Nest sites and breeding ecology of the Másafuera Rayadito (Aphrastura masafuerae) on Alejandro Selkirk Island, Chile

Abstract

The first nest sites of the endemic Ma´safuera Rayadito (Aphrastura masafuerae) are described, the first one being found on 16 December 1992. Ma´safuera Rayaditos breed in small natural holes in steep rocks, the nest being hidden within the rock and not visible through the 3 cm-wide entrance. All nest sites were located in the summit region of Alejandro Selkirk Island above 1,200 m altitude, characterised by fern stands. Nesting has been reported from early December to late January. Feeding frequency increases only slightly during nestling time. Both parents feed the nestlings in similar proportions. During the daily round no regular variation in feeding frequency occurs, although it is often higher during the first hours after sunrise. In general, it decreases strongly when a Ma´safuera Hawk (Buteo polyosoma exsul) is present close to the nest site. It hunts intensively on Rayaditos, both adults and juveniles. Habitat destruction and predation pressure have caused the Ma´safuera Rayadito to be the most endangered bird species in Chile (total population c. 140 individuals). More detailed studies on its breeding ecology are urgently needed, especially on reproductive success.

Interpopulation Comparisons of Antipredator Defense Behavior of the Thorn‐Tailed Rayadito (Aphrastura spinicauda)

“…In the vast majority of cases, rayaditos did not enter in the nest when the adult predator was present, which was also found for a congeneric species ( Aphrastura masafuerae ) (Hahn et al. ). Although the adult predator elicited a longer vocal response, the mobbing alarm calls were acoustically similar toward the adult and nest predators, as well as the non‐threatening passerine bird.…”

First Description of Nesting Ecology of the Endemic Grey-Flanked CinclodesCinclodes oustaleti baeckstroemiifrom the Juan Fernández Islands, Chile

“…Besides, nest holes in soft substrate like earth, sand or wood, would not be sufficiently protected against hawk predation. The Mása-fuera Hawk Buteo polyosoma exsul was observed to actively search for nest holes of Aphrastura masafuerae and then to try to throw out the host offspring (Hahn et al 2004). Thus the few data provide evidence that baeckstroemii uses a rather narrow substrate spectrum of nest sites.…”

Phylogenetic Position of the Most Endangered Chilean Bird: The Masafuera Rayadito (Aphrastura Masafuerae; Furnariidae)

“…The vegetation of the area consists of dominant fern Lophosoria quadripinnata (95–100% cover), tree-ferns ( Dicksonia externa and Blechnum cycadifolium ) and the tree Drimys confertifolia. See Hahn et al [6] for detailed information regarding the nesting habitat of the species. Blood samples were obtained by puncturing the brachial vein and stored on FTA cards (Whatman, Germany).…”

“…Usually found in dense vegetation cover [5], the Masafuera Rayadito ( Aphrastura masafuerae ; Furnariidae) is a small, buff-brownish bird characterized by reddish spine-like tail feathers and a light superciliary stripe ([6] and references therein). This species is endemic to Alejandro Selkirk Island (Juan Fernández Archipelago, Chile) and is declared a Critically Endangered species by the International Union for Conservation of Nature (IUCN) [7].…”

“…The grazing of goats and cattle has increased habitat loss for the species. The lack of nesting sites, introduced species such as feral cats and rats ( Rattus rattus and R. norvegicus ) and increased populations of natural predators like the Masafuera Hawk ( Buteo polyosoma exsul ) are threatening this bird as well [6,10].…”