The Scandinavian Brown Bear
Project
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Within the project there
have been more than 270 publications discussing different topics.
For a complete list of publications please download the publication list as pdf-file.
By clicking on the
Publication nr at the table it will pop up a small window with the
abstract.
All the abstracts you can find in chronolocical order
below the table.
Keyword
|
Publication nr.
|
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HOMERANGE |
|
|
ACTIVITY |
|
|
POPULATION
ESTIMATING/DYNAMIC |
|
|
DISTRIBUTION |
|
|
MANAGEMENT |
|
|
BEAR/HUMAN
- DAMAGE- HUNTING |
A2, A4, A5, A10, A12, A15, A17, A20, A21, A24, A26, A27, A30, A31, A32, A34 |
|
CONSERVATION |
|
|
MORTALITY
/SURVIVAL RATE |
|
|
GENETICS |
|
|
ANATOMY |
|
|
INFANTICIDE-
INTRASPECIFIC PREDATION |
|
|
DENNING |
|
|
TRANSLOCATION |
|
|
MOVEMENTS |
|
|
DIET |
|
|
PHYSIOLOGY |
|
|
BEHAVIOUR |
|
|
HABITAT |
Abstract:
In 1984-85, 4 brown bears (Ursus arctos)
were radio-tracked in the alpine and northern boreal zones in northern Sweden,
and 3 bears were radio-tracked in the northern middle boreal zones in central
Sweden to obtain information on movements, home ranges, food habits, and
activity patterns. With 1 exception, ear-attached transmitters were used. They
functioned well on 1 bear for 2 seasons but not as well on 6 other bears. In 4
cases, the signal gradually weakened until bears could not be relocated. Preliminary
results indicate home range sizes varied from about 50 km² (yearling bear) to
500 km² (adult male). In the northern area, activity seemed closely related to
daylight. Activity pattern were diurnal in summer, with 24 hours of daylight,
and in autumn.
1987, Int. Conf. Bear Res. And Management 7:9-12
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Abstract:
The brown bear (Ursus arctos)
was once distributed throughout the Swedish mainland. But provincial laws
requiring hunting of bears and high bounties reduced the species distribution
and numbers last century. Steps were already taken in the 1890’s to protect
bears, and the species have slowly recovered the last 40 years due to this
protection. The bear population was in mid 1970’s estimated to 400-600 bears,
and the population still shows increasing tendency. Hunting season is between the first of September throughout October. The EPB
sets yearly a maximum harvest number for each region, and approximately 30
bears have yearly been shot in the last three years.
1990, Aquilo Ser. Zool. 27:17-19
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Abstract:
Radio-collared brown bears were studied in 2 areas, one located in northernmost
Sweden, the other in the center of the Scandinavian Peninsula on both sides of
the border between Norway and Sweden. Most bears were tracked on snow in spring
and radio-collared after being darted from a helicopter. When possible all the
bears were monitored once a week by fixed-wing aircraft. Some bears were
monitored more continuously several days each week by car from forest roads. In
1984-88, 48 individual bears were radio-equipped in the project. Males used
larger home ranges than females. In the northern study area 4 adult males had
minimum annual ranges of 726-2,634 km². Seven adult females in the same area
used annual home ranges of 171-1,002 km². Eight adult males in the southern
study area used annual home ranges of 1,200-4,297 km², while minimum annual
home ranges of 4 adult females in the same area ranges between 254-531 km².
Bimonthly aerial monitoring would have given home ranges of both adult males
and adult females of approximately 60% of those obtained by weekly monitoring.
A female in the north, monitored since she was a yearling, had her first litter
of cubs at 5 years of age.
1990, Proc. Int. Conf. on Bear Res. and Manage. 8:237-241.
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Abstract:
The density of adult (³3 years) female brown bears Ursus
arctos was estimated in two areas of Sweden from
ratios of radio-marked and unmarked females consorting with radio-marked adult
males during the breeding season. The resulting densities were 1×2 ± 0×8 (95%
confidence interval) adult females/1000 km² in a northern study areas and 1×06
± 3×44 adult females/1000 km² in a southern study area. These estimates were
extrapolated to obtain a population estimate for Sweden using relative
densities throughout the range of the species in Sweden, based on hunter-kill
statistics, and observed rates of reproduction and juvenile and subadult survival. The total population in spring 1991 was
estimated to be about 620 bears, with almost all females confined to four
geographically separated areas, termed female core areas. A supplementary
estimate, based on estimated kill rates of adult females in the study area, was
about 660 bears, Estimates based on hunter kill rates
of marked bears gave minimum and maximum estimates of about 300 and 900 bears,
respectively. Although these are not confidence intervals of the total
population estimate, we believe that the true population size is included
within these limits. Densities within the female core areas varied from 50 to
100% of those in similar habitats in European Russia. The bear population in
Sweden appeared to have increased at a stable rate of about 1×5% annually
during the past 50 years. Mean annual rate of legal harvest during 1943-1991
was estimated to be 5×5% (±2×1% SD), suggesting a maximum sustainable rate of
7×0% for this population. The harvest increased at a rate of 9×6% annually during
1981-1991, and apparently was at the maximum sustainable level during 1987-91.
1994, Biol. Conserv.
70:9-17.
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Abstract:
Records of bounties brown bears Ursus arctos in Norway and Sweden were analysed
to estimate population size in the mid-1800’s, and changes in population size
and distribution in relation to the bear management policies of both countries.
