“Stop!” hissed our guide Fernando, putting his hand in the air as he halted mid-stride along the jungle trail. Since we had spotted a Central American coral snake earlier that morning my first thought was that we had encountered another venomous denizen of the thick rain forest. There are many dangerous snakes in that region, and while creatures like the golden-colored eyelash viper might be fascinating to observe, they are best avoided. After a few seconds, Fernando waved the five of us forward slowly and quietly so we could all see for ourselves.

To my relief, we found ourselves staring not at a pit viper but a mass of ants. Since we had seen untold numbers of leaf cutter ants in preceding days, I was not that excited about seeing more ants, especially since the jungle was alive with bird calls just after dawn. But as Fernando explained what we were witnessing we came to understand how lucky we were to observe this event closeup. The story involved a panoply of jungle creatures including insects, invertebrates, birds, and small mammals.

We were tromping through a lush forest a few miles north of the Panama Canal. The dirt trail is known in birding circles as Pipeline Road for the oil pipeline mostly buried along the trail, installed by the US military many years earlier but never used. The trail was poorly maintained, like many of the former U.S. facilities in the Canal region, since the Panamanian government seems to have neither the resources nor the interest to keep all those facilities in good condition. As we drove away from the Canal in the pre-dawn light, Pipeline Road began as a paved road, then a graded gravel road, then eroded into a 4×4 jeep track. Recent rains made for muddy conditions in low spots and warm, humid weather for hiking.

At the time of my early January 2025 trip, the Panama Canal had been much in the news thanks to heated conversations between the U.S. and Panamanian governments. Having learned a bit about the Canal back in high school, it was fascinating to finally see this engineering marvel, labeled one of the Seven Wonders of the Modern World by the American Society of Civil Engineers. To my disappointment we did not see much ship traffic during our daily commutes along the Canal to birding destinations because drought conditions had forced the Canal authorities to restrict shipping traffic (it takes an estimated 52 million gallons of fresh water for each ship to travel the length of the Canal). This caused a traffic jam of ships on both ends of the Canal since the route is critical to international ocean freight companies.

The Canal was first envisioned in 1513 by the Spanish conquistador Vasco Nunez de Balboa, who is reported to have written in his diary that walking across the 51-mile route over what came to be called the Isthmus of Panama was too hazardous but might merit a shipping route. It was not until 1881 that the French mounted a massive effort to build a canal through treacherous jungle and rugged terrain. The leader of the French project, Ferdinand de Lessups, was highly regarded for his successful construction of the Suez Canal in Egypt. Despite a massive workforce of over 40,000 laborers, mostly local indigenous people and conscripted workers from West Africa, the French soon discovered that digging sand in the Egyptian desert was far different from digging a huge trench in a rain forest filled with dangerous snakes, biting insects, mudslides, yellow fever, and malaria.

By the time the French threw in the towel in 1889, 22,000 people had died and the project finances were in a shambles. It was not until 1904 that the U.S. took up the challenge and opened the Canal in 1914 to world-wide acclaim. Much of the route goes through an artificial reservoir called Gatun Lake, created by damming the Chagras River and Lake Alajuela to reduce the amount of excavation required along the route. Gatun Lake sits at 85 feet above sea level, and three pairs of locks were constructed on each end of the Canal to lift ships up and down while steaming between the Pacific and Atlantic sides of the isthmus. The original locks were 110 feet wide but wider locks were completed in 2016 to accommodate massive container ships. Today the Canal allows over 15,000 ships annually to save valuable time and fuel in avoiding a long trip around the southern tip of South America.

The area around the Canal is known for massive colonies of ants, with over 500 species identified so far. We saw colonies along the trail that spread up to 30 feet in circumference with multiple holes in the ground to caverns that reached up to 30 feet deep according to our guide. The ants we spotted that morning were Army ants (Eciton burchelli), among 200 species of carnivorous and nomadic ants found in Central America as well as in South America and Africa. Many of these ant species are blind, moving around in highly ordered groups by following pheromone trails that have been left by other ants.

Army ants generally do not have a fixed home, rather they are in near constant motion across the landscape. They move by sending out hunting parties with up to 200,000 individuals seeking food sources to sustain their queen and millions of ants. As the ants forage, they walk in orderly paths that can be over 50 feet wide. Outbound ants use the outer two lanes and returning ants walk the central lane, perhaps to protect the prey they are carrying back to the main colony. The ants are capable of walking over all kinds of terrain and vegetation, even using their bodies to make bridges to span gaps in the trail.

