Wolf Pack Dynamics(Preliminaries)

Virginia Stoll

Wm. D. Stone

A Mexican Lobo

The ‘Lobo’

• Smallest subspecies of North American Gray Wolf

• 50 – 80 pounds

• ~30 inches at the shoulder

• Original range much of Mexico, NM, AZ

History

• Almost extinct by mid-20th century

• Listed as endangered 1976

• Recovery effort started 1977

• Small population captured in Mexico

• Two small captive populations

• 7 founders.

Wolf Packs

• Basic unit of population – the pack– One alpha pair

• Normally the only breeders

– Young adults• Help hunt and baby-sit

– Pups

Formation of new packs

• Young adults can leave the pack – become ‘lone wolves’

• New packs can be formed by a pair of lone wolves joining up

• Very large packs can split

• Death of one of the alpha pair can cause pack to split

Pack size

• Prey– Size

• Mostly elk

– Availability• Lots of elk

• Scavengers– Ravens

• Can eat 2 lbs. of meat per day each

Population Pressures

• In the New Mexico re-established wolf population, two largest sources of adult mortality are– Cars – Illegal shooting

Natural Mortality

• Food pressure mostly affects survival of pups to weaning

• Inter-pack battles can be a significant cause of death

Genetics

• Starting with tracking one locus, with one marked gene in a single individual

• Probability of duplicate copies in an individual

• (comparative only)

Input from Federal Wolf Biologists

• New Mexico packs rarely are larger than a breeding pair plus pups– Subspecies difference?– Growth stage vs. steady state?

• So far, little food or territory pressure

Genetics

• US Fish & Wildlife has full genetic profiles of every wolf they have handled

• Very small number of founders

• Selective breeding for genetic diversity

• They hope our model can help

Model Results

Wolf P opulation

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Female with pups