Abstract
Preserving avian flyway connectivity has long been challenged by our capacity to meaningfully quantify continental habitat dynamics and bird movements at temporal and spatial scales underlying long-distance migrations. Waterbirds migrating hundreds or thousands of kilometers depend on networks of wetland stopover sites to rest and refuel. Entire populations may rely on discrete wetland habitats, particularly in arid landscapes where the loss of limited stopover options can have disproportionately high impacts on migratory cost. Here, we examine flyway connectivity in water-limited ecosystems of western North America using 108 GPS tagged greater sandhill cranes. Bird movements were used to reconstruct wetland stopover networks across three geographically unique sub-populations spanning 12 U.S.–Mexican states and Canadian provinces. Networks were monitored with remote sensing to identify long-term (1988–2019) trends in wetland and agricultural resources supporting migration and evaluated using network theory and centrality metrics as a measure of stopover site importance to flyway connectivity. Sandhill crane space use was analyzed in stopover locations to identify important ownership and landscape factors structuring bird distributions. Migratory efficiency was the primary mechanism underpinning network function. A small number of key stopover sites important to minimizing movement cost between summering and wintering locations were essential to preserving flyway connectivity. Localized efficiencies were apparent in stopover landscapes given prioritization of space use by birds where the proximity of agricultural food resources and flooded wetlands minimized daily movements. Model depictions showing wetland declines from 16% to 18% likely reflect a new normal in landscape drying that could decouple agriculture–waterbird relationships as water scarcity intensifies. Sustaining network resilience will require conservation strategies to balance water allocations preserving agricultural and wetlands on private lands that accounted for 67–96% of habitat use. Study outcomes provide new perspectives of agroecological relationships supporting continental waterbird migration needed to prioritize conservation of landscapes vital to maintaining flyway connectivity.
| Original language | English |
|---|---|
| Article number | e03543 |
| Journal | Ecosphere |
| Volume | 12 |
| Issue number | 6 |
| DOIs | |
| State | Published - Jun 2021 |
Funding
We thank the late John P. Taylor, (former) Senior Wildlife Biologist, Bosque del Apache National Wildlife Refuge, for his ongoing inspiration and original vision that helped to make this work a reality. We too thank Idaho Department of Fish and Game and the U.S. Fish and Wildlife Service Migratory Bird Program for funding that made this work possible. We recognize Colorado Parks and Wildlife, Oregon Department Fish and Wildlife, Montana Fish Wildlife and Parks, New Mexico Game and Fish, and the U.S. Fish and Wildlife Service Migratory Bird Program—Upper Colorado Basin Region for their support and coordination of sandhill crane capture and GPS deployment. Views in this manuscript from United States Fish and Wildlife Service authors are their own and do not necessarily represent the views of the agency. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
| Funders |
|---|
| Montana Fish Wildlife and Parks |
| New Mexico Department of Game and Fish |
| California Department of Fish and Wildlife |
| Idaho Department of Fish and Game |
Keywords
- North America
- agricultural irrigation
- agroecology
- flyway connectivity
- migratory networks
- network analysis
- sandhill crane
- water scarcity
- waterbirds
- wetlands
