Bluish-fronted jacamar (Galbula cyanescens) located in bamboo at LABO. PC: Tom Matia

At the time of my encounter, I did not realize the rarity of the event. I was walking across an old channel of the Los Amigos River that is in its early successional stages. There are no tall trees, instead, there are many shrubs covered in vines. Bordering this channel are the towering trees of the floodplain forest, making this edge habitat an ideal location for a Tiny hawk (Accipiter superciliosus) (Global Raptor). I had just walked past a resting bluish-fronted jacamar (Galbula cyanescens) when my eye caught a glimpse of a bird careening through the vegetation. I followed the shadow through the vegetation and, in the clearing that the trail made behind me, watched a small flying raptor raise its feet forward and pin the bluish-fronted jacamar to its perch.

A photo taken through binoculars of the Tiny Hawk after pinning the jacamar to its perch. PC: Tom Matia

The small raptor (22-28cm/8-11in) is known to be a specialist at predating on avifauna and had the jacamar in its grip (Global Raptor). It seemed the attack would prove fatal as there was hardly a fight from the jacamar. The hawk soon took notice of my presence and, not wanting to disrupt its natural behavior and its success, I walked away from the scene. A few hours passed by the time I returned to investigate the scene; there was not a feather or scrap to be found. This could mean two things, the jacamar made it out the talons of the tiny hawk, however, due to the elongated nature of their talons, I choose to believe that the later, the jacamar left the scene in the grasp of the hawk.

When I returned to eat dinner, I learned that little is known about this species of raptor and that the sighting was very rare! Looking further into this species, I discovered that there is hardly any information on their populations. With the help of citizen science, specifically from eBird by Cornell University, I found that only 130 observations have been recorded in Peru over the past ten years. With such little documentation on this uncommon bird, it is alarming that they are estimated to lose 19-24% of suitable habitat in the next twenty-two years (BirdLife).

The Tiny hawk has an assumed population of 670-6,700 individuals and is currently listed as ‘least concern’ by the IUCN, and BirdLife, due to its expansive range (BirdLife). Hearing these statistics shocked me and I immediately searched population sizes of species that are rare to see. The jaguar (Panthera onca), an animal that is incredibly elusive, yet possibly more likely to be encountered, has roughly 15,000 individuals according to the WWF (Quigley). And so I thought, “a tiny hawk is not something you see every day”.

References:

Global Raptor Information Network. 2018. Species account: Tiny Hawk Accipiter superciliosus. Downloaded from http://www.globalraptors.org on 15 Sep. 2018
BirdLife International (2018) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 16/09/2018.
Quigley, H., Foster, R., Petracca, L., Payan, E., Salom, R. & Harmsen, B. 2017. Panthera onca(errata version published in 2018). The IUCN Red List of Threatened Species 2017. Downloaded on 15 September 2018.

If you find yourself in the rainforest, it is almost impossible to miss the endless organized columns that army ants form. This group of ants are carnivorous and forage in swarms, raiding everything in their way. If you are not fast enough, you will fall prey to these voracious predators no matter how big you are. If you do outrun them, there are different predators waiting to trap you. Even if you are not an expert birder you probably have heard of Antbirds. This insectivorous group of birds belongs to the family Formicariidae and forage by following army ants. Eciton burchelli and less often Labidus praedator are the species of army ants that Antbirds follow. As simple as this may seem, the relationship is more complex than it sounds, as not all Antbirds are obliged to follow ants.

Hairy-crested Antbird (Rhegmatorhina melanosticta) perched above an army ant swarm | Photo by Will Sweet

This foraging behavior has no counterpart outside the tropics but within them, you can find ant-followers in different altitudes and elevations. Different species attend the raids with different frequencies. The species that regularly attend them and that in some cases depend entirely on the raiding to find their food are known as obligate, or true, Antbirds. A different name is given to the birds that follow the swarms but are also capable of foraging independently of them, they are referred to as regular followers. Lastly are the opportunistic followers, the species that are only seen foraging when the swarm crosses their territory, for which up to 70 species have been identified. In this grouping, there are some non-insectivorous species that opportunistically take advantage of the raid.

Obligate Antbirds, exclusively found in the Amazon region, are limited to the family Thamnophilidae, also known as typical Antbirds. 16 species have been recorded that completely depend on army ant swarms. They depend on army ant raiding swarms to such a degree that in patches of isolated forest where army ants disappear, the Antbirds are gone within a short period of time.  The hairy-crested Antbird (Rhegmatorhina melanosticta), a not easily seen Los Amigos resident, is an example of an obligate Antbird that depends solely on army ants year-round and can be seen in Terra Firme perching low to the ground feasting at the army ants expense.

Following the raids can provide more food than one individual can eat. But for obligate Antbirds, having developed such specialized foraging behavior has its shortcoming. The frequency, abundance, and distance away from their meals depend on the life cycle of army ants. Their life cycle alternates between periods of mobility and stillness, which makes their presence and location in a forest patch unpredictable. Due to army ants’ mobility, their nests are not as you may imagine. They don’t build a nest to live in; rather they sleep in bivouacs. Bivouacs are living ball-shaped nest made out of the workers that protect the queen and her brood.  They alternate between periods of low food ingestion needs and periods of activity every three-weeks, raiding to meet the food requirements of newly born larvae Because of the periods of ants’ stillness, obligate Antbirds have to wander off outside their home range looking for swarms to follow, as a result, they haven’t developed a strict territorial behaviour. In this case, evolution has favored birders; within a swarm raid you can observe several individuals of the same and different species. Make notice that individuals will defend their place along the raid, the closer to the front and the center they get the better the prey they could trap.

If you’re interested in birds, the next time you come to the tropics you might want to go for an early hike and look for the columns of army ants. If you wait patiently, you will be amazed by one of the greatest performances in the rainforest and see several species of highly adapted birds along the way.