In the mid- 1800’s about 65% of the bears in Scandinavia were in Norway
(perhaps 3,100 in Norway and 1,650 in Sweden). Both countries tried to
eliminate the bear in the 1800’s; Sweden was more effective. By the turn of the
century, the number of bears were low in both
countries. The lowest population level in the population remnants have
subsequently survived occurred around 1930 and was estimated at 130 bears.
Sweden’s policy was changed at the turn of the century to save the bear from
extinction. This policy was successful, and the population is now large and
expanding. Norway did not change its policy and bears were virtually eliminated
by 1920-30. Since 1975, bear observations increased in Norway. This coincided
temporally with an abrupt increase in the Swedish bear populations, and bears
reappeared sooner in areas closer to the remnant Swedish populations. Both
conditions support our conclusion that the bear was virtually exterminated in
Norway and suggest that bears observed now are primarily immigrants from
Sweden, except for far northern Norway, which was recolonised
from Russia and Finland. Today, we estimate that the Scandinavian bear
population numbers about 700, with about 2% in Norway (on average about 14 in
Norway, 650-700 in Sweden). This is a drastic reduction in the estimate of
bears in Norway, compared with earlier studies. The trends in bear numbers
responded to the policies in effect. The most effective measures used in
Scandinavia to conserve bears were those that reduced or eliminated the
economic incentive for people to kill them. Our analysis also suggest that
population estimated based on reports from observations made by the general
public can be greatly inflated.
1995, Wildl. Biol. 1:11-25.
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Abstract:
In Europe the brown bear (Ursus arctos)
is represented by two different mitochondrial DNA 8mtDNA) lineages, which
probably diverged about 0.85 million years ago. Scandinavia has been colonized
by representatives of both lineages, from the north (eastern lineage) and from
the south (western lineage), and now bears occur primarily in four main regions
called female concentration areas. For management purposes the localization of
the contact zone between these two genotypes is important. Using hairs as a
source of DNA, 127 individual brown bears from throughout the Scandinavian
populations were assayed for lineage assignment. A part of the mtDNA control region was amplified via the polymerase chain
reaction, and the product was either sequenced (14 individuals) or digested
with two diagnostic restriction endonucleases (113
individuals). Fifty-six and 71 bears were assigned to the western and eastern
lineages, respectively. The geographic distribution of the two genotypes
allowed precise localization of the contact zone. Only two males from each
lineage had crossed the border between the two lineages. We used dispersal data
from bear radio-marked as yearlings to determine whether potential mtDNA introgressions agreed with the dispersal behavior of
bears. The males in the “wrong” areas were all within the 95th-percentile
dispersal distance from the “correct” area. Females were more philopatric than males, and none were found in the wrong
areas. The two female concentration areas flanking the contact zone were 134km
apart. Thus, radiotelemetry results on dispersal
distances could explain the occurrence of the males in the wrong genetic area.
In the absence of information concerning possible male-mediated gene flow, a
conservative management approach would be to consider the southern and the
three northern female concentration areas as two distinct conservation units.
1995, Conserv. Biol.
9:1255-1261.
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Abstract:
Regressions are presented to predict the total weight (TW) in kg of
Scandinavian brown bears Ursus arctos
from field-dressed weights (FW), where TW = 4.01 + 1.15 * FW, and slaughter
weights (SW), where TW = 4.63 + 1.49 * SW. Both regressions had high predictive
values (r2 = 0.97) and were not significantly affected by sex r genetic lineage
of the bears. Formulas to calculate confidence intervals are also presented.
1995, Wildl. Biol.
1:177-179.
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Abstract:
We compared a hunter-provided index of the annual population trend of brown
bears (Ursus arctos) in
Sweden during 1963-91 with harvest rates with time lags of 0-20 years. We
conclude that this trend index probably reflected at least the major trends of
the population. Harvest rates 6, 8, and 14 years earlier explained 83% of the
variation in the population trend, as perceived by the hunters. From these
data, we estimated a sustainable legal harvest of 44.5 bears in 1991. This
estimate is very close to that of 43-50 bears, which we have estimated using
independent methods. In addition, estimates of the harvest level to maintain
the present rate of increase calculated by both methods were also similar.
Although man hunters have been unhappy with the present quota system, this
analysis of hunter-provided data gave support to the present quota levels.
1996, J. Wildl. Res.
1:228-231.
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Abstract:
We have estimated the average number of brown bears Ursus
arctos L. in Finnmark, the
northernmost county in Norway. We started by estimating the number of bears
where reproduction has been documented in the Pasvik
Valley (1,330 km²) and published densities of brown bears from 1) female
concentration areas in Sweden (12,6 bears per km²). We
then expanded this estimate to all of Finnmark using
observations of bears far from the Pasvik Valley. We
estimate that there are on average 7-17 bears in Sör-Varanger
Municipality, and totally 8-21 in Finnmark County.
The brown bears in Finnmark comprise 31-38% of the
total estimated number of bears in Norway of 26-55, respectively. An area of
only 1,330 km² in the Pasvik Valley is the major
Norwegian brown bear area, contains about 30% of the bears in Norway, and this
is the area where reproduction is observed most regularly.
1996, Fauna norv. Ser. A.
17:11-15.
