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