Table 1 A priori hypotheses for variables affecting natal dispersal and interannual adult breeding movement distances
Explanatory variable | Age class | Type | A priori hypothesis |
|---|---|---|---|
Estimated hatch date | Natal | Individual | Individuals hatched later in the breeding season will disperse shorter distances |
Nest initiation date at settled site | Adult | Reproductive success | Individuals will start nests later after longer breeding dispersal movements |
Previous or natal habitat type | Both | Habitat | Individuals hatched on or previously bred on reservoirs will disperse longer distances |
Settled habitat type | Both | Habitat | Individuals settling on river habitat will move the shortest distances |
Available habitat index at previous or natal site | Both | Habitat | When more habitat is available at the previous or natal site, individuals will move shorter distances |
Available habitat index at settled site | Both | Habitat | When more habitat is available at the settling site, individuals will move farther distances |
Chick density | Natal | Social | Sites with high densities of chicks will have increased natal dispersal distances |
Adult density at previous site | Adult | Social | Sites with high densities of adults will have increased movement distances |
Adult density at settled site | Both | Social | Individuals will move farther distances to nest with more conspecifics |
Mate fidelity at settled nest | Adult | Individual | Retaining a mate between consecutive nesting attempts will decrease the distance between nesting attempts |
Reproductive success at previous site | Adult | Reproductive success | Individuals with unsuccessful nesting attempts will move farther between nests |
Reproductive success at settled nest | Adult | Reproductive success | Individuals that moved farther between nest attempts will have better reproductive success |
Average proximity to other nesting areas of settled nest | Both | Habitat | Farther distances between nesting areas will increase breeding movement distances |