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Abstract:
In 1992, the Norwegian Parliament adopted a plan for brown bear Ursus arctos management. The main
goal of the plan was two-fold: (1) ensure viable bear populations within five
core areas along the border of neighbouring
countries; and (2) limit the damage caused by bear on sheep Ovis
aries grazing on open
rangeland, which has increased over the last few years. In this study we have
examined the possibility of attaining both these political aims. Sheep losses
in two study areas within bear core areas rose considerably during the period
1981-1993, when the Scandinavian bear population increased by 1,5% a year. We found a significant correlation between the
estimated number of bears and the loss of grazing ewes in both areas. No such
relationship was found in the control areas (considered to be without bears)
adjacent to the study area. W found no relationship between number of ewes lost
and number of ewes grazing. Shooting of bears that presumably killed sheep had
no effect on the number of ewes lost during the following season, probably
because the number of bears killed in Norway was less than the number of bears
immigrating from Sweden. Killing more bears is not compatible with the
political aims of the management plan. It is difficult to reach all the
political goals under the current situation. The loss of sheep will probably
continue to increase unless changes are made in sheep husbandry methods in the
core area. Alternatively, sheep must be moved out of the areas set aside for
the re-establishment of bears.
1997, Biol. Conserv.
81:91-95.
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No Abstract
1997, Nature 386:450-451.
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Abstract:
Winter den abandonment by brown bears Ursus arctos in south central Sweden and southeastern Norway was
found to occur in 9% of 194 bear-winters, based on 68 radio-marked bears almost
two years old and older. There was no statistical difference between the sexes,
between adults and subadults, nor did protection from
military or timber-harvesting activities reduce the rate of abandonment.
Although anecdotal, observation suggest that human
disturbance was a major cause of den abandonment. Most abandonment occurred
early in the denning period, before mid-winter. Bears
moved up to 30 km before denning again. Distance was
not related to sex, age, or time of abandonment. Apparently for the first time,
a fitness cost of den abandonment is documented: pregnant females that changed
dens prior to parturition lost young in or near the den significantly more
often than those did not move.
1997, Wildl. Biol. 3:35-38.
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Abstract:
Translocation of individual carnivores has been a standard management tool for
decades in North America and southern Africa in response to livestock
depredation and other conflict behaviours. As
carnivore populations across Europe begin to increase it is expected that
management problems will also increase. Before translocation becomes
established as a management tool in Europe its success needs to be reviewed. In
general, there has been very little follow-up of translocated
animals. Almost no data exist on the subsequent levels of damage after
translocation. Large carnivores have shown a consistent ability to return to
the site of capture over distances of up 400 km. Even those individuals that do
not succeed in returning home roam over very large distances, best measured in
units of hundreds of kilometers. Very few individuals remain at the release
sites. Survival of translocated animals has
occasionally been shown to be poor, often as a result of the large movements.
In general, there needs to be a large area (hundreds or thousands of square
kilometers) without conflict potential where the individuals can be released for
the strategy to work. When such areas are not available,
management efforts should concentrate on reducing conflict potential, or, where
this is not practical, lethal control.
1997, Biodiversity and Conserv.
6:1245-1257.
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Abstract:
The young of brown bears Ursus arctos
Linneaus, 1758 are sometimes orphaned and found by
humans. People and authorities often want to help these young survive by taking
them into captivity. We report on the fate of five young-of-the-year brown
bears in two litters that lost their mother in May and September. We left food
for one of the two cubs that were abandoned in May after the other one had
died. He was shot four years later and had a normal weight at that time. The
other three lost their mother in September, probably to illegal hunting. One
was lighter than normal the following May and died that year. The two other are
still alive at almost six years of age, and have shown normal growth and
reproduction. We conclude that young-of-the-year brown bear cubs in Scandinavia
can survive well on their own from the beginning of July, and recommend that
they be left where they are found.
1998, Acta Theriologica
43:213-218.
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Abstract:
There were about 4,000-5,000 brown bears (Ursus arctos) on the Scandinavian Penisula
around 1850; 65% were in Norway, which had the densest population. Apparently
because of overexploitation, numbers declined rapidly until about 1930, when
the brown bears was virtually extinct in Norway and about 130 were left in the
4 isolated population that survived in Sweden. After 1930, the population began
to increase after stringent protection. There are now about 700 bears in
Scandinavia, with 2% in Norway. Although the forest of Scandinavia have been totally changed by intensive, large-scale
forestry, harvest pressure still seems to be the major factor affecting the
population. Managers haven an obvious need for information to manage this
increase in population. They want to know how and where the increase will
occur, when it will occur, and what they can do to manage it. Currently we are
studying (1) population dynamics and dispersal to learn about mechanisms and
patterns of increase and (2) relationships between bears and people, domestic
sheep, and moose (Alces alces).
We have found that females recolonize areas much more
slowly than males, so the expansion wave front is steep for females and much
flatter for males. The result is female areas with a high density of bears
surrounded by areas with relatively low density. Outside the expanding front of
females, the population is dominated by males (about 85%), predominately subadults or young adults (i.e., dispersing individuals).
Mean home range of adult males are much larger in the
peripheral areas (7,760 km²) than in the female areas (1,530 km²). Brown bears
in Scandinavia seem to present little threat to people. Preliminary data
suggest a low predation rate on adult moose, but a higher rate on claves. The
greatest management challenge of the increasing bear population is depredations
on the 2.2 million unattended domestic sheep on open range in Norway. These
issues will become more important also in other areas as we are more successful
in saving bear populations.
1998, Ursus 10:17-24.
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Abstract:
1. The distribution of brown bears (Ursus arctos L.) expanding into suitable habitat in Sweden
following near extermination was estimated using harvest data from the period
1981-93. Core areas were defined as female concentrations areas, where 90% of
the hunter-killed females were taken.
