A Northwoods Almanac for July 30 – August 12, 2010
Lake Superior “Running a Fever”
A recent headline in the New York Times read, “Lake Superior, A Huge Natural Climate Change Gauge, Is Running a Fever.”
I suspect most folks who know Lake Superior would say, “Impossible!” Anyone who has ever swam in the biggest freshwater lake in the world knows exactly what is meant by the phrase “a bone-chilling experience.” Like swimming in a glass of ice water, there is no more “refreshing” an experience to be found in the Midwest. Most folks come out blue after a quick dip.
But not this year. Mid-July usually marks the time when Lake Superior reaches the toasty high of 39°F and goes through its summer turnover, a process where the water layers mix throughout the lake. But by July 9th this year, the lake had already soared to 59°F, 20 degrees warmer than it normally is on that date.
And it’s getting warmer. By July 20th the lake had hit 66°F, and please note, this was measured from a buoy in the center of the lake. Barring a lengthy cold front, the all-time record high of 68°F reached in 1998 may be broken before the end of July, and record highs will very likely be reached by mid-August, the typical peak for water temperatures.
Why is it so warm this year? Two reasons. One – a lack of ice-cover this last winter and the very warm spring that followed. Two – Lake Superior’s summer water temperatures have been warming twice as fast as air temperatures over the past 30 years. This 30-year trend is one of the most pronounced temperature increases on the planet and reflects the positive feedback loop that is occurring – the warmer the air and water, the less ice forms in the winter and the sooner it melts in the spring. Less ice means warmer water in the summer, which leads to less ice forming in the winter, and on it goes. Total ice cover on the lake has shrunk by about 20 percent over the past 37 years.
Less ice and warmer waters also lead to greater evaporation. Currently, Lake Superior is down a foot, and while lake levels have cycled up and down forever, this is a new twist in the tale, one that scientists believe will keep lake levels low.
The warm temperatures aren’t just being seen in Lake Superior – they’re being recorded in all of the Great Lakes. All the lakes are either at or approaching temperatures seen only in late August.
As for what the warmer and shallower waters may mean to the community of life in Lake Superior, scientists are most concerned about the many species of Lake Superior fish that are sensitive to warmer waters. A lake fisherman near Sault Ste. Marie, Michigan, reports that whitefish are much harder to find because the warmer water has chased them out deeper into the water column. Lake trout will also have to move deeper or further offshore to find the cold waters they require. Fall spawning fish like coaster brook trout, herring and whitefish may see their timing delayed by weeks or even months, the effects of which are unknown. And the invasive blood-sucking sea lamprey thrives in warmer water, growing bigger and laying more eggs.
The lake buoys show a distinct 30-year trend toward dramatically warmer temperatures, all a sign of climate change according to Bob Krumenaker, the Superintendent of the Apostle Islands National Lakeshore. Average water temperatures have increased 4.5°F since 1980, an enormous increase for a body of water as large as Lake Superior. Krumenaker notes that on the Madeline Island Ice Road (the “road” that one can drive to cross the ice from Bayfield to Madeline Island), which has been monitored since 1856, the ice duration has decreased at a rate of 14.7 days per decade since 1975. It had been decreasing at a rate of 3.4 days per decade prior to 35 years ago.
Krumenaker also notes that evaporation is modeled to increase by nearly 40% by 2090, and ice cover will be somewhere between 2 and 11 percent of the historical average.
I heard a talk on climate change given last week by Mike Dombeck, former chief of the U.S. Forest Service. Dombeck began with this quote: “The misery of uncertainty is worse than the certainty of misery.” What is certain, as long as you take the time to look at the actual scientific research and data, is that climate change is occurring now, and every model shows it increasing at alarming rates, even those models that take the most optimistic viewpoint on our willingness to change our production of greenhouse gases (see www.wicci.wisc.edu for data within Wisconsin).
In the meantime, it’ll be great swimming in Lake Superior for the foreseeable future. No more blue lips and uncontrollable shivering. And that’s a great loss.
Learning to Sing
Over the last few weeks, Mary and I have been listening to the cries of baby catbirds, purple finches, and cedar waxwings begging to be fed. Although fledged, they still need their parents to feed them for a few weeks before they assume the mantel of adulthood and begin foraging on their own. They are also now learning the songs that define their species, which led Mary to question how the babies learn the songs when the singing males are now at the end of the nesting season and are so reticent to sing.
