The objective of our study was to compare winter movement patterns of sympatric greater and lesser sandhill cranes (Grus canadensis tabida and G. c. canadensis) wintering in the Sacramento-San Joaquin Delta region of California (Delta). We marked 31 greaters and 45 lessers with VHF radios and recorded their roosting and feeding locations throughout the wintering periods in 2007/08 and 2008/09. Ten of the lessers were also marked with platform terminal transmitters and tracked via the Argos Satellite System. Compared to lessers, locations of greaters were much more predictable. Greaters showed strong fidelity to wintering sites and moved between discrete wintering areas less frequently. During the second year of our study, 90% of the [...]
Summary
The objective of our study was to compare winter movement patterns of sympatric greater and lesser sandhill cranes (Grus canadensis tabida and G. c. canadensis) wintering in the Sacramento-San Joaquin Delta region of California (Delta). We marked 31 greaters and 45 lessers with VHF radios and recorded their roosting and feeding locations throughout the wintering periods in 2007/08 and 2008/09. Ten of the lessers were also marked with platform terminal transmitters and tracked via the Argos Satellite System. Compared to lessers, locations of greaters were much more predictable. Greaters showed strong fidelity to wintering sites and moved between discrete wintering areas less frequently. During the second year of our study, 90% of the greaters returned to the study area, compared to 69% of the lessers. Only two greaters (7%) were located in more than one discrete wintering area, compared to 40% of the lessers. Average flight distances from night roost sites to feeding areas were lower for greaters than for lessers and consequently, winter home range sizes were smaller for greaters. These results have application for conservation of wintering cranes at a landscape scale and indicate that habitat protection and mitigation for the state-threatened greater sandhill crane must occur very close to existing use areas to be successful.
