COSEWIC Assessment and Update Status Report on the Whooping Crane in Canada 2000

1. Table of Contents
2. Assessment Summary
3. Executive Summary
4. Species Information
5. Distribution
6. Habitat
7. General Biology
8. Population Size and Trends
9. Limiting Factors and Threats
10. Special Significance of the Species
11. Evaluation and Proposed Status
12. Technical Summary
13. Acknowledgements
14. Literature Cited
15. The Author
16. Appendix

COSEWIC status reports are working documents used in assigning the status of wildlife species suspected of being at risk. This report may be cited as follows:

Please note: Persons wishing to cite data in the report should refer to the report (and cite the author(s)); persons wishing to cite the COSEWIC status will refer to the assessment (and cite COSEWIC). A production note will be provided if additional information on the status report history is required.

COSEWIC 2000. COSEWIC assessment and update status report on the Whooping Crane Grus americana in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. vii + 28 pp. (www.sararegistry.gc.ca/status/status_e.cfm)

Wapple, R.D. 2000. Update COSEWIC status report on the Whooping Crane Grus americana in Canada, in COSEWIC assessment and update status report on the Whooping Crane Grus americana in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. 1-28 pp.

Previous reports:

Gollop, M.A. 1978. COSEWIC status report on the Whooping Crane Grus americana in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. 23 pp.

Également disponible en français sous le titre Mise à jour évaluation et rapport de situation du COSEPAC sur la Grue blanche (Grus americana) au Canada.

Cover illustration:
Whooping Crane -- Judie Shore, Richmond Hill, Ontario.

©Her Majesty the Queen in Right of Canada 2004
Catalogue No. CW69-14/154-2002E-IN
ISBN 0-662-32327-0

Common name : Whooping Crane

Scientific name : Grus americana

Status : Endangered

Reason for designation : This globally endangered species occurs in very small numbers in a very restricted breeding range within a portion of Wood Buffalo National Park and adjacent area. Human activity and resource development are potential threats to the population, primarily during migration.

Occurrence : Northwest Territories , Alberta

Status history : Designated Endangered in April 1978. Status re-examined and confirmed in November 2000. Last assessment based on an update status report.

Adult Whooping Cranes have pure white plumage with black primaries with black and red facial markings. The long legs and large bill are black or grayish-black. Immature birds have a combination of grayish-white and rusty coloration with no facial markings.

Whooping Cranes formerly bred across much of the central and northern prairies of North America (a small population also bred in Louisiana) and wintered from New Jersey to Northern Mexico but vanished from these areas following human settlement around the beginning of the 20^th century. Today the only remaining nesting grounds for this population lie in an area between the headwaters of the Nyarling, Sass, Klewi and Little Buffalo Rivers in Wood Buffalo National Park (WBNP). The core breeding area in WBNP has recently expanded south into the Alberta portion of the park. These birds migrate 4000⁺ km from WBNP to winter at and near the Aransas National Wildlife Refuge (ANWR) along the Texas Gulf Coast.

A second wild flock was established in 1975 in southeastern Idaho from Whooping Cranes cross-fostered by resident Sandhill Cranes. This flock winters in the middle Rio Grande Valley of New Mexico. A third non-migratory wild flock was established in 1993 at Kissimmee Prairie, Florida.

The nesting grounds in the central portion of WBNP are localized in marshes, bogs, and shallow lakes that are separated by narrow elevated ridges dominated by an overstory of black spruce, white spruce, tamarack, and a variety of willows. Understories consist of dwarf birch, Labrador tea, and bearberry. Nesting areas are dominated by stands of bulrush, cattail, sedges, musk-grass, and other aquatic plants.

During migration, Whooping Cranes utilize a variety of wetlands and croplands along their migration corridor for feeding and roosting. Wetlands are more important feeding areas for family groups than non-families. Roosting and feeding sites within one kilometer of each other are preferred.

The wintering habitat at ANWR on the Texas Gulf Coast consists of estuarine marshes dominated by salt grass, saltwort, smooth cordgrass, glasswort, and sea ox-eye, and salt flats dominated by gulf cordgrass. Oak, redbay, and bluestem characterize upland areas that are managed for cranes and other wildlife.

Spring migration commences in late March and is usually complete by the end of April. The only naturally occurring population of Whooping Cranes breeds in and around WBNP. Breeding commences at approximately four years of age and occurs annually thereafter. Nest building commences immediately after arrival and clutch initiation occurs shortly thereafter. Perennially monogamous pairs lay two eggs per clutch but rarely fledge more than a single young. The eggs are incubated for approximately 28 days. Upon hatching, precocial young grow rapidly and begin sustained flights in mid-August. Young production appears to be associated with approximately 10-year wet-dry cycles with fewer young produced during dry years. Of 13 breeding pairs studied, mean home range size was 4.1 km². Departure from the breeding grounds occurs in mid-September. Fall migration is protracted and often involves staging for one to five weeks in south-central Saskatchewan. Arrival on ANWR wintering grounds occurs in late October and mid-November.

Longevity in the wild is estimated to be 22-30 years. Overall mortality for the WBNP/ANWR population is 9.9% per year. Unguarded eggs and flightless young can be vulnerable to a variety of terrestrial predators, especially during periods of drought. Most adult mortality occurs during migration or on the wintering grounds, mainly due to human-related factors. Non-breeding sub-adults begin fall migration earlier than family groups. During the period of 1982-84, 68.4% of crane-use days during fall migration were spent in Saskatchewan. Pairs and family groups establish territories during their winter tenure at ANWR. During the 1980’s, the average winter territory size was 117 ha but this has declined recently. Juveniles leave ANWR with their parents in spring and accompany them on the majority of their northward migration, separating at or near the breeding grounds. During the period of 1982-84, 43.7% of crane use-days during spring migration were spent in Saskatchewan.

Whooping Cranes are omnivorous throughout the year. The diet during the breeding season includes insects, crustaceans, minnows, frogs, snakes, small rodents, seeds and berries. Staging areas used during migration provide waste grains, as well as tubers, a variety of insects and small rodents. On the wintering grounds, Blue Crabs and a variety of clams are the most important food items. Wolfberry and acorns are consumed in adjacent uplands.

