Grus americana

Taxonomy

Assessment Information

Geographic Range

Population

Habitat and Ecology

Threats

Conservation Actions

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Taxonomy [top]

Kingdom	Phylum	Class	Order	Family
ANIMALIA	CHORDATA	AVES	GRUIFORMES	GRUIDAE

Scientific Name:

Grus americana

Species Authority:

(Linnaeus, 1758)

Common Name/s:

English	–	Whooping Crane
Spanish	–	Grulla Americana, Grulla Gritona, Grulla Trompetera

Assessment Information [top]

Red List Category & Criteria:

Endangered D ver 3.1

Year Assessed:

2008

Assessor/s:

BirdLife International

Reviewer/s:

Bird, J., Butchart, S.

Contributor/s:

Archibald, G., Stehn, H., Reid, B., Stehn, T., Reid, H.

Justification:
This species is listed as Endangered because it has an extremely small population. However, the conservation status of the species is improving, with not only increases in the natural wild population but also establishment of two reintroduced flocks that may become self-sustaining. If the number of mature individuals continues to increase, this species may merit downlisting to Vulnerable.

History:

2006	–	Endangered
2004	–	Endangered
2000	–	Endangered
1996	–	Endangered
1994	–	Endangered

Geographic Range [top]

Range Description:	Grus americana declined from historic estimates of 10,000+ prior to European settlement of North America to 1,300-1,400 birds by 1870 to 15 adults in 1938². The three wild populations totalled 382³ in December 2007, including two reintroduced populations in the eastern U.S. that are not yet self-sustaining. The only natural wild population breeds in Wood Buffalo National Park, on the border of Northwest Territories and Alberta, Canada, and winters at and near Aransas National Wildlife Refuge, Texas, USA⁵. It totalled a record 266 birds in 2007³, with 65 active nests¹⁴. A reintroduced, non-migratory flock in Florida numbered c.41 individuals in 2007, with additional releases put on hold³. A reintroduced flock migrates between Wisconsin and Florida, numbering 75 birds in 2007³. The first wild born chick fledged in Wisconsin and migrated successfully in 2006³. Captive flocks totalled 148 birds in 2007 at 5 breeding centers and 6 display facilities in the USA and Canada³. The global wild population has increased in numbers for the past 68 years.
Countries:	Native: Canada; United States
Range Map:	Click here to open the map viewer and explore range.

Population [top]

Population:	The total population in the wild numbers 382 individuals (T. Stehn in litt. 2007). However, the only self-sustaining population breeding in Northwest Territories/Alberta, Canada and wintering in Texas, USA numbers 266 individuals, fewer than 250 of which are mature. Hence we retain a precautionary estimate of <250 mature individuals.
Population Trend:	Increasing

Habitat and Ecology [top]

Habitat and Ecology:	It breeds in prairie wetlands, preferring small, shallow lakes and ponds, willow communities, marshes, mudflats and perhaps sedge meadows, but this may be atypical considering its historical range^1,11. Eggs are laid from late April to mid-May¹. It winters in coastal brackish wetlands.
Systems:	Terrestrial; Freshwater; Marine

Threats [top]

Major Threat(s):	Over-hunting, habitat conversion and human disturbance were the main causes of the decline. Currently, the most significant known cause of death or injury to fledglings is collision with powerlines⁷, and in 2007 a lightning strike during severe weather killed 17 young birds being housed in a top-netted release pen in Flordia³. Pre-fledged eggs and chicks are subject to predation (raven, bald eagle, wolf, black bear, lynx)². Powerline markers can reduce collisions by 50-80%¹⁶, but most power lines remain unmarked and collision is a major and growing problem⁷. 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 power lines³. Drought is detrimental to all habitats utilized year around, but is especially harmful by dramatically lowering production on the nesting grounds⁹. Coastal development, sea level rise, climate change, chemical spills, reduced fresh water inflows, and human disturbance threaten the Texan wintering grounds^2,9. Aransas NWR can only support a maximum of 500 birds through the winter³ 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 habitat¹³. Much of the currently unoccupied crane habitat at Aransas where the cranes would be expected to expand into is being threatened with construction of homes³. There are currently concerns about oil spills and about river inflows to Aransas National Wildlife Refuge², and the spread of West Nile virus and avian influenza in the future may pose a threat to the species¹⁵. The long-term effects of genetic drift after a severe population bottleneck are unknown⁴.

