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Polar bear · A marine bear whose seal-and-ice budget made Churchill, Knut and climate models into one public animal.

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Quick answers

Why is resilience low if some subpopulations look stable?

IUCN VU and the 2008 ESA listing rest on ice-season length. A few stable stocks do not cancel a circumpolar ice forecast. High resilience in this atlas means secure (koi, many owls), not famous.

What did the 2008 US listing change?

It treated greenhouse gases as a listed-species threat. Courts later limited how far that could reach power plants; the biological finding stayed.

Is Churchill typical?

Western Hudson Bay is an early-ice-loss stock and a tourist town. It is a visible subpopulation, not the whole Arctic.

Who was Knut?

A hand-reared Berlin cub (2006-2011) whose fame and death made zoo ethics a tabloid. He is culture, not a sea-ice time series.

Do polar bears eat only seals?

Seals (especially ringed) are the fat that pays. Bird eggs, carrion and land food appear more in long ice-free summers -- a budget problem, not a new niche that replaces ice.

What is Nanook of the North to this file?

The 1922 film staged Inuit life for a southern camera. It is a portrayal, not an ethnography of nanuq knowledge.

IUCN: Vulnerable

Operating a polar bear life is a loop: sense, decide, act, and stay inside an energy and legal envelope.

Steps are type-level -- hunt, migrate or spawn -- not a promise that every individual follows the same film sequence.

Principles

Energy in, work out

Still-hunt at seal holes and break-in on birth lairs. Fat, not lean meat, pays the ice year. Onshore summers are a deficit for many stocks.

Information before motion

Smell through ice and a patience that looks like stillness. Vision is secondary to a hole in the ice.

Replacement rate

Slow breeders (whales, apes, albatrosses, tigers) cannot outrun a short political cycle. Fast clutch species still fail if the nest site vanishes.

Place is part of the phenotype

A polar bear without its lake, ice, anemone or gravel is a different, usually failing, animal.

Human systems are now habitat

Quotas, feeders, reserves and films rewrite survival as much as weather. Ice-season length. A stable stock in one basin does not retire a VU card written on a melt curve.

Diagrams

Polar bear forage / hunt loop

Type-level sequence from detection to the next generation -- not a single filmed hunt.

Polar bear life-cycle loop

Recruitment path that sets replacement rate and therefore resilience.

Life-cycle steps

01 Walk the ice

A bear is a commuter on a moving platform.

02 Wait on a hole

Still-hunt -- the energy-positive method.

03 Break a lair

Spring cubs of seals are a fat pulse.

04 Fast on shore

Ice-free weeks are a budget hole.

05 Den in snow

Pregnant females overwinter; the den is a climate-sensitive room.

06 Meet a town

Churchill and Arctic camps -- conflict as a calendar.

Hard limits

Physiological envelope

Ice-season length. A stable stock in one basin does not retire a VU card written on a melt curve.

Place dependence

Without the breeding site or forage pulse, brochure behaviour is theoretical.

Human and legal limits

Quotas, listings and trade rules now bound real populations as tightly as weather.

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