Chapter 14 - Habitat Use by the Reintroduced Eastern Migratory Population of Whooping Cranes

Abstract

It is difficult to predict how reintroduced Whooping Cranes will use habitats in regions where they have been extirpated for over a century. Knowledge of habitat use in the core, historical nesting area of the upper tallgrass prairie is limited and it is likely that high quality habitats used by Whooping Cranes in the late 1800s have been substantially altered in the highly developed and fragmented landscape of the mid-western United States. Here we provide new habitat use data in the upper tallgrass prairie nesting area that reintroduced Whooping Cranes of the Eastern Migratory Population (EMP) have used during summer (predominantly central Wisconsin). We also summarize habitat use data for the EMP during migration and winter (in the southeastern part of the U.S.) and suggest how these data might guide future reintroduction efforts. Habitat composition and use for territorial and nonterritorial cranes in summer were determined 2011–14 by tracking cranes using very-high frequency transmitters and various satellite-based transmitters. Home range of eight territorial birds averaged 4.58 (SE = 1.68, range: 0.78–14.64) km2 in summer (April–September) while home ranges of nine nonterritorial birds averaged 7,750 (SE = 5,564) km2 during their second year (beginning January 1 following their hatch year) and averaged 415 (SE = 414, n = 4) km2 during their fourth year, April–September. During the day, 75% of territorial Whooping Cranes locations were found in wetlands during summer even though wetlands comprised 57% of the territory habitat composition. During remigial molt (synchronous molt of flight feathers rendering the bird flightless), however, 92% of recorded locations for territorial (n = 2 pair) and nonterritorial (n = 2) Whooping Cranes were in wetlands. Home range size during the remigial molt for two pairs and two nonterritorial birds combined averaged 0.45 (SE = 0.12, range: 0.29–0.58) km2, smaller than pre- or postmolt home range averages of 51.67 (SE = 77.44) km2 and 82.90 (SE = 100.44) km2 respectively (Pairwise t-test, P < 0.02). Over 13 years, the winter distribution of Whooping Cranes in the EMP has shifted north dramatically and wetland use in winter declined from 52.4% (2004–2006) to 32% (2014–2015). Wetlands were used the least during migration (18.4%). In comparison to the 4,600 km2 Glacial Lake Wisconsin Sand Plain that EMP nests were located in, natal dispersal distances were short so wetland selection occurred among a relatively small variety of wetlands. A second release location within Wisconsin was established with the goal of more quickly dispersing Whooping Cranes outside the Glacial Lake Wisconsin Sand Plain to areas without ornithophilic black flies (that limit hatch success) and to areas that contain more diverse wetlands than found in the sand plain alone. Facilitated dispersion might more quickly reveal new interactions between Whooping Cranes and novel wetland habitats that can inform management needs of the EMP and of crane reintroduction more generally.