Whooping Crane
An adult whooping crane is white with a red crown and a long, dark, pointed bill. However, juvenile whooping cranes are cinnamon brown. While in flight their long necks are kept straight and their long dark legs trail behind. Adult whooping cranes' black wing tips are visible during flight. The whooping crane is roughly the fifth largest extant species of crane in the world, on average. Whooping cranes are the tallest bird native to North America and are anywhere from the third to the fifth heaviest species there, depending on which figures are used. The species can reportedly stand anywhere from 1.24-1.6m in height. Wingspan, at least typically, is from 2-2.3m. Widely reported averages put males at a mean mass of 7.3kg, while females weigh 6.2kg on average.t The body length, from the tip of the bill to the end of the tail, averages about 132cm. The standard linear measurements of the whooping cranes are a wing chord length of 53–63cm, an exposed culmenlength of 11.7–16cm and a tarsus of 26–31cm.
Habitat
The muskeg of the taiga in Wood Buffalo National Park, Alberta, Canada, and the surrounding area was the last remnant of the former nesting habitat of the Whooping Crane Summer Range. However, with the recent Whooping Crane Eastern Partnership Reintroduction Project, whooping cranes nested naturally for the first time in 100 years in the Necedah National Wildlife Refuge in central Wisconsin, United States. They nest on the ground, usually on a raised area in a marsh. Breeding populations winter along the Gulf coast of Texas, United States, near Rockport on the Aransas National Wildlife Refuge and along Sunset Lake in Portland, Matagorda Island, Isla San Jose, and portions of the Lamar Peninsula and Welder Point, which is on the east side of San Antonio Bay
Diet
They are omnivorous, and they eat a range of wetland animals. Winter foods include clams and blue crabs; in the summer they eat aquatic invertebrates, frogs, small fish, and berries. During migration they mainly eat waste grain from agricultural fields
Breeding
They are monogamous and usually the pair-bonds are for life. As spring approaches, the flock at the winter site grows restless: calling, dancing and flying before pairs and family groups finally set off on the journey north. The birds arrive at their nesting area in April, pairs returning to the same territory for subsequent years. The breeding season takes place from late April until May. Both males and females take part in building a flat nest on the ground, usually on top of a mound of vegetation that is surrounded by water. Two eggs are laid and incubation lasts for 28-31 days, mainly by the female but shared by both parents. Both adults feed the chicks. Very soon after hatching, the chicks follow the parent birds to the foraging areas. Chicks fledge at about 80-90 days and stay in their family groups until the next breeding season. They gain sexual maturity at 3-4 years.
Population
The total population in the wild numbers 483 individuals. However, the only self-sustaining population breeding in Northwest Territories/Alberta, Canada and wintering in Texas, USA numbers 329 individuals, fewer than 250 of which are mature. Hence we retain a precautionary estimate of 50-249 mature individuals. The natural flock has increased at 4.2% per year over the past 20 years, excluding the drop in 2009, slightly below the growth rate of 4.6% since 1938 . This equates to a moderate increase over the last three generations.
Threats
Over-hunting, habitat conversion and human disturbance were the main causes of the species's decline. Currently, the most significant known cause of death or injury to fledglings is collision with powerlines. Powerline markers can reduce collisions by 50-80%, but most powerlines remain unmarked and collision is a major and growing problem. The anticipated placement of thousands of wind turbines in the migration corridor will decrease availability of crane stopover habitat and may also dramatically increase the number of powerlines. In 2007, a lightning strike during severe weather killed 17 captive-bred young birds being housed in a top-netted release pen in Florida. Eggs and pre-fledged chicks are subject to predation by various birds and mammals including raven, bald eagle, wolf, black bear and lynx, while harassment of nesting individuals by parasites such as black flies can lead to nest abandonment, and this has been proposed as a key reason for failed breeding in one of the introduced populations. Drought is a serious threat to the species as it is detrimental to all habitats utilized by this species, but is especially harmful by dramatically decreasing production on the nesting grounds. In early 2009, a prolonged drought and reduced water inflow to coastal wetlands led to a reduction in availability of blue crabs Callinectes sapidus and wolfberries Lycium spp. (important food items), causing Whooping Crane mortality rates to double. Coastal development, sea level rise, climate change, chemical spills, reduced fresh water inflows, and human disturbance threaten the Texan wintering grounds. Aransas National Wildlife Refuge(NWR) can only support a maximum of 500 birds through the winter and falls short of the initial downlisting target of 1,000 birds. Continued population growth may force some cranes in future to use disturbed and suboptimal habitat. Much of the currently unoccupied crane habitat at Aransas where the cranes would be expected to expand into is being threatened with construction of houses. There are currently concerns about oil spills and river inflows to Aransas NWR, as well as reduced water flows in the central Platte River Ralley, Nebraska, a key stopover site for migrating Whooping Cranes. The spread of West Nile virus and avian influenza in the future may pose a threat to the species. There have been incidences of illegal shooting of the species in Alabama and Indiana.
Conservation
Conservation Actions Underway
A U.S. District Court has ruled to restrict water offtake from the Guadalupe River, Texas, as so much water was being taken it was a breach of the Endangered Species Act against this species. There is an international recovery plan focusing on increasing the size of the natural flock, establishing additional wild populations through experimental releases, teaching captive-bred birds to migrate, and increasing the captive population for experimental releases and ecological research(e.g. habitat selection). Considerable progress has been made in improving the genetic health of captive stock and in breeding under-represented genetic strains, but delayed reproduction in captivity and the failure of some pairs to breed at all has slowed down progress. In the past, recruitment was increased in certain years in Canada by removal of a single egg from two-egg broods; the removed eggs are used to supplement captive flocks, but the overall impact of the egg pickup program is largely undetermined. An eastern migratory population which mostly winters in Florida and summers in Wisconsin has now been established but only four instances of successful breeding has been recorded so far. If passed, the Crane Conservation Act would allocate $5 million per year over five years to be spent on crane conservation efforts world-wide, with strict limitations on the amount going to help them. A process has been initiated as a collaborative project to conduct a Population Viability Analysis and a Population and Habitat Viability Assessment to aid in the recovery of this species
Conservation Actions Proposed
Survey and monitor breeding grounds to determine nesting effort, and the wintering grounds to determine flock size. Research food resources and high mortality. Alleviate threats in Texas. Reduce powerline collisions, and take into account potential migration stopover sights when planning potential developments, such as wind farms. Continue establishment of further self-sustaining populations. Continue raising cranes for reintroduction.