Abstract
Changes in ecological conditions can induce changes in behavior and demography of wild organisms, which in turn may influence population dynamics. Black brant (Branta bernicla nigricans) nesting in colonies on the Yukon–Kuskokwim Delta (YKD) in western Alaska have declined substantially (~50%) since the turn of the century. Black brant are herbivores that rely heavily on Carex subspathacea (Hoppner's sedge) during growth and development. The availability of C. subspathacea affects gosling growth rates, which subsequently affect pre- and postfledging survival, as well as size and breeding probability as an adult. We predicted that long-term declines in C. subspathacea have affected gosling growth rates, despite the potential of behavior to buffer changes in food availability during brood rearing. We used Bayesian hierarchical mixed-effects models to examine long-term (1987–2015) shifts in brant behavior during brood rearing, forage availability, and gosling growth rates at the Tutakoke River colony. We showed that locomotion behaviors have increased (β = 0.05, 95% CRI: 0.032–0.068) while resting behaviors have decreased (β = −0.024, 95% CRI: −0.041 to −0.007), potentially in response to long-term shifts in forage availability and brood density. Concurrently, gosling growth rates have decreased substantially (β = −0.100, 95% CRI: −0.191 to −0.016) despite shifts in behavior, mirroring long-term declines in the abundance of C. subspathacea (β = −0.191, 95% CRI: −0.355 to −0.032). These results have important implications for individual fitness and population viability, where shifts in gosling behavior putatively fail to mitigate long-term declines in forage availability.
| Original language | English |
|---|---|
| Pages (from-to) | 5281-5291 |
| Number of pages | 11 |
| Journal | Ecology and Evolution |
| Volume | 9 |
| Issue number | 9 |
| DOIs | |
| State | Published - May 2019 |
Funding
The authors thank the 200+ technicians, volunteers, and graduate students who collected data at the Tutakoke River brant colony during this study. Data were collected on the Yukon Delta National Wildlife Refuge. We thank J. Pearce who provided helpful com‐ ments on earlier versions of this manuscript. M. Anthony and T. Day assisted with aerial imagery habitat classification. Data used in this study are publicly available via the U.S. Geological Survey Alaska Science Center (Uher‐Koch 2018). Field work at the Tutakoke River brant colony was funded by the Alaska Science Center, U. S. Geological Survey, Migratory Bird Management Region 7, U. S. Fish and Wildlife Service, Ducks Unlimited, the Morro Bay Brant Group, Phil Jebbia (in memory of Marnie Shepherd), and The National Science Foundation (OPP 9214970, DEB 9815383, OPP 9985931, OPP 0196406, DEB 0743152, DEB 1252656). T. V. Riecke was also supported by the Bonnycastle Fellowship in Wetland and Waterfowl Biology from the Institute for Wetland and Waterfowl Research. The Alaska Landscape Conservation Cooperative pro‐ vided funding. Any use of trade, firm, or product names is for de‐ scriptive purposes only and does not imply endorsement by the U.S. Government. Institute for Wetland and Waterfowl Research, Ducks Unlimited Canada; Morro Bay Brant Group; Western Alaska Landscape Conservation Cooperative; National Science Foundation, Grant/Award Number: DEB 0743152, DEB 1252656, DEB 9815383, OPP 0196406, OPP 9214970 and OPP 9985931; Phil Jebbia; U.S. Fish and Wildlife Service; U. S. Geological Survey; Alaska Science Center; Migratory Bird Management Region 7; Ducks Unlimited The authors thank the 200+ technicians, volunteers, and graduate students who collected data at the Tutakoke River brant colony during this study. Data were collected on the Yukon Delta National Wildlife Refuge. We thank J. Pearce who provided helpful comments on earlier versions of this manuscript. M. Anthony and T. Day assisted with aerial imagery habitat classification. Data used in this study are publicly available via the U.S. Geological Survey Alaska Science Center (Uher-Koch 2018). Field work at the Tutakoke River brant colony was funded by the Alaska Science Center, U. S. Geological Survey, Migratory Bird Management Region 7, U. S. Fish and Wildlife Service, Ducks Unlimited, the Morro Bay Brant Group, Phil Jebbia (in memory of Marnie Shepherd), and The National Science Foundation (OPP 9214970, DEB 9815383, OPP 9985931, OPP 0196406, DEB 0743152, DEB 1252656). T. V. Riecke was also supported by the Bonnycastle Fellowship in Wetland and Waterfowl Biology from the Institute for Wetland and Waterfowl Research. The Alaska Landscape Conservation Cooperative provided funding. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
| Funders | Funder number |
|---|---|
| Ducks Unlimited | |
| DEB 1252656, DEB 0743152, OPP 0196406, OPP 9214970, OPP 9985931, DEB 9815383 | |
Keywords
- Carex subspathacea
- behavior
- black brant
- growth
- population dynamics
- survival