Transcript PPT - Wildlife Ecology and Conservation

Dall’s Sheep & Stone’s Sheep
Presented by
Chelsey Faller
Classification / Taxonomy
• Ovis dalli dalli & Ovis
dalli stonei
• Class: Mammalia
– Order: Artiodactyla
• Family: Bovidae
– Subfamily: Caprinae
Populations / Sub-populations
• Stone’s sheep is a subspecies of Dall’s sheep
– Sub species designation is due to color difference
– Also Known As:
• Thinhorn sheep, Fannin sheep
• Closest relatives are in
Siberia, immigrated
~ 100,000 years ago
N.A.
Distribution
Stone’s sheep is south of Dall’s sheep
Identification
• Dall’s
– White
– up to 300lbs
• Stone’s
– Slate gray to black
– White belly
– White rump, inside of legs
– Up to 240lbs
Identification
• Both sub species have yellowish horns
– Rams can be 122cm, ewes 25cm
• Ewes smaller (48kg), males larger (77kg)
• Only sheep in their range – high elevation 15002000 meters
– Tiny bit of overlap with Mtn Goat, sheep prefer drier
sites.
• Craggy cliffs and steep slopes
Habitat
• Mountains of Alaska and Canada
• Dall’s sheep
– Dry, open areas.
– Steep sloping meadows and ridges
• Stone’s sheep (British Columbia)
– Rock faces, above treeline
• 1500 – 2500 meters
Don Siebel
Natural History I
• Two ranges - Summer and Winter
– Summer = higher elevation, alpine
– High range fidelity (90%-75%)
• Social structure
– Sexes separate
• Reproduction
– Ewes have a single lamb
– Begin breeding at adult
weight rather than age 2-5 years
Jason Ahrns
Natural History II
• Rams resemble ewes
until 3 years of age
• Horns grow in yearly
rings called annuli
• Based on annuli
count top ages are in
the 16-20 year range
Stone’s ram – 3.5 yrs
Stone’s ram – 4.5 yrs
Stone’s ram – 6 yrs
Stone’s ram – 7.5 yrs
Stone’s ram – 8.5 yrs
General Population Trends
• Dall’s
– Healthy populations
– Wide fluctuations
– Big decline in 90s due to several years of harsh
winter, still recovering
– 100,000
• Stone’s
– Far fewer
– 18,000
Conservation Status & Legal Status
• Not in any danger
• Stones sheep in slow decline, may become
threatened in British Columbia
Behavior
• Mating season: November – December
• Lambing: May-June
– Ewes find most inaccessible cliffs to give birth on
– Weaned at 9 months
• Social hierarchy based on age
• During the rut males butt heads to establish
dominance
Diet
• Summer: Grass, forbs, lichen
• Winter: frozen grass, lichen, moss
• Mineral licks – fidelity to a favorite mineral lick
is 100% for ewes and 80% for rams
Diet
• 88% or more dried grass in winter
• Location dependent
– Records of up to 43% lichen
• Lichens highly digestible and nutritious, moss
not digestible
– Lichens critical during bad winters
• Willows important during summer
Predators I
• Wolves, eagles, coyotes, lynx, grizzly bear,
wolverine, black bear, cougar
• Use rocks and crags to hide
– Eyesight as good as a human binoculars
Predators II
• Not a cause for population decline unless
specific conditions in play
• Higher density of competitors = more
predators = more pressure on sheep
• More rams predated than ewes – more likely
to go exploring
– Reckless during rut
Competitors
• Deer, moose, elk, bison, goats
• Very little direct competition
• Growing problem due to past policies of fire
suppression
• Predators increase as cervid presence
increases, but often selectively kill sheep
instead
Mortality
• Most mortality in first 30 days or during first winter
• Loss of teeth causes death of older animals at 1218years
• Dalls sheep: primary causes are predators and winter
weather
• Stones sheep primary causes: predation, winter
weather, and industry such as mining and oil
exploration
Disease & Parasites
• Very little documented transmission to or from
livestock
– Not a lot of livestock that far north
• Pneumonia (can be caused by 4 bacteria species)
• Lungworm, lumpy jaw, nematodes
• Use of lamas for backcountry access starting to
become a problem.
• Very susceptible to domestic sheep pathogens –
more so than bighorns
Economic Value I
Economic Value II
• Alaska Dall Sheep Hunting
– Hunted in August – September
– Draw Hunts: done by lottery, must pay to enter and pay fee
if drawn.
– Subsistence: hunting permitted by state residents with
special license
– General Season: need a license, tags
– Auction: 2 permits auctioned off for Dall sheep per year –
funds go to state wildlife agencies
• Good meat, but little of it
– 230lbs ram when dressed is 140lbs, yield 80lbs of meat.
