It’s been another roller coaster spring thus far and we can measure it in a number of ways, not just temperature charts. Recent headlines this week include a migratory bird traffic jam in Duluth since it appears spring is far from near in northeast Minnesota.
Take a look at the snow cover on April 27th still:
The Mississippi River and the North Shore of Lake Superior are both major flyways, or basically freeways for migratory bird species between tropical climates and Minnesota and Canada and even to the arctic.
Instead of soaring down a nice freeway with the cruise control on however, this spring has been more like Hennepin Avenue: one stop light after another. It’s warm and sunny, birds fly in droves and then you hit a pothole and a red stoplight forever (i.e. abnormally cold or wet weather).
While it’s not necessarily the temperature the birds precisely care about (many of our little wintering birds in the tropics can handle our cold temps at least briefly), food and water do matter and in early spring those things are directly correlated.
Take a look at this chart of bird traffic this spring so far from the Cornell Lab’s BirdCast:
You’ll notice some crazy spikes and dips. To be sure, migration is never a smooth line: birds migration based on weather conditions among other things but it’s not usually this crazy. The gray area is the average number of birds migrating daily.
You may have already guessed the spike in migration was our heat wave the second week of April with a major dip with the return of cold, soggy weather. I grabbed this bird data and overlapped it with average daily temperature and you definitely see some correlation:
So while the heat wave caused birds to really pack up and move, the cold stalled them and the fact that the cold and wet weather has been prolonged now, late in the season has led to a bird back up in Duluth. Why Duluth? Probably because it’s the only urban area along the edge of what remains of winter and urban areas yield open areas for food, bird feeders, open water, etc.
We’re behind overall for bird migration too as a result of spring’s overall slow and cold performance:
Depending on the exact figures, we’re about 10% to 28% behind for total number of birds that have migrated through Minnesota to date.
And while ONE season does not a trend make, many of them do. I’ve discussed how spring has become more volatile in recent years and how April is one of the few months trending cooler in the recent decade or so. A lot of research is pointing to ‘Arctic amplification’ and more wobbly, extreme jet stream patterns that result.
Look at last year: we had a very cold April followed by about a two week transitional ‘spring’ and then an incredibly hot June. 2018 was an example of April temperatures that were average for March and a May that was average for June- a literal jump from winter to summer in just days.
The consequences on our weather are that increasingly, springs seem to have fits and starts, even more than normal. The impact on migratory wildlife can be detrimental or catastrophic. If we have a heat wave, such as the one we had earlier this month that lasted a bit longer or even earlier, nature tries to catch up but then reality often smacks you back, hard.
Sharon Stiteler, also known as ‘Bird Chick’ a birder and writer on social media may be familiar to you from her regular PBS and MPR appearances in the Twin Cities. She noted that not only is the increase in weather variability affecting Minnesota but “I saw it firsthand when I was in Texas for the late deep freeze of 2021. Many birds over winter there. Many bluebirds died that winter.”
She noted, one consequence of heat that increasingly comes too early due to these volatile patterns, is also “trees budding out (too early). That attracts certain types of insects that are crucial for warblers when they arrive. IF those insects hatch too early, they wont be there when we get the big warbler push in early May.”
If their food develops too early, there won’t be enough of it when they arrive or, just as bad, if we head back into a deep freeze, because, well it’s April, and kills everything that blew up too early that’s just as bad too.
Another recent example was last week when loons were falling out of the sky due to icing. To be sure this has happened in the past, but one can’t help but draw the parallel to a sudden northward surge of ice outs due to our unprecedented early April heat wave and then literally the PAUSE button was hit.
Take a look at the Minnesota DNR ice out map:
There’s only been one new lake ice out reported in the past week. That’s very unusual for this late in the season. Here’s a view from space/satellite imagery below:
Note the open water lakes (they’re dark, like Lake Minnetonka) versus the ice covered, white lakes north.
Compare this year to the median ice out date map:
We’re about 100 miles behind where ice outs should be. This time of the season the ice out line’s northern extent should be moving about 8 miles per day but for a week it’s been a stalemate.
Spring in Minnesota is never a smooth and pretty process, but several years in the recent decade may be an indication of an unintended climate change trend with consequences on wildlife, not just our moods. It’s too early to call these part of a definitive trend yet, such as winters in Minnesota undeniably warming at a rapid pace, but something to watch carefully.
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