Habitat alteration, hunting, and vulnerability to disturbance on the remaining breeding grounds were likely major factors in the extirpation of prairie and aspen parkland Whooping Crane populations. The current breeding grounds in WBNP are isolated and relatively undisturbed. On the wintering grounds, Whooping Cranes are less wary and tolerate human disturbances from barge traffic along the Gulf Intracoastal Waterway (GIW) and from eco-tourist boats.

Sandhill Cranes likely do not compete with Whooping Cranes for breeding territories and there is likely little competition with other species for resources in these areas. On the wintering grounds, however, cranes must share the resources of these coastal habitats with large numbers of other bird species.

Whooping Cranes were never a common species and their maximum population probably did not exceed 1,500 individuals. As of 1999-2000, the total population of wild Whooping Cranes was 260 individuals (187 in the WBNP/ANWR population, two in the Rocky Mountain population and 87 in the Florida population). Along with the 106 individuals in captivity, the overall population is 382 individuals. The WBNP/ANWR population has increased by 36.6% over the last ten years (1989-1999) and has an overall population growth of 3.7% per year.

The breeding range in WBNP is very restricted. Habitat quality, and subsequently, food resources, is the most important factor regulating Whooping Crane numbers. Along with perils faced during migration, factors affecting the wintering grounds at ANWR appear to be more limiting than factors affecting the breeding range at WBNP. The concentration of Whooping Cranes in the vicinity of ANWR makes them vulnerable to catastrophic events such as hurricanes or chemical spillage.

The Canadian and U. S. Whooping Crane Recovery Program calls for the maintenance of a minimum of 40 breeding pairs in the WBNP/ANWR population and a minimum of 25 breeding pairs at each of two additional sites. Central Wisconsin has been recommended as the primary site for the establishment of another migratory flock. Several sites in Saskatchewan and Manitoba have also been evaluated for future releases. Whooping Cranes are protected in Canada under the Migratory Bird Treaty, Migratory Birds Convention Act, National Parks Act, Canada Wildlife Act as well as by provincial/territorial wildlife acts. This species is also protected in the United States by the Endangered Species Act.

The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) determines the national status of wild species, subspecies, varieties, and nationally significant populations that are considered to be at risk in Canada. Designations are made on all native species for the following taxonomic groups: mammals, birds, reptiles, amphibians, fish, lepidopterans, molluscs, vascular plants, lichens, and mosses.

COSEWIC comprises representatives from each provincial and territorial government wildlife agency, four federal agencies (Canadian Wildlife Service, Parks Canada Agency, Department of Fisheries and Oceans, and the Federal Biosystematic Partnership), three nonjurisdictional members and the co-chairs of the species specialist groups. The committee meets to consider status reports on candidate species.

Species : Any indigenous species, subspecies, variety, or geographically defined population of wild fauna and flora.

Extinct (X) : A species that no longer exists.

Extirpated (XT) : A species no longer existing in the wild in Canada, but occurring elsewhere.

Endangered (E) : A species facing imminent extirpation or extinction.

Threatened (T) : A species likely to become endangered if limiting factors are not reversed.

Special Concern (SC)* : A species of special concern because of characteristics that make it particularly sensitive to human activities or natural events.

Not at Risk (NAR)* : A species that has been evaluated and found to be not at risk.

Data Deficient (DD)*** : A species for which there is insufficient scientific information to support status designation.

* Formerly described as “Vulnerable” from 1990 to 1999, or “Rare” prior to 1990.
** Formerly described as “Not In Any Category”, or “No Designation Required.”
*** Formerly described as “Indeterminate” from 1994 to 1999 or “ISIBD” (insufficient scientific information on which to base a designation) prior to 1994.

The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) was created in 1977 as a result of a recommendation at the Federal-Provincial Wildlife Conference held in 1976. It arose from the need for a single, official, scientifically sound, national listing of wildlife species at risk. In 1978, COSEWIC designated its first species and produced its first list of Canadian species at risk. Species designated at meetings of the full committee are added to the list.

Environment Environnement
Canada Canada

Canadian Service canadien
Wildlife Service de la faune

The Canadian Wildlife Service, Environment Canada, provides full administrative and financial support to the COSEWIC Secretariat.

The common name of the Whooping Crane is likely derived from guard call or unison call vocalizations (Lewis 1995). The Latin name, Grus americana (Linnaeus), translates as “crane of America” while the French name, Grue blanche d’Amerique, translates as “white crane of America”. The Whooping Crane is placed in the order Gruiforme, along with 14 other species worldwide, and belongs to the familyGruidae. The genusGrus contains nine species that includes both native North America cranes, the Sandhill Crane and the Whooping Crane. The Whooping Crane has no subspecies. DNA studies indicate that the Common Crane (Grus grus), a Eurasian species, is its nearest relative (Love and Deninger 1992).

Adult Whooping Cranes have pure white plumage with black primaries that are visible only when the wings are outstretched. A red patch covers the crown and black markings on the forehead extend beneath the eye to form an angular malar stripe. There is also a dark gray wedge-shaped patch that extends from the back of the crown over the nape. The long legs and large bill are black or grayish-black. Immature birds have a combination of grayish-white and rusty coloration with no facial markings. Adult plumage is acquired during their second year. In flight, cranes fly with legs and neck fully extended outward. Standing at »1.5 m, the male whooping crane is the tallest bird in North America. Males are slightly larger than females (see Table 1).

Whooping Cranes share their range with several similar looking species. These include the Snow Goose (Chen caerulescens) and American White Pelican (Pelecanus erythrorhynchos), both of which have white plumage with black primaries but have short necks and legs, and very different bill morphology. Egrets and swans also have white plumage but do not have black primaries. Swans have short black legs that do not extend noticeably in flight and although egret’s long black legs trail in flight, they fly with their necks folded on their shoulders.

