Flocking Amazing

Flocking and swooping, and schooling and swimming.

With regard to the recent Staff Report by colibri:

http://www.straightdope.com/mailbag/mflockswoop.html

There is not nearly the same level of information in this link as in the Staff Report, but coincidentally this was on the radio this morning. It parallels the activities of flocking birds and schooling fish.

http://www.earthsky.org/shows/shows.php?t=20040312

This study supplements Reynold’s fundamental laws of “separation”, “alignment” and cohesion, with another law of “avoidance”.

Interesting topic.

I am wondering what the birds are doing. I often see flocks (from 60 to 500) of small black birds, I’m guessing they are starlings, swooping and swirling around usually in the evening before sundown. They create unusal patterns in flight as they bank and turn. Separating sometimes and then coming back together. They are not fleeing preditors and don’t seem to be feeding on anything just flying around and around. It doesn’t seem to be related to mating that I can see.

So what are they doing? I see this in cities, but that may be because I am usually in the city at sundown.

My guess is that they are coming into to a communal night-time roost site. The birds are coming together after having spent the day foraging in different localities. The different flock members may have different ideas on where exactly they want to roost within the site. They will swoop and zoom around until a “consensus” develops about where to go. Individuals will be reluctant to leave the flock on their own just in case a predator is lurking around near the roost.

Flocks display this swooping behavior not only when they are directly under attack, but whenever a majority of the flock doesn’t have a clear consensus of a single direction to head in.

Not unlike the American voting public, eh?

This concept is inherent in Colibri’s report, but he didn’t emphasize it as much as I think it could be.

There are two possibilities that come to mind to explain the “how” of flocking behavior. One is that each element of the group computes the positions of all other elements and acts according to complex rules in 3-dimensional space. The other is that each element has only a few simple rules coded (e.g., if something black is to your left, turn right) and the group actions are the sum of all the individual, independently-derived actions.

A google search hasn’t yet turned up the person I am thinking of, but isn’t there a researcher who creates mechanical/electrical “insects” made out of ultra-primitive junk-box components, programs them with a very small number of simple rules, and sets them free to explore their world? He seems to have shown that postulate #2 can work, where postulate #1 (complex computation) requires too much computing power to be practical in a bird-brain-sized object.

And Occam’s Razor would lean towards the simple as well.

Another google search turned up Dr. Chris Melhuish, but I’m not sure this is the guy I was thinking of. This interesting link talks about behavior in groups of ants.

Yes, I would agree that the voting behavior of the American public is pretty flocked up.

There is another interesting flocking behavior which I have seen many times. A large flock of birds will land in a large field to feed. Almost immediately, a line of birds on one side of the outside of the group will fly directly over the flock to the opposite side. Soon after another line of birds will do the same so the flock slowly moves across the field.

I thought these birds were grackles, but I am unable to confirm that with Google. It seems like a very efficient feeding strategy for methodically covering a large field. I wonder if there is a name for this behavior?

Are there any birds that do follow a leader? I ask because the standard line in dealing with pet parrots is to show them you’re the alpha bird, as if they have a dominance hierarchy.

Smaller flocks, especially made up of family groups, may follow dominant individuals. And as I mentioned, flocks of large birds that fly in formation will have temporary leaders. My report mainly addressed the maneuvers of flocks made up of hundreds or thousands of birds.

You mentioned four reasons why flocking/herding reduces the chances of predation, but you omitted a very important one: if a group of 100 prey animals encounters a predator, each individual is 100 times less likely to be attacked than if it met the carnivore on its own. This applies especially to animals that aren’t very good at hiding, such as large ungulates.

I’m new to the site so my observation may be a bit wide of the mark.
While flying south, down the east coast of the US, we noticed many flocks of Canada Geese heading north - other passengers saw them also. Upon landing I asked the pilot what our altitude was as we flew over the Carolinas He replied “37,000 feet”. I mentioned the Geese and he seemed shocked! Searching Google was a little less than helpful. If you or anyone knows of a source for this type of information I would be greatful.

My dad, the rocket scientist (he graduated with a degree in aerospace engineering), has had me proofread proposals that deal with the simulation of small autonomous planes. I don’t remember if any of it resulted in flocklike behavior, but I do recall that the rules for collision avoidance were pretty simple. (Something to the effect of “go where you don’t see any other planes within the collision detection boundary”.)

This is far higher than I would expect Canada Geese to be flying in that area, and if correct would be a record altitude for North America by 16,000 ft. However, it is somewhat below the known altitude record for birds, which is 37,900 ft. See the Staff Report by me (George) and Doug:

How high can birds and bees fly?

Ah, yes! The old “eat my brother! He’s really slow!” defense. Another strong argument for anthropomorphism. :slight_smile:

Like the old joke goes:

Two hikers are walking along in bear country. Suddenly they see a grizzly bear, who starts to approach them. One pulls a pair of running shoes out of his pack, and starts to put them on.

“What are you doing?” the other one says. “You’ll never be able to outrun that bear!”

The other replies, “I don’t have to outrun the bear. I only have to outrun you!”