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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

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Take-home message

It is vital to understand the population dynamics to

understand the long term impacts

The effects of poaching can be long lasting

If carefully planned and the proper individuals

taken, trophy hunting can be scientifically

sustainable