Cordillera Azul Antbird: New Bird Species Discovered in Peru

A distinctive new species of antbird has been discovered in the humid montane forests of the San Martin region in north-central Peru.

The Cordillera Azul antbird (Myrmoderus eowilsoni). Image credit: Andrew Spencer / Macaulay Library.

The antbirds are a large family of insect-eating passerine birds, Thamnophilidae, known for habitually following columns of marching ants.

There are more than 210 species in roughly 45 genera, known variously as antshrikes, antwrens, antvireos, fire-eyes, bare-eyes and bushbirds. They are found across subtropical and tropical Central and South America, from Mexico to Argentina.

The antbirds are highly diverse; all are of small to medium size (between 4 and 14 inches, or 9.5-37 cm).

The newly-discovered species, named the Cordillera Azul antbird (Myrmoderus eowilsoni), is typically 5.5-6 inches (14-15 cm) long, has a wingspan of 8.7 inches (22 cm), and weighs 27 g.

The songs of both males and female Cordillera Azul antbirds are distinguished from those of other members of the Thamnophilidae family by a combination of a clear whistled quality, few notes, and a simple pattern.

The species is restricted to tall, montane, evergreen forest with intact understory characterized by small trees and ferns, many moss-covered logs, and extensive dead leaf matter on the ground.

“We observed Cordillera Azul antbirds only within 3.3 feet (1 m) of the ground, and individuals typically moved by short, low flights and by walking slowly along the ground,” said Andre Moncrieff from the Louisiana State University Museum of Natural Science and co-authors.

“Walking involved deliberate steps accompanied by a jerking, dove-like head bob, with the tail held straight out behind.”

The Cordillera Azul antbird inhabits forests surrounding the small coffee-growing town of Flor de Cafe, previously called ‘Plataforma,’ at 5,250 feet (1,600 m) above sea level in the western Cordillera Azul.

“We believe it is very likely that this species is found on additional ridges within the Cordillera Azul, and it should be looked for farther afield, perhaps as far as the Cordillera El Sira,” the ornithologists said.

The species has an estimated population of 7,000-34,000 individuals and is threatened by clearance of forest.

“Human colonists from other parts of Peru are rapidly clearing forest in the area and may soon eliminate much of the remaining forest around Flor de Cafe,” Moncrief and colleagues said.

“Chainsaws were an overwhelming component of the soundscape around town. We even asked some locals to delay cutting activities so that we could get better voice recordings of the antbird.”

“Sun-coffee farming, which necessitates clear-cutting, is the main source of income for the residents of Flor de Cafe. By contrast, birding ecotourism benefits only a few residents, leading to some unfortunate and ongoing tensions within the town. There is clearly a great need for environmental education and conservation work in the region.”

According to the team, survey work is urgently needed to determine the full distribution of the Cordillera Azul antbird, to assess territory size and occupancy, and to improve estimates of population size.

“Despite the restricted distribution and habitat loss in the immediate vicinity of the type locality, we consider an IUCN Red List status of ‘Data Deficient’ as most appropriate until the distribution and population trends can be further evaluated,” the scientists said.

Details of the bird’s discovery are published in the journal Auk.

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Andre E. Moncrieff et al. 2018. A new species of antbird (Passeriformes: Thamnophilidae) from the Cordillera Azul, San Martín, Peru. The Auk 135 (1): 114-126; doi: 10.1642/AUK-17-97.1