2. Three predictions were tested, based on results of earlier bear dispersal
studies, which show that females are extremely philopatric.
Prediction1: the relative density of females declines more rapidly from the
center of a core area towards the edge than for males. Prediction 2: males
dominate in the peripheral areas, especially males in the age of most active
dispersal (2-4 years of age). Prediction 3: females in the periphery are found
closer to the edge of the core area than males.
3. The results of the present study supported Preditcions
1 and 2, but not Prediction 3. This indicates that males were more prone to
disperse from the core areas than females. However, females that did disperse
did not differ from males in distance from the core areas, and females were
found up to 80-90km from them. Such long-distance female dispersal has
apparently not been previously documented in other bear populations that are
stable or declining. The results strongly suggest that presaturation
dispersal, i.e. dispersal occurring before the carrying capacity of the habitat
has been reached, is occurring in this increasing population. This phenomenon
might be more common in increasing populations of large mammals than was
previously thought. Regarding conservation of bears, this result is positive
for gene flow and metapopulation dynamics and
negative for livestock losses in formerly bear-free areas.
4. Core and peripheral areas can be identified based on the age and sex of shot
bears. This allowed us to classify Norway as a peripheral area. Bear density
appears difficult to estimate near an expansion front because of large
differences in densities over short distances.
1998, J. Animal Ecol. 67:819-826.
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Abstract:
The seasonal food habits of brown bears Ursus arctos were estimated based on the analysis of 266 scats in
central Norway and Sweden. Free-ranging domestic sheep Ovis
aries were common in the
Norwegian part of the study area, but were not found in the Swedish part.
Correction factors were used to correct for differences in digestibility and
nutritional value of different foods. Because correction factors for ungulates
are difficult to estimate, the results should be interpreted with some caution.
In terms of digestible energy, ungulates, mostly carrion, were the most
important food in both areas during spring. During summer, ants, forbs, and
ungulates (reindeer Rangifer tarandus
and moose Alces alces) were
the most important food items in the Swedish area, and sheep were most
important in the Norwegian area. The autumn diet was dominated by berries in
the Swedish area and sheep and berries in the Norwegian area. Among berries,
crowberry Empetrum nigrum
was the most important species followed by bilberry Vaccinium
myrtillus in Sweden. The major difference between the
Swedish and Norwegian areas was the large consumption of sheep in Norway, which
provided protein and lipids, and was associated with a relatively reduced
consumption of ants and forbs in summer and berries in the autumn. Based on
different ingestion rates among the seasons, we estimated the relative
contribution of major foods to total digestible energy. In the Swedish area, bears
obtained 44-46 and 14-30% of their total annual energy from berries and
ungulates, respectively. The remaining energy was obtained from insects
(14-22%, mostly ants) and forbs and graminoids
(12-18%, mostly blue sow thistle Cicerbita alpina). In Norway, bears obtained 65-87% of the energy
from ungulates (mostly sheep), 6-17% from berries, 5-13% from insects, and 2-6%
from forbs and graminoids. To gain weight prior to denning, brown bears in Norway selected lipid-rich and
easily obtainable sheep in summer and autumn. In Sweden, they relied on
carbohydrate-rich berries in autumn.
1998, Wildl. Biol.
4:147-158.
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Abstract:
Based on data from radio-collared individuals, we present an analysis of the
viability of two small populations of the Scandinavian brown bear, Ursus arctos. The northern and
southern populations had different demographic characteristics, even though the
population growth rate r and the demographic variance s2d were high in both
populations (r = 0.13 and s2d = 0.180 in the north, and r = 0.15 and s2d =
0.155 in the south). In the northern population the environmental variance s2e
was not significantly different from 0, whereas in the south s2e = 0.003. In
the south, this was related to high environmental stochasticity
in the survival rate of the youngest animals, which resulted in an increase in
survival with age in this population. In contrast, in the north, the
probability of survival showed a slight decrease with age. Uncertainties were
obtained from the joint distribution of bootstrap replications of r, s2d and
s2e. Although the uncertainty in these estimates is quite large, it is unlikely
that even relatively small populations (> 10 females ³ 1 year old) will
decline to size less than 1 after 100 years. Analysis of the distribution of
the critical population size (i.e. the population size where the population’s
logarithmic growth rate is zero) shows that these brown bear populations must
be larger than 3-4 females 1 year or older to secure a positive growth rate. Similarly,
if we define a viable population as the population size where the chance of
survival is greater than 90% during a period of 100 years, 8 females ³ 1 year
old must be present in the north and 6 females in the south. This high
viability of even small brown bear populations is due to high reproductive and
survival rates. A relatively small increase in the mortality rate will strongly
reduce the viability of even relatively large brown bear population.
1998, Oikos 83:403-416.
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Abstract:
Two hundred and three sera obtained in 1993-96 from red foxes (Vulpes vulpes), lynx (Lynx lynx), brown bears (Ursus arctos) and wolverines (Gulo gulo) in Fennoscandia (Norway,
Sweden, and Finland) were examined for the presence of anti-orthopoxvirus
antibodies by a competition enzyme linked immunosobent
assay (ELISA). High prevalences were found for the
red foxes in Norway (7/62, 11%) and Finland (7/14, 50%). While only one of 73
(1%) lynx from Finland had anti-orthopoxvirus
antibodies, a high prevalence was found in sera from the Sarek
National Park in Sweden (5/17, 29%). In addition, anti-orthopoxvirus
antibodies were found in one brown bear from the same area (1/45, 2%), whereas
none of the 14 wolverines were seropositive. This is
the first report of anti-orthopoxvirus antibodies in
the brown bear and the lynx, and the first screening for such antibodies in
Sweden and Finland. These results indicate that orthopoxviruses
are distributed in Sweden and Finland as well as Norway, and that the red fox
and the European lynx may serve as indicator species for the presence of orthopoxviruses in the local populations of small mammals.
