Every evening, the pigeons gather at an intersection about one block from my home in North Phoenix. They break up into 2-3 groups of approximately 100 birds each, then fly in circles–first one group, then another–around the intersection. Occasionaly a group will land on a building in the perimeter of the circle, then they get up and fly around again. Sometimes they change direction, but they don’t leave the area. I have observed the same behavior in Salt Lake City, so I am guessing it to be an instinct thing. Anybody know why they do this?
How long do the pigeons do this for?
I know that ravens have a similar behavior where they will circle over an area in flocks to attract more ravens to their ranks. Then the large group makes its way to a roost or migrates to a food source.
I guess they do it until dark–I never watch that long. But the thing you said about the ravens makes sense. That still leaves me wondering: why? Why would they gather up their fellow pigeons at bedtime? Is there a survival behavior that is served by everyone going to bed at once? Are they just very social? I watch them while I am waiting for the light to change and ask myself, “what are they thinking?”
At least you didn’t tell me that is was some sort of aviary-precognizant reaction to something in the environment. That would be way too creepy for me. (Anybody read “Dark Half” by Stephen King?)
I honestly don’t know, but maybe a WAG will draw the fire of the more bird-knowledgeable among us (is brachyrhynchos or Wood Thrush out there?).
Could they be circling the area searching for the best place to roost/food source/scouting for potential threats?
Also, if they are gathering more birds to their group, could it be because there’s safety in numbers? The more birds in a flock, the greater the chance that one of them will spot a potential predator and take wing, thereby also alerting all the others in the flock. Or the greater the chance one of them will spot a tasty morsel, drawing the other birds to a good food source as well.
Anyone out there know?
According to Clive Barker, they’re circling above the Gyre at the center of Weaveworld. Any large, Oriental-looking carpets lying around the vicinity? 
(In other words, I don’t know either; but for some reason it reminds me of a dog turning several circles before lying down. Probably not the same thing, though.)
::sniff, pardon me:: Actually that’s a poor ornithology joke that might only be marginally applicable here. Zugunruhe refers to “migratory restlessness,” the increase and change in behavior that orients birds toward the direction they should be going on migration. And secondly, let me just say I know essentially nothing about pigeon behavior so what follows is entirely a SWAG.
Scenario A Like many birds, pigeons roost communally when the breeding season is completed. They wake up in the morning at the roost (or loft, in pigeonspeak) and go out for their morning forage. They rest during the midday, forage again during the afternoon, and head back to the roost in the early evening. Now, assuming that their roost site is not on the buildings at their foraging area, they then have to orient themselves toward the roost. Pigeons use several methods to do this: the sun in combination with geomagnetism, along with experience. (Interestingly, there is a classic bit of work done on this showing that pigeons got lost on cloudy days when wearing magnetic hats. They did not have the sun information and the hats screwed up their ability to use magnetic information. They didn’t get lost on cloudy days, however, when the hats were made of brass.) From my understanding, when racing pigeons are released, they will circle around a bit before taking off in the direction of their loft. This is, I presume, their way of orienting to the proper direction using solar and magnetic cues. And, as others have mentioned, there may also be a bit of “advertising” to flock members prior to heading toward the roost by circling the area.
Scenario B: Perhaps the pigeons are roosting there in the surrounding buildings so they really don’t need to orient themselves to fly anywhere. They haven’t settled in for the night quite yet - I’ve seen this behavior in American Crows everytime I’ve observed them at a local roost. The roost begins to fill up in the mid-afternoon. Entry into the roost really climbs at about sunset and then drops off abruptly. While the roost is filling up, the entire congregation will, on occasion, rise up and move. They may settle down back in the area they came up from or they may move a short distance (300 meters?) away. They are up in the air for a fairly short period of time before landing. Why would they do this? A bird may gain an advantage by moving itself in toward the center of the roost through predator avoidance (a real possibility since Great Horned Owls are known to snag their victims at roosts) or through thermal protection (the latter probably not applicable to crows). But not everyone can be in the middle of the roost and perhaps when too many birds attempt to move inwards, the roost rises up en masse. Much yelling and confusion ensues and the roost slowly settles back down.
So, as far as your pigeons are concerned…I don’t know. We need more info, such as final destination. Maybe, masterminx you could be more leisurely in getting home next time and tell us if the pigeons stick around or fly off.
I can’t resist…
To get to the other side.
Thank you, and goodnight!
At least this ain’t about head-bobbing or baby pigeons.
While brachyrhynchos probably got us most of the way there, I seem to remember a Cecil column on “bird rush hour” that is: a.) not online, b.) eluding my pitiable searching skills or c.) a figment of my imagination. Anybody else recall something like that?
I think brachyrhynchos has satisfied most of my curiosity on the subject. Based on my observation of the same behavior in Salt Lake City, the roosting thing makes sense. That building was definitely their roost, and every night they would gather, rise up in a circle, and land there again. Sometime there would be a bit of commotion, and a few pigeons would go somewhere else. For the most part, they all stayed on the roof of this building.
I’ll try to keep an eye on the structures in the area of this intersection to see where all the birdies go tonight and I’ll let you know.