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. For the wild population winter mortality appears to be correlated with blue crab availability at the Aransas National Wildlife Refuge, with higher mortality in years of lower crab abundance (Pugesek et al. 2013). The natural population are known to feed on beetles, crabs/crayfish, vegetation, seeds, molluscs and other vertebrates with introduced populations thought to feed on largely the same sources alongside benthic invertebrates, and amphibians and reptiles (Dinets 2016, Caven et al. 2019, Neri 2020). Stopover sites typically comprise wetland land-cover types and lowland grasslands (Baasch et al. 2019).

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). As of 2016/17 there are four wild populations totalling c.483 individuals, including three 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, U.S.A. (Meine and Archibald 1996) (although in 2011-2012 they were observed up to hundreds of kilometres away from here [Wright et al. 2014]). 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. As of winter 2015-2016 this population contained 329 individuals, including 122 adult pairs (Butler and Harrell 2016). A reintroduced, non-migratory flock in Florida numbered c.41 individuals in 2007, but due to lack of reproductive success and high mortality rates this project was discontinued in 2007 (T. Stehn in litt. 2007, W. Harrell in litt. 2016). This population contains a dozen or less individuals (H. Ray in litt. 2016). A separate reintroduced flock migrates between Wisconsin and south-eastern USA. This population numbered 75 birds in 2007 (T. Stehn in litt. 2007), increasing to c.90 birds in 2008 (Stehn 2008), and as of January 2017 the population numbers 104 individuals (Whooping Crane Eastern Partnership 2017). 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). A new reintroduced flock comprising 10 juveniles was established in south-western Louisiana in early 2011 (Zimorski 2011), and this population now numbers 38 individuals (Department of Wildlife and Fisheries State of Louisiana 2017, H. Ray and W. Harrell in litt. 2016). 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.

Conservation Actions Underway
CITES Appendix I and II. CMS Appendix II. 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 (Beilfuss 2013). 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 four instances of successful breeding has been recorded so far (J. Hook in litt. 2007, Garland and Peterson 2009, H. Ray in litt. 2016). 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. 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 (Harrell and Bidwell 2015).

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, and take into account potential migration stopover sights when planning potential developments, such as wind farms (see Belaire et al. 2013). Protect and enhance wetlands stopover sites (Baasch et al. 2019). Continue establishment of further self-sustaining populations (Meine and Archibald 1996, RENEW report 1999). Continue raising cranes for reintroduction (RENEW report 1999).