About Sandhill Cranes
The Sandhill crane, or Grus canadensis, is Michigan’s largest bird and its oldest living bird species.
Sandhills are a tall, long legged, long necked gray bird with a bright red crown. From wingtip to wingtip their outstretched wings can measure up to 7 feet. Their stately appearance can give a false impression of size; the males weigh an average of about 10-12 pounds and the females around 9 pounds. Except for this size difference and slightly thicker tail feathers of the male, both sexes look alike.
The large wingspan make cranes very skilled soaring birds, often using thermals to obtain lift and stay aloft for many hours, requiring only occasional flapping of their wings and consequently expending little energy.
The fossil record shows sandhill cranes have one of the longest fossil histories of any extant bird. The oldest unequivocal sandhill crane fossil is 2.5 million years old, older by half than the earliest remains of most living species of birds. A 10-million-year-old crane fossil may be from a prehistoric relative or the direct ancestor of sandhill cranes.
Sandhill cranes have been protected in the Great Lakes State since 1916 under the Migratory Bird Treaty Act (i.e., closure of hunting in 1918), which makes it unlawful to "take" (pursue, hunt, shoot, poison, wound, or kill) the sandhill crane within the state of Michigan.
Sandhill cranes are one of the slowest reproducing birds in North America. This slow rate of what biologists call “recruitment” has resulted in a very long and slow recovery from near extirpation in Michigan. Although some sandhill cranes are physically capable of breeding as early as two years of age, most sandhill cranes may reach the age of four to seven years of age before breeding. The non-hunted Eastern Population of sandhill cranes has an average recruitment of 12 percent and scientific studies suggest that recruitment rates of 5 to 10 percent are necessary for population maintenance at current levels.
Michigan is at the northern most breeding range and our recruitment rate falls within the necessary percentage to simply maintain the current population status. Populations studies - while notoriously inconsistent - also indicate the EP of sandhill cranes is stabilizing and leveling out, due to wetland habitats reaching self-regulating natural carrying capacities within prime breeding habitats.
Monogamous, cranes mate for life - which can mean two decades or more - and stay with their mates year-round. Cranes are seen together as bonded pairs. The oldest sandhill crane on record was at least 36 years, 7 months old.
Among northern races of sandhill cranes, the diet is most varied, especially among breeding birds. They feed on berries, tubers (plants), small vertebrates (fish, mammals, etc), and invertebrates (snails, insects, etc). Waste corn is useful to cranes preparing for migration in the fall and for cranes raising young in the spring.
Lots of factors determine nest success or failure for sandhill cranes. Predation is a common reason for nest failure. The parents will attempt to defend the nest, but eggs and nestlings can be lost to raccoons, coyotes, bobcats, foxes, ravens, crows, hawks, eagles and owls. Low water levels and flooding also account for nest failures. During drought years, the risk of predation increases. Sandhill cranes will sometimes abandon nests if their mates die or because of human disturbance.
Sandhill cranes raise one brood per year. In Michigan, nesting usually begins in April or May. Both members of a breeding pair build the nest using plant material from the surrounding area. Nest sites are usually in or within 300 yards of marshes or bogs, though occasionally (rarely) on dry land. Females lay one to three (usually two) oval brown eggs with reddish markings. Both parents incubate the eggs for about 30 days.
The chicks are called colts and are precocial; they hatch covered in down, with their eyes open, and able to leave the nest within a day. The parents brood the chicks in the nest for up to three weeks after hatching, feeding them intensively for the first few weeks, then gradually weaning until they reach independence at 9 to 10 months old. Only one colt typically survives to fledge per breeding pair per year.
The chick remains with its parents until one to two months before the parents lay the next clutch of eggs the following year, remaining with them 10–12 months. After leaving their parents, the colts form nomadic flocks with other juveniles and nonbreeding adults. They remain in these flocks until they form breeding pairs, usually between four and seven years old.
Opening a hunting season would risk orphaning still-dependent young. While sandhill crane chicks hatched in late spring are able to leave the nest within a day under the parents supervision, they continue to be dependent upon both parent birds well into and past the hunting season. If Michigan opens an annual shooting season in the fall, before family units migrate to their wintering grounds, either parent, or the still-dependent young, could be killed by hunters.
The degree of inaccuracy in the annual sandhill crane hunt is significant and lack of information also applies to the crippling loss rate. Unofficial reports suggest that the unretrieved birds, which are crippled by hunters and left to die, may number at least 15 percent of the retrieved kill, which are those birds comprising a hunter's legal quota. Hence, sandhill cranes that are taken by the gun each autumn may approach 35,000 birds. One would question the sustainability of these numbers on a bird that is known to have a low recruitment rate.
Cumulative lead deposits pose a significant risk to ground-feeding sandhill cranes and to other wildlife that directly and indirectly ingest toxic lead shot - including protected birds of prey such as eagle, falcons, hawks, and owls. Sandhill cranes nest on the ground, they can be susceptible to lead pellets and deposits of lead shot pose a lingering environmental management problem on crop-growing fields.
Sandhill cranes are social birds that usually live in pairs or family groups through the entire year. During migration and winter, unrelated cranes come together to form "survival groups" that forage and roost together.
The trumpeting call is a loud, rolling sound whose unique tone is a product of anatomy: a long trachea windpipe that coil into the sternum and help the sound develop a lower pitch and harmonics that add richness. They can be heard from a long distance and mated pairs of cranes engage in "unison calling" - the female makes two calls for every one from the male.