The whooping crane once occupied a much wider breeding range that is believed to have extended in a southeasterly direction from the central and northern prairies of Alberta and Saskatchewan into southwestern Manitoba, northeastern North and South Dakota, northwestern Minnesota and Iowa and central Illinois (Allen 1952). In 1939, a small disjunct population was also found breeding in the marshes north of White Lake, Louisiana.

Today the only remaining nesting grounds for this population lie in Wood Buffalo National Park (WBNP), which straddles the Northwest Territories border in northeastern Alberta. Nesting is concentrated in an area lying between the headwaters of the Nyarling, Sass, Klewi and Little Buffalo Rivers (see Figure 1). Although the park itself is 44,807 km² and is the largest Canadian national park, the core breeding area, located in the northeastern corner of the park, is »6400 km²(Brian Johns pers. comm.) The last documented nesting of a pair of wild Whooping Cranes south of WBNP occurred in 1929 at Luck Lake, Saskatchewan (Hjertaas 1994).

The migratory route extends 4000⁺ km from the breeding grounds in WBNP to their wintering grounds in the vicinity of Aransas National Wildlife Refuge (ANWR) along the Texas Gulf Coast (see Figure 2). The route passes in a southeasterly direction through northeastern Alberta, south-central Saskatchewan, southwestern Manitoba, northeastern Montana, western North and South Dakota, central Nebraska and Kansas, west-central Oklahoma and finally to east-central Texas along the Gulf Coast (Howe 1989, Kuyt 1992). The wintering area for this population is localized in the estuarine marshes and tidal flats of ANWR and adjacent areas of the central Texas Gulf Coast (Allen 1952). Spring migration follows the reverse path of the fall trip but it is usually done in less time, as little as 10-11 days for experienced pairs.

In addition to the WBNP/ANWR flock, a second wild flock was established in 1975 in the Rocky Mountains of southeastern Idaho from Whooping Cranes cross-fostered by resident Sandhill Cranes. This population winters in the middle Rio Grande Valley of New Mexico. A third wild flock was established in 1993 at Kissimmee Prairie, Florida. This non-migratory population descends from captive-reared birds.

The only self-sustaining population of Whooping Cranes breeds in WBNP in northeastern Alberta and southern Northwest Territories. Their migratory route passes through northeastern Alberta, south-central Saskatchewan, and southwestern Manitoba (see Figure 3).

The nesting grounds of the WBNP/ANWR population are localized in a fragile area consisting of marshes, bogs, and shallow lakes that vary considerably in size, shape and depth. Distributed across this poorly drained region of WBNP, these wetlands are separated by narrow elevated ridges dominated by an overstory of Black spruce (Picea mariana), white spruce (Picea glauca), tamarack (Larix laricina) and a variety of willows (Salix spp.). Understories are typically dominated by dwarf birch (Betula glandulosa), Labrador tea (Ledum groenlandicum) and bearberry (Arctostaphylos uva-ursi). Nesting areas are dominated by stands of bulrush (Scirpus validus), cattail (Typha spp.), sedges (Carex spp.), musk-grass (Chara spp.) and other aquatic plants (Allen 1956, Novakowski 1966, Kuyt 1976b, 1981).

The core breeding area in central region of WBNP was approximately 625 km² in the mid-1970’s (Gollop 1977), by 1999 it had expanded to include approximately 6400 km² (Brian Johns pers. comm.). This recent expansion has been to the northwest and south into the Alberta portion of WBNP (Kuyt 1978, Johns 1998). Despite this expansion, apparently suitable habitat in other regions of WBNP and in other portions of the Canadian Sub-Arctic remain unoccupied by Whooping Cranes (Brian Johns, pers. comm.).

The few remaining birds in the failed Rocky Mountain population summers around the Grays Lake National Wildlife Refuge, an 8,900 ha high elevation (1,946 m) marsh that borders agricultural fields and other wetlands. The resident Florida population inhabit a 2,000 km² area of flat, open saw-palmetto (Serenoa repens) prairie that contains numerous shallow marshes and lakes. This region is surrounded by a wide variety of private and publicly owned ranches and wetlands.

During migration, the WPNP/ANWR Whooping Crane population utilizes a variety of wetlands and croplands along their migration corridor, feeding largely on aquatic organisms and waste grains. Utilizing different wetland types for roosting during their spring and fall migration, Whooping Cranes favor temporary and seasonal wetlands in spring, and prefer semi-permanent and permanent wetlands in fall (Johns et al. 1997). Howe (1989) found that 70% of feeding sites used by non-family groups were croplands, while 67% of feeding sites used by families were wetlands. Family groups appear to use more heavily vegetated wetlands than non-family groups. More densely vegetated wetlands may decrease predation on young inexperienced birds. Juveniles allocated 25% more time to foraging than parents, therefore roosting wetlands are likely important feeding sites for young and may provide a higher protein diet required by juveniles that are not fully grown. Wetlands constituted 67% of feeding sites for family groups and only 30% for non-families. Although large wetlands are used by migrating cranes, 41% of roosting wetlands were <0.5 ha, of which 15% were <0.1 ha. Cranes favoured roosting and feeding sites that were within one kilometer of each other (Howe 1989, Johns et al. 1997).

The wintering habitat in the vicinity of ANWR on the Texas Gulf Coast consists of estuarine marshes dominated by salt grass (Distichlis spicata), saltwort (Batis maritima), smooth cordgrass (Spartina alterniflora), glasswort (Salicornia spp.,) and sea ox-eye (Borrichia frutescens), and salt flats dominated by gulf cordgrass (Spartina spartinae). Oak (Quercus virginiana), redbay (Persea borbonia) and bluestem (Andropogonspp.) characterize upland areas that are managed for cranes and other wildlife (Allen 1952, Labuda and Butts 1979).

The Rocky Mountain population stages in southern Colorado where they roost in wetlands and feed in adjacent barley fields (Lewis 1995). These birds winter mainly along a 50-km portion of the middle Rio Grande Valley in the vicinity of Bosque del Apache NWR, NM. The Rio Grande and adjacent managed wetlands are used for roosting, while feeding is concentrated in nearby wetlands and agricultural fields (Lewis 1995).

