We’ve Been Invaded

Bohemian waxwings in a spring mountain ash tree

The yard this morning is filled with hundreds of Bohemian waxwings. They’re in all the trees, all the bushes and on the fences. It’s noisy out there! They have temporarily displaced a yard full of American robins who are not quiet this time of year either.

It’s been a great winter for the waxwings in Canada, as huge flocks have been reported in many provinces in the last few weeks. We’ve always had them in the yard, but never in such large numbers. There isn’t a berry left on any mountain ash tree for miles.

I was reading an interesting article this morning about the bird population in North America  shifting north. It seems they had more than 22,000 Bohemian waxwings in Anchorage, Alaska for their Christmas bird count, more than any other bird species.

Long-term global warming is prompting North American birds to winter farther north, according to the Audubon Society:

• the American robin in now wintering 200 miles further north than it used to
• birds that winter in Alaska that shifted their range the greatest distance north included the marbled murrelet, 361 miles; spruce grouse, 316 miles; red-breasted nuthatch, 244 miles; varied thrush, 229 miles
• Texas now has fewer robins each winter, while New Hampshire has five times more

As the northern climate warms, the vegetation responds accordingly. While on the surface this influx of southern birds might make northern birders happy, there is a limit.

Northern species dependent on shore ice or northern tundra — both of which have been shrinking in recent years — aren’t as fortunate. Birds that nest on the tundra have nowhere further north to go. Birds like dunlins, sandpipers and murrelets could be in real trouble. The population of Kittlitz murrelets in Prince William Sound has declined by 84 percent over 11 years.

Things are changing drastically in bird world. No one knows how fast birds can adapt to the changing conditions, but we can at least be happy the Bohemian waxwing is a long way from being listed as an endangered species.

Filed under: Global Warming, Songbirds, bohemian waxwings, northerrn birds

Shifting Birds

A study carried out by the Audubon Society has discovered that climate change is pushing North American birds northward, with some finches and chickadees moving hundreds of miles into Canada.

As the temperatures across the US have gotten warmer, the birds are spending their winters farther north than they used to. The study found more than half of 305 bird species in North America are wintering about 35 miles further north than they did 40 years ago.

Some species, such as the purple finch and boreal chickadee, spend their summers in the forests of Canada and fly south into the US for the winter. Climate change could be playing a role in why they are not flying as far south as they used to, and are no longer as common as they were in states like Maine, Vermont and Wisconsin.

Pine Siskin

The purple finch, pine siskin and boreal chickadee moved deep into the Canadian boreal forest, shifting their ranges 313, 246 and 211 miles, respectively. Previous studies of breeding birds in Great Britain and the eastern US have detected similar trends, but the Audubon study covers a broader area and many more species.

“There’s a thousand things that cause birds to change their range, and so if you do a study of a whole bunch of birds, you’ll see some moving north, some moving south, some moving west,” report co-author Greg Butcher said. “What was real surprising about this study is to see the birds moving so uniformly in one direction.”

Scientists were able to relate this movement with temperature changes from 1966 through 2005.

All kinds of birds moved north, but more of the highly adaptable forest and feeder birds — upward of 70% — made the move, compared with only 38% of grassland species.

Only 10 of 26 grassland species made significant moves north. Birds including the eastern meadowlark, vesper sparrow and burrowing owl may have been unable to move despite more moderate northern temperatures because grassland habitats have been converted to human uses such as row crops, pasture and hayfields.

Unlike most global warming stories in the media, this is not something predicted to happen in the future. It’s been happening for over 40 years. And provides yet another reason why it is vital to save our boreal forests, natural grasslands and wetlands.

Filed under: Global Warming, climate change, finches, pine siskins