animal harvest in the news - granger high school harvest in the news ... green ≥ 6 years old blue...
TRANSCRIPT
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MINIMIZING IMPACTS OF ANIMAL HARVEST
ANIMAL HARVEST IN THE NEWS
Animal Harvest: Removing an animal from the wild
population through killing or capture:
Culling Population/ecosystem maintenance, human
conflict mitigation
Poaching Bushmeat, illegal trade (pet, body parts, etc.)
Legal Harvesting Food, introduction to captivity, regulated hunting
Minimizing Impacts of Animal Harvest
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Sex Ratio
Age Ratio
Genetic Composition
Spatial Structuring
Describing Population Composition
SUSTAINABLE TROPHY HUNTING OF AFRICAN LIONS
K. Whitman, A.M. Starfield, H.S. Quading and C. Packer
NATURE, VOL 428, 11 MARCH 2004. www.nature.com/nature
African lion (Panthera leo)
IUCN status: Vulnerable
(CITES appendix II)
Current populations are
estimated to be declining
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Lion Prides
Average of 6 breeding females and a coalition of
2-3 adult males in a pride
Coalition sires all cubs born during their tenure
Coalitions taking over a new pride will kill all
cubs ≤ 9 months old (older cubs are evicted)
Cubs typically reach independence ≈ 2 years
Lion Prides
Trophy hunting might increase the rate of male
take overs (a loss of a male from a dominant
coalition could leave it vulnerable to being ousted)
If there is too much trophy hunting, could coalition
takeovers (and the resulting infanticide) prevent
cubs from reaching adulthood?
“Study Population”
Simulation based on 40 years of demographic data
from northern Tanzania (Serengeti National Park and
Ngorongoro Crater)
Each of 100 replications began with the same age
structure, reproductive history, pride affiliation and
distribution.
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Number of females after 30 years:
Non-infanticidal males
Annual quota
Age of harvested males:
Green ≥ 6 years old
Blue ≥ 5 years old
Orange ≥ 4 years old
Red ≥ 3 years old
Average outcome after 100 runs is shown
Effects of trophy hunting as a function of quota size and male age
If older males are killed
populations can still be
maintained.
If too many young males
are killed (quota size
increases), populations
go to extinction.
Infanticidal males
Annual quota
Age of harvested males:
Green ≥ 6 years old
Blue ≥ 5 years old
Orange ≥ 4 years old
Red ≥ 3 years old
Effect is pronounced in
infanticidal populations:
Effects of trophy hunting as a function of quota size and male age
Populations can be
maintained if only 5 and 6
year olds are harvested
Female population size (over the course of 50 years)
as a function of quota size and age of harvested males
Quota Sizes
Green - 2 males
Blue - 4 males
Orange - 6 males
Red - 10 males
Female population size when hunters shoot males that are
(a) ≥3 yr old (b) ≥4 yr old (c) ≥ 5 yr old (d) ≥ 6 yr.
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Female population size (over the course of 50 years)
as a function of quota size and age of harvested males
Quota Sizes
2 males
4 males
6 males
10 males
Female population size when hunters shoot males that are
(a) ≥3 yr old (b) ≥4 yr old (c) ≥ 5 yr old (d) ≥ 6 yr.
Different colors are different quotas – the only quota that
appears sustainable might be green (=2 males)
Female population size (over the course of 50 years)
as a function of quota size and age of harvested males
Quota Sizes
Green - 2 males
- 4 males
Orange - 6 males
10 males
Female population size when hunters shoot males that are
(a) ≥3 yr old (b) ≥4 yr old (c) ≥ 5 yr old (d) ≥ 6 yr.
Different colors are different quotas all quotas appear
sustainable (red is the highest = 10 males)
Sustainable trophy hunting of African lions
What does this mean for the types of lions they should target
with trophy hunting and the potential quotas? Why is this the
case?
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Sustainable trophy hunting of African lions
An analysis of population consequences of lion trophy hunting
based on quota size and male age “suggest that quotas
would be unnecessary in any male-only trophy species where
age determination could be reliably implemented”
Sustainable trophy hunting of African lions
An analysis of population consequences of lion trophy hunting
based on quota size and male age “suggest that quotas
would be unnecessary in any male-only trophy species where
age determination could be reliably implemented”
How do we age
them then?
Male lion basics
Males sexually mature ≈2.5 years
Mane full ≈ 4 years
Lifespan ≈ 15 years
Sustainable trophy hunting of African lions
K. Whitman, A.M. Starfield, H.S. Quading
and C. Packer
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Age estimation for adult lions using nose colouration
ID photo of 3-year old Serengeti male
Excised photo of
nose tip
GIS rendering
Each pixel categorized as
“black”, or “not black”
Age estimation for adult lions using nose coloration
After controlling for age, there was no effect of sex on nose colour
in the Serengeti, but Ngorongoro males had lighter noses than
Ngorongoro females and Serengeti males.
Based on 189
photos of 105
known-aged lions
(73 females and
32 males) in
Serengeti and
Ngorongoro
Sustainable trophy hunting of African lions
Whitman et al. 2004. Nature
Cautions:
•Age should be assessed
independent of the “trophy”
phenotype
•This study is based on northern
Tanzania populations and may not
apply to all lion populations.