Loss of isolated wetland habitat required for breeding is likely a primary reason why the WBNP/ANWR population of Whooping Cranes does not currently breed south of WBNP. Repopulation of breeding habitat in these areas is very unlikely because of high disturbance levels from humans and loss of isolated habitat. Breeding habitat in WBNP is rather restricted but local pioneering of unclaimed habitat is possible due to the ample presence of unoccupied suitable habitat within the park and in adjacent areas. There is a general consensus among experts that the inability for Whooping Cranes to further expand their breeding grounds may be regulated by conditions on their wintering grounds at ANWR (USFWS 1994, Lewis 1995, Johns 1998). Since ANWR is situated in an area with heavy boat traffic, much of which is involved in the transport of petrochemical products, there is potential for this crucial habitat to become contaminated due to accidental spills. Boat traffic through this area also causes habitat degradation. Whooping Cranes must also compete with many other bird species that winter in this region.

The Whooping Crane nesting grounds were protected from competing land use activities and development in 1922 with the establishment of WBNP, an expansive (4,288,542 ha) area of Sub-arctic boreal forest and muskeg. This protection was coincidental and rather fortuitous since the park was established to protect the herds of wood bison that inhabit the park and another thirty years would pass before it was discovered that the entire wild population of Whooping Cranes also nested there. This area is designated as a Zone 1 Special Preservation Area. No access is allowed between April 15 and October 31, except for park staff and scientists. WBNP was also designated a World Heritage Site in 1983 by the United Nations Educational, Scientific and Cultural Organization (UNESCO), which designates it as a place of exceptional universal value which deserves protection for the benefit of all humanity. The International Union for the Conservation of Nature (IUCN) designated the Whooping Crane nesting area in WBNP as a Ramsar site in 1982. Ramsar is an inter-governmental treaty that provides the framework for national action and international co-operation for the conservation and wise use of wetlands and their resources.

Howe (1989) and Johns et al. (1997) found that most Whooping Crane roost sites used during migration were on private land, illustrating the importance of co-operation between private landowners and wildlife managers in protecting feeding and staging sites for migrating cranes. Some major wetlands along the Whooping Crane’s migration corridor are also protected, such as Last Mountain Lake National Wildlife Area (also a Ramsar site) and Luck Lake Heritage Marsh, both of which lie within fall staging areas in Saskatchewan.

Identification and potential protection for other important Whooping Crane staging sites in this region via the Important Bird Area (IBA) initiative is currently in progress. The IBA program in Canada was initiated in 1996, along with parallel programs in the United States and Mexico. The goal of the program is to identify and protect a worldwide network of sites necessary to ensure the long-term viability of naturally occurring bird populations. Sites designated as IBA’s (as of 2001) include WBNP nesting areas near Fort Smith, NWT and in the Alberta portion of the park, and a number of sites in Saskatchewan that are known to be used by migrating Whooping Cranes. These include Eyebrow Lake, Middle Lake, Basin Lake, Blaine Lakes, Last Mountain Lake (north end), Luck Lake, Midnight Lake, Radisson Lake, Quill Lakes, and Buffer Lake.

In 1978, the U.S. Fish and Wildlife Service designated critical habitat for Whooping Cranes at the following nine sites in six U.S. states: Monte Vista NWR, CO; Alamosa NWR, CO; Grays Lake NWR, ID; Cheyenne Bottoms State Waterfowl Management Area, KA; 88 km along the Platte River, NE; Bosque del Apache NWR, NM; Salt Plains NWR, OK; and ANWR, TX (USFWS 1994).

The only naturally occurring population of Whooping Cranes breeds in WBNP. Migration between WBNP breeding grounds and wintering grounds at ANWR extends in a direct corridor in a southeasterly direction (see Figure 3). Spring migration commences in late March and is complete by the end of April. It is usually direct and rapid, taking as little as 10 days for experienced adults (Kuyt 1992). These experienced birds arrive at the breeding grounds first, often exhibiting site fidelity to nesting territories held in previous years. Nest building commences immediately after arrival. Clutch initiation occurs shortly thereafter and is usually complete by mid-May. The eggs are incubated for 30-35 days (Kuyt 1981). Upon hatching, precocial young grow rapidly and begin sustained flights in mid-August. Departure from the breeding grounds occurs in mid-September. Fall migration is often protracted and may take as long as 50 days due to staging for one to five weeks in south-central Saskatchewan (Kuyt 1992). Arrival on wintering grounds on the Texas Gulf Coast occurs in late October and mid-November.

Breeding commences at four years of age and may occur annually thereafter. Some birds fail to nest every year (George Gee, pers. comm.). Perennially monogamous pairs lay two eggs per clutch but rarely fledge more than a single young. Both parents share parental duties. Due to the short summer season on the breeding grounds, only one brood is raised per season. Longevity in the wild is estimated to be 22-30 years (Kuyt and Goossen 1987, Mirande et al. 1993). Whooping Cranes usually breed in isolated locations, but nests have been recorded as little as 500 m apart in the highest nesting area densities along the Klewi River and Preble Creek (Brian Johns pers. comm.). Inexperienced pairs nesting far from running water appear to move their nest sites closer to running water in successive years (Kuyt 1993). The sex ratio of the wild population is unknown.

Overall mortality for the WBNP/ANWR population is 9.9% per year (Brian Johns pers. comm.). Based on resighting data of marked birds, mortality of wild Whooping Cranes in their first year of life has been 26.7% and 9.06% during their second year (Lewis 1995). Female survival to one year of age is half of the rate for males. Survival rate for both sexes from one year to two years is similar. Older females average slightly lower survival (78%) than for males (86%). Young production appears to be associated with approximately 10-year wet-dry cycles with fewer young produced during dry years. Recruitment rate of birds breeding in WBNP has decreased from a mean of 16.1% during the period of 1938-1966, to 11.5% during 1967-1992. The mean recruitment rate during this entire period (1938-1992) was 13.9% (Drewien et al. 1995).

