February 9, 2016
What sorts of behaviors do you see?
Dominance interactions are playing out at your bird feeder, in the woods, in the field, and anywhere birds occur! Researcher Eliot Miller from the Cornell Lab of Ornithology wants to know about them. Learn how you can contribute your observations using our new bird interaction data form.
In a popular All About Birds blog post, we previously learned about how dominance hierarchies can play out at your feeder. To name just a few examples, woodpeckers might chase nuthatches off suet blocks, big sparrows might chase little ones from seeds scattered below a feeder, and nuthatches might get into it with chickadees. Scientists believe interactions like these might influence species’ distributions at a large scale, yet we really only have anecdotal information about these interesting interspecific interactions. Who chases whom? Which species are dominant, and which are subordinate? Do some species have more aggressive interactions than others? Do the outcomes of these interactions vary seasonally or regionally? We want your valuable input! Tell us what interactions occur at your feeder.
Because interpreting behavior can be difficult, we have purposefully limited this project to three target behaviors: predation, mobbing, and displacement. Two examples are discussed below. Please read more about the target behaviors and how to collect and submit observational data for this study before beginning your observations. The online data form can be used to contribute observations between any species of birds on your FeederWatch checklist. As data come in, and we begin to analyze it, we may be able to expand the project to include other behaviors and natural history observations. The number of questions scientists can address with observations like these is unlimited! Do crows chase ravens, or do ravens chase crows? What about invasive species? Are they displacing native species from feeders or other food resources? Which hummingbird species are dominant at your feeder? Are migrant species subordinate to resident species on their wintering grounds? What do you see when you’re birding? What do you see at your feeder?
Below are two projects of immense interest to researchers at the Cornell Lab of Ornithology. Have you seen Cooper’s Hawks try to nab birds from your feeders? What about Collared-Doves, are they displacing other birds at your feeders?
Urban Cooper’s Hawks
Over the last few decades, and particularly in the last 15 years, Cooper’s Hawks have been increasing dramatically in numbers in urban areas. If you go to the FeederWatch trend graphs and type in “Cooper’s Hawk,” you can see your valuable observations at work detecting the increase in Cooper’s Hawk visits to feeder areas. Scientists believe the increase, particularly in urban areas, is due in large part to a reliance on European Starlings, Rock Pigeons, Eurasian Collared-Doves, and White-winged Doves, all of which are common or increasing in urban areas around the country. But scientists do not have a clear understanding of what these hawks eat across their range. Do their diets differ notably between different urban areas? Do the diets of urban Cooper’s Hawks differ from their woodland counterparts? Observers throughout North America, from people watching feeders to those leaving the office for a quick lunch break, see these attempted and successful predation events. Some of these people contribute their bird sightings via eBird and FeederWatch, but until now there hasn’t been any systematic way to record predation events. Scientists want and need information about Cooper’s Hawk predation to better understand what is driving the increase in urban Cooper’s Hawk abundance. Fortunately, there is now a dedicated venue for FeederWatch participants to record their important observations.
Beginning around 2000, Eurasian Collared-Doves have undergone truly impressive population surges across the continent, particularly in the western US. Like Cooper’s Hawks, this surge has been well captured by citizen scientists like you (check out the FeederWatch trend graphs for details)! Collared-Doves now rival Mourning Doves in the percent of feeder areas visited in the Northwest and Southwest United States. White-winged Doves, particularly in the Southeast US, have also increased modestly in abundance over this time. What sorts of aggressive interactions take place between these species? Does one chase the other away from grain, feeders, and other food sources? Will this ultimately influence the abundance of the less aggressive species? Do urban hawks focus more of their attacks on one species or another, and does this vary seasonally or regionally? Scientists simply don’t have enough information to answer these questions yet. A single scientific study would struggle to gather enough information, but as a community eventually we should be able to paint a good picture of how interactions with other species shape these doves’ distributions.
Use the bird interaction data form to submit your valuable natural history observations. Don’t forget to read the instructions first! And check out this page for more information about what behaviors researchers at the Cornell Lab of Ornithology are currently interested in.