in recently harvested grain fields, eating insects 

 and wasted grain, especially corn. 



SHELTER REQUIREMENTS 



Not known. 



NESTING OR BEDDING 



Nests, 15 to 60 cm above the water, are made 

 of rushes [Scirpus validus), sedge [Carex sp.), or 

 cattail {Typha latifolia). Nests are restricted to 

 areas with limited terrestrial accessibility, and are 

 not usually reused in subsequent years; but a new 

 nest is generally built in the same area (Kuyt 

 1976a). Allen (1952) describes in detail nests and 

 their construction in historic breeding localities. 



RITUAL REQUIREMENTS 



Premigration behavior in December or January 

 includes a restless shifting of habitual winter terri- 

 tories, increasing in frequency of dancing displays 

 and circling flights which eventually result in 

 actual movement northward (Allen 1952, WCRT 

 1977). Generally the cranes leave Aransas National 

 Wildlife Refuge between the end of March and 

 the middle of April. They arrive at Wood Buffalo 

 National Park 18 to 28 days later (Allen 1956, 

 WCRT 1977). 



OTHER CRITICAL ENVIRONMENTAL 

 REQUIREMENTS 



Climate plays a vital role in whooping crane 

 survival. Extreme dryness has little effect on nest- 

 ing success, but can force young and parents to 

 travel farther in search of food (Novakowski 1966) 

 and render nesting areas more accessible to terres- 

 trial predators (E. Kuyt, personal communica- 

 tion). Departure of cranes on spring migration is 

 assisted by strong prevailing southeast winds 

 (WCRT 1977). However, a hurricane or large 

 storm could interfere with migration (Allen 1952). 



The average territory size is about 162 ha on 

 the wintering ground. In tlie Sass River area, 

 Wood Buffalo National Park, the radii of the nest- 

 ing territories average 0.9 km. Rarely, however, 

 are nests of two different pairs closer than 1.3 

 km, and when they are closer, nesting success is 

 below average (Kuyt 1976a). 



POPULATION NUMBERS AND TRENDS 



The numbers have increased since a low of 21 

 birds in 1941 -1942. The 1977 count of whooping 

 cranes was 75 birds in the wild (Aransas Refuge - 

 Wood Buffalo National Park had 69 birds, and 

 experimental Rocky Mountain flock had 6) and 



27 in captivity (Patuxent Wildlife Research Center 

 had 22; International Crane Foundation, 3; and 

 San Antonio Zoo, Texas, 2) (WCRT 1977). 



The potential for population growth in the 

 wild is quite low for many reasons (Stevenson 

 and Griffith 1946). Major reasons are that only 

 one young survives and there is high juvenile 

 mortality during migration. Erickson (1961) 

 suggests that although numbers have increased, 

 there has not been an increase in rate of annual 

 production per breeding pair. Thus, while the 

 average annual production per pair has remained 

 essentially the same, an increasing proportion of 

 the older birds is returning to Aransas without 

 progeny. Novakowski (1966) also suggests that 

 early separation of young from adults during 

 spring migration may account for high losses of 

 young of the year. 



Allen (1952) estimated that the historical 

 (1870) population was about 1,500 birds. 



REPRODUCTION 



Usually two, smooth, buff eggs with dark 

 blotches are layed in late April or early May. The 

 incubation period is 29 days. Incubation is shared 

 by both parents, with one parent generally inclin- 

 ed to spend more time on the nest (Allen 1952). 

 Parents and young leave the nest site 2 to 3 days 

 after hatching, and spend the summer traveling 

 from pond to pond feeding (E. Kuyt, personal 

 communication). The family unit is maintained 

 through the winter, with the young gradually 

 gaining more independence. Just before the migra- 

 tion, the parents begin to drive the young away, 

 but do not separate entirely until enroute to the 

 nesting grounds (Allen 1952, Novakowski 1966). 



MANAGEMENT AND CONSERVATION 



Early accounts of a superabundance of 

 whooping cranes probably caused a delay in rec- 

 ognizing and responding to the decline in popula- 

 tion. Many people probably misidentified the 

 more numerous sandhill crane (Allen 1952). 



Efforts to prevent whooping crane extinction 

 have been considerable and have succeeded mar- 

 ginally in increasing the total numbers in the wild. 

 The sequence of events is detailed in Allen (1952) 

 and WCRT (1977). 



The Migratory Bird Act of 1918 provided 

 legal protection of migratory birds and paved the 

 way for cooperation in whooping crane manage- 

 ment between the United States and Canada. 

 Aransas National Wildlife Refuge was established 

 in 1937 to protect whooping cranes, waterfowl. 