There are several major causes of mortality. Unguarded eggs and flightless young and can be vulnerable to terrestrial predators, especially during periods of drought which allows easier access to nesting areas. Potential drought-related mortality factors on the breeding grounds include prolonged food shortages (Kuyt 1976a) and lightning-caused fires (Lewis 1995). Black Bear (Ursus americanus) and Common Raven (Corvus corax) are known predators of eggs, and Wolf (Canis lupus), Red Fox (Vulpes velox), and Common Raven are known predators of young cranes (Kuyt et al. 1981, Johns pers. comm.). Other potential predators on the breeding grounds include Coyote (Canis latrans), Wolverine (Gulo luscus), and Lynx (Lynx canadensis).

Most adult mortality occurs during migration or on the wintering grounds (Kuyt 1992), mainly because of human-related factors. Collisions with power wires during periods of low visibility are a major cause of mortality during migration and is a significant factor affecting long-term recovery of the Whooping Crane (Howe 1989). At least 21 Whooping Cranes have been killed or seriously injured from such collisions between 1956-1999 (Lewis 1995, Brian Johns pers. comm.). Although illegal shooting is less of a problem nowadays, there are four documented cases of birds being illegally shot at ANWR and a fifth was suspected to have been shot (Lewis et al. 1992), and one case in Saskatchewan.

Natural predation is also a factor. There is at least one documented case of a Golden Eagle attacking and killing a Whooping Crane from the Rocky Mountain population (Windingstad et al. 1981). Another eagle attack was documented in 1997 (Brian Johns pers. comm.). Kuyt (1992) suspected a Golden Eagle of attacking and injuring an adult crane in Saskatchewan and suggested that perhaps a Great-horned Owl may have caused the death of a bird at ANWR.

Whooping Cranes are susceptible to a number of diseases, including avian tuberculosis (Lewis 1995) and avian cholera (Snyder et al. 1987). Coccidia, a parasitic soil protozoan that can be pathogenic, have been found in droppings collected on crane wintering grounds (Forrester et al. 1978). Lead poisoning has also been documented (Snyder et al. 1992) and one adult was known to die of heart disease near its nest in WBNP (Kuyt 1992).

Ellis et al. (1991) describe behavior mechanisms Whooping Cranes use to regulate body temperature. These include tucking in legs during flight or standing on one leg during cold weather, adjusting feathers, panting, shivering, and sunbathing. Upon hatching, the insulative properties of the chick’s plumage appear to allow sufficient thermoregulation in most conditions (Lewis 1995).

The migration of the Whooping Crane, like all other migratory birds, is greatly affected by weather. Crane departure from ANWR is associated with the eastward passing of high-pressure systems with accompanying warm southerly winds, high barometric pressure and excellent visibility. Unfavorable weather, such as strong crosswinds or precipitation, will limit the progress of migrating cranes until conditions improve. Increased barometric pressure and associated northerly winds, as well as good visibility stimulate departure from the breeding grounds (Kuyt 1992).

Juveniles leave ANWR with their parents and accompany them on the majority of their northward migration, separating at or near the breeding grounds. During the period of 1982-84, 43.7% of crane use-days during spring migration were spent in Saskatchewan (Howe 1989). Juvenile separation from their parents during spring migration has been documented in Saskatchewan but often does not occur until family groups reach their nesting grounds in WBNP (Kuyt 1992). Stehn (1984) documented increased parental aggression towards their young as migration progressed.

Following chick hatching on the breeding grounds, pedestrian movements of family groups occurs entirely within the breeding territory (Kuyt 1976). After the young are capable of sustained flight, family groups move about further from the natal territory but the distance is minimal (Howe 1989). Non-breeding sub-adults leave WBNP earlier than family groups. The departure of crane groups from the nesting grounds may stimulate neighboring groups to begin their exodus (Lewis 1995). An 85,000-km² area of south-central Saskatchewan provides a fall staging area where Whooping Cranes may spend from one to five weeks. During the period of 1982-84, 68.4% of crane-use days during fall migration were spent in Saskatchewan (Howe 1989).

Pairs and family groups establish territories during their winter tenure at ANWR. During the 1980’s, the average winter territory was 117 ha (Stehn and Johnson 1987). The average territory size has recently declined due to an increase in the Whooping Crane population. Sub-adults and unpaired adults form small winter flocks that border existing territories (Blankinship 1976). The Rocky Mountain population is not territorial in winter (Lewis 1995).

Whooping Cranes are omnivorous throughout the year. The diet on the breeding grounds is poorly documented but is known to include a wide variety of insects and crustaceans. Berries are consumed in early autumn (Novakowski 1965). Other food items that are likely important include mollusks, minnows, frogs, snakes, and small rodents (Allen 1956, Novakowski 1966). Whooping Cranes are also known to stalk ducklings and a juvenile was observed with a live blackbird in its bill. Observations of adults feeding on a dead grebe and a flightless young feeding on a dead juvenile American Bittern suggest carrion may be opportunistically consumed (Cooch et al. 1988). Young cranes are fed a diet rich in aquatic invertebrates, most notably dragonfly nymphs (Bergeson and Bradley in press).

Staging cranes in south-central Saskatchewan feed largely on waste grains (barley, wheat) as well as tubers, a variety of insects (grasshoppers, crickets), small rodents (Microtus spp., Peromyscus maniculatus) and snakes (Thamnophis spp.). Agricultural lands used by migrating cranes between Saskatchewan and ANWR likely provide a similar diet.

On their Texas wintering grounds, Blankinship (1976) found Blue Crabs (Callinectes sapidus) and a variety of clams (Tagelus plebius, Ensis minor, Rangia cuneata, Cyrtopleura costada, Phacoides pectinata, Macoma constrica) to be the most important food items. Water level is believed to influence which species are most accessible for capture and consumption. Blue Crabs dominate the diet when tidal flats are flooded due to heavy rain and during high tides (Nelson et al. 1996). In December and January tidal flats typically drain due to lower tides. During this time clams are more predominate in the diet because lower water levels make them more accessible.

