North American Crane Working Group

 

Date of this Version

2001

Document Type

Article

Citation

Austin, Jane E., Ball, I. J., and Henry, Adonia R. Nesting ecology of sandhill cranes at Grays Lake, Idaho. In: Ellis, David H., ed., Proceedings of the Eighth North American Crane Workshop, 11–14 January 2000, Albuquerque, New Mexico (Seattle, Wash: North American Crane Working Group, 2001), p. 221.

Comments

Reproduced by permission of the North American Crane Working Group (NACWG).

Abstract

We examined the nesting ecology of greater sandhill cranes (Grus canadensis tabida) at Grays Lake, Idaho during 1997-99 to detennine the effects of nest-site characteristics and land use on crane nest success. These are preliminary results from 3 years of a 4-year study. Crane nests were located in portions of the Grays Lake basin from early May through late June each year (n = 131 in 1997; n = 131 in 1998; n = 143 in 1999). Apparent nest success varied among years (54% in 1997, 71% in 1998, and 53% in 1999; overall average of 59%). We estimate that 10% of nests found in 1999 were renests. Most crane nests were located in baltic rush/spikerush (Juncus balticus/Eleocharis sp.; 46% of nests), semi-wet meadow (19%), and bulrush/cattail (Scirpus sp./Typha sp.; 19%) plant communities; 62% of nests during early May were in:;; 12 cm of water. As indicated by plant community, water depths at nests, and nest isolation rankings, nest success tended to be higher where nests were in relatively deep water (ca. >40 em) and were relatively isolated from access by mammalian predators. Nest success rates during 1997-99 were lower than those recorded in 1950-51 (90%, n = 107; Steel 1952) and 1970-71 (78%, n = 308; Drewien 1973). A variety offactors likely contribute to lower nest success, including changing predator communities over the past 30-40 years. Differences among years in our study may be affected by changing availability of alternate prey. Small mammal populations and crane nest success were the highest in 1998. Water-level management, relating to cranes and other waterbird populations, plant communities, and ecosystem function, is an emerging issue for land managers in the Grays Lake basin.