|Scientific Name:||Grus americana|
|Species Authority:||(Linnaeus, 1758)|
|Red List Category & Criteria:||Endangered D ver 3.1|
|Reviewer/s:||Butchart, S. & Symes, A.|
|Contributor/s:||Archibald, G., Cannon, J., Hook, J., Johns, B., Reid, M., Stehn, H. & Stehn, T.|
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.
|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, and only 15 adults in 1938 (CWS and USFWS 2007). The three wild populations totalled 385 in December 2008 (Stehn 2008), 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 to Aransas National Wildlife Refuge, Texas, USA (Meine and Archibald 1996). It totalled 266 birds in 2007 (T. Stehn, in litt. 2007), with 65 active nests (B. Johns, in litt. 2007), followed by a record 270 birds in spring 2008 (Archibald 2009), dropping to 247 in spring 2009 (Archibald 2009) following a drought in the wintering quarters in Texas. A reintroduced, non-migratory flock in Florida numbered c.41 individuals in 2007, with additional releases put on hold (T. Stehn, in litt. 2007). A reintroduced flock migrates between Wisconsin and Florida, numbering 75 birds in 2007 (T. Stehn, in litt. 2007), increasing to c.90 birds in 2008 (Stehn 2008). A new reintroduced flock comprising 10 juveniles was established in south-western Louisiana in early 2011 (Zimorski 2011). The first wild born chick fledged in Wisconsin and migrated successfully in 2006 (T. Stehn, in litt. 2007) and another wild born chick hatched in June 2009 (Garland and Peterson 2009). Captive flocks totalled 151 birds in 2008 at 5 breeding centres and 6 display facilities in the USA and Canada (Stehn 2008). Overall, the global wild population has increased in numbers since 1938.|
Native:Canada; United States
|Range Map:||Click here to open the map viewer and explore range.|
|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 50-249 mature individuals. This equates to 75-374 individuals in total, rounded here to 70-400 individuals.|
|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 (Archibald and Meine 1996, Timoney 1999). Eggs are laid from late April to mid-May (Archibald and Meine 1996). It winters in coastal brackish wetlands.|
|Systems:||Terrestrial; Freshwater; Marine|
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 (Lewis 1997). Powerline markers can reduce collisions by 50-80% (T Stehn and T. Wassenich in press), but most powerlines remain unmarked and collision is a major and growing problem (Lewis 1997). 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 (T. Stehn, in litt. 2007). In 2007, a lightning strike during severe weather killed 17 captive-bred young birds being housed in a top-netted release pen in Florida (T. Stehn, in litt. 2007). Eggs and pre-fledged chicks are subject to predation by various birds and mammals including raven, bald eagle, wolf, black bear and lynx (CWS and USFWS 2007). Drought is a serious threat to the species as it is detrimental to all habitats utilized year around, but is especially harmful by dramatically decreasing production on the nesting grounds (RENEW report 1999). 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 (Archibold 2009). Coastal development, sea level rise, climate change, chemical spills, reduced fresh water inflows, and human disturbance threaten the Texan wintering grounds (RENEW report 1999, CWS and USFWS 2007). Aransas National Wildlife Refuge (NWR) can only support a maximum of 500 birds through the winter (T. Stehn, in litt. 2007) 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 (M. Reid. in litt. 2003). 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 (T. Stehn, in litt. 2007). There are currently concerns about oil spills and river inflows to Aransas NWR (CWS and USFWS 2007), as well as reduced water flows in the central Platte River Ralley, Nebraska, a key stopover site for migrating Whooping Cranes (Chavez-Ramirez 2008). The spread of West Nile virus and avian influenza in the future may pose a threat to the species (Chu et al. 2003). The long-term effects of genetic drift after a severe population bottleneck are unknown (Glenn et al. 1999) There have been incidences of illegal shooting of the species in Alabama and Indiana (MacKenzie 2011, Shaw 2011).
Conservation Actions Underway
CITES Appendix I and II. CMS Appendix II. There is an international recovery plan (CWS and USFWS 2007) focusing on increasing the size of the natural flock, establishing additional wild populations through experimental releases, teaching captive-bred birds to migrate (Lewis 1995, Line 1995, RENEW report 1999), 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 (Putman 2007). In the past, recruitment was increased in certain years in Canada by removal of a single egg from two-egg broods (Boyce et al. 2005); the removed eggs are used to supplement captive flocks, but the overall impact of the egg pickup program is largely undetermined (CWS and USFWS 2007). An eastern migratory population which mostly winters in Florida and summers in Wisconsin has now been established but only two instances of successful breeding has been recorded so far (J.Hook in litt. 2007, Garland and Peterson 2009). 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. Due to the loss of 17 captive-bred cranes in a severe storm in 2007, the ultralight-led juveniles from Necedah NWR are now split into two wintering groups, with half spending the winter at Chassahowitzka NWR and half at the St. Marks NWR along Florida's Gulf Coast.
Conservation Actions Proposed
Survey and monitor breeding grounds to determine nesting effort (RENEW report 1999), and the wintering grounds to determine flock size. Research food resources and high mortality (RENEW report 1999). Alleviate threats in Texas. Reduce powerline collisions. Continue establishment of two further self-sustaining populations (Meine and Archibald 1996, RENEW report 1999). Continue raising cranes for reintroduction (RENEW report 1999).
|Citation:||BirdLife International 2012. Grus americana. In: IUCN 2012. IUCN Red List of Threatened Species. Version 2012.2. <www.iucnredlist.org>. Downloaded on 18 June 2013.|
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