Economic Value III
• Alaska Dall Sheep Hunting
– Only rams with “full curl” or 8yrs
– In Alaska out-of-state hunters must have guide
from Alaska
– Permits split evenly in and out of state
– 2007: 403 by non-residents, 513 by residents
– Guided hunt can cost $14,000 - $16,000
Economic Value IV
• Texas Dall Sheep Hunting
– Breed trophy rams with extravagant horns
– $1400 - $3500 for a “record” ram…but they’re not real!
Interactions with Humans
• More of an issue with Stones sheep
populations
• Industry, development
• Mineral exploration in BC cutting roads
through habitat
Interactions with Humans II
• More paved roads into the mountains have
caused problems in Alaska.
• Often get into trouble on roads
– Minerals from road building, cars, etc.
Interactions with Humans III
• Specific types of development
– Hydro-electric in 1960s split habitats and isolated
populations
• Helicopters
– Recreation or otherwise
• Oil development attracts sheep
– Salt on ground
Population Dynamics I
• Difficult to determine populations
– Yearling ewes and male lambs same size by late
summer
– 1-2 year old rams same size as ewes and same horns
• Gender ratios rams:ewes can be from 57:100 to
93:100
• Populations can swing quickly due to weather
• Different dynamics in populations that are
expanding vs stable
Management of Populations I
• Example: British Columbia
– Stones sheep in decline
– Management plan involves
increasing elk and bison harvest
– Encourage hunting of predator species
– Controlled burns where fire was historically
• Can be problematic
Management of Populations II
• Example: British Columbia
– Industrial development and agriculture
• Don’t know if they’re a problem
• Need better info
– Recreation
• Invasive plants brought in by horses
• Awareness program has started
Management of Populations III
• Example: British Columbia
– High fidelity to a specific
mountain/home range
requires manager
consideration of
metapopulations
• Find sources and sinks
• mtDNA has revealed that
traveling rams connect
populations
Management of Populations IV
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•
Can be very hard to study
Remote
Cliffs/mountains
Ewes and young rams look the same
Can re-seed old mining lands, but must be
right species
– Usibelli mine, Alaska, had to figure out diet before
re-seeding
Future Outlook
• Positive except for probable continued
declines in BC.
• Possibility of listing Stones sheep in BC ground
for funding further research
Future Management
• Better outreach
• More research
• Mitigate oil/gas development impacts by
– Not drilling during critical periods
– Proper disposal of waste
– Less use of salt to de-ice
– Ban hunting where sheep concentrate to cross
roads
Future Management II
• Wildlife corridors
• Focus on restoring
meta-population
connections
• Overpasses
Future Management III
• Possible restrictions on lama use in BC and
some US National parks.
• Vaccine for pneumonia – after known
breakout of domestic sheep
Current Events
• Dalls sheep showing a decline in some parts of Alaska
• Alaska Dept. of Fish and Game currently in the middle
of a project to determine cause
• Captured and radio-collared 200 adults and 150 lambs
over 5 years
• So far: ruled out hunting and predation, along with
indirect effects of both.
• Extremely low pregnancy rates and very poor overall
condition
• Study concludes field work this year
Sources
• Alaska Department of Fish and Game, Species Profile at
http://www.adfg.alaska.gov/index.cfm?adfg=dallsheep.main
• National Park Service – Denali at
http://www.nps.gov/dena/naturescience/dallsheep.htm
• National Park Service – Inventory and Monitoring at
http://science.nature.nps.gov/im/units/cakn/vitalsign.cfm?vsid=44
• National Park Service – Gates of the Arctic at
http://www.nps.gov/gaar/naturescience/dalls-sheep.htm
• http://www.ferris.edu/card/Animals/Herbivores/Stone-Sheep.pdf
• Yukon Wildlife Preserve at
http://www.yukonwildlife.ca/animalshabitats/ouranimals/thinhornsheep/
• A.W.F. Banfield (1974). The Mammals of Canada. University of Toronto Press
• Guide Outfitters Association of British Columbia at http://www.goabc.org/huntguide/?adventure=30
• Demarchi, R.A., and C.L. Hartwig. 2004. Status of Thinhorn Sheep in British Columbia.
B.C. Minist. Water, Land and Air Protection, Biodiversity Branch, Victoria BC. Wildl. Bull.
No. B-119. 96pp.
Sources II
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Government of the Yukon at http://www.env.gov.yk.ca/animals-habitat/mammals/sheep.php
Archive, photographs at http://www.arkive.org/thinhorn-sheep/ovis-dalli/image-G84642.html#imageG85331.html
Alaska remote Guide Service at http://www.alaskaremote.com/dall_sheep_hunts.htm
Texas hunt lodge at http://www.texashuntlodge.com/texas_dall_sheep_hunt_package.asp
Qwest Helicopters Wildlife Management at http://www.qwesthelicopters.com/serviceswildlifemanagement
People and Stone’ sheep at http://www.env.gov.bc.ca/wld/documents/stonessheep/stonesheep_3.pdf
Alaska Dispatch at http://www.alaskadispatch.com/article/20130507/predation-not-likely-cause-dallsheep-crash-alaskas-chugach-mountains
Sources III (Pictures)