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Management implications ??
“studies by Whitman et al (2004) with field
data from Tanzania demonstrated through
modeling that harvesting only lions of six
years and older is not harmful to a normal
lion population.
Based on their results, the Wildlife Division
is considering a system of discouraging the
export of lion trophies from animals less
than six years old.”
Dennis K. Ikanda, 2008. NON-DETRIMENT REPORT UNDER CITES
REGARDINGTHE EXPORT OF AFRICAN LIONS PANTHERA LEO FROM
THE UNITED REPUBLIC OF TANZANIA
Management implications
…Whitman, et al. (2004) showed that trophy hunting is
likely to have minimal impacts on lion populations if offtake
is restricted to males that are at least 6 yrs of age
…The most important lesson from these simulations is that
there is no risk of over-harvesting a lion population when
hunting is restricted to males that are at least 6 yrs of age –
regardless of the quota
Packer, et al. Impacts of Trophy Hunting on Lions in East and Southern Africa: Recent
offtake and future recommendations
BACKGROUND PAPER FOR THE EASTERN AND SOUTHERN AFRICAN LION
CONSERVATION WORKSHOP, JOHANNESBURG, SOUTH AFRICA, 11-13
JANUARY 2006
Management implications
Kristin Nowell – member of the IUCN Cat Specialist Group
Denis Dilba, 1/27/2006. Killing Lions to Save Them: Is Trophy Hunting the Way to
Rescue Africa’s Lion Kings?
“The conservationists from IUCN are
now betting on a completely different
strategy. They even want to do away
with hunting limits, which have until now
been determined by each country on its
own. ‘If one only shoots male lions that
are older than six, there’s no longer a
need for a limit,’ says Nowell. ‘The
population will regulate itself’.”
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http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0073808
The Trophy Hunting of African Lions:
Scale, Current Management Practices and
Factors Undermining Sustainability
Lindsey, et al. Sep 18, 2013
What’s happening now? Learn more:
LONG-TERM IMPACTS OF POACHING ON RELATEDNESS,
STRESS PHYSIOLOGY, AND REPRODUCTIVE OUTPUT OF
ADULT FEMALE AFRICAN ELEPHANTS
Gobush, et al. 2008. Conservation Biology
Elephant basics
Matriarchal society
Females within groups are highly related
(typically don’t leave their family group)
Female African elephants have tusks that increase in size with age
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218 female elephants (108 groups) from
Mikumi National Park, Tanzania
Mikumi populations were subject to heavy
poaching before 1989 ivory ban
Up to 75% of the Mikumi population may
have been killed, with 80% of the poached
skulls female, averaging 32.4 years old.
Group compositions in poached populations
such as Mikumi differ significantly from those
of unpoached populations
Study population
Adult females that lack an old
matriarch, close adult female kin,
strong adult social bonds, or
reside in an area with historically
high risk of poaching maintain
higher physiological stress and
lower reproductive output than
females from groups possessing
these elements or that reside in
areas of low poaching risk.
• Female elephants in
areas of high poaching
(or who have lost close
relatives) get stressed
out!
• High levels of stress
lead to decreased
reproduction
Hypothesis
.
Group size distributions (number of females per group)
(a)Mikumi elephants
n = 189
adult females in 102 groups
(b) Amboseli
n = 304
adult females in 45 groups
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Fecal glucocorticoid levels for
female elephants according
to first-order adult relative
presence (kin) or absence
and poaching risk of home-
range location (low and high)
Stress hormones based on poaching risk
and presence of relatives
No close relatives,
high poaching risk
= Highest stress hormones
Percentage of female elephants in disrupted and intact groups that
(a) were nonreproductive and (b) had an infant <2 years old.
Long Term Impacts of Poaching on African Elephants
Long-Term Impacts of Poaching on Relatedness, Stress Physiology,
and Reproductive Output of Adult Female African Elephants
K.S. Gobush, B.M. Mutayoba, and S. K. Wasser
• Small group size
• Less relatedness
• Higher stress hormones
• Lower reproductive output
15 years after poaching ban…
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Long-Term Impacts of Poaching on Relatedness, Stress Physiology,
and Reproductive Output of Adult Female African ElephantsK.S. Gobush, B.M. Mutayoba, and S. K. Wasser
Gobush et al.’s results “suggest that long-term negative
impacts from poaching of old, related matriarchs have
persisted among adult female elephants 1.5 decades after
the 1989 ivory ban was implemented.”
In the 1980s young orphaned male African
elephants (survivors of culling in Kruger
National Park) translocated to Pilanesberg,
South Africa:
•Matured early (~10 years) in the absence of
older males
•Killed more than 40 white rhinoceros between
1992 and 1997
Slotow, et al. 2000. Nature
Older bull elephants control young males:
Orphaned male adolescents go on killing sprees
if mature males aren’t around
Older bull elephants control young males:
Orphaned male adolescents go on killing sprees
if mature males aren’t around
In 1998 six older male elephants
were introduced from Kruger Park
•Killing of the rhinos ended
•Musth in younger bulls shortened
Why?
Slotow, et al. 2000. Nature