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Birds' lives changing rapidly in Finland, signalling ecosystem shift

Common birds are proliferating while rarer species' populations have plunged by more than 90 percent.

Telkkiä ja sinisorsia merisavussa.
Goldeneyes and mallards amid arctic steam fog. Image: Heikki Eriksson
Yle News

Beyond shifts in migratory patterns, birds in Finland are showing dramatic changes in their lifestyles and cycles as the climate warms. That is according to a book published on Thursday by a leading ornithologist from the University of Helsinki.

Aleksi Lehikoinen, curator at the Finnish Museum of Natural History and head of the Helsinki Lab of Ornithology, co-authored the book Linnut ja ilmasto ('Birds and Climate') with nature journalist Mari Pihlajaniemi.

While many have noticed that birds are migrating at different times during this record-warm season, the book shows that climate change is impacting birds in Finland in a myriad more subtle, complex ways as well. These include habitat choice, food supply, interaction with other species and genetic changes.

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lintututkija Aleksi Lehikoinen ja luontotoimittaja Mari Pihlajaniemi lintutornissa
Ornithologist Aleksi Lehikoinen and journalist Mari Pihlajaniemi Image: Markku Pitkänen / Yle

"There is no area of birds' lives that has not in some way shifted as a result of climate change or that will change in the future," says Pihlajaniemi.

Some species are moving to new areas and the timing of their life cycles are changing. Others are finding more food while others face a shrinking supply. Some are no longer reaching the same average size as in the past.

"Particularly in the past 20-30 years, the changes have been astonishingly fast," she says.

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Viisi haahkaa lentää lähellä vedenpintaa.
Eider ducks need sufficiently large clams to survive the winter. Image: Heikki Eriksson

If mussels disappear, eiders are in trouble

The effects of Finland's warmer winters and springs are complex. Even those species that should theoretically benefit from them are not necessarily able to do so due to a wide array of factors. Meanwhile those that depend on specific types of food and habitats to survive are most vulnerable. Common species are succeeding and spreading while specialists suffer.

"They can't necessarily keep up with climate change. They may have less food, like the eider ducks, or face more parasites or predators as the whole food chain changes," Lehikoinen tells Yle.

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The ruff population has plunged by more than 90% in a short time. Image: Heikki Eriksson

Eider ducks' main food, blue mussels, need salt water to survive. Climate change is bringing more rain to the Baltic Sea region, pushing more freshwater from rivers into the sea. As the water becomes less salty, mussels may disappear from the northern Baltic, leaving Finland's eider ducks in peril.

"Eiders can eat other food to some degree, but there is no way a sizeable eider population will survive completely without blue mussels," Pihlajaniemi says.

Brown tawny owls are beginning to outnumber grey ones as winters become less snowy in southern Finland. Image: Heikki Eriksson

Mallard ducks meanwhile, are among the winners. They are benefiting from warmer winters and longer periods of ice-free water. Like most common species, they eat a wide variety of foods. As the climate warms, they can move further north to find suitable living conditions.

On the other hand, the ruff, a type of sandpiper that lives in marshes and shoreline meadows, is a signal of global change. These birds spend their winters in the Sahel region, which is now exceptionally dry. The number of ruffs nesting in Finland has dropped by more than 90 percent within a short period.

"The pace of decline has been unbelievably fast. The life of the ruff is really no longer what it was," Pihlajaniemi says.

Some species, such as teals, are able to move to their nesting areas earlier to cope with the new, uncertain timetable.

Conservation areas help birds

The researchers say that such variations in birds' lives provide crucial evidence about the impact of climate change on the entire ecosystem and the biodiversity crisis.

Nearly 12 percent of all species in Finland are classified as threatened according to the International Union for Conservation of Nature (IUCN) criteria. Proportionally hardest-hit are birds and mosses.

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Kiiruna osin lumipeitteisessä tunturissa.
A ptarmigan grouse in the northwestern arm of Finnish Lapland. Image: Heikki Eriksson

On the positive side, research confirms that conservation areas clearly provide buffers against the impacts of climate change. The community of species within a protected area changes more slowly than that of adjacent unprotected land.

"In particular, conservation lands that include topographical variation such as hills, valleys and different kinds of habitats provide excellent protection for various species," Pihlajaniemi explains.

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