the state into many
administrative zones to manage the wildlife
(including deer)
Minnesota DNR Administrative Areas
36 Wildlife Administrative
Areas or “wildlife work areas”
as depicted by the black lines
on the area manager map
Each has an area wildlife
manager who makes decisions
regarding deer management
and provides
recommendations regarding
season setting.
Each state has its own system for
determining populations.
 Systems used
 Sex-Age-Kill – a census system based on bucks and antlerless deer harvested at ages 1
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- 4 1/2 years old.
Pellet count – a census system based on droppings. A series of plots around a deer
yard area. This system is very time consuming and costly. it is no longer used in
Minnesota.
Trail count – a system of counting deer along trails.
Aerial count – airplanes or helicopters are used to count deer that can be seen from
the plane. This system has been criticized for not being accurate.
Infrared photography
Simulation model – a computer used to evaluate the population dynamics of deer in
the forested area
Proportion of fawns in prefawning population – the number of fawns in the spring
divided by the total population.
Possible Systems (Continued)
 Proportion of adult males in prefawning population – the number of
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adult bucks divided by the total population.
Summer mortality – the proportion of deer that will die during the
period from post hunting to pre-fawning (late November to mid-May).
Winter mortality – the proportion of deer that will die during the
period from post hunting to pre-hunting (early June to late October).
Fawns per pregnant adult doe – the number of “new” fawns divided by
the number of pregnant fawn does. Based on data collected from 19711981 describing the number of fetuses per pregnant doe and
summarized according to DMU.
Winter severity index (WSI) – the number of days with 18” snow cover
on the ground plus the number of days temperature is 0 F or less = WSI.
Winter is mild if WSI = > 119, winter is moderate if WSI = 119-170,
winter is severe if WSI = < 170.
Minnesotas Methods
 In 2013, Minnesota currently has 129 deer permit areas.
 For each permit area, population goals are set using a public
input process (5-10 year basis) and estimate populations on
an annual basis.
 The DNR uses both population modeling and aerial surveys.
 Each year, aerial surveys are conducted on a portion of the
DPAs to recalibrate the models.
 In farmland areas, the DNR uses distance sampling (instead
of aerial surveys) to recalibrate the models.
Minnesota Deer Management
 Forest Wildlife Populations and Research Group
 Manages the Northeastern forested area of Minnesota
 Farmland Wildlife Population and Research Group
 Manages the rest of the state
Minnesota DNR Forest Wildlife
Populations Research Group
 The role of the Forest Wildlife Populations and
Research Group is to provide inventory information on
wildlife populations, project how populations will respond to
management, and develop a better understanding of how
populations are impacted by changes in their environment
 The forests of northern Minnesota create their own special
blend of problems for wildlife managers and it is the
responsibility of this group to help solve these problems.
 Important wildlife species such as white-tailed deer, moose,
black bear, grouse and furbearers are particularly difficult to
inventory because of the enormous area they inhabit and the
difficulty in observing these species in a forested
environment. For these reasons, most species are monitored
with a combination of surveys and computer simulation
models. The group is responsible for designing and
coordinating all surveys and analyzing the results. They have
developed population models for most species that allow
wildlife managers to project the outcome of specific
management practices.
 The ecosystems inhabited by wildlife are not static and the
group conducts research to better understand how wildlife
responds to its changing environment. The winters of 1995-96
and 1996-97, for example, were two of the of the most severe
on record and research by the group was instrumental in
understanding how deer responded. This research will provide
long term information on how deer respond to increased
logging on their winter range. The group is internationally
famous for its work on black bear population dynamics and
methods for managing and studying bear are used throughout
the world.
MN DNR Farmland Wildlife Population
and Research Group
 This group is responsible for providing information needed
to manage major wildlife species in Minnesota's farmland
zone which comprises all or parts of 74 counties and totals
almost 49,000 square miles. To accomplish this responsibility,
the group (1) coordinates and interprets population surveys;
(2) conducts research which provides wildlife management
information; (3) develops techniques needed to monitor and
manipulate wildlife populations, manage critical wildlife
habitats, and reduce or prevent wildlife damage; (4) evaluate
management practices and programs; and (5) provides
technical assistance and information to other DNR staff and
the public.
MN DNR Farmland Wildlife Population
and Research Group
 Managing Minnesota's productive farmland deer populations
requires information from several annual surveys.
Reproduction is determined from examining over 300 does
during the months of February through May. The age and sex
composition of the deer harvest is collected by biologists at
selected registration stations. And, car-killed deer
information is summarized from peace officers and highway
maintenance reports. All this information is combined with
the registered deer harvest in a population model developed
by the staff. Modeling results project deer densities and
desired antlerless permit numbers for each of the 84 quota
areas in the farmland zone.
Roadside Surveys
Research, Program Evaluation and
Technical Assistance
 The staff is presently involved in several timely research and
evaluation projects. One field project, using radio telemetry,
is attempting to determine deer population dynamics and
movements in the vicinity of the Mille Lacs Wildlife
Management Area. This information will be used to
determine the potential impacts of late fall and early winter
harvest of deer by American Indians allowed under the
resolution of the 1837 Treaty court case. With this
information, American Indians and DNR will be able to
adjust harvesting regulations so that the area's deer
populations will not be negatively impacted.
