[Samuel Bisson (OP)]

When I go jogging I notice that one seagull will spot me and start cawing its heart out, circling me. Before too long a whole crowd of seagulls will be circling me as I go.

I can't help but think this is some predatory instinct to follow prey until it dies. They must think I am in distress and about to drop down and die a.k.a free lunch. I don't think they got the memo about the human sedentary lifestyle.

Now, seagulls don't have teeth, or at least the genes coding for teeth have been switched off for a long time. So I wonder, if given the chance, they would even swoop down and pick at the carcass of a human being. They seem more content with picking at trash. Of course, one could always test this but the question then would be... why? Stupid seagulls!

I have ruled out that it is a form of exercise for seagulls. Energy seems scarce enough as it is for them to waste energy flapping around and cawing at everything that moves. It's more likely that it's a form of sexual indicator, showing that the fittest birds are able to spot potential food and signal it out to the group.

Damn you birds, just let me exercise in peace.

[Colin2B]

They might think you are carrying food. Near the coast we have problems with them dive bombing people to knock food out of their hands.

Otherwise they might know something about your health - keep checking that pulse and if you can't feel it don't stop running, they'll have you!

[chris]

This is an @atrox or @SquarishTriangle topic!

[jeffreyH]

If something is running then something else may be chasing it. So there may be left overs.

[RD]

People in colorful sportswear more likely to be eating than jogging.

[SquarishTriangle]

Are we talking silver gulls when when we say "seagulls"?

Without being able to observe the exact circumstances, it's a bit hard to say what is going on. I would guess that they have likely been conditioned to think "food" when they see humans (through many people feeding them previously), and they are surveying you for goodies from overhead. Alternatively, they could think that you are running from a potential danger, perhaps a predator, and that they should be on the lookout for whatever is causing you to run. Or if you happen to be running close to their breeding grounds, that would be another reason for the adults to keep a close eye on you.

Perhaps not in silver gulls, and perhaps not from just the heat energy given off by a running human, but some of the larger seabirds (some albatrosses and larger gulls) are extraordinarily efficient at maintaining flight on a just bit of rising warm air current. They may get so much uplift from the rising air, that they essentially catch a "free ride", hardly ever needing to flap their wings.