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43 Cards in this Set
- Front
- Back
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POLAR BEARS |
Largest terrestrial carnivore One of 8 species of bears in the world Closely related to brown bears - Diverged 150,000 - 600,000 yrs ago |
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Mitochondrial DNA is from mother
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Polar bears carry introgressed brown bear mitochondrial DNA due to pasthybridization.
• Multilocus genomic analyses are crucial for an accurate understandingof evolutionary history. Low genetic diversity in polar bears suggests that changes in theenvironment, such as warm phases, caused population bottlenecks. |
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Ice-obligate species - found throughout circumpolar region in 19discrete subpopulations
Global population between 20,000 and 25,000 |
Polar bears primarily consume 2 species of sealRinged seal (smallest seal sp)
Bearded seal (largest seal sp) |
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In winter polar bears need energy they so consume blubber if they consumed protein they would need to consume more water via snow which would cool down there body temp they can recycle nitrogen
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Habitat Selection
Depends on distribution & availabilityof prey (i.e. ringed seals) Seals prefer land fast ice or areaswith complete cover |
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Habitat Selection Prefer areas with large deformationstructures and significant snow cover. Avoid wind-packed snowdrifts, nodrifts or heavily deformed ice. |
Intraspecific variation in use of high‐qualityforaging habitat Females with cubs of the year avoid habitat preferred by adults
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Sea ice is unpredictable. Openings vary in time andspace. |
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Female Home Range 125,100 km2 Grizzly bear 70km2 Black Bear 5.2 km 2 |
Hudson Bay |
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Males stay near the coast |
Females move inland |
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Seasonal feeding of non-pregnant polar bears |
Seasonal feeding of pregnant polar bears |
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Cubs stay with mothers 2 1⁄2 years, so females breedevery 3 years. Adult males are twice as big as females Large body size in males due to male-male competition for feeding |
What is their mating system? In the evolutionary biology of sexual reproduction, operational sex ratio (OSR) is the ratio of sexually competing males that are ready to mate to sexually competing females that are ready to mate, or alternatively the local ratio of fertilizable females to sexually active males at any given time. |
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operational sex ratio (OSR) = is the ratio of sexually competing males that are ready to mate to sexually competing females that are ready to mate, or alternatively the local ratio of fertilizable females to sexually active males at any given time. |
Females breed every 3 years •Operational Sex Ratio isstrongly male-biased Conservation of Polar Bears •Sexual dimorphism •Males with wounds/scars & brokenteeth Mating system: Male-malecompetition |
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Tooth breakage increases with age in males, but not females |
Males aggregate along the coast in the fall |
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Sociality in polar bears |
Autumn interactions are non-aggressive, & few injuriesoccur outside of breeding season. |
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But energetically Bears have fasted to 4 months |
So why interact? |
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Hypotheses: • Assessment • Dominance • Practice • Physical Exercise Predictions can be tested by collecting behavioural data |
Photoidentification
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Polar Bears Facial scars vary
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Whiskerpoints |
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Body condition
If lots of fat left over may be more willing to expend energy on play and vis versa |
Polar bear conservation 1973 - International agreement on polar bear conservation Canada USA Norway Denmark (greenland) USSR Set limited conditions for hunting or capturingResearch programs – conservation & managementProtect ecosystems in which bears live |
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the International Union for Conservation of Nature (IUCN)Polar Bear Specialist Group reviewed the status of polar bears usingthe IUCN Red List criteria. •Upgraded status from Least Concern to Vulnerable In 2008, the U.S. listed the polar bear as a threatened species underthe Endangered Species Act |
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Polar Bear Conservation: What are the potentialways humans couldimpact polar bears? |
Polar Bear Conservation: Impacted by: Tourism, Hunting, Industrial activity, Contaminants (pollution), Climate changeResearchers? |
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Tourism to watch Polar Bear Play |
Tourism
• Original “tundra buggy”built in 1980 • National Geographic filmthe following year • Led to expanding touristindustry in Churchill |
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Tourism
• Up to10,000 touristsper year in Churchill • vehicles • ‘hotels’ • helicopters |
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Potential problems: 1) Habituation (animals get used to humans)
No longer careful around humans |
2) Attraction: Can be attracted to human by-productsi.e. smells |
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Effluent Water |
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Other chemicals (antifreeze)
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Infanticide by males
Bears can interactaggressively Females brought into tourist area instead of inland |
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Bears approach human areas
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Bear trap
Bear jail |
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THE EFFECTS OF ECOTOURISM ON POLAR BEARBEHAVIOUR
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Body condition – lowest point of the year • Inefficient walkers? Locomotion = high cost? Polar bears have a high cost to locomotion |
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Objectives:
• Investigate response of bearsto tourist vehicles – Does behaviour change? – What influences the likelihoodof changing behaviour? Identify bears via whisker or scars |
Methods • Vehicle access allows data collection on bear behaviour, aswell as experimental methodology |
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• Bear behaviour – presence/absence of vehicles • Number of vehicles per bear recorded |
Does the presence of tourist vehicles affect behaviour?
