Wildlife impacts

DragonflyOn this page, you will learn about climate change impacts

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From penguins in New Zealand to polar bears in Manitoba, wildlife all over the world are struggling to keep up with our rapidly changing climate. Over time, animals are often capable of adapting to new conditions. However, the process of  recent climate change is too fast for many animals to adjust.

At the end of the Triassic, increased levels of atmospheric carbon dioxide and global warming are believed to have caused one of the largest mass-extinction events in Earth’s history (1).

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Scientists around the world have noticed a wide variety of animals changing their habits in response to climate change. Some have been successful in adapting to climatic change. Others have not been as fortunate.

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  • Pacific salmon – Usually restricted by cold water temperatures, Pacific salmon species such as sockeye, pink, and Coho salmon have been found far outside their normal ranges (1). A Coho salmon was found almost 2,000 km further into northern waters than usual (2). Temperature increases in the Arctic as a result of climate change have allowed these temperate-water salmon to expand their ranges.
  • Trout – Trout are a cold-water fish, thriving in spring- and glacier -fed water. Already struggling under the burden of pollution, erosion and diversion projects, trout are now – literally – in hot water. As climate change raises temperatures in North America, streams, rivers and lakes are becoming too warm for trout to survive (3). Brook, brown and rainbow trout will lose up to 76% of their habitat if greenhouse gases continue to build up and trap heat in the atmosphere (4).

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Insects and other invertebrates

  • Butterflies – In North America and Europe, over 35 species of butterflies have been expanding their ranges northward by up to 200 km (5). In the western U.S., Edith’s Checkerspot butterfly has not only shifted its range 92 km northward since the early 20th century, but has also gained 124 m in elevation (6).
  • Coral reefs – Coral reefs provide food and shelter in one of the most biodiverse ecosystems on earth. Coral reefs have undergone global mass-bleaching events whenever sea temperatures have exceeded summer averages by more than 1°C for several weeks (7). Since 1979, mass-bleaching events are become more frequent and destructive.

In 1998, the most severe event thus far occurred, killing off 16% of the world’s coral reefs (8). New evidence suggests that that the increased levels of carbon dioxide in the atmosphere is acidifying the oceans and weakening the corals’ calcium carbonate skeletons. This makes them more vulnerable to storm damage and other erosion (9).

Coral reefs cover less than 1% of the ocean floor, yet provide food and shelter for over one-third of all marine fish (10).

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  • SalmonGrizzlies – Nutritious whitebark pine seeds are a major food source for grizzly bears in western North America. The ability of a grizzly sow to successfully bare young is linked to pine seed abundance – more seeds mean healthier bear families (11). Unfortunately, whitebark pine is vulnerable to the impacts of climate change. Warm temperatures allows pine blister rust – a deadly, introduced fungus – to thrive and spread, killing up to 90% of whitebark pine in a given area (12). Less trees, less seeds, less bears.

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Reptiles and amphibians

FrogEcosystemIn Costa Rica and North America, disastrous losses in frog, toad and salamander populations are climate related (13). With less winter precipitation, breeding pools aren’t deep enough to protect eggs and tadpoles from damaging ultraviolet rays. Weakened by UV-B radiation, they become susceptible to fungal infection, dying at epidemic rates. With inadequate water, over 50% of western toads succumb to fungal infection (14).

In many reptiles, temperature determines the sex of offspring. Increased global temperatures could seriously skew sex ratios. A shortage of either sex could undermine a species’ ability to replace itself from generation to generation. In painted turtles, offspring sex ratio is correlated with mean July temperature (15). Even a modest temperature increase (2 – 4°C), could dramatically reduce the number of male turtles produced (16).

