Beautiful Treerunner

The beautiful treerunner, Margarornis bellulus, is a modestly sized bird, measuring 14 to 15 cm in length and weighing between 18 to 19 grams. Exhibiting no sexual dimorphism, both male and female share the same plumage. This bird is adorned with a buffish-white supercilium that stretches to the nape, a subtle reddish-brown line behind the eye, and dark brown ear coverts with delicate whitish streaks. A dark brown "moustache" marked with white spots that transition into stripes towards the neck adds to its distinctive appearance. The crown is olive brown, while the upperparts and wing coverts are a warm olive-brown. The flight feathers are dark fuscous with tawny-ochraceous edges, and the tail is a dull reddish brown with a unique spiny appearance due to the lack of barbs at the ends of the tail feathers. The throat is whitish, transitioning to rufescent brown underparts. The upper breast features whitish oval spots encircled by dark brown, which become narrow stripes on the belly. The bird's iris is brown, the maxilla brownish, the mandible pinkish, and the legs and feet are a gray hue.

Identification Tips

When identifying the beautiful treerunner, look for its distinctive buffish-white supercilium and the spiny appearance of its tail. The bird's unique pattern of white spots and stripes on the upper breast and belly can also aid in identification.

Habitat

This species is a denizen of montane evergreen forests, typically found at elevations between 1,350 and 1,600 meters, though it can occasionally be spotted as low as 900 meters.

Distribution

Endemic to Panama, the beautiful treerunner's range is disjunct within the country, occurring in the Serranía de Majé of Panamá Province and several ranges in the extreme east of Darién Province.

Behaviour

The beautiful treerunner is a permanent resident within its range. It is known for its acrobatic foraging behavior in the subcanopy of the forest, where it gleans arthropods from branches and epiphytes, sometimes even while hanging upside down.

Song & calls

As of the latest data, there is only a single recording of the beautiful treerunner's call available, with no known recordings of its song.

Breeding

Currently, there is no information available regarding the breeding biology of the beautiful treerunner.

Similar Species

While there has been some debate, the beautiful treerunner is not conspecific or a sister species to the pearled treerunner, as previously suggested by some authors.

Diet and Feeding

The beautiful treerunner's diet consists primarily of arthropods. It is often observed foraging within mixed-species feeding flocks.

Conservation status

The IUCN has classified the beautiful treerunner as Near Threatened. Its range is very small, and while the population size is unknown, it is believed to be stable. However, habitat loss due to mining, agriculture, and coca cultivation, as well as potential vulnerability to global climate change, pose significant threats to this species. Notably, all known locations of this bird in Darién Province are within the protected bounds of Darién National Park.