Best ways to find birds in the tropics

When birding in the tropics, if you visit a forest in areas such as national parks, wildlife refuges and biological reserves, the great majority of the birds will be detected by their calls. This is especially true in the rain forest where the dense foliage full of epiphytes, tall canopy, thick bushes and fallen trunks make it difficult for a birdwatcher to catch a glimpse of the bird singing. This can be tricky, overwhelming, and sometimes frustrating if you don’t recognize those sounds and even if your guide tells you what species called, you might not remember them all!

To maximize spotting multiple species -apart from being patient and observant- what you need is to find resources that congregate different groups of birds. On this occasion, I will be referring to three of these resources where food is involved: mixed species flocks, army-ant swarms and blooming/fruiting trees. These three treasures can be found during a tour in Costa Rica whether it is the rainy or the dry season, and the first two are among the most spectacular birdwatching phenomena in the Neotropics.

1. Mixed flocks

A flock is when two or more birds actively move together. The congregation of birds in mixed flocks has been poorly studied, but it is known they do it as a strategy to avoid predators, usually raptors with agile techniques that make them quintessential forest hunters which, depending on where you are, can be hawks from the genus Accipiter (Bicolored and Tiny Hawks), forest falcons or pygmy owls. Species are presumed to have functional roles in a mixed flock and therefore have been categorized: core or leader species initiate the flock and tend to be gregarious, noisy, and very active; some examples are Lesser Greenlet, Carmiol’s Tanager, Common Chlorospingus and Black-faced Grosbeaks. When you hear them, it is a good time to raise your binoculars and check if more species are following them, you might be in the presence of a mixed flock!

Black-faced Grosbeak © Paz A. Irola

Satellite species are followers that join the flock incentivized by the actions of leaders. At Carara National Park, White-shoulder Tanagers and Tawny-crowned Greenlets are leader species followed by a great number of woodcreepers, antwrens, flycatchers and trogons foraging at different levels of the forest. I know, you will have a hard time deciding where to look: it is difficult to ignore a Black-striped Woodcreeper beating a grasshopper against a trunk or the explosive “juiiugüiit” call of the Rufous Piha when you have a colorful Baird’s Trogon in front of you mashing a green caterpillar. The best thing you can do is let your guide point out the species because he/she will know which ones you have not seen or which ones you won’t see again because they are more likely to show in a mixed flock.

Northern-barred Woodcreeper © Paz A. Irola

Baird’s Trogon © Paz A. Irola

Pay attention to any movement, sallying or leaves crunching; there could be a Green-shrike Vireo calling from the canopy, a Dot-winged Antwren foraging in a vine tangle or a Scaly-throated Leaftosser scratching on the ground! When you witness such a show, as a birder you try to take advantage of the opportunity to spot the specialties, but the most important thing is to enjoy; you won’t see all the species nor will you be able to follow the flock until the end so relax and live the spectacle.

Scaly-throated Leaftosser © Paz A. Irola

2. Army ant swarm

Army ants are nomadic insects that constantly move in search of arthropods which they catch to feed their colony. When this happens, thousands of ants cover parts of the forest floor forming a massive front and many arthropods such as crickets, grasshoppers, roaches, scorpions and spiders get chased out of their hiding places. The forests at Arenal, La Selva Biological Station and Carara National Park are good places to experience such a wild treasure: the array of birds that congregate at the army ant swarms to catch the escaping arthropods.

Army ants © Paz A. Irola

Having an encounter with a swarm of army ants is the best opportunity to spot secretive species of birds that forage in the dark forest understory and typically are challenging to find, some examples are Ocellated, Bicolored and Spotted Antbirds, Buff-throated and Chiriquí Foliage-Gleaners, Black-faced Antthrush, or even raptors like Barred Forest-Falcon. Even migratory birds like Canada Warbler, Acadian Flycatcher and Swainson’s Thrush are opportunistic and have learned to follow the ants for an easy meal.

The birding scene in Costa Rica was dominated in 2021 by the appearance of a very enigmatic bird that inhabits the understory of mature lowland and foothill forests: the Rufous-vented Ground-Cuckoo. This species is one of the most-wanted for any birder because it is extremely difficult to spot due to the kind of habitat it uses and its elusive terrestrial habits. Hundreds of Costa Ricans enjoyed the cuckoo-mania precisely thanks to army ants!

Rufous-vented Ground-Cuckoo © Paz A. Irola

3. Blooming/fruiting plants

Another great way to have many bird species congregated is to find trees full of juicy fruit like the ones within the genus Ficus or Miconia. You can easily spend a whole afternoon there! Tanagers, thrushes, honeycreepers, woodpeckers, guans, euphonias, trogons, grosbeaks, toucans and flycatchers put on an incredible show of colors, movement and sounds. I can swear you will not want to leave!

Tawny-crested Tanager © Paz A. Irola

In the dry forest, many species of deciduous trees lose their leaves exposing flowers to pollinators like hummingbirds and orioles. There is also a particular plant that attracts a great number of species with the copious and very sweet nectar its flowers hold: the chameleon vine. Butterflies, birds and even the White-faced Capuchin monkeys feed from this vine blushing their faces with its orange powdery pollen!

Whether you are in the rainforest, the dry forest or the cloud forests of the high mountains, finding one of these phenomena can make a huge difference in the number of birds you may see and how well you see them!