This Wasp-Eating Falcon Laughs at Your Puny Stings
Wasps really, really don’t want you to bother them. They sting. They bite. They use chemical signals to summon relatives to come help drive you off. And yet, one amazing bird in Central and South America not only eats wasps, but specializes in feeding them to its babies. Even more strange?
It’s a falcon.
Falcons are best known as fast-flying predators of small birds. Red-throated Caracara (Ibycter americanus) are falcons about the size of a big crow, found in neotropical forests. They have a lot of odd habits for a raptor. Caracara snack on wasps rather than smaller birds and mammals. They breed communally and share brood care, also very unusual for a raptor.
Caracara chicks look just like other falcon chicks though: fluffy and adorable. I mean, look at this face.
Up to 77% of caracara chick nutrition can be wasps; the other major proportion of their diet is millipedes. In this video, you can see an adult bring the chick a multilayered wasp nest. Wasp nests are full of protein-rich larvae, and come pre-packaged for a busy bird parent as a take-out meal in a portable wrapper. The chick in this video ate about 15 wasp nests every day.
As you can see in this photo, wasps are not entirely happy about having their nests photographed, much less eaten. I don’t know about you, but my first thought when looking at this is NOT “I could eat that.”
Why would these birds specialize in eating the most feared of stinging insects? Do caracara have protective chemicals that repel wasps? Do they have a special attack strategy? To answer those questions, Sean McCann and his research collaborators wandered around a French Guiana rainforest at night harvesting wasp nests. Very, very carefully.
They relocated the wasp nests to a video arena where they waited for caracaras to attack, and videotaped what happened. The researchers also stroked, tapped, and poked wasp nests in various ways to see how the insects responded to vespiary disturbance. (Vespiary is a fancy name for wasp nest that really needs to be in common use). There is, remarkably, an actual literature of wasp nest fondling, which includes heavy breathing on the nest.
If you want to know how wasps react to disturbance of their nest, this is a perfectly logical way to go about it. Those of us in the US or Europe that have tried to to remove a nest of extremely irritable and aggressive paper wasps probably find that logic … faulty.
These tropical wasps aren’t mellow. They do sting, and you can see the wasps attacking the birds initially in this video.
But after their initial defense, something very strange happens. The wasps seem to give up and abandon their nest, leaving their delicious and helpless infants (larvae) behind for the caracara to feast on. An early researcher declared “only a pusillanimous creature fails to employ powerful weapons to protect its young.” (Skutch, 1959)
The highly irritable wasps of North America have a short breeding season, and most don’t have the ability to independently establish new nests. So it makes evolutionary sense that they would fiercely defend nests where their larvae are growing.
Tropical wasp species aren’t as seasonally limited as their northern relatives, and are able to establish new nests by swarming. While an initial vespiary disturbance triggers a defensive response, repeated, persistent attacks cause some wasp species to run away and abandon their nest.
The researchers’ videos show caracaras engaging in a “hit-and-run” tactic. They swoop down, whack the wasp nest, and then withdraw; they then repeat their air strikes until the wasps give up. The wasps may have evolved to respond to persistent attack by a predator in the classic manner: Running Away. (Who knew Monty Python was illustrating an important natural history strategy?)
It’s long been suspected that caracara might have a form of chemical protection against wasps. That’s rare in birds, but not unknown. McCann sampled the head, feet, and feathers of adult caracaras for protective compounds, but didn’t find any that were derived from the birds. They did find chemicals left behind by other angry wasp relatives, though–ants. So of course, the next step in the research was to go provoke a whole new group of hymenopterans, with fairly predictable annoyed and venomous results:
Caracara don’t have feathers on their faces, so they have little physical protection against wasps and ants. It doesn’t appear that the ant chemicals found on the birds have a function in repelling wasps, though; it’s just a side effect of living and perching around cranky ants.
Five years of research spent tromping around a forest getting stung helped establish that this amazing falcon species has found a way to exploit wasp behavior to become a specialist on an unusual food source.
What’s next for the researchers? One species of Mesoamerican caracara became extinct in the last century, and Red-Throated Caracara populations have been declining over the last 15 years. McCann hopes to do additional work in the Honduras on conservation of this fascinating raptor species that manages to inflict a little revenge on wasps for the rest of us. You might also enjoy McCann’s blog; he is a talented nature photographer.