Do antbirds eat ants?

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Of course not. Ants are an important source of food,  but if they eat the ants their food supply runs out. Antbirds use ants only to find food, but they do not eat ants.

In this blog I am going to talk about a group of birds that have a very interesting behavior and that I have not seen in any forest outside of the tropical Americas. They are the group of Antbirds. Not all antbirds belong to the same family and some common names can be confusing. The antwren is not a wren, the ant-tanager is not a tanager, the ant-vireo is not a vireo, the antthrush is not a thrush, the antshrike is not a shrike, and the antpita is not a pita. So what do they have in common? They feed on insects and most of them belong to the Thamnophilidae.

There are 234 species of antbirds and they are only found in the Neotropics, in rainforests of Central and South America. In Costa Rica we have 22 species of antbirds. In the neotropics there are 31 species threatened with extinction as a result of the destruction of their environment, as tamnophilids are not hunted or used as cagebirds.

Antbirds are not very attractive, they have rounded wings and strong legs. Its color is mainly dark gray or brown. They are shy, and usually  live deep in the forest, and birders can usually see them only for a very short time. People who visit Costa Rica for photography and birdwatching and find these birds in the forest know that they have been lucky .

What makes antbirds really attractive is their behavior. They have developed an adaptation that allows them to live in the forest using other species that find food for them.

These birds are specialized in following swarms of army ants Eciton burchelli in the tropical forest. Ants are predators and hunt for insects, spiders, and lizards. When ants move on the forest floor, cockroaches, grasshopers, and many other insects and arthropods try to escape. Birds find them easily and catch them. As you can see, antbirds do not eat ants but instead use ants to get their food.

I am going to talk about  one of my favorite species as an example, because it is one of the most attractive birds within the antbird group and it is one of the species that all birdwatchers who visit costa Rica look for. It’s called Ocellated Antbird. (Phaenostictus mcleannani). The observations on this antbird are based on the results of the article by Johel Chaves-Campos published in

 Zeledonia 16: 2 Noviembre 2012 (¿Cómo localizan las aves a las hormigas arrieras Eciton burchellii? El caso del seguidor obligatorio de hormigas arrieras Phaenostictus mcleannani – Ocellated Antbird).

Most species of antbirds look for ants when they want to, as they also forage for food by hunting directly, and they hunt within the swarm of ants only when they find them by accident. But Ocellated Antbird only feeds on army ants and that is why they are called specialists. But it is not easy to live their lives following army ants, especially since E. burchellii colonies are nomadic and can move their nest hundreds of meters a night while the birds sleep. It is not uncommon for ocellated to lose their location. these birds are not very good at finding colonies of army ants if they do not know exactly where they are.

That is why the antbirds have to go out every morning to look for the place where the ants moved to be able to eat.

How do the Ocellated  find ants in a big and dense forest? Good question.

They use several tricks:

1. The ocellated takes time out of their day to check where active swarms are, so they can be found more easily the next day. They remember the places where the ants were hunting the day before. Ocellated do not move erratically in the forest. They always move in a straight line toward the swarm of ants.

Each individual sings at dawn immediately before leaving its dormitory and calls its couple to follow him. They fly in a straight line towards the first swarm they visited the day before. If that swarm is not active, the ocellated should look for the next one.

Swarms that are closer to the ocellated’s territory are better, since the pair that lives in that territory and their neighboring pair can eat 60% more insects than birds that come from further afield. When the swarms are not around, the pairs have to fly farther and eat less. That’s not a good deal. Some couples travel more than a kilometer to check their first swarm of the day.

2.  They listen to the songs of other species that follow army ants, and move through the forest until they reach the activity (that is, the food. Each individual ocellated has its own song, which suggests that they can recognize to each other from a far away.

3 Ocellated ones cannot find swarms of ants by sound or smell. They must use their sight or by chance. That is why it is safer to follow other individuals who  know where the swarms are.

So it is common to observe birds traveling in groups in a straight line from one swarm to another. At the end of the day, between 4-5 pm they return to their dormitory.

Note: This is a series of articles about birds of the Neotropics.  The species of birds that will be covered in this collection of articles are toucans, quetzal, motmots, manakins, tanagers, and many other species.

  The articles do not have a scientific format, but rather have a general informative character. The text is the product of the investigation of works written on the subject, although bibliographic citations are not provided.

Wildbird is a tour operator agency that organizes birdwatching trips to Costa Rica and Panama. Tours for photography and birding holidays.