Sandhill cranes are known for their complex courtship dancing skills. Dancing facilitates pair bonding and allows rivals to assess one another, parents educate their young chicks by dancing with them. Pre-adult cranes practice dancing for years before they select a mate. Courting cranes stretch their wings, pump their heads, bow, and leap into the air in a graceful and energetic dance. The beauty and elegance of cranes has inspired people in cultures all over the world and has made them an important part of a multi-billion dollar backyard bird watching and feeding industry.
Sandhill cranes fly south for the winter, although trends of milder winters have allowed them to overwinter in southern Michigan longer. In their migration and wintering areas, they form flocks that can contain thousands of birds. One place this happens is at Baker Sanctuary near Bellevue, Michigan. An annual Sandhill Crane Festival is held there every October, see the Michigan Audubon position here. Live birds have a significant economic value and continue to be popular attractions for wildlife watching. More Michigan residents participate in wild bird watching, and spend more money doing it, than participate in any other outdoor activity - including all forms of hunting and fishing, combined.
As a conspicuous ground-dwelling species, sandhill cranes are at risk from several predators, which are probably the main non-human source of mortality. Mammals (such as fox, raccoon, and coyote) and corvids (such as crows and red-tailed hawks) feed on young cranes and eggs. Cranes of all ages are a food source for American bald eagles.
The sandhill crane's scientific research and increased population has been almost exclusively funded by the Michigan Nongame Wildlife Fund in Michigan.
Sandhill cranes are intolerant of human disturbance. Their numbers were significantly reduced by habitat loss/farmland conversion and shooting in the early part of this century. With human hunting pressure removed in Michigan, the population of sandhill crane has slowly grown, more noticeably in past 30-40 years. A current two year survey funded by the Michigan Nongame Wildlife Fund confirmed 805 breeding pair statewide. Most breeding pairs in the Lower Peninsula were found in a six county area near Jackson and Ann Arbor. Highest concentrations in the Upper Peninsula occurred in the eastern counties.
The population is still recovering and a lot is still not known or understood. The conservation story is a success, but the population is still far from stable and still in recovery. Additionally, biologists note long-term survey studies cannot be relied upon or of any use consistent with scientific research standards or basic principles of sound science. Population studies are specifically noted in status reports as having a low in precision of indices of accurate population estimates - there simply are no reliable or consistent long-term population status reports and some studies are noted as introducing bias. Even long-term surveys by the USFWS have to be excluded from analysis due to significant inconsistencies.
Sound scientific research studies indicate the hunting of sandhill cranes could threaten their diversity. Cranes are genetically diverse and six subspecies have been officially recognized in recent times, the northern populations of subspecies exist as fragmented remains primarily in the contiguous U.S. and parts of Canada. While populations of cranes is noted as stable in many areas, there is still a concern about habitat fragmentation, changes in agricultural practices, low recruitment and harvest pressure impacting the population. Many subpopulations were destroyed by both hunting and the reduction of habitat. Recent research studies in Wisconsin have noted that opening a recreational hunting season on the Eastern Population could easily wipe out unique populations and all of that genetic variation necessary for long-term survival of the species - especially in the northern most range of the unit.
Critically endangered whooping crane deaths have occurred and have been documented as a result of accidental shootings by sandhill crane hunters. There is also the potential for changes to whooping crane use of habitats if hunting is introduced to those areas within the Eastern Population.
Statewide opinion polls over the last 20 years have repeatedly shown the vast majority of Michigan citizens, including the majority of Michigan hunters, are opposed to Sandhill crane hunting in Michigan.
The Michigan Department of Natural Resources "anticipates significant social concern with establishment of sandhill cranes as a game species." The Michigan United Conservation Club's Wildlife Committee, in discussing their agenda to open season on cranes, has also acknowledged that this may require "a unit" plan (similarly "a unit" plan attempted with mourning doves; i.e. initially six southern counties before statewide expansion), to help manipulate "social acceptance from birding groups and hunters alike."
Hunting cranes is easier than shooting skeet...shooters simply set out taxidermy decoys, hide in a blind together in a row, call the birds in, then jump out all at once to blast family groups out of the sky with lead shot that spreads as they fly in to land among decoys. That's it. Shooters refer to this style as "crane wrecking" and "a blast."
There are no accurate estimates for the sandhill crane population in Michigan - they simply do not exist. It is believed there is an "estimated" population of 30,000 in the Eastern Population (which include Minnesota, Wisconsin, Michigan, and Ontario).
While the presence of sandhill cranes in various crop fields does not necessarily indicate conflict, crop depredation conflict complaints are sometimes used as justification for opening a sport hunting season on sandhill cranes. However, it is widely understood by wildlife biologists and state and federal agencies that an annual fall hunting season would not provide direct assistance to farms impacted by spring crop damage.
For corn farms afflicted with losses, farmers have access to a kill permit; but even the necessity for depredation permits can be effectively avoided with Anthroqionone treated seed, an affordable and effective non-lethal bird-repellent seed coating, making the seed unpalatable to sandhill cranes.
More than 38 species are classified as "game" in Michigan - many of which are birds. Turkeys, pheasants, geese, ducks, woodcock, rails, snipe, and dozens of other bird species give recreational hunters more than ample shooting opportunities at all times of the year in Michigan. In fact, hunting seasons are longer and bag limits are larger than ever for many species. There are plenty of other species to pursue.
In the acknowledgments of A Chorus of Cranes, ornothologist Paul Johnsgard wrote, “Since long before medieval times cranes have been considered messengers of the gods, calling annually from on high to remind humans below of the passing years and of their own mortality. Now it is up to humans to take responsibility for controlling our own fate - and also to cry out to protect not only cranes but all the other wonderful creatures that share our increasingly fragile and threatened planetary ecosystem with us."
Songbird Protection Coalition