While the ants are tiny as individuals, in their vast numbers they represent a nearly irresistible force that strikes terror in a wide range of potential prey species encountered by the ant army. As we stood quietly on the trail our eyes gradually adjusted to the dim light so that we could see huge numbers of ants on one side of the trail, and hundreds of creatures scurrying, jumping, or flying across the trail in advance of the ant swarm. Flies, ticks, crickets, spiders, scorpions, moths, centipedes, earthworms, bees: nothing is safe from the ants that will sacrifice their own lives to overwhelm any edible prey.

The hunter ants have powerful mandibles to bite and tear apart their prey. Small creatures may be carried intact back to their colony while larger prey is ripped into small pieces. Scientists have observed that in some cases ants will make temporary mobile nests out of their own bodies to shelter the queen, larvae, and eggs. The mobile nests can later be picked up and moved quickly as the ants continue their ceaseless quest for more food. Our guide made sure to keep us back from the lines of ants so that we did not end up becoming the target of painful ant bites.

While the ants and their panicked prey species were interesting enough, we had the excitement of watching many birds that joined the frenzy. Fernando advised us to be on the lookout for three species that he called the “ant swarm triplets” – the bicolored antbird, the spotted antbird, and the chestnut-backed antbird. These reclusive little fellows long ago figured out that hanging around the ant colonies and their hunting parties was a good way to find easy food pickings among the insects fleeing the ant swarm. Wikipedia calls this behavior kleptoparasitism, from the Greek terms for “thief” and “one who eats at the table of another.” Over 500 species have been observed by scientists as participating in this behavior, forming the largest known animal association in the world, including lizards, snakes, and fish who benefit from the predatory ants.

It was a mad scramble among the birds to grab food before someone else moved in. The bushes and trees around us were full of action as the birds flitted back and forth, diving down to snatch a morsel from the path and darting back into cover to consume it. Normally shy birds abandoned any sense of the risk from our presence, at times flying or landing within easy reach of us in their movements. We were scrambling ourselves, trying to make sense of the chaos around us, making notes, identifying fast moving birds with our binoculars, and trying to take photos of birds in mad-dash mode. In addition to the triplet species, we were joined by others like the lovely gray-headed tanagers and stunning blue-black grosbeaks. Our guide later explained that other species benefit from the ant swarms, for instance, butterflies that feed on the droppings of ant-following birds and parasitic flies that lay eggs in the bodies of insects fleeing from the ants.

There is a good reason why these ant swarms are constantly on the move: a colony can consume hundreds of thousands of prey animals in a day. Because the ants have such a big local impact on the populations of their prey species, they must keep moving to new hunting grounds to ensure adequate food supplies for their queen and workers. Some ant species hunt only on the ground while others are capable of hunting under the earth, sometimes targeting different ant species. Other ants hunt high in the forest canopy, consuming birds, lizards, caterpillars, and any other edible creatures encountered along the way.

Fernando encounters ant swarms a couple times each year in places that are safe for his birding groups. Some scientists follow ant swarms in the jungle but this involves a level of risk that is not appropriate for tourists like our birding group. In addition to the snakes and biting insects, the Panamanian jungle hosts jaguars, American crocodiles, and spectacled caimans. The good news is that ant swarms attract other fascinating creatures like silky anteaters and nine-banded armadillos. Near the ant swarm we were delighted to spot some of the most beautiful birds on offer in Panama like the white-whiskered puffbird, broad-billed motmot, and the cocoa woodcreeper. In earlier trips to Central America, I had not had much luck finding the many species of antshrikes and antbirds, but the Army ants gave us a morning walk to be remembered.

During my Panama trip I stayed at the Canopy Tower, part of the Canopy Family of adventure lodges around the country. Located in Soberania National Park, the Tower is a converted U.S. radar facility that rises about 75 feet in the air on top of a prominent volcanic hill. The dining room and lounge are located on the fourth floor of the Tower, allowing you to see visiting monkeys and other night creatures each evening (sometimes a bat or kinkajou will manage to sneak in, but they do not eat much!). On the roof of the Tower is an observation deck that is a gathering place at dawn each day, offering stunning views and tree-top close encounters with a wide range of birds, sloths, and other creatures of the diverse jungle habitat. With excellent food, expert guides, and over 800 bird species recorded in the region, it is a wonderful place to visit for beginning birders or experts looking for their next rare sighting.

If you like Ed Robinson’s writing, check out his two Nature Notes books! Click here for more information.