1998, J. Wildl. Diseases
34:443-450.
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Abstract:
A critical assumption of radiotelemetry studies is
that the radiotransmitters themselves do not
influence mortality. Here we report the effects of marking techniques on
survival of moose (Alces alces)
calves from birth to the beginning of the autumn hunting season. We marked and
followed 181 moose calves with ears tags and 71 with ear transmitters, and we
also followed 175 unmarked control calves, all with marked mothers, in 5 study
areas in Sweden; 2 areas had resident brown bears (Ursus
arctos), and 3 did not. Survival was lower for claves
with ears transmitters than for those with ear tags (P < 0.001) and for
control calves (P < 0.001). There was no difference in survival between
control calves and calves with ear tags (P = 0.09). Survival was lower in areas
with bears, but bears apparently did not prey differentially on calves marked
with ear transmitters. Marking newborn moose calves with plastic ear tags did
not have measurable effects, but we do not recommend marking calves with ears
transmitters, because of the high mortality rates calves experienced.
1999, J. Wildl. Manage.
63:354-358.
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Abstract:
We have analysed 114 meetings between brown bears (Ursus arctos) and personnel in
bear research projects in Sweden and Norway, reviewed the Scandinavian
literature, 1750-1962, regarding people injured and killed by bears, and analysed instances of human injuries relating to bear
attacks during the more recent period, 1976-1995. The last time people were
killed by bears was in 1902 in Sweden and in 1906 in Norway. However, most
meetings between bears and humans result in the bear leaving. We observed no
direct attacks, but bluff charges occurred in 4 % of the meetings. Blowing and
growling were apparently warning behaviors associated with the presence of cubs
or carcasses. Seven people have been injured in Scandinavia in the past 20
years. 6 were hunters, and in five cases the bear was wounded or possibly wounded.
We conclude that the most dangerous situation is when a bear is wounded. In
addition, we identified several situations that contributed to increase levels
of aggressiveness among bears. They are, in decreasing importance: the presence
of cubs, proximity to a carcass, proximity to a den, and the presence of a dog,
Our results showed that the Scandinavian brown bear is
not particularly dangerous. A relatively high proportion of wounded bears may
have contributed to the apparently higher levels of fatalities in the last
century.
1999, Biosphere Conserv.
2:1-9.
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Abstract:
The World Conservation Union (IUCN) defines populations as vulnerable if the
probability of extinction is larger than 10% within the next 100 years. With the
objective of minimizing problems with predation on domestic livestock and, at
the same time, conserving a viable population, we consider different threshold
harvesting strategies for a small population of brown bear, based on a
population dynamics model with growth rate and demographic and environmental
variances estimated from the present Swedish population. Talking into account
uncertainties in present estimates of the demographic parameters and in
population size, we show that the population can be harvested when the
population size exceeds 34 female bears aged one year and older, if the entire
population exceeding the threshold is harvested. To minimize the expected
long-term population size, however, we show that it is optimal to harvest only
a proportion equal to 35% of the population exceeding a lower threshold of 12
female bears. This strategy gives an expected long-term population size of
around 20 female bears. If the growth rate of the population is reduced by ca.
3 %, the threshold must, under some conditions, be doubled. We argue that the
small threshold are mainly a result of the high
intrinsic growth rate of the population considered in the present paper.
However, the analysis also suggests that IUCN’s criterion might allow a rate of
extinct that is too high.
2000, Proc. R. Soc. London B 266:961-967.
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Abstract:
To determine general patterns of myrmecophagy in
bears, we tested hypotheses regarding selection of ant species, factors
important to bears when selecting ant species, factors influencing seasonal use
of ants, and foraging behavior of brown bears (Ursus arctos) in central Sweden. Ants were an important food for
these bears, constituting 12, 16, and 4% of fecal volume in spring, summer, and
autumn, respectively. Ants were abundant, 30.5-38.5 tonnes
per bear, and bears excavated 8-33% (mean 23%) of the mounds of red forest ants
annually. Carpenter ants (Camponotus herculeanus) were highly preferred. Among mound-building
red forest ants, the Formica aquilonia/polyctena complex was preferred over Formica exsecta and Formica lugubris. The
ants selected by bears had high digestible energy and low formic acid content
and behaved passively when the colony was disturbed. Colony size and density
may also have influenced the selection of ants. Seasonal use of ants was
related not to the availability of pupae or the quality of plant foods but
probably to the availability of other foods. Bears consumed only a small
proportion of the ants, 4000-5000, each time they opened a mound, probably
because of rapidly increasing difficulty in capturing them after the colony was
attacked. Eurasian brown bears feed more on ants than North American bears do,
perhaps because of greater availability of large colonies of red forest ants.
Carpenter ants may have been especially available in our study area following
intensive clear-cutting.
1999, Can. J. Zool. 77:551-561.
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No Abstract:
2001, Wildl. Soc. Bull. 27:698-705.
