The beautiful treerunner (''Margarornis bellulus'') is a
Near Threatened species of
bird in the Furnariinae subfamily of the ovenbird
family Furnariidae. It is
endemic to
Panama.
[
]
Taxonomy and systematics
Some authors have proposed that the beautiful treerunner and the pearled treerunner
The pearled treerunner (''Margarornis squamiger'') is a species of bird in the Furnariinae subfamily of the ovenbird family Furnariidae. It is found in Bolivia, Colombia, Ecuador, Peru, Venezuela, and possibly Argentina.Remsen, J. V., Jr ...
(''M. squamiger'') are conspecific or sister species, but these treatments were disproven in a 2011 publication.[Derryberry, E. P., S. Claramunt, G. Derryberry, R. T. Chesser, J. Cracraft, A. Aleixo, J. Pérez-Emán, J. V. Remsen, Jr., and R. T. Brumfield. (2011). Lineage diversification and morphological evolution in a large-scale continental radiation: the Neotropical ovenbirds and woodcreepers (Aves: Furnariidae). Evolution 65(10):2973–2986. https://doi.org/10.1111/j.1558-5646.2011.01374.x]
The beautiful treerunner is monotypic.[
]
Description
The beautiful treerunner is long and weighs . The sexes have the same plumage. Adults have a buffish-white supercilium
The supercilium is a plumage feature found on the heads of some bird species. It is a stripe which runs from the base of the bird's beak above its eye, finishing somewhere towards the rear of the bird's head.Dunn and Alderfer (2006), p. 10 Also ...
that extends to the nape, a dull reddish brown line behind the eye, dark brown ear coverts with whitish streaks, and a dark brown "moustache" with white spots that become stripes toward the neck. Their crown is olive brown and their upperparts and wing coverts warm olive-brown. Their flight feathers are dark fuscous with tawny-ochraceous edges. Their tail is dull reddish brown; the ends of the tail feathers lack barbs, giving a spiny appearance. Their throat is whitish and the rest of their underparts rufescent brown. Their upper breast has whitish oval spots with dark brown rims that become narrow stripes on the belly. Their iris is brown, their maxilla brownish, their mandible pinkish, and their legs and feet gray.[Remsen, Jr., J. V. and C. J. Sharpe (2020). Beautiful Treerunner (''Margarornis bellulus''), version 1.0. In Birds of the World (J. del Hoyo, A. Elliott, J. Sargatal, D. A. Christie, and E. de Juana, Editors). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.beatre1.01 retrieved September 9, 2023]
Distribution and habitat
The beautiful treerunner has a disjunct distribution
In biology, a taxon with a disjunct distribution is one that has two or more groups that are related but considerably separated from each other geographically. The causes are varied and might demonstrate either the expansion or contraction of a s ...
within Panama. It is found in the Serranía de Majé of Panamá Province and in several ranges in the extreme east of Darién Province. It inhabits montane evergreen forest, mostly at elevations between but in a few places as low as .[
]
Behavior
Movement
The beautiful treerunner is a year-round resident throughout its range.[
]
Feeding
The beautiful treerunner feeds on arthropods. It usually forages as part of a mixed-species feeding flock. It acrobatically moves through the forest's subcanopy, gleaning prey from branches and epiphyte
An epiphyte is an organism that grows on the surface of a plant and derives its moisture and nutrients from the air, rain, water (in marine environments) or from debris accumulating around it. The plants on which epiphytes grow are called phoroph ...
s, sometimes while hanging upside down.[
]
Breeding
Nothing is known about the beautiful treerunner's breeding biology.[
]
Vocalization
As of September 2023, xeno-canto and the Cornell Lab of Ornithology's Macaulay Library each had a single recording of a beautiful treerunner call and none of its song.[
]
Status
The IUCN
The International Union for Conservation of Nature (IUCN; officially International Union for Conservation of Nature and Natural Resources) is an international organization working in the field of nature conservation and sustainable use of natu ...
has assessed the beautiful treerunner as Near Threatened. It has a very small range and an unknown population size, though the latter is believed to be stable. "Habitat in the region is being cleared and degraded for mining, agriculture and cultivation of coca", and because it is a high elevation species "it could be vulnerable to global climate change".[ All of its known locations in Darién Province are within Darién National Park.][
]
References
{{Taxonbar, from=Q796676
Margarornis
Endemic birds of Panama
Birds of the Darién Gap
Birds described in 1912
Taxonomy articles created by Polbot