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  • Songbirds – Many songbirds are laying their eggs earlier in the United Kingdom. One-third of U.K. bird species are starting families 8.8 days sooner than usual (17). Birds of every feather are picking up the nesting pace: waterbirds, resident and migrant insect eaters, and seed-eaters are all responding to earlier spring-like temperatures and longer growing seasons.
  • Sandpipers – Arctic regions will experience the strongest global warming as carbon dioxide levels rise. Over half of the tundra is expected to be replaced by boreal forest. Approximately 14 million Calidrid sandpipers (95% of the world’s population) raise young on the tundra (18). Scientists expect 7.5 million sandpipers to be lost as climate change eliminates their habitat (19).
  • Penguins – In four years of unprecedented warm winters Adelie and Chinstrap penguin populations on King George Island have declined by 40 and 35% (20), respectively. Sea-ice cannot form on Antarctic seas warmed by climate change. The krill that typically feed on the algae are the primary food source of the penguins. As krill becomes scarce, penguins starve.

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Arctic species

Many arctic animals rely on the predictable ebb and flow of sea ice for food and shelter:

  • Arctic cod – Arctic cod are an important food source for seals and whales. Cod gather underneath sea ice, feeding on zooplankton. The abundant zooplankton subsist off algae that grows on the underside of the ice.
  • Ringed seals – See Ringed seals in Manitoba Wildlife below
  • Walruses – Walruses require a delicate balance of ice thin enough to break through with their heads, but thick enough to support their weight (21).
  • Narwhals – Narwhals are almost always found close to sea ice. They prefer to forage for arctic cod at ice edges and cracks (22).
  • See also Beluga whales in Manitoba Wildlife
  • Beluga whales – See Beluga whales in Manitoba Wildlife below
  • Bowhead whales – Bowhead whales feed on zooplankton, using sieve-like baleen in their mouths to filter massive mouthfuls of the tiny crustaceans (23). Without sea ice, the whales will have little to eat.

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Polar bears

Polar bear, www.iStockPhoto.com: File# 3820730In the last two decades, polar bears living in the western Hudson’s Bay area have undergone a change for the worse. Bears are returning from the sea ice underfed and underweight. In poor condition, mother bears are less likely to successfully raise offspring. The plight of Manitoba’s great white bears is inexorably linked to climate change.

The polar bear is the most carnivorous of the bears, feeding primarily on ringed seals and occasionally on bearded seals. Polar bears are at their leanest in March, just before the seal pupping season. Bears rely heavily on the predictable spring abundance of ringed seal pups to provide energy and nourishment for survival throughout the year – particularly for raising and nursing cubs (1).

At six weeks of age, the body weight of ringed seal pups is about 50% fat (2).

Seal pups are abundant from their birth in April to the breakup of the sea ice in early summer. The pups are easier for polar bears to catch because they are inexperienced. As a result, the bears are usually able to refill much of their dwindling energy stores every spring, stalking seals on the sea ice.

Polar bears need stable sea ice as a solid surface on which to hunt ringed seals. Anything that affects the distribution and annual duration of sea ice has a profound effect on the health and well-being of polar bear populations (3). Since 1981, ice breakup on Hudson Bay has occurred earlier and earlier, forcing bears to come ashore in progressively poorer condition (4). Their hunting season cut short, they do not have enough time to regain their energy stores.

Increased temperatures caused by human-made greenhouse gas emissions are responsible for melting the arctic ice out from under the bears’ feet.

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Ringed seals

Ringed seals are an important food source for Polar Bears. They also depend on stable, landfast sea ice and adequate snow cover to rear pups (5).

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Beluga whales

Beluga whales are found in Hudson’s Bay, and almost always close to sea ice. They prefer to forage at ice edges and cracks (6).

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In Canada, general warming is allowing red foxes to expand their range northward (7). Unfortunately for arctic foxes, redfoxes are better suited to living in a warmer environment. Arctic foxes are retreating further north as their habitat shrinks.

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Wolves, moose, and trees

Image of "howling wolf" by Terry Spivey, USDA Forest Service, Image # 1374864, www.forestryimages.orgWith increased winter snowfall in the North Atlantic region of North America, wolves are hunting in larger packs (8).

Triple the numbers of moose are killed per day, compared to less snowy years when wolves hunt in smaller packs (9).

With fewer moose feeding on their lower branches, fir trees quickly fill in the forest’s understory.



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