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Abstract:
The accuracy of using cementum layers in teeth to
reconstruct reproductive histories has been evaluated for black bears (Ursus americanus) but not for
brown bears (Ursus arctos).
We tested the hypothesis that years when brown bears successfully reared cubs
could be identified in teeth by a cementum layer that
was thinner than layers in either the preceding or the following year. Using
teeth from 29 brown bears with known reproductive histories, we identified
potential cub-rearing years (“cub years”) based on measurements of cementum layer thickness and compared results to known
years of cub rearing. Of 62 known years when females reared cubs, only 13 were
correctly identified. We failed to identify 49 known cub years, and we
incorrectly identified as cub years 30 years when females did not rear cubs. We
conclude that this method, though successful for black bears, was unreliable
for brown bear populations.
1999, Ursus 11:275-280.
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Abstract:
When exposed to human disturbance, most large carnivores are able to move away
from the source with little energetic costs. Bears represent an exception in
that during winter, most individuals spend several month
in an energy-saving state of hibernation in a den. This implies that
disturbance of denning bears has the potential to
have a large energetic cost, although data on the subject are rather diffuse.
We reviewed the literature on densite selection, denning physiology, and responses to disturbance for the
brown bear (Ursus arctos),
black bear (U. americanus), and polar bear (U. maritimus). Generally, bears select dens one to 2 km from
human activity (roads, habitation, industrial activity) and seemed to tolerate
most activities that occurred more than one km from the den. Activity closer
that one km and especially within 200m caused variable responses. Some bears
tolerate disturbance even inside the den, but bears will abandon dens in
response to activity within this zone, especially early in the denning period. Den abandonment by brown and black bear
females with cubs of the year can lead to increased cub mortality. Specific
excavated or ground dens are rarely reused, whereas natural caves or hollow
trees are reused with varying frequency. There is often some distance between
an individual bear’s consecutive dens. This indicates that loss of a single denning area following human disturbance will not always
lead to deleteroiut effects, if alternative denning areas are available within the home range.
2001, Wildl. Soc. Bull.
28:400-413
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Abstract:
Literature from Eurasia was reviewed for information to test the hypothesis
that hunting of brown bears (Ursus arctos) makes them more wary of humans. The results were
not rigorous enough to test the hypothesis scientifically. However, the common
impression were that bears are more wary of humans where they are hunted than
where they are protected and that bears remained wary in several low-density
populations that had been protected for a long time. In spite of this, bears in
several increasing populations that were hunted became less wary. Use of
human-derived food was involved when wariness toward humans was lost and
appeared to be a more important factor influencing wariness than human. I
tentatively conclude that accessible human-derived foods for bears must be
controlled to maintain the bear’s wariness towards people. When this has been
done, hunting may contribute to increasing bear’s wariness. This subject
requires that more research and scientific experiments be conducted, because
people are more willing to accept wary bears.
1999, Ursus 11:157-163
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Abstract:
In the 1930’s the Scandinavian brown bear was close to extinction due to
vigorous extermination programmes in Norway and
Sweden. Increased protection of the brown bear in Scandinavia has resulted in
the recovery of four subpopulations, which currently contain close to 1000
individuals. Effective conservation and management of the Scandinavian brown
bear requires knowledge of the current levels of genetic diversity and gene
flow among the four subpopulations. Earlier studies of mitochondrial DNA (mtDNA) diversity revealed extremely low levels of genetic
variation, and population structure that grouped the three northern
subpopulations in one genetic clade and the
southernmost subpopulation in a second highly divergent clade.
In this study, we extended the analysis of genetic diversity and gene flow in
the Scandinavian brown bear using data from 19 nuclear DNA microsatellite loci.
Results from the nuclear loci were strikingly different than the mtDNA results. Genetic diversity levels in the four
subpopulations were equivalent to diversity levels in nonbottlenecked
populations from North America, and significantly higher than levels in other
bottlenecked and isolated brown bear populations. Gene flow levels between
subpopulations ranged from low to moderate and were correlated with
geographical distance. The substantial difference in results obtained using mt DNA and nuclear DNA markers stresses the importance of
collecting data from both types of genetic markers before interpreting data and
making recommendations for the conservation and management of natural
populations. Based on the results from the mtDNA and
nuclear DNA data sets, we propose one evolutionarily significant unit and four
management units for the brown bear in Scandinavia.
2002, Mol. Ecol. 9:421-431.
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Abstract:
Large carnivores are often used as focal species (indicators, umbrellas,
flagships or keystones) in conservation strategies either aimed at conserving
carnivores, the rest of the biodiversity that occupies their habitats, or both.
We evaluate their suitability for these roles in the context of boreal forest
biodiversity conservation in the muti-used landscape
of Scandinavia. The enormous conflicts, especially with
livestock, that carnivores cause in these areas makes them very controversial
flagships to the extent that it may affect rural people’s attitudes to
conservation in general. Because of the broad habitat tolerance of large
carnivores and their prey, and the difficulties in surveying carnivore numbers,
they are very insensitive and impractical indicators of forest biodiversity.
This ability of large carnivores to thrive in industrial forests means that the
many species that are sensitive to modern forestry will not fall under the
umbrella of areas managed for large carnivores. If large carnivores have a
keystone function with respect ot
affecting the density of their ungulate prey it is likely to lead to even
further conflicts with hunters who gain economic benefit from harvesting wild
ungulates. In other words, none of the classic “ecological” arguments are
likely to help justify large carnivore conservation, and large carnivore
conservation is unlikely to help conserve the rest of the boreal forest’s
biodiversity. Based on these arguments we recommend that (1) justification for
large carnivore conservation focus on the real philosophical and value
orientated reasons rather than ecological justifications, (2) that this
conservation should be brought about in practice by dedicated management
programs that specifically address the conflicts caused by large carnivores,
and (3) that boreal forest biodiversity is best conserved by specific actions
designed to establish reserves or change forestry practices.