Whooping cranes also forage in adjacent uplands to consume wolfberry (Lycium carolinianum) and acorns (Quercus virginiana), but croplands are rarely visited (Bishop and Blankinship 1982). Other food items consumed on the wintering grounds include a variety of shrimp (Callianassa spp., Penaeus spp., Cragnon spp.), crayfish (Cambarus hedgpethi), snails (Melampus coffeus) and the roots of three-square (Scirpus olneyi) and cordgrass (Spartina spp.).

Whooping Cranes are vulnerable to disturbance on their breeding grounds. This species’ inability to adapt to increased disturbance in the vicinity of wetlands used for breeding in the late 1800’s and early 1900’s was likely a major factor in the extirpation of prairie and aspen parkland populations. The current breeding grounds in WBNP are isolated and relatively undisturbed.

On the wintering grounds, it is generally felt that Whooping Cranes are less wary and tolerate human disturbances from barge traffic along the Gulf Intracoastal Waterway (GIW) and from eco-tourist boats. The heavy barge traffic through this area is composed largely of petrochemical products. Relatively small chemical spills have occurred here in the past and there is potential for catastrophic spills in the future (USFWS 1994). Degradation of wintering habitat from activities associated with the GIW, such as erosion and waterway maintenance, has caused some habitat losses. Although hurricanes occur at ANWR, the hurricane season is generally complete by the time the cranes arrive in November, however, they have devastating potential. A disastrous hurricane in 1940 caused the deaths of seven of the remaining 13 Whooping Cranes in the Louisiana flock, which led to the extinction of this population in 1948.

The Canadian Wildlife Service and the United States Fish and Wildlife Service have co-operated in attempts to recover this species. Between 1967 and 1996, 453 Whooping Crane eggs were removed from nests in WBNP for captive rearing, use in cross-fostering experiments with Sandhill Cranes and in ultralight experiments for reintroducing flocks. Although both Sandhill and Whooping Cranes lay two eggs per clutch, it is rare for more than a single young to fledge. Opinions on the effects of egg removal on Whooping Crane recruitment vary. Mirande et al. (1993) state that the removal of one of the eggs from the nest does not adversely affect productivity in the wild breeding population, while Cannon et al. (in press) argue that juvenile recruitment into the WBNP/ANWR population was significantly greater during years of no egg collection. The lack of appropriate controls and the number of confounding variables make these studies difficult to interpret (George Gee pers. comm.).

The Canadian and U. S. recovery program consists of maintaining a minimum of 40 breeding pairs in the WBNP/ANWR population and a minimum of 25 breeding pairs at each of two additional sites (USFWS 1994, Edwards et al. 1994). The Canadian Recovery Plan calls for the establishment of one of those additional sites in Canada by 2020 (Edwards et al. 1994). Lyon et al. (1995) evaluated three regions in eastern Saskatchewan/western Manitoba: Yorkton, Saskatchewan River delta, and Overflowing River, as potential sites for whooping crane reintroduction. Logistically, the Yorkton region would be the easiest location for such a reintroduction program; however, it also has the greatest number of hazards. Sommerfeld and Scarth (1998) evaluated five marsh complexes in the Interlake Region of Manitoba as potential sites for Whooping Crane reintroduction. While this area would provide suitable habitat for 25 breeding pairs, land management and associated disturbance are the most important factors affecting the success of such as reintroduction in this region. In 1998, the Whooping Crane Recovery Team (WCRT) made the following recommendations:

1. That a second migratory population be initiated in two phases: Wisconsin to Florida, and Manitoba to Florida or Louisiana;

2. The feasibility of a reintroduction in Wisconsin should be examined;

3. The first choice for a wintering site is Chassahowitzka, Florida and the second choice is Marsh Island, Louisiana.

In 1999, the WCRT made the following recommendations:

1. That a second migratory population be reintroduced in the eastern U.S. with birds summering in Wisconsin and wintering at Chassahowitzka NWR/St. Martins Marsh Aquatic Preserve, Florida;

2. The first releases should occur in central Wisconsin depending on satisfactory results from the assessment of contaminant levels that a summering Whooping Crane population could be exposed to, assessment of aircraft overflights that could affect a breeding Whooping Crane population, reintroduction efforts using ultralight aircraft, and a Sandhill Crane trial migration from central Wisconsin to Florida by ultralight (Brian Johns pers. comm.).

Once the migratory route and amount of dispersal of the new population ensures that no significant mixing will occur with the WBNP/ANWR population, additional release sites will be considered. These include other sites in Wisconsin, Seney NWR in Michigan, the Interlake region of Manitoba, and a wintering population at Marsh Island Wildlife Refuge in Louisiana (Brian Johns pers. comm.).

There are three captive Whooping Crane flocks managed by the U. S. Fish and Wildlife Service (USFWS), U. S. Geological Survey, and the Canadian Wildlife Service (CWS). The first was established in 1966 at Patuxent Wildlife Research Center, Maryland. A second flock was established at the International Crane Foundation (ICF) at Baraboo, Wisconsin, and a third flock was established by CWS at the Calgary Zoo in Calgary. As of 1999, the Patuxent flock had 44 birds, the ICF flock had 31 birds, while the Calgary Zoo flock had 21 birds (see Appendix 4). Other captive birds include four adults at the San Antonio Zoological Gardens in Texas and two birds at the Audubon Institute in Louisiana (Brian Johns pers. comm.).

Whooping Cranes are territorial on both the breeding and wintering grounds. The male crane usually defends territories. In WBNP, family groups of Whooping Cranes do not socialize with conspecifics; thus breeding territories are usually well spaced. Kuyt (1993) found that territory sizes for isolated breeding pairs of cranes varied from 12.0 km² to 18.9 km², while pairs using more densely populated regions had territory sizes that varied from 3.2 km² to 4.2 km². Of 13 breeding pairs studied, mean home range size was 4.1 km².

Whooping Cranes are known to adapt to varying water levels on the wintering grounds that affect prey availability (Blankinship 1976). Although they are omnivorous, the importance of Blue Crab in the winter diet of the Whooping Crane suggests that factors affecting crab populations may have major consequences for cranes (Johns 1998). No information is available on the effects of drought on the food supply on the breeding grounds. Low young production during dry years suggests it is likely affected by wet-dry climatic periodicity.

