The sap is flowing in the sugar maples. The crows have returned to the nest at the top of the tall ash across the alley. Listen closely and you can hear the bugling cries of sandhill cranes and, in the woods, the whispered note of the brown creeper. Raucous flocks of red-winged blackbirds and grackles add life to quiet winter landscapes, and mergansers dive for fish in the lakes. It's spring (which in Chicago means at least one major snowstorm).
For much of the past few weeks, temperatures have been below freezing at night and above freezing in the daytime. These are ideal conditions for stimulating the flow of tree sap. Sap is mostly water, but it includes small amounts of minerals and sugars as well. Sugar-maple sap is as much as 2 to 3 percent sugar, which is what makes the tree attractive to sugar tappers.
Native Americans were the first maple tappers, and we stole from them the secret--and for that matter, the trees. Their taps were hollow sticks inserted through small holes in the bark into the xylem, the vascular tissue that carries stuff from the roots up to the twigs and buds. We use steel and plastic for taps these days, but the principle is the same, and so is the joyfulness of the occasion. Indian families used to gather in a sugar grove to work together and party in celebration of this preview of warmth and sunshine. These days, nature centers near the scattered groves of sugar maples in the Chicago area hold special festivities--and pancake brunches--to mark the flowing of the sap.
At peak flow, a single tap in a large tree can deliver as much as eight quarts a day. Since the sap is flowing through the entire circumference of the tree and the tap is draining only one small spot, healthy trees can be tapped year after year without injury.
The sap from early in the period of flow is the choicest stuff. Late sap develops a woody taste and is definitely not something you would want to pour over pancakes.
The collected sap is boiled until enough water has been cooked off to turn what remains into a sweet syrup. Native Americans usually boiled off all the water, leaving behind maple sugar, which they used much as we use salt--as a universal condiment.
We have no sugar maples near our house, but the red flower buds on the silver maple that grows in the parkway are starting to open. Soon they will produce thousands of seeds that will find their way, with unerring accuracy, into our gutters. One of the many advantages of oak trees is that their acorns fall directly to the ground, where they can be gathered with almost no risk of fatal injury.
Our neighbors the crows are beginning what is at least their third year in the ash tree across the alley. The nest was in the tree when we arrived in December 1996, which means they must have used it in the spring of 1996. They may have used it in prior years as well. Last year they fledged two young. If this year's nest users are indeed the same birds as last year, the young of last year are still with the family. Crows are traditionalists; the kids live at home until they get married.
The adults copulated two days ago. They will not begin incubating eggs until the whole clutch, which may include as many as six or seven eggs, has been laid. Both sexes sit on the eggs, with the female taking most of the time. The male brings food to the female at the nest. The whole process, from the beginning of incubation to the young leaving the nest, takes a little less than two months. By Memorial Day the clumsy young will be stumbling around the neighborhood begging from their parents.
I have written before about the resurgence in numbers of sandhill cranes. Nesting populations in Wisconsin and Michigan's Upper Peninsula seem to have occupied all the suitable nesting habitat there, so the birds are spreading south into northern Illinois. They currently nest in McHenry, Lake, Cook, and Du Page counties. Now that the Canada goose has become an abundant year-round resident, the bugling cries of passing flocks of sandhills have replaced the honking of geese as major harbingers of warm weather and flowers.
Last Saturday I visited McGinnis Slough in Orland Park to check out the waterfowl. I was there for about 40 minutes, and at least 200 sandhills passed over in that time. They flew in shallow Vs of 20 to 30 birds each. With their long necks stretched out before them and their long legs extended behind, they are unmistakable.
Sandhill cranes often pass over the city. You are more likely to hear them along the river than along the lakefront, but if you live on a quiet street and have a window open, you can hear their cries a mile away.
A pair of mute swans were swimming in the inlet at the east end of McGinnis Slough. The presence of these Eurasian imports is an ambiguous blessing. They certainly are beautiful birds. They are also large and aggressive, and their increasing numbers in this area may not bode well for other marsh birds. When swans take over a marsh they expect everybody else to get out of their way. However, if the birds they drive out are Canada geese, it would be hard to get too upset.
McGinnis Slough is famous as a place to see waterfowl early in spring. On Saturday I saw ring-necked ducks and two species of mergansers, but no huge flocks of anything. Ducks are a varied group. Some eat plants almost exclusively; some specialize in crustaceans and mollusks; some are almost exclusively fish eaters. The dabblers--such as mallards--feed by tipping as they swim. Heads extended downward, tails pointed up, they grab what they can reach. Plants make up most of their diets. Diving ducks--like the ring-necked--can swim underwater, and some species actually reach depths of 150 feet or more. Mergansers are fish eaters whose long, slender bills have serrated edges that help them hold slippery prey.
The two species of large merganser, the common and the red-breasted, usually gather in large numbers along the lakefront in early spring. I assume that they are attracted by the smelt runs. Smelt numbers have been down during the past few years, so merganser numbers may follow suit.
I have always thought of the arrival of red-winged blackbirds as the real beginning of spring. Noisy, conspicuous, and aggressive, they have the uncontrollable vigor of nature in full cry. They will be arriving in waves during the next few weeks. They ride southerly winds from their wintering grounds in the mid-south. Sudden cold snaps, which are the result of major masses of cold air blowing in from the north, interrupt the migration.
The first redwings to arrive are always males, but the earliest birds seem to avoid display. Their fiery red epaulets stay hidden under the glossy black of their body plumage. But as more males and the first females arrive, the rituals of springtime begin. The males display to each other and to the females. The species is polygynous, and males try to get as many females as possible to build nests in their territories. The male acts as if all the females in his territory are his mates, but DNA tests have revealed that the females are messing around at a furious rate. The male in charge of the territory may not be the actual father of any of the offspring on his turf. Hey, it's spring.
Chicago springs are famous for cold weather, high winds, and all-day rainstorms chilly enough to induce hypothermia. The veteran resident learns to ignore the weather and concentrate on maple syrup, nesting crows, cranes, mergansers, and redwings. They are what spring is really all about.