Understanding the Dominance Hierarchy of North American Feeder Birds Eliot T Miller David N. Bonter Charles Eldermire Benjamin G. Freeman Emma I. Greig Luke J. Harmon Wesley M. Hochachka Unlike many organisms, for which competition must be inferred, birds sometimes compete in dramatic, readily quantified ways. Birds at feeders are a good example. * Are the outcomes of these interspecific aggressions predictable? * Can feeder birds be put into a linear dominace hierarchy? * What predicts dominace between these species? ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● Merlin Black Vulture Black−billed Magpie Northwestern Crow Pileated Woodpecker Boat−tailed Grackle Yellow−bellied Sapsucker Western Scrub−Jay American Crow Turkey Vulture Mallard Ring−necked Pheasant Fox Sparrow Eurasian Collared−Dove Evening Grosbeak Band−tailed Pigeon Palm Warbler Red Crossbill Gray−crowned Rosy−Finch Canyon Towhee Varied Thrush Black−crested Titmouse Eastern Phoebe Oak Titmouse Northern Mockingbird Common Grackle Red−bellied Woodpecker Northern Flicker Red−headed Woodpecker European Starling Blue Jay Hairy Woodpecker Red−winged Blackbird American Robin Baltimore Oriole Western Tanager yaJ s'relletS Brown−headed Cowbird Eastern Towhee Gray Catbird Mourning Dove Pine Grosbeak Northern Cardinal Eastern Bluebird White−throated Sparrow Song Sparrow Downy Woodpecker White−crowned Sparrow House Sparrow Yellow−rumped Warbler Spotted Towhee House Finch Chipping Sparrow White−breasted Nuthatch Carolina Wren Red−breasted Nuthatch Pine Warbler Dark−eyed Junco Pine Siskin Purple Finch American Tree Sparrow American Goldfinch Common Redpoll Tufted Titmouse Bushtit Black−capped Chickadee Carolina Chickadee Lesser Goldfinch Chestnut−backed Chickadee White−winged Dove Brown Thrasher Golden−crowned Sparrow California Towhee Swamp Sparrow Orange−crowned Warbler Carolina:Black−capped Chickadee Brown Creeper Mountain Chickadee Ruby−crowned Kinglet hcniF s'nissa C Brown−headed Nuthatch Boreal Chickadee Hermit Thrush Sharp−tailed Grouse Wood Duck Last year we harnessed the power of citizen scientists, participants in Project FeederWatch, to address these questions. This pilot effort, run externally, still received over 2,000 submissions. This coming season the project will be integrated directly into FeederWatch, and we anticipate much greater participation. Find out more at http:// eliotmiller.weebly.com/feederwatch-interactions The vast majority (99%) of interactions between three species are transitive. However, there are some notable three-species intransitive (cyclic) relationships, and a number of larger cycles. This makes assigning species to a linear dominance hierarchy somewhat difficult. Still, there are few instances where inferred subordinate species displaced inferred dominant species (red lines to right). Much of the variance (~35%) in rank is explained by body mass, with some notable phylogenetic influences: woodpeckers are more dominant than expected based on body mass, while parids are less dominant than expected. Downy Woodpecker White-breasted Nuthatch Red-breasted Nuthatch Example of a cyclic (intransitive) triad Email: eliot.isaac@gmail.com Twitter: @EliotITMiller House Sparrow Blue Jay Downy Woodpecker European Starling Northern Cardinal House Finch Dark-eyed Junco American Goldfinch Mallard Ring-necked Pheasant Tufted Titmouse Common Grackle Red-winged Blackbird Mourning Dove Frequency of interaction Rare Frequent Aggressive interactions may shape species' distributions. Can we predict the direction of these interactions? Sharp−tailed Grouse Ring−necked Pheasant Mallard Wood Duck Merlin Eastern Phoebe Western Scrub−Jay Blue Jay yaJ s'relletS American Crow Northwestern Crow Black−billed Magpie Oak Titmouse Tufted Titmouse Black−crested Titmouse Carolina Chickadee Black−capped Chickadee Carolina:Black−capped Chickadee Mountain C