Allen (1952) concluded that Whooping Cranes were never a common species and that their maximum population probably did not exceed 1,500 individuals. Approximately 90% of the population disappeared between 1870 and 1900 due to the encroachment of civilization on its breeding grounds south of WBNP. Wintering sites on the east coast of the United States disappeared around this time due to the greatly increasing human population and subsequent drainage of marsh habitats (George Gee pers. comm.).

The concentration of Whooping Cranes in the vicinity of ANWR in winter allows wildlife agencies to very accurately determine population levels and annual trends (see Figure 4). Breeding grounds censuses are less reliable because of the vastness of WBNP. The total population of wild Whooping Cranes in the winter of 1999-2000 was 276 individuals (187 in the WBNP/ANWR population, two in the Rocky Mountain population and 87 in the Florida population). Along with the 106 individuals in captivity, the overall population is 382 individuals (see Appendices 1-4).

Since there is no age structure data for the WBNP/ANWR population, it is unknown exactly how many breeding individuals there are. Kuyt (1981) estimated that 80% of the adult population of cranes breed in a given year at WBNP, with 60% producing young. Between 1976 and 1989, 172 of 234 hatchlings (»73%) reached ANWR on their first trip. Boyce (1987) demonstrated a 10-year periodicity in Whooping Crane populations. This may be associated with 10-year wet-dry cycles on the breeding grounds since fewer young are produced during dry years (Lewis 1995). Although slight decreases in the WBNP/ ANWR population occasionally occur, the WBNP/ANWR population of Whooping Cranes has been slowly increasing since intensive population monitoring was initiated in 1938 (see Appendix 1). Beginning in 1977, the core breeding area expanded south into the Alberta portion of WBNP, representing the first Alberta breeding record in 63 years (Kuyt 1978). Eight pairs bred in this newly pioneered Alberta region in 1997 (Johns 1998). The WBNP/ANWR population has increased by 36.6% over the last ten years (1989-1999). Overall population growth for this population is 3.7% per year (Brian Johns pers. comm.).

The breeding range in WBNP is very restricted, although apparently suitable habitat in other areas of the park and in adjacent areas is presently unoccupied by Whooping Cranes. Lewis (1995) identified habitat quality, and subsequently, food resources, as the most important factor regulating Whooping Crane numbers. Poor chick production and low survival appear to be associated with drought conditions on the breeding grounds.

Along with perils faced during migration, factors affecting the wintering grounds at ANWR appear to be more limiting than factors affecting the breeding range at WBNP. The concentration of Whooping Cranes in the vicinity of ANWR makes them vulnerable to catastrophic events such as hurricanes or chemical spillage. One of the major concerns on these wintering grounds has focussed around the Gulf Intracoastal Waterway (GIW), which extends from Carrabelle, FL to Brownsville, TX, to protect boats from wind and high seas. Construction of this waterway in the early 1940’s caused some loss of wetland habitat. Fifteen per cent of Whooping Crane wintering habitat has been lost since the early 1940’s due to erosion from boat traffic along the GIW. It is estimated that 1.6 ha of wintering habitat per year is lost. The Army Corps of Engineers recently installed concrete slabs along portions of the GIW to reduce erosion (Halpern 1992). This project will be completed during the summer of 2000 (Stehn pers. comm.).

The heavy barge traffic along the GIW is composed largely of petrochemical products. Relatively small chemical spills have occurred in this region in the past and there is potential for catastrophic spills in the future. The security of the food base in this area is also a concern. In 1994, after a winter of low Blue Crab populations, the number of nesting attempts in WBNP dropped from 43 in 1993 to only 28 (Johns 1998).

Fall staging Whooping Cranes are sometimes found in the company of Sandhill Cranes during the fall crane hunting season in Saskatchewan. When this occurs, these sites are closed to hunting until the Whooping Cranes vacate the area. It is also possible for Whooping Cranes to be mistaken for snow geese during the fall hunting season.

Whooping Cranes do not compete with any other species for breeding territories and there is likely little competition with other species for resources in these areas. On the wintering grounds, however, cranes must share the resources of these coastal habitats with large numbers of pelicans, herons, egrets, waterfowl shorebirds, gulls, and terns. There is also competition from humans harvesting clams and crabs (Edwards et al. 1994).

There is little human disturbance on the breeding grounds since there is no access to the breeding area between April and September, except for park staff and scientists. Subsistence hunting, fishing and trapping still occurs in WBNP by local Aboriginal groups. These activities are considered an important part of the park’s cultural history and are not considered to be a threat to nesting Whooping Cranes.

The only naturally occurring population of whooping cranes breeds in WBNP. It is a relict population of a once much more widespread species. Concern has been expressed about the effects of the genetic bottleneck that occurred when the overall population dipped to 16 birds in 1941. Mirande et al. (1993) found that 87% of gene diversity was still present in wild Whooping Crane population through 1990 and 95.8% of diversity existing when the Patuxent captive flock was established still exists.

Glenn (1997) found a greater loss in mtDNA using microsatellites. Only three of nine haplotypes present in the pre-bottleneck population persists in today’s WBNP/ANWR population. The least common haplotype before the bottleneck is now the most common, therefore a genetic shift may have occurred.

A generally cherished and admired species, the whooping crane has been described as the flagship species of the North American wildlife conservation movement, symbolizing the critical status that is typical of endangered species worldwide. Whooping Cranes are a major tourist attraction in staging areas in southern Saskatchewan, and at their wintering grounds at ANWR. Lewis (1995) reported that an estimated 70,000-80,000 people visit ANWR each year, mostly in winter. In 1990-91, Whooping Crane tour boats took in $340,000 (American funds) from approximately 17,000 patrons. Eco-tourism contributes an estimated $6 million/year (American funds) of gross economic benefits to the local economy of Rockport, TX. Much of this revenue is derived from the viewing of Whooping Cranes.

