ARI SHAPIRO, HOST:
Now a story about what happens when you turn society upside down - specifically, pigeon society.
STACEY VANEK SMITH, HOST:
It turns out there is a social hierarchy among pigeons, and it definitely pays to be the big bird on campus.
STEVE PORTUGAL: Being top of the dominance hierarchy basically gives you preferential access to everything. It means you get priority access to food, priority access to mates.
SHAPIRO: That's Steve Portugal, a zoologist and biologist at Royal Holloway, University of London. And contrary to what you may have heard about the early bird getting the worm, in the case of pigeons, it is heavier birds that get all the perks.
VANEK SMITH: So Portugal and his colleagues wondered what would happen if you made lighter pigeons feel heavier. If you beefed them up, would they punch above their weight?
SHAPIRO: They tested their theory in a captive flock of homing pigeons. They identified the birds in the bottom half of the hierarchy and loaded them up with tiny weights - little bird backpacks, actually.
PORTUGAL: And sure enough, when I did that, they became much more aggressive, started much more fights and won many more fights as well.
VANEK SMITH: The former head honcho pigeons took notice.
PORTUGAL: What was fascinating just to sort of watch anecdotally was, you know, they could see that they were a bit like, what's going on? You know, what's happening? We're being sort of - there's a military coup, almost, against us.
VANEK SMITH: Apparently, they fought back at first. But eventually, among the males, the birds with the little backpacks prevailed.
SHAPIRO: The researchers say the extra weight might have made the lighter pigeons feel like they were in better shape, like they had more energy to burn picking fights.
VANEK SMITH: Or perhaps they just hunted for food more aggressively than usual because, you know, strutting around with weights meant burning more calories and needing more food. The findings appear in the journal Biology Letters.
SHAPIRO: Portugal says this research is important because scientists often attach tiny trackers to pigeons and other animals, and that adds extra weight.
PORTUGAL: They might not be physiologically impeded by them, but they - it might be having an impact on their social structure, their social networks, their group dynamics.
VANEK SMITH: As for the pigeons in this study, once the backpacks came off, the old pecking order snapped right back into place. The lightweights were back to scratching out a living at the bottom of the heap.
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