A Ruddy woodcreeper, a bivouac-checking species. Credit: Sean O'Donnell/Drexel University
Army ants scare up a lot of food when they're on the move, which makes following them valuable for predator birds. But instead of competing and chasing each other off from the ant "raids," as scientists had thought, birds actually give each other a heads up when the ants are marching, according to a new Drexel University study.
Phys.org: Birds of all feathers work together to hunt when army ants march
Rather than the competitive approach we expect from wild creatures, they cooperate for the common goodness. Bounce that metaphor off the wall all you like.
They have some clever moves.
In watching for the raids and the flocks that "attend" them, a key to avian cooperation may be what are termed "bivouac-checking" birds. These are birds that perch near the sites where army ants make their nests (bivouacs) and watch to see where and when the ants move. Birds that fall into that category include the ocellated antbird and the blue-diademed motmot.
The prevailing thought has been that these specialized birds liked to keep the ant colonies they watched to themselves, not allowing other species to horn in on their finds.
But a frequent high diversity of species in flocks following the ant columns showed O'Donnell that birds that didn't specialize in tracking army ants (like the migrant species Kentucky warbler) were allowed to join and hunt.
So when bivouac-checking birds see the movement of the columns and take off, other birds take the cue. They either know birds like the ocellated antbird follow ant columns or recognize vocalizations the specialized birds make when chasing the colonies.
"Birds may use each other as a way of finding army ant raids, which are very hard to locate in the forest because they are widely spaced and the ants are mobile," O'Donnell said. "Observations suggest some birds are attracted to other birds at raids, and birds may even follow each other when moving among raids of different ant colonies."
- PO
The cooperation isn't at the level of a Roman legion but it's most impressive from a flock of birds.
If we go too far with the metaphor then we wind up anthropomorphizing the birds but they don't organize horse races or play golf so we're quite sure their behavior is only distantly related to anything we manifest. Nevertheless, the lesson isn't too bad. There's a Golden Ant Rush taking place and rather than fighting over it the birds cooperate. Most impressive.
It's not all peaches on the ant trail.
O'Donnell noticed some pairs of species were almost never found in flocks together despite, independently, being ant-chasers. That indicated that these bird species might chase each other off as competition, or just avoid each other entirely. Pairs that seemed to be unable to be around each other included the blue-throated toucanet and the brown jay, as well as the wood thrush and the white-eared ground sparrow.
"These antagonistic pairs were often species of very similar body size or feeding behavior," O'Donnell explained. "Perhaps these species do compete very strongly at army ant raids."
All in all, finding that birds largely work together to forage at army ant raids seems to demonstrate that cooperation is a better survival strategy than trying to keep food from the raids for their own species.
- PO
Ethology or study of animal behavior can be as much of a fascination and a passion in life as any of the unusual things people do and the watchers don't have the answer but they try to deduce one by continuing to observe.
"Having other birds around may be an advantage because there are more eyes and ears to detect predators," O'Donnell said. "If the raid is hard to monopolize, and food is very abundant there, then the costs of allowing other birds to attend may be low, further favoring positive species interactions."
- PO
Professor Ponderous has a few words on the matter.
The behavior of the birds is likely dictated by some particular gene sequence within the genome for that species of bird. There's a tremendous level of genomics research into that aspect of life insofar as they want to map all the gene sequences for form and function, etc and that's a colossal job even when confined to a single species.
When you consider the larger conception of a genome in terms of every genome which ever existed, we move to the level at which there can be cross-comparisons for the existence of any given gene sequence within any known genome. Moreover, the linkage through the evolutionary ladder will give some of the deepest insights into evolution yet.
How far research of that wider nature has progressed is unknown to the Rockhouse but there's some of it in terms of comparing the genomes for H. sapiens to H. anything else to identify branches in human evolution. How far that has gone toward mapping all of the primate genomes for cross-referencing is not known here but seems it will yield extraordinary things and it's inevitable.
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