The Migratory Bird Treaty of 1916 between Canada and the United States, and the Migratory Birds Convention Act in 1917, provided the first government protection for migratory birds, a category that includes the Whooping Crane. They are also protected in Canada under the National Parks Act, Canada Wildlife Act as well as by provincial/territorial wildlife acts. In addition to the Migratory Bird Treaty Act, this species is also protected in the United States by the Endangered Species Act of 1973.

The Whooping Crane was designated as endangered in 1978 by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC 1998). An endangered species is defined as one that is facing imminent danger of extirpation or extinction. The Nature Conservancy has given this species a G1 ranking, which is defined as very rare and may be especially vulnerable to extirpation. The Whooping Crane is also designated as endangered by the Manitoba Department of Natural Resources and Saskatchewan Environment and Resource Management. The Manitoba Conservation Data Centre and the Saskatchewan Conservation Data Centre assign the Whooping Crane an S1 ranking, which is defined as extremely rare and critically imperiled.

While massive human alterations to the landscape across their pre-1900 breeding range preclude their re-establishment in these areas, Whooping Cranes should continue to expand and increase their breeding range within WBNP and possibly into surrounding regions. Although the attempt to establish a breeding Whooping Crane population in the Rocky Mountains of Idaho was a failure, other recovery efforts have been successful thus far. Wild populations of this species are now more numerous than they have been in nearly a century and although the reintroduced flocks are yet to become self-sustaining, all three captive flocks are able to maintain themselves and produce offspring for release in Florida (Brian Johns and Doug Bergeson pers. comm.).

Despite this encouraging news, Whooping Cranes are still vulnerable to imminent extirpation or extinction. Conditions on the wintering range at ANWR, such as overcrowding, habitat loss and degradation, disturbance, and competition from other wildlife species and humans appear to be the most serious threats. Low recruitment, small clutch size, and delayed sexual maturity limit this species’ ability to rapidly increase their populations or recover from catastrophic events. Numerous migration hazards faced during their 4,000-km one-way migration include collisions with man-made obstructions, inclement weather, predation, and illegal hunting. The very restricted breeding and wintering areas make Whooping Cranes vulnerable to natural and human-caused catastrophic events. For these reasons, the Whooping Crane should remain classified as an endangered species.

Grus americana

Whooping Crane: Grue blanche

Occurrence in Canada : NWT, AB

Extent and Area information

· extent of occurrence (EO)(km²): 44,807 km² -area of Wood Buffalo National Park (WBNP)

· specify trend (decline, stable, increasing, unknown): stable

· are there extreme fluctuations in EO (> 1 order of magnitude)?no

· area of occupancy (AO) (km²): 6400 km² core breeding range in Wood Buffalo National Park

· specify trend (decline, stable, increasing, unknown): increasing; core breeding range is expanding into Alberta portion of the WBNP

· are there extreme fluctuations in AO (> 1 order magnitude)?no

· number of extant locations: 1

· specify trend in # locations (decline, stable, increasing, unknown): stable

· are there extreme fluctuations in # locations (>1 order of magnitude)?n.a.

· habitat trend: specify declining, stable, increasing or unknown trend in area, extent or quality of habitat: stable; breeding habitat abundant in WBNP & in neighbouring areas in AB.

Population information

· generation time (average age of parents in the population) (indicate years, months, days, etc.): several years (~10 yrs)

· number of mature individuals (capable of reproduction) in the Canadian population (or, specify a range of plausible values)

Total # birds: 183 (1988-1999)
Mature birds: 165 (1988-1999)
source: graph on pg 29
Note, effective number < 165

· total population trend: specify declining, stable, increasing or unknown trend in number of mature individuals: Increasing 36% increase over last 10 years
source: page 29-30

· if decline, % decline over the last/next 10 years or 3 generations, whichever is greater (or specify if for shorter time period)

· are there extreme fluctuations in number of mature individuals (> 1 order of magnitude)?no

· is the total population severely fragmented (most individuals found within small and relatively isolated (geographically or otherwise) populations between which there is little exchange, i.e., < 1 successful migrant / year)?Only one breeding population.

· list each population and the number of mature individuals in each: Apparently no significant population subdivision in Canada - thus just one population with 165 individuals

· specify trend in number of populations (decline, stable, increasing, unknown):stable

· are there extreme fluctuations in number of populations (>1 order of magnitude)?no

Threats

Species is vulnerable on wintering grounds in Texas – there is overcrowding, competition from other wildlife species for food, and risk of catastrophic events such as hurricanes and chemical spills. At risk of catastrophic events also on breeding grounds.

Rescue Effect (immigration from an outside source): none through natural processes

· does species exist elsewhere (in Canada or outside)?USA

· status of the outside population(s)?

G1 'Critically Imperilled'

- ABI ranking

Endangered D

- IUCN Red List

Rocky Mountain population in Idaho

4 individuals

Florida population (non migratory)

73 individuals

In captivity

104 individuals

· is immigration known or possible?not from natural source

· would immigrants be adapted to survive here?yes, for captive birds

· is there sufficient habitat for immigrants here?

-in WBNP, yes

-resources limited in the wintering range

Quantitative Analysis: none available

The author wishes to thank Brian Johns (CWS, Saskatoon) and Colleen Hyslop (COSEWIC) for providing the opportunity to prepare this report. Brian Johns supplied the required literature and reviewed the manuscript, George Gee and Doug Bergeson provided editorial comments, Dale Hjertaas (Saskatchewan Environmental Resource Management) provided assistance with critical Whooping Crane habitats in Saskatchewan, and Alan Smith (CWS, Saskatoon) provided the Whooping Crane illustration. Funding provided by the Canadian Wildlife Service, Environment Canada.

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Robert Wapple received a Bachelor of Science in biology from the University of Saskatchewan in 1996. He has had a lifelong interest in nature and environmental issues and has prepared numerous reports and articles on Saskatchewan fauna.

Appendix 1. Composition of WBNP/ANWR Whooping Crane flock, 1938-1999 from winter counts in December each year

Appendix 4. Population structures of captive Whooping Crane flocks at Patuxent Wildlife Research Center (PWRC), International Crane Foundation (ICF), and Calgary Zoo (beginning in 1993, 20-30 fledged young per year were shipped to Florida)