2000, Biodiversity and Conserv.
9: 857-868
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Abstract:
The use of domestic animals to protect livestock was reviewed through visits to
actual users, discussions with experts and thorough literature search. Costs
and benefits were analysed in terms of reduced
livestock losses. The most common guardian animals are dogs, which have been
shown to reduce predation (documented mostly for coyote) by 11- 100%. Livestock
guardian dogs have also been used effectively against bear, wolf and cheetah.
Donkeys are also used as guardian animals, and their effectiveness lies in
their natural herding behaviour and aggression,
especially against canids. The effectiveness of
donkeys varies considerably dependent upon the predator species and the
temperament fo the
individual donkey. Lamas are also used as a guardian animal, with approximately
the same characteristics as the donkeys, and will defend themselves against
most predators. The use of guardian animals appears to be an effective tool for
reducing livestock predation and should be evaluated in areas with high predation
losses against the cost of changing production systems.
2000, Acta Agriculturæ Scandinavica Section A, Animal Science 50: 279-290.
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Abstract:
The use of aversive conditioning, repellents and deterrents in the management
of predator-livestock problems is evaluated based on a comprehensive literature
review, contact with leading authorities and visits to areas with similar
predation problems. The status of these management tools is reported and their
applicability under Scandinavian conditions valuated. Aversive conditioning
usually involves treating baits with an emetic compound (usually lithium
chloride), and has shown inconsistent and inconclusive results. Repellents and
deterrents include physical, chemical and acoustic stimuli or devices that
cause predators to stop an unwanted behaviour or to
retreat from an area. Chemical repellents are not particularly effective
against coyotes but have been effective for wolverines and bears under some
conditions (e.g. with the availability of untreated, alternative prey).
Projectile repellents give an immediate, positive result with bears, but their
use is limited. Visual and acoustic devices work well, but only for a limited
time, as predators quickly habituate to these devices. To summarize, these
methods generally show little promise in reducing livestock depredation on a
large-scale or long-term basis, especially under the conditions prevailing in
Scandinavia.
2000, Acta Agriculturæ Scandinavica Section A, Animal Science 50: 304-315.
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Abstract:
The current extinction of many of Earth’s large terrestrial carnivores has left
some extant prey species lacking knowledge about contemporary predators, a
situation roughly parallel to that 10,000 to 50,000
years ago, when naïve animals first encountered colonizing human hunters. Along
present-day carnivore recolonization fronts, brown
(also called grizzly) bears killed predator-naïve adult moose at
disproportionately high rates in Scandinavia, and moose mothers who lost
juveniles to recolonizing wolves in North America’s
Yellowstone region developed hypersensitivity to wolf howls. Although prey that
had been unfamiliar with dangerous predators for as few as 50 to 130 years were
highly vulnerable to initial encounters, behavioral adjustments to reduce
predation transpired within a single generation. The fact that at least one
prey species quickly learns to be wary of restored carnivores should negate
fears about localized prey extinction.
2001, Science 291: 1036-1039.
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Abstract:
The seasonal composition of an annual variation in the diet of the brown bear Ursus arctos in the Pasvik Vally, northeastern
Norway, were estimated based on the analysis of 137 bear scats. The importance
of moose Alces alces and
reindeer Rangifer tarandus
in the diet was given special attention, because results from Russia suggest
that brown bears are generally more carnivorous in the north. Ungulates,
especially adult moose, comprised the most important food item for bears in the
Pasvik Vally during spring
and summer, contributing 85 and 70% of the Estimated Dietary Energy (EDEC),
respectively. During autumn, when the bears have to build up fat reserves and
increase lean body mass for hibernation, berries were the most important food
item, contributing 49% of the EDEC, but ungulates were still important,
contributing 30% of the EDEC. Insects and vegetation were of low importance in
all seasons. The proportion of ungulates in the diet of brown bears in the Pasvik Valley was considerably higher than farther south in
Scandinavia, and this regional differences is
important concerning bear and moose management in northern areas.
2001, Wildlife Biology 7: 27-37.
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Abstract:
In a recent analysis Woodroffe (2000) found a
positive relationship between historical patterns of large carnivore extinction
probability and human population density. However, much of the data in this
analysis came from a period when carnivore extermination was a management
objective. In order to explore the hypothesis that large carnivores can persist
at high human densities when the management regime is more favourable
we have repeated the analysis using up-to-date data from North America and
Europe. In North America we found that large carnivore populations have
increased after favourable legislation was
introduced, despite further increases in human population density. In Europe we
found no clear relationship between present carnivore distribution and human
population density. We therefore believe that the existence of effective
wildlife management structures is more important than human density per
se.
2002, Animal Conservation 4: 345-349.
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Abstract:
During 1986-98, the denning chronology of 54 radiocollared female brown bears (Ursus
arctos) was documented 112 times in central Sweden.