Urban Area Deer
 Deer populations in urban areas present the need for unique
management strategies. Over the last several years, we have
evaluated the effectiveness, costs, and acceptability of several
hunting strategies (e.g., sharp shooting, trap and shot, special
hunts). Presently, a field study is using radio marked deer to
better understand the population dynamics and movement of
deer in an urban landscape. All this information should help
perpetuate deer in our urban areas while reducing, to an
acceptable level, problems caused by deer.
Minnesota Deer Population Estimating
 2012 Report: The DNR will conduct aerial surveys over
portions of the state later this winter. Population modeling,
coupled with select aerial surveys, will be used to determine
deer density. Management designations for 2013 deer permit
areas will be determined once the new density estimates are
compared to established population goals.
 Upon estimating the final population they reduce this by 10%
to ensure they are on the conservative (safe) side of the
population estimate that may account for any errors or
factors that may not be accounted for or over looked.
What is an appropriate population
density to maintain?
 Populations in land areas vary greatly and relies on a wide
range of factors. Each area has its unique features of cover,
openings, edges, browse and water. Each area must be
analyzed on its own merits.
 An area’s ability to sustain a healthy habitat depends on
numerous factors.
 Evidence of an overpopulated area is revealed by an increase
in “road kill” reports and an increase in “nuisance” complaints
filed by citizens.
What are mortality factors that affect
white-tailed deer populations?
 Starvation
 During winter months deer “yard up.”
 Helps deer conserve energy
 Avoid heavy winds
 “Yarding up” also restricts their browse area and leads to over-browsing
which in return leads to starvation.
 During winter deer use up their body fat reserves and begin to
suffer from malnutrition which also leads to starvation.
 Severe winters where below 0 degree temperatures last for days
and the snow is deep
Winter Severity Index
 The Minnesota Department of Natural Resources measures the
Winter Severity Index (WSI) by applying a point for everyday the
temperature is below zero and applying a point for every day the
snow is 15-inches or deeper.
 A typical Minnesota winter scores a WSI of about 120.
 Once the WSI begins to rise above that point, a winter is considered
harsh, particularly if it reaches the 140 or 150 range.)
 Winter severity, specifically
snow depth and duration of
snow cover, is the most critical
factor affecting white-tailed
deer survival in the northern
forest.
 Deer movement is now heavily
restricted, especially up in the
border country. Deer are in
heavy conifer cover.
 With restricted mobility, wolf
predation will increase as the
tables have now turned against
deer. .
Predation
 Most common predators of white tailed deer include: wolves,
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hunters, and occasionally bobcats, bears and coyotes.
Old, weak and diseases deer are preyed upon as they are easier to
catch
Predation alone does not severely reduce the deer population.
Approximately 1.2 million white-tailed deer live in Minnesota.
Minnesota hunters harvested:
1991
2012
Firearms season
206,284
155,599
Bow and arrow season
12,964
21,556
Muzzleloader season
961
7,494
Total
220,209
184,649
Accidents
 Automobile collisions with
white-tailed deer are
significant in Minnesota
 2009 – over 2,600 collisions
 2010 0ver 1,900 collisions
Incidental Causes
 Disease
 Weakens deer making them more open to starvation, predation or accidents.
 Many diseases are found in deer, among them brucellosis and leptospirosis can
be transferred to humans and cattle
 Parasites
 Parasites do not kill deer directly.
 The most common parasite found in deer are the liver fluke, bladder worm and
the throat bots.
 Deer also host to the Deer Tick (Ixodes Dammini) that causes lyme disease in
humans and dogs, but not the deer.
 Competitors
 Competitors such as the snowshoe hare compete for winter food with the deer.
 Humans and livestock also compete with deer for food and space. Over
Population
 Overpopulation of deer causes stress and starvation.
What mortality factors affect Black
Bear?
 Predation
 Predators mainly include humans. Small cubs have been known
to be preyed upon by wolves and adult male bear.
 In 2012, Minnesota hunters harvested 2,604 black bear.
 Highest harvest was in 1995 – 4,956 bears taken
 Approximately20,000 black bear live in Minnesota.
 Incidental Causes
 Bear rarely die from disease and parasites directly. Diseases and
parasites will usually make the bear more susceptible to other
mortality factors.
What Mortality Factors Affect Moose
 Parasites
 Parasites in moose are often transmitted by white-tailed deer.
 The most common and deadly parasite is the “brain worm.” It is transmitted
to the moose by shared browsing and watering sites. The worm works its
way to the moose brain and deteriorates it slowly.
 Tick infestations can be serious if they cause the moose to rub off its coat,
leaving bare patches which is dangerous for a moose during winter weather.
 Disease
 Moose are very susceptible to many diseases that are transmitted by livestock
and white-tailed deer.
 Incidental Causes
 Malnutrition leading to starvation during severe winters is possible.
Competitors for habitat such as white-tailed deer and humans lead to moose
migration and possible loss of life because of reduced habitat.
Predators
 Predators include: wolves,
humans and occasionally
bear may prey on young
calves.
