White-browed Ground-Tyrant Muscisaxicola albilora Scientific name definitions

The White-browed Ground-Tyrant is common species of the Andes mountains and surrounding mountain ranges. It breeds in central Chile and Argentina (mainly between 2,300 and 2,800 m) to southern Patagonia, where it reaches lower elevations. In late summer and early autumn, it migrates north to higher elevations in northern Bolivia, Peru, and Ecuador, above 2,900 m. It is common throughout most of its distribution, and is generally the most abundant ground-tyrant in much of its breeding range.

Like other ground-tyrants, its habits and appearance can be inconspicuous, and it can easily go unnoticed despite its propensity for prominent perches on rocks and bushes. Its main identifiable features are its white supercilium and a diffuse rufous patch on its crown. It is most reliably observed in open areas, especially near water sources. It is an active forager, and can be observed running and vigorously pursuing insects. Throughout most of the year it is largely silent, making only short monosyllabic calls; however, it performs aerial displays and aggressively defends its territory on its breeding grounds. Nests are typically well concealed; sited in small crevices between rocks or in rock walls, and built up with grasses and feathers. It is generally solitary, but may be found in pairs or sparse groups. During migration, it forms small groups, sometimes with other muscisaxicolas, occasionally numbering in the hundreds.

Despite its relative abundance, it remains poorly studied, with many aspects of its natural history and ecology known only from isolated observations. As with many other species that breed in the Andes of Chile and Argentina, there are very few detailed studies of the species, and its population status remains unclear. Neither is there an understanding of the impacts that human activities and climate change will have on its breeding habitat.