Spring Migration Ecology of the Mid-Continent Sandhill Crane Population with an Emphasis on Use of the Central Platte River Valley, Nebraska

• Main Authors: Krapu, Gary L., Brandt, David A., Kinzel, Paul J., Pearse, Aaron T.
• Format: Text
• Language: unknown
• Published: DigitalCommons@University of Nebraska - Lincoln 2014
• Subjects: body mass; Central Platte River Valley (CPRV); fat reserves; food habits; Grus canadensis; habitat use; Mid- Continent Population (MCP); migration chronology; roost-site use; sandhill crane; Saskatchewan; satellite telemetry; spring staging areas; subspecies; subpopulations; time budgets; Nunavut; Canada; Alaska; Siberia
• Online Access: https://digitalcommons.unl.edu/usgsnpwrc/289; https://digitalcommons.unl.edu/context/usgsnpwrc/article/1289/viewcontent/Krapu_WM_2014_Spring_Migration_Ecology.pdf

We conducted a 10-year study (1998–2007) of the Mid-Continent Population (MCP) of sandhill cranes (Grus canadensis) to identify spring-migration corridors, locations of major stopovers, and migration chronology by crane breeding affiliation (western Alaska–Siberia [WA–S], northern Canada–Nunavut [NC–N], west-central Canada–Alaska [WC–A], and east-central Canada–Minnesota [EC–M]). In the Central Platte River Valley (CPRV) of Nebraska, we evaluated factors influencing staging chronology, food habits, fat storage, and habitat use of sandhill cranes. We compared our findings to results from the Platte River Ecology Study conducted during 1978–1980. We determined spring migration corridors used by the breeding affiliations (designated subpopulations for management purposes) by monitoring 169 cranes marked with platform transmitter terminals (PTTs). We also marked and monitored 456 cranes in the CPRV with very high frequency (VHF) transmitters to evaluate length and pattern of stay, habitat use, and movements. An estimated 42% and 58% of cranes staging in the CPRV were greater sandhill cranes (G. c. tabida) and lesser sandhill cranes (G. c. canadensis), and they stayed for an average of 20 and 25 days (2000–2007), respectively. Cranes from the WA–S, NC–N, WC–A, and EC–M affiliations spent an average of 72, 77, 52, and 53 days, respectively, in spring migration of which 28, 23, 24, and 18 days occurred in the CPRV. The majority of the WA–S subpopulation settled in the CPRV apparently because of inadequate habitat to support more birds upstream, although WA–S cranes accounted for >90% of birds staging in the North Platte River Valley. Crane staging duration in the CPRV was negatively correlated with arrival dates; 92% of cranes stayed >7 days. A program of annual mechanical removal of mature stands of woody growth and seedlings that began in the early 1980s primarily in the main channel of the Platte River has allowed distribution of crane roosts to remain relatively stable over the past 2 decades. Most cranes ...