An intensive study in 1998 investigated the predenning
movement patterns of 9 females. Female brown bears spent on average 181 days in
winter dens. Females that gave birth to cubs during winter spent one month
longer in and at the den (196 days) than adult solitary females (168 days) or
those that entered the den with cubs (161 days). Subadult
females (<3 years old) spent less time in dens (163 days) than adults (183
days) and the duration of denning increased with
increasing age. The mean entry date of all females was 28 October. However,
significant differences in denning dates were
observed depending on their reproductive status. Females that were pregnant in
the fall denned earlier and emerged from the den later compared to females
entering the den with cubs. During 1998, females moved on average 3.4 km/day.
Females with cubs moved on average shorter distances than those without cubs,
but from late September to date of denning, no
variation in movement patterns among females in different reproductive status
was found. Six weeks before female brown bears entered the den, a reduction of
movements of about 5%/week was observed. In the last week before they entered
the den the movements were further reduced by 40%. Female brown bears visited
their den areas (1 km around the den) about once a month, which was more often
than expected. Thus we suspect that they choose a known place to den for the
winter.
200,1Ursus 12: 37-46.
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Abstract:
We documented the loss of brown bear (Ursus arctos) cubs-of-the-year (cubs) in 2 Swedish populations
for 11 years in the north and 12 years in the south, and made spatial and
temporal comparisons to examine whether nutritional, social (sexually selected
infanticide), or den disturbance factors best explained the observed variation.
Annual cub loss was 0.04 (n = 78) in the north and 0.35 (n = 126) in the south.
The loss of cubs at both levels of comparison was best explained by social
factors. Disturbance was only evaluated in the south and explained significant
variation. In the north, few adult males died and 3 adult males lost early in
the study there were not replaced for many years, presumably due to little
immigration of new males. Immigration was probably low due to high illegal
mortality around the study area and lack of bear habitat on one side of the
study area. In the south, 5 times as many males died annually, and in years
with recorded adult male mortality, an average of 20% of the adult males died.
The number of adult males remained stable, presumably due to immigration by new
males. Illegal mortality appeared to be less in the south, and the study area
was surrounded be bear habitat. Number of adult males dying in cub areas (the
composite area of all radiomarked females with cubs)
2 years previously was correlated negatively with cub survival in the south. In
the north, no factors correlated with temporal patterns of cub loss, but loss
of adult males 1-2 years previously was the best variable we tested. We suggest
that immigrating males kill cubs, as predicted by the sexually selected
infanticide hypothesis. Some other studies have yielded similar results. We
recommend that managers assume that loss of adult male bears is depensatory until this question is adequately resolved.
2002, Ursus 12: 69-80.
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Abstract:
The total number of brown bears (Ursus arctos) in Europe is presently about 50,000 (about 14,000
outside Russia), within an area of more than 2.5 million km² (8000,00 km² outside Russia). About 37,500 bears are found in the
northeastern European population; 8,100 in the Carpathian Mountains; 2,800 in
the Alps-Dinaric-Pindos; 1,000 in Scandinavia; 520 in
the Rila-Rhodope Mountains; 200 in the Stara Plania Mountains; 50-65 in
the western Cantabrian Mountains; 40-80 in Apennine Mountains; 20 in the eastern
Cantabrian Mountains; 6 in the Western Pyrenees; 5 in the Central Pyrenees; and
4 in the southern Alps. The brown bear is either a protected or game species in
all of the countries discussed in this paper. Most countries manage the brown
bear at the national level, although several ministries are often involved. All
European countries with bears within their national borders (except Bosnia and
Herzegovina and the Yugoslavia Federation) have signed the Bern Convention;
almost half have prepared, or are preparing, a management plan for brown bears.
In addition, most countries engage in monitoring, research, information
dissemination, and conservation activities. In areas where bear range includes
human settlements, damage to livestock, orchards, and beehives occurs but, in
most countries, stakeholders are compensated for damage, either by the state,
regional government, or hunter clubs. In 1995-96 about 1.15 million US$ was
paid to compensate such damage throughout Europe.
2001, Ursus 12: 9-20.
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Abstract:
Intraspecific predation of bears > 1 year old is
observed occasionally, but the mechanism behind it are poorly understood and
often debated. We documented 13 cases of intraspecific
predation in brown bears (Ursus arctos)
in 2 Scandinavian study areas during 668 bear-years of radiotracking
238 brown bears. We found ares differences in the
rates of intraspecific predation only for yearling
females. Annaul yearling female mortality due to intraspecific predation was higher (0.162,6
of 38) in the south than in the north (no mortality recorded, 28 yearling
followed). No older subadult females were killed by
other bears. Annual mortality rated due to intraspecific
predation for males, areas combined, were: 0.032 for yearlings, 0.040 for
2-year-olds, and 0.061 for 3-year-olds, for a combined rate from age 1 through
3 years of 0.127. one adult females was killed.
Staying with their mother did not significantly reduce intraspecific
predation among yearlings. Neither population density, a the
levels we observed, nor reduced food abundance influenced rates of intraspecific predation on yearlings in our areas. In our
study areas, intraspecific predation on yearling
females was correlated positively with the number of adult males that had died
3 years previously and whether any adult male had died 2 years previously. In
an earlier study, we found that cub mortality was elevated during breeding
season 2 years after the death of adult males. As we found a similar pattern
for intraspecific predation on yearling females, we
speculate that infanticidal males may be prone to
kill subadult bears. Although based on a relatively
small sample of mortalities, our results strengthen our earlier conclusion that
the killing of adult males may have a population consequence that managers
should consider.
2001, Ursus 12: 81-92.
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Abstract:
PARENTE is a user-friendly software package that conducts parentage inference
using molecular data from diploid <