 In addition to the chart (on
right) in 2012 Indian
Reservations issued
permits and harvested 34
moose
Year
Moose
Harvested
Party
Success
1993
264
84%
1998
125
69%
2003
141
70%
2008
110
45%
2009
103
51%
2010
109
51%
2011
53
58%
2012
46
53%
What Mortality factors Affect Wolves
 Disease
 Diseases that kill wolves include: Rabies, Distemper and Parvovirus.
 Predation
 Predators of wolves are very few. Usually only young pups are preyed upon
by eagles and occasionally bear. Adult wolves will kill other wolves if they
intrude on their territory.
 Wolves are no longer protected from hunting by the federal “Endangered
Species Protection Act.” They can now be hunted by humans.
 Wolves can go long periods without eating. Two weeks without food
doesn’t weaken their muscle activity
 Incidental Causes
 Injury, pack stress, parasites and some diseases such as arthritis make the
wolf more susceptible to predation, malnutrition, and accidental death.
What are common predators of large
wildlife mammals in Minnesota
 Coyote
 Minnesota’s most abundant predator.
 Prefer habitat is the transitional land area, but also live in prairie and
dense coniferous forest.
 They are omnivorous and can adapt readily to changing habitat
conditions.
 Coyote feed mostly on small mammals such as: snowshoe hare,
mice, squirrels, grouse, muskrat, moles and small young
livestock. They have also been found to prey on white-tailed deer
(mostly fawns). Coyote generally consume deer meat that is
carrion, a result of road kill, disease, starvation or another
predator’s leftovers
 The coyote population is stable in northern Minnesota and
is increasing in density in southern Minnesota.
 The coyote is often called the “Brush Wolf.” It should not
be confused with the wolf.
Other Predators Bobcat
 Bobcat
 Prefer habitat in the northern third of Minnesota, specifically
areas with heavy brush in dense timber.
 Primary prey consist of snowshoe hare, closely followed by
white-tailed deer.
 Generally they do not east carrion and instead prefer fresh
meat.
 The are nocturnal and hunt solitary.
 The bobcat is 20-30 inches at the shoulder and weighs between
15-40 pounds. It has a distinctive feature of short black tufts
coming from the tips of its ears
Other Predators - Lynx
 Rare Wildcat in Minnesota
 Prefer mature forests of northern Minnesota. The most
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northern counties in Minnesota are the southern boundary
for lynx.
Primary prey and diet consists of the snowshoe hare.
Occasionally will eat white-tailed deer.
It is larger than the bobcat, 2 feet at the shoulder.
Its most distinctive features include: long feathered ear tufts,
ear to chin ruff and usually a pale grey or buff color with
streaks of brown.
Primarily is a nocturnal hunter.
Other Predators - Wolf
 Takes advantage of weak, ill, old or diseased animals for prey.
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These animals are easier to catch.
Wolves usually hunt in packs with the alpha leading the hunt.
The dominant wolves will generally feed first, then allow the
others to finish the remains.
Generally wolves will go without eating for 3-4 days. When they
make a kill they will gorge themselves filling their large stomachs.
Wolves leave little remains of a carcass. Only large bones such as
the spinal column, skull and large leg bones and hair are left for
scavengers such as ravens, black birds and possibly coyotes.
Other Predators – Black Bear
 The bear is an omnivore and will eat animal matter such as:
grubs, insects, worms, mice, snakes or nesting birds.
Occasionally, but rarely, they prey upon larger mammals such
as fawns, cubs, or young livestock.
 Less than five percent of the bear’s diet consists of fresh
meat.
 The bear relies heavily on its senses in the search for food.
 The bear is solitary in its search for food but will share
common feeding grounds.
Other Predators - Humans
 Humans prey on wildlife during highly regulated hunting
seasons.
 Reasons for hunting include:
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food and fiber
population management of large mammals
monitor the environments
enjoy nature and the outdoors
provide funding for wildlife management programs
recreation
 Poachers are humans that prey on wildlife during off seasons
and illegally and unethically kill animals for economic gain.
What are the results of predation on
wildlife populations
 Four results occur as a result of predation on wildlife
populations:
 Inferior prey animals are culled. These animals are typically old,
weak, diseased, malnourished, or young.
 Partial population control due to mortality caused by predator.
 Stimulation of productivity in herds of prey animals. This is
accomplished by eliminating the potential of over-browsed
habitat by a high population which then results in better
nutrition for the surviving animals which in return leads to
better reproductive health.
 Other wildlife populations are fed such as: ravens, coyote, bear,
insects, fox, fishers, eagles, red squirrels, bobcats, etc.
What impact does large mammal disease and
parasites have on large mammal populations?
 Most diseases and parasites do not have direct impact on the
population. Instead disease and parasites may contribute to
incidental mortality resulting from weakened condition
caused by the disease or parasite. The exception are moose,
they are more susceptible to death directly as a result of
parasites or disease.
 Some diseases and parasites carried by wildlife can be
transferred to domestic animals and humans, such as: Lyme
disease, brucellosis, rabies, leptospirosis. Many large
mammals serve as host and do not actually become infected
with the disease.