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Conservation of Polar Bears Vehicle Approach Experiments: • Do bears respond to vehicleapproach? • Does response change over time(i.e. habituation)? |
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Results: Approach Experiments
24% responded (n=169 approaches) • 39% sit/stand up • 57% walk away • 4% run away |
What variables predict response?
• Sex • Body condition • Speed of vehicle • Angle of approach Model Selection Logistic regression & AIC |
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Males are more likely to respond than females |
Body Condition Bears that respond are in lower body condition |
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Speed of Vehicle Bears respond more to faster speed |
Angle of Approach bear respond less to indirect approach bears respond more direct approaches |
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Probably of response declines with repeated approaches -> Habituation |
Can behaviours predict response? • Lip jut• Yawn• Body shift• Lip smack• Tongue flick • Eye contact• Look away• Ears back• Headup frequency• Headup duration |
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Behaviour Variables: Response Best supported model: •Body shift •Tongue flick •Lip smack |
Implications Tour operators can minimize responses & humaninduced locomotion by: •Minimizing direct approaches
•Minimizing speed •Recognizing behavioural predictors |
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Conclusions about tourism • Disturbance by humans islow (76% did not respond tovehicle approach) – Vehicle speed & approachangle affect response; can becontrolled by drivers • Bears that remain in touristregion habituate quickly |
Researchers Conservation of Polar Bears Shorter-term, post-capture effects do not appear tohave translated into any long-term effects on bodycondition, reproduction, or cub survival. Current capture-based research methods do nothave long-term implications, and are notcontributing to observed changes in bodycondition, reproduction or survival in the southernBeaufort Sea. |
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Hunting
Approximately 800/year killed legally inCanada, Greenland & USA In USSR, hunting banned in1955 Modern Russia, no research- Poaching?
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In Canada, about 600 permits issued to the Inuit(mostly in Nunavut) Sell hides for $1-3,000 May sell permit to hunters from US & Europe: $28,000 each In 2005 harvest levels were increased by 28.5% based on increased sightings even though populations are declining partially reversed in 2010 In 2017 numbers of tags reduced again In 2008 the U.S. listed polar bears as threatenedunder the Endangered Species Act • Can’t import trophies into the US |
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increased protection
Banned international commercial trade |
Industry Oil & gas explorationOil spillsOil tankers Arctic National Wildlife Refuge– major denning site for polar bears |
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Contaminants in the Arctic Where does the pollution in the Arctic come from? |
Contaminants:
• Organochlorines stored in fat • Heavy metals (lead, mercury) stored in skin, muscle |
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Marine food web longer then terrestrial food web Cubs are actually top of food chain recieve food from mothers Biomagnification - contaminants persist in fat, magnifies up food chain |
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Levels of organochlorines veryhigh, especially in Europe |
Innuit women are advised not to breast feed as are feeding on same food sources as bear
Mothers that lost cubshad much higherconcentrations ofpollution |
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The Arctic is warming
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Western Hudson Bay Timing of break-up of sea ice inChurchill is at least 10 daysearlier Timing of freeze-up of sea ice inChurchill is at least 15 days later From 1980 to 2014, open-waterperiod has increased by nearly40 days! While hunting, bears gain 10 kg per week
fasting bears lose 0.85 kg per day 3 weeks lost hunting = 35 days lost fasting ability |
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Mean mass of female polarbears 1980 - 2004 Females <230kg have small young Females <189kg, young don’t survive |
Female survival affected by sea ice break-up date |
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Churchill Manitoba Population Estimates declined 22% from 1987-2004, but have stabilized |
By 2040, only small fringe of summer ice –multiyear ice predicted to persist By 2050, 30% may be gone |
