You can hear sandhill cranes long before you see them. The migrating flocks fly high–a thousand feet or more. In fact, cranes have been seen flying as high as 13,000 feet. Standing at the south edge of the prairie at Miami Woods, I was watching a red-tailed hawk soaring over the open ground when I heard the distant tone. The books all talk of trumpeting calls, but I think the sound is more like that of a French horn. A French horn with a mute stuffed in its bell. But that describes only the quality of the tone. For the volume, imagine that somebody bought the sound system formerly used by the Grateful Dead and is now amplifying the French horn with all that wattage. Cranes are loud.

The volume is believed to result from the length of the trachea. In cranes the trachea is looped through the keel of the breastbone. A whooping crane–the slightly larger cousin of the sandhill–has a trachea nearly five feet long.

The birds I saw at Miami Woods–62 in all–flew by in two long Vs at a height that made the soaring hawk look like it was standing in a hole.

The story of cranes in North America has been generally sad for the past century or so. Both of the native species suffered drastic declines in population. Whooping cranes used to live in the Chicago area, but they were gone very early in our history. Sandhill cranes lingered a bit longer, but they were still quite scarce. For almost a century even migrants were rarely seen. Birds of the Chicago Region by Edward R. Ford, published by the Chicago Academy of Sciences in 1956, records sightings of fewer than 20 birds as if these were notable events. In 1956 the traditional staging area of migrants at the Jasper-Pulaski fish and game area in Indiana harbored flocks as large as 600 birds in early spring.

The account of sandhill cranes published in 1926 in Arthur Cleveland Bent’s Life Histories of North American Birds has a distinctly elegiac tone. “The advances of civilization, the drainage of swamps and the cultivation of prairies have doubtless driven this wary, old prairie scout away from all the central portions of the United States; and they are still driving it farther west and north into the unsettled wilderness; the wilderness is fast disappearing and with it will go the cranes and many other interesting forms of wildlife.”

Describing the distribution of the bird, Bent outlines a historic breeding range extending from British Columbia to Ontario and from California to Ohio. However, he notes that the “outline indicates the former breeding range of this species, for at the present time its habitat is greatly restricted. It is now known to breed in only southern Canada, Minnesota, and the western and Rocky Mountain states south to northern Colorado.”

Sandhill cranes are birds of marshes and wet prairies. They are extremely wary and generally intolerant of humans near their nests. Their favored nesting locations are in the middle of shallow ponds on the prairie, where they can build nests on masses of vegetation piled up above water level.

They feed on the ground, often walking long distances in search of something to eat. Their choice of foods is quite broad, ranging from seeds and plant roots to mice, voles, small snakes, and crayfish. They can run as fast as a human and can leap ten feet into the air without any help from their wings.

The long decline of sandhill cranes was in large part the result of habitat loss, but hunting contributed too. An adult sandhill can weigh anywhere from 5 to 15 pounds, making it definitely worth hunting. Bent relays an extraordinary story first published in the scholarly journal the Auk in 1893. A hunter wounded an immature sandhill that was part of a flock feeding at a distance. At the sound of the gun all the birds flew away except the wounded immature and another bird that was apparently its parent. “The wounded bird, after a number of unsuccessful attempts to fly, finally succeeded in rising some 10 or 15 feet from the ground, but it evidently could not long sustain itself in the air. The parent bird, perceiving this, deliberately placed itself underneath the wounded one, allowing it to rest its feet on her back, both birds flapping away all the while. In this position she actually succeeded in bearing it off before our eyes for quite a distance to a place of safety.”

Sandhill cranes apparently mate for life, and they strengthen their bonds with elaborate leaping dances accompanied by very loud calls. At the International Crane Foundation near Baraboo, Wisconsin, keepers have learned to imitate these dances well enough to make female cranes in captive flocks receptive to artificial insemination.

Sandhills have two distinct breeding populations. A southern sedentary group nests in Florida, Mississippi, and Cuba. Northern migratory populations nest from Siberia to Alaska to the upper midwest. It may be that in the remote past, intermediate populations occupied the ground between these separate groups.

In recent years sandhill cranes have reversed their long decline and begun to expand their nesting range into Wisconsin and upper Michigan. The cranes I saw flying over Miami Woods two weeks ago probably nested in Wisconsin, where they are now considered to have occupied all the suitable habitat. They were headed to Florida for the winter. They still stop to rest and feed at the Jasper-Pulaski game area, but their numbers have grown to the point that visitors to the preserve can see as many as 10,000 birds in a morning.

As their numbers have increased, they have returned to Illinois. The last 19th-century record for the species was in Champaign County in 1872, but in 1979 a few pairs began to nest in Chain-O-Lakes State Park, which is on the border between Lake and McHenry counties. Their status in the state changed from extirpated to endangered–one of the few instances where being added to the endangered species list recorded an improvement in an animal’s situation. This year they nested in Du Page and Cook counties. The more sites they occupy, the more secure the population becomes.

Twenty years ago the honking cries of migrating Canada geese presaged both the coming of spring and the coming of winter. The birds passed through here on their way to and from nesting grounds near Hudson Bay. We saw and heard them in March and April and again in October and November. People from Chicago drove up to the Horicon marsh in Wisconsin to see the large flocks of geese that gathered there.

Now we have resident flocks of Canada geese doing their bit for the environment by messing up golf courses. The call of the wild goose has lost its seasonal significance. Instead of telling us that spring is coming, it just tells us that we have left our windows open.

But the bugling calls of the sandhill crane still retain their significance. In March and April they tell us that spring is coming. Now they warn us of short days and cold nights.

Twenty years ago you had to be really lucky to spy a flock of sandhills passing over the Chicago area. Now you just need to pay attention. Their calls are especially likely to be heard near our rivers–they seem to use these north-south streams as navigation aids–but you can sometimes hear them in the middle of the city as well. If you hear the call, look up. You will be looking at a little success story. In the midst of a flood of environmental bad news, the story of the sandhill cranes is at least mildly heartening.