First, not all birds need to learn their songs from their parents. Of the roughly 10,000 species of birds in the world, they are almost equally divided between those that must learn their songs and those that know their songs innately. Loons, ducks, geese, gulls, shorebirds, gulls, doves, owls, woodpeckers, herons, in fact nearly all bird groups, except songbirds, leave nothing to chance and simply know their songs at birth. However, except for the flycatchers – phoebes for instance – which also know their songs innately, nearly all songbirds must learn to sing. Each songbird species has a particular strategy that requires them to learn at the right place, at the right time, and from the right adults. Why some species must learn their songs and others don’t is a heavily studied mystery, and one of interest to humans since we, too, must learn from adults in order to speak our language.
So, for example, let’s look at how a chipping sparrow chick learns its song. If he hatches in May, he’ll have plenty of time to learn his song from males who are still singing into early July. If, however, he hatches in a second nesting in late July after the adults have stopped singing for the year, he will have to wait to develop his song until he migrates back the next spring and can hear males in full song.
Another example - a chestnut-sided warbler chick can learn his female-attraction songs at any time and any place from any adult, but the songs he uses in male-to-male interaction must be learned the next spring when he arrives on the territory that he wants to claim for the rest of his life.
Songs are learned most easily early in life – the male white-crowned sparrow, for instance, learns his song best between day 10 and day 50 of his life. Note, however, that the chick isn’t ready immediately after hatching to learn his song. Researchers took white-crowned male chicks from their nests in the wild at eight or nine days and kept them in a lab. The result – the birds developed highly abnormal songs.
Then there are a few birds, like mockingbirds, that never stop learning new songs, acquiring new phrasing and nuances throughout their lives.
The songbirds that must learn their songs are born with a template of their species’ songs. However, the young must practice their songs just like human children must practice to learn our language. A study done with Bewick wrens, which sing 16 different songs, found the young chick repeatedly singing each individual song, and slowly building up his ability to master the song, then moving on to the next song. Each attempt at the song was different, and eventually the young wrens learned to be competent singers, but not without lengthy attempts filled with mistakes.
As for the flycatchers, researchers proved the young chicks didn’t need to hear their parents sing in order to learn their songs by taking four baby phoebes and removing the cochlea from the inner ear of each bird. Even without the ability to hear, a few months later the young phoebes produced perfectly normal phoebe songs in perfect tempo.
Sightings
Jan Evan sent the following e-mail: “Last week two of our guests saw an eagle snatch a fish out of Edith Lake. Then he used his wings like oars to get the fish to land. Two other eagles spotted the feast and joined him. Then two more came down, and our friends witnessed five eagles gouging themselves on that one fish. (It must have been a large bass.) When they finished, the only thing left was a three- inch fin.”
Debra Heidenreich lives on Squirrel Lake and sent me a photo of an adult and a juvenile red-headed woodpecker (see the photo). A pair has raised young in their yard every summer over the past 5 years. She notes: “The babies seem to be out of the nest and feeding in early to mid July. We feed suet cakes, as well as black sunflower seed. They feed the babies suet while they are waiting perched on the side of the trees. The babies are black and white, but missing the red head.”
On a similar note, Gary Ruesch has lived on the Rainbow Flowage for 15 years, and this is the first year he’s had a pair of red-headed woodpeckers bring their young to his feeders. He also has a pair of pileated woodpeckers and a pair of hairy woodpeckers bringing their young to his feeders, so he’s hit the trifecta.
Celestial Events
If you want to see planets in the night sky in August, dusk is the best time, and the action is in the west. Mercury is very low in the west for the first half of the month. Venus is also very low in the west and sets after 9 p.m. Mars is low in the southwest, setting at around 10 p.m. Jupiter rises in the east after 9 p.m. And Saturn can be seen very low in the west, setting soon after nightfall.
August 6th puts us halfway between summer solstice and autumn equinox.
On 8/9, look for Venus about three degrees southwest of Saturn.
The Perseid meteor shower begins on August 8th and peaks on the night of August 12th. With no moon to interfere, it could be a great night to see meteors!
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