November 08, 2019
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How climate change may be affecting Maine birds

Bob Duchesne | BDN
Bob Duchesne | BDN
A boreal chickadee

This Halloween, I’ve decided to dress up as something truly scary: climate change. Now I realize that there is a small subset of people who believe that climate change is a hoax, and that 97 percent of the world’s scientists are in on it. Apparently, wildlife is in on the hoax, too.

There are the big, obvious signs, like the fact that winter ticks are able to survive warmer Maine winters and decimate the moose herd. There are also the less obvious signs that only a birder might notice. I refer to mola molas.

The mola mola is also called an ocean sunfish. It’s the largest bonefish in the world, achieving the equivalent size and weight of a Volkswagen. It’s a warm-water fish. It primarily eats jellyfish, another warm-water fish. This past summer, the Gulf of Maine was full of them. Only five years ago, whenever I went out with Bar Harbor Whale Watch, looking for ocean birds, the boats would stop to look at a mola mola and explain how rare it was in Maine’s cold gulf. This year, the captain could barely avoid hitting one. I saw 50 on my last trip out to sea.

This is truly worrisome. Cold-water lobsters cannot coexist for long with warm-water fish. The Gulf of Maine is heating up faster than 99 percent of the world’s oceans. That’s an undisputed fact, given that the thermometer is a proven technology that has been around since Daniel Gabriel Fahrenheit perfected it in 1714.

This is also the first year in history that I have failed to spot a boreal chickadee along the Maine coast. A couple of decades ago, I could find these brown-capped chickadees as far south as Vinalhaven. Until 10 years ago, I could find them in Stonington. Five years ago, I could still locate a few around Jonesport and Roque Bluffs. Last year, Lubec was the closest I could find one. This year, I did not find a single one.

Habitats change with a changing climate, but not that fast. Maine’s maritime forest is still full of the spruce and fir that boreal chickadees like. There must be another explanation for the disappearance. Sometimes, competition from another species forces a bird out. But boreal chickadees don’t have much competition. They may squabble a little bit with black-capped chickadees, but both coexist just fine in Maine’s north woods.

So it’s likely that something has diminished the boreal chickadee’s coastal food supply. Boreal chickadees are masters at surviving harsh winters. They stash away a lot of food in autumn, and they are particularly adept at finding insects, spiders, larvae and eggs concealed in bark and cones. Some of these insects survive the winter by producing a natural antifreeze that prevents cell damage. A spruce budworm can survive at 20 below zero.

This insect antifreeze strategy works in a cold climate, but does it work in a warmer one? Can these critters survive the freeze/thaw cycles of Maine’s winters today? Who knows? A tiny change can make a big difference, and it’s happening so fast that there’s been no time to study it.

Of course, the fossil fuel industry will argue that bird ranges change all the time, and that redistribution of birds on the map is a natural occurrence. Maybe so, but if such redistribution is not related to climate change, then we should see southern birds moving north and northern birds moving south.

Let’s test that assertion. Here’s a partial list of southern birds that have moved north into Maine: tufted titmouse, red-bellied woodpecker, northern cardinal, turkey vulture, Carolina wren and white-faced ibis. Here’s a list of northern birds that have moved south: none.

Several more southern species are currently nesting at the New Hampshire border, and possibly north of it, including eastern screech owl, king rail and Mississippi kite. Others are headed this way, including black vulture, white-winged dove and Eurasian collared-dove. Even within Maine, some of our breeding birds are expanding northward. Pine warblers used to be rare in Aroostook County. Not anymore. Prairie warblers have lived in southern Maine for years, but they’ve now expanded closer to Bangor.

Those of us who watch birds, even if just out the back window, notice these changes. When cardinals and titmice moved into Maine, they were mostly confined to cities. But now even rural bird-watchers are seeing them at the feeder. They’re getting pretty comfortable in a state that was once too cold for them. I think the birds are trying to tell us something.

Bob Duchesne serves as vice president of Maine Audubon’s Penobscot Valley Chapter. He developed the Maine Birding Trail, with information at mainebirdingtrail.com. He can be reached at duchesne@midmaine.com.

Watch: How to identify the songs of 5 common Maine birds

 



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