BRIAN ALLEN: Weather can cause migration ‘traffic jams’

By BRIAN ALLEN
Guest Columnist

It’s been a long winter in Manistee and perhaps a bit cruel as we’ve enjoyed several warm spells that seemed to make spring feel close just to have another blizzard and dropping temperatures arrive.

We get stuck in long periods of colder than average weather often in spring. Climate scientists say these are caused by Rossby Waves, large undulations in the jet stream that lock in and hold the cold over a region. Rossby Waves have been stronger in recent years possibly due to the warming of the Arctic regions.

What happens to birds when these long unseasonable cold snaps occur?

Barn Swallow

Barn Swallow

One question I have heard often this month is why are there so many robins around? They’ve been in large flocks in the snow free fields or on south facing hillsides recently. Another bird in large flocks (sometimes at feeders) is the Red-winged Blackbird.

Both of these birds are early spring migrants, coming north into Michigan in late February or early March with the first major thaws. They head north and hold up when they get to the boundary of the cold weather, which was finally north of Manistee in late March but slipped back to Ohio and Indiana in mid-April.

The robins and blackbirds have committed themselves to migrating and all of them that are normally found here in the summer in addition to most that are still on their way to the UP or Canada are held up in a migration “traffic jam” in our part of the state. The next pronounced warm spell with southerly winds will help the UP and Canadian birds on their way and we won’t see the large flocks again until fall.

This weather caused traffic jam will probably happen again in late April or May and will hold up other species. If it happens in April we may have hundreds of kinglets around like last year when this woodland bird was easily seen even in downtown Manistee.

One of the worst of these happened a few years ago when I lived in Bear Lake. In mid-May a cold front hit after all the swallows had returned. There was a dusting of snow with a frigid north wind and daytime temperatures stayed in the 30s. Hundreds of Barn, Cliff, Tree and Rough-winged Swallows along with Chimney Swifts tried to feed on insects above the relatively warm waters of the lake and then rested on the warm blacktop of South Shore Road.

Our family was horrified to see dozens die when motorists sped down the road oblivious to the carnage they were causing as the swallows tried to lift away in front of them. My boys and I made makeshift road signs to help alert the drivers to slow down and give the swallows a chance and it seemed to help. I still cringe when I think of all the times and other places this has happened without someone out there trying

A flock of Tree Swallows on the road. (Courtesy photos)

A flock of Tree Swallows on the road. (Courtesy photos)

to help.

Sometimes these cold fronts are good for the birds and the birders or bird watchers. If you have seen the film “The Big Year” with Steve Martin, Jack Black and Owen Wilson, you saw the front and “dropout” when thousands of birds decended on the Texas coast to the delight of the birders. Hundreds of species are present making it a visual feast for birders and the dropout also can keep the birds south away from the hard cold up north. Dropouts like this have happened in Manistee, and I’ll never forget the day I saw 15 species of warblers in one birch tree at the Lake Bluff Audubon Center.

Please remember when these cold fronts hit that we are not the only ones that have to put up with the dissapppointment of a delayed spring. Think of the birds and their life and death struggles to make it home. Do what you can to save their habitat, contribute to conservation organizations that work for them and keep an eye out and or drive slow when you see them along the roads!

Brian Allen has been watching birds and doing bird research for over 40 years. Readers can contact him at manisteebirder@gmail.com for more information or to send questions that could be answered in a column.

 

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