Major Threat(s):

Over-hunting, habitat conversion and human disturbance were the main causes of the decline. Currently, the most significant known cause of death or injury to fledglings is collision with powerlines⁷, and in 2007 a lightning strike during severe weather killed 17 young birds being housed in a top-netted release pen in Flordia³. Pre-fledged eggs and chicks are subject to predation (raven, bald eagle, wolf, black bear, lynx)². Powerline markers can reduce collisions by 50-80%¹⁶, but most power lines remain unmarked and collision is a major and growing problem⁷. 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 power lines³. Drought is detrimental to all habitats utilized year around, but is especially harmful by dramatically lowering production on the nesting grounds⁹. Coastal development, sea level rise, climate change, chemical spills, reduced fresh water inflows, and human disturbance threaten the Texan wintering grounds^2,9. Aransas NWR can only support a maximum of 500 birds through the winter³ 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 habitat¹³. Much of the currently unoccupied crane habitat at Aransas where the cranes would be expected to expand into is being threatened with construction of homes³. There are currently concerns about oil spills and about river inflows to Aransas National Wildlife Refuge², and the spread of West Nile virus and avian influenza in the future may pose a threat to the species¹⁵. The long-term effects of genetic drift after a severe population bottleneck are unknown⁴.

Conservation Actions [top]

Conservation Actions:	Conservation Actions Underway CITES Appendix I and II. CMS Appendix II. There is an international recovery plan² focusing on increasing the size of the natural flock, establishing additional wild populations through experimental releases, teaching captive-bred birds to migrate^6,8,9, and increasing the captive population for experimental releases and ecological research. Considerable progress has been made in improving the genetic health of captive stock and breeding under-represented genetic strains, but delayed reproduction in captivity and the failure of some pairs to breed at all has slowed down progress¹⁷. In the past, recruitment was increased in certain years in Canada by removal of a single egg from two-egg broods¹²; the removed eggs are used to supplement captive flocks, but the overall impact of the egg pickup program is largely undetermined². An eastern migratory population which mostly winters in Florida and summers in Wisconsin has now been established but only one instance of successful breeding has been recorded so far¹⁸. If passed, the Crane Conservation Act (H.R. 1771 and S. 1048) 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 Whooping Cranes. Conservation Actions Proposed Survey and monitor breeding grounds to determine nesting effort⁹, and the wintering grounds to determine flock size. Research food resources and high mortality⁹. Alleviate threats in Texas. Reduce powerline collisions. Continue establishment of two further self-sustaining populations^5,9. Continue raising cranes for reintroduction⁹.

Conservation Actions:

Conservation Actions Underway
CITES Appendix I and II. CMS Appendix II. There is an international recovery plan² focusing on increasing the size of the natural flock, establishing additional wild populations through experimental releases, teaching captive-bred birds to migrate^6,8,9, and increasing the captive population for experimental releases and ecological research. Considerable progress has been made in improving the genetic health of captive stock and breeding under-represented genetic strains, but delayed reproduction in captivity and the failure of some pairs to breed at all has slowed down progress¹⁷. In the past, recruitment was increased in certain years in Canada by removal of a single egg from two-egg broods¹²; the removed eggs are used to supplement captive flocks, but the overall impact of the egg pickup program is largely undetermined². An eastern migratory population which mostly winters in Florida and summers in Wisconsin has now been established but only one instance of successful breeding has been recorded so far¹⁸. If passed, the Crane Conservation Act (H.R. 1771 and S. 1048) 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 Whooping Cranes.

Conservation Actions Proposed
Survey and monitor breeding grounds to determine nesting effort⁹, and the wintering grounds to determine flock size. Research food resources and high mortality⁹. Alleviate threats in Texas. Reduce powerline collisions. Continue establishment of two further self-sustaining populations^5,9. Continue raising cranes for reintroduction⁹.

Citation:	BirdLife International 2008. Grus americana. In: IUCN 2011. IUCN Red List of Threatened Species. Version 2011.2. <www.iucnredlist.org>. Downloaded on 08 February 2012.
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