A PEACEABLE KINGDOM?

5 December 2021

  The last couple of mornings,  I’ve paid a little more attention than usual to the birds feeding outside my window. My grandson, John, had sent me a news article about observed dominance of various bird species at feeders. The source of the story was an analysis of bird observations made by Project Feeder Watch[1], published in 2017[2] and supplemented by more recent work by the same authors.

   Using hundreds of sightings of birds seen at feeding stations in the northeastern United States, a general hierarchy of dominance was identified. As blue jays were one of the more dominant species, they based their list on how other species reacted around blue jays. More likely to “rule the roost” (i.e., the bird feeders) than jays were crows, grackles, and red-bellied woodpeckers. Robins and starlings appeared to have somewhat equal standing with jays. Below jays, in more or less descending order of aggressiveness were red−winged blackbird,  mourning dove, hairy woodpecker,  brown−headed cowbird,  northern cardinal, song sparrow, downy woodpecker, house sparrow,  white−breasted nuthatch, white−throated sparrow, Carolina wren,  tufted titmouse, house finch,  red−breasted nuthatch,  dark−eyed junco,  purple finch,  American goldfinch,  black−capped chickadee, and Carolina chickadee.

   If (like me) you are not up to speed with Twenty-first Century mathematics and statistics, you may find it hard to determine exactly what “dominance” looked like to the observers. To take their own statement from the published paper: “In this study, we focused on the most overt of these (aggressive interactions): displacements in which one bird displaces or chases another from a perch at or near a bird feeder. We did not include subtle interactions such as one bird waiting until another finished feeding, or accidental displacements such as one bird arriving suddenly and temporarily frightening off birds that had been present.”

   On that basis, it appeared to them that the majority of dominance was associated with the size of the bird, bigger birds being more dominant at the feeders than smaller ones. There were exceptions to this, but in general the differences were more nuanced.

   Here in northwest Oregon, we don’t have the same species they were studying in the Northeast. We do have similar species, and similar groupings of species, that should behave comparably.  My list: crow, northern flicker (in place of red-bellied woodpecker), starling, scrub jay and Steller’s jay (stand-ins for blue jay), robin, ringed dove (for mourning dove), hairy woodpecker, song sparrow, downy woodpecker, golden-crowned sparrow (for white-throated sparrow), Bewick’s wren (for Carolina wren), house finch, red-breasted nuthatch, dark-eyed junco, purple finch, American goldfinch (also, lesser goldfinch and pine siskin), and black-capped chickadee (also chestnut-backed chickadee). In addition, we have spotted towhees, yellow-rumped warblers, varied thrushes, and occasional fox sparrows.

   Surprise! In over 40 years of bird feeding at this location, I have seldom seen “displacements in which one bird displaces or chases another from a perch at or near a bird feeder.” Perhaps the most obvious antagonistic encounters occur when a group of starlings try to land on a suet feeder already occupied by a flicker. The flicker may make an open-beaked lunge at the nearest starling, causing that starling to move out of reach. If the starlings move to the back side of the suet block – or even move just out of immediate reach of the flicker – both species will remain feeding together.

   The researchers note that hairy and downy woodpeckers “punch above their weight,” but I’ve never seen our woodpeckers (mostly downys) make any aggressive moves against other species. There can be a lot of “waiting” for a suet block to clear, but no antagonism.

   They noted dominance between house finches, purple finches, and juncos – house finches over purple finches, purple finches over juncos, but juncos over house finches. All three feed side by side on our sunflower feeder; there may be a little jostling for position, but never any attacks.

   Some other species they mention:

   Crows may come down to the feeding area to get water, but never to acquire food. Other than the “startle” response of having a huge bird land in your midst, I’ve never seen any feeding interactions with other species.

   Arrivals of scrub jays at the bird feeders often produce short-term “startles,” but no bird is attacked and no bird leaves for long. The jays create a commotion chasing each other, but usually it has nothing to do with the food.

   The researchers noted the  “chaos” that occurs when mixed flocks of goldfinches and pine siskins show up and “they get in tons of squabbles both with themselves and everybody else.” This is a common occurrence at our house, too, usually caused by one hundred or so little birds all trying to land simultaneously on the twenty available perches of the thistle feeder. These dramas seem to be of the “no harm, no foul” variety: nobody gets hurt, and probably everybody eventually gets their turn at the thistle seeds.

   Whether there is one bird or 100 birds present, red-breasted nuthatches always act the same: a bee-line to a feeder to get a seed, and a bee-line out. They seldom interact with any other species. Black-capped chickadees and chestnut-backed chickadees spend a little longer feeding than the nuthatches, but they usually come and go without other contact. Golden-crowned sparrows and song sparrows seem oblivious to other species around them. Towhees and wrens make brief forays to feed unmolested, but quickly return to the nearby shrubbery.

   Seldom is there a significant disturbance of the peace.

***

    You may wonder (as I do) why my “study” shows such different results than theirs. There are a couple of possibilities:

   1. We are understanding “dominance” differently. This may be true in individual cases, but their definition is clear that there must be actual “chase” or displacement from a perch to be a sign of dominance. I don’t see that.

   2. Most of their data come from areas in which winter weather is much more severe than here in Oregon. We get ice and snow, but even in a big storm, our snow cover doesn’t last more than a few days at a time. It may be that the birds in the Northeast are much more dependent on feeders, and access to food becomes a more serious business.

   3. It may be that our bird feeding area is much better supplied for handling many species at once without the need for conflict. I suspect that many sites have only two or three feeders to handle whatever comes to their yards. Within about a 10 foot square area, we have: two birth bath/fountains; two hummingbird feeders; two tube feeders for thistle seeds; one large (almost) squirrel-proof sunflower seed dispenser; two suet feeders (both usable from both sides); five plant boxes (for flower growing in summer, sprinkled with seed in winter); and a ground-level seed tray for towhees and fox sparrows. Flickers and smaller woodpeckers can almost always find an unoccupied block of suet. Goldfinches and siskins can squabble over the thistle feeders, while house finches and purple finches are relatively unmolested on the sunflower seed feeder. Juncos and golden-crowned sparrows have the plant boxes almost to themselves; Anna’s hummingbirds have two feeders (although sometimes one male will try – often successfully – to keep other hummers off both); and various species can come for water without disturbing the feeders.

   Ours usually is a peaceable kingdom.

  =======================

[1] Project Feeder Watch is a volunteer program sponsored by the Cornell Lab of Ornithology. Participants from all over the United States and Canada send in their observations made at bird feeders – species, numbers, unusual occurrences or behavior, etc. Like the Christmas Bird Counts and the Breeding Bird Surveys, the data are periodically analyzed to measure population trends.

[2] Miller, E. T. 2017. Fighting over food unites the birds of North America in a continental dominance hierarchy. Behavioral Ecology 28(6):1454-1463.

 

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