The entire surface area of the Juan Fernandez Islands (~ 95 km²) (Chile) was mapped accord- ing to bird habitats. Twelve principal habitat types were described. Comparisons of an avifaunal recon- struction with our recent findings show that the number of regularly breeding terrestrial bird species increased from 7 to 11 since the discovery of the islands in 1574 until today. Six out of the seven native landbird species are endemic, each being restricted to a single island. Distribution and abundance patterns are given for all landbird species and habitat types. Endemics generally show preference for habitat types dominated by native plants. Although non endemic birds have invaded such habitats also, they prefer hab- itats with introduced plants. Non endemic species were found in a broader range of habitat types than

The habitat and nest sites of an island-endemic, the Masafuera Grey-flanked Cinclodes, are described for the first time. The species breeds only in natural cavities in steep rock-walls and rocky slopes or ridges. The nest entrance diameter ranges from 5.5 to 20 cm, the nest chamber being placed within the rock so as to be invisible from the outside. The nest sites found - solely on Alejandro Selkirk Island - were located from a little above the sea-level to the summit region, the preferred habitats being barren canyon bottoms with small streams, and humid alpine plateaus. Nesting extends from early December to late January, indicating a core breeding season from November to January. Fledgling numbers per clutch average about two.

The diet of Black-necked swans, Cygnus melancoryphus (Anatidae), was studied in two southern Chilean wetlands in 1993–1995; the Cruces River Sanctuary and the Chihuao-Pichoy River, both near Valdivia. The diet of swans was analyzed by using microhistologic techniques of cell remains in feces collected in the field. The analysis showed that swans were eating predominantly the most abundant submerged aquatic plant, Brazilian waterweed, Egeria densa (Hydrocharitaceae), at both Cruces River (91.9% of diet) and Chihuao-Pichoy River (71.7%). The foraging action of this species was estimated using four forage exclosures in the Chihuao-Pichoy River wetland free from swan grazing, which were compared with foraged controls. Aquatic plant biomass taken in the exclosures was significantly higher (p < 0.05) than biomass sampled outside the exclosures. Cygnus melancoryphus might play an important role as a regulator of aquatic plant biomass, thus contributing to cause a delay in ecological succession. The potential impact of this slowing down is discussed in terms of a natural ecological process in wetland environments.

Population trends of Black-necked Swans (Cygnus melancoryphus) at Rio Cruces Sanctuary are analyzed and discussed in light of annual and seasonal fluctuations at this Ramsar site. Aerial, boat or ground surveys of swans have been made every month since 1985. Pronounced annual and seasonal fluctuations in numbers, with lows during the wet autumn/winter and peaks during the dry spring/summer, characterize this population. Numbers of swans more than doubled during the La Nina periods of 1989-1991 and 1996-1997. These periods coincided with macro-regional droughts that forced swans to move nomadically in the southern cone of the Neotropic. Rio Cruces is a stable wetland and a likely demographic source for Black-necked Swans in the region, where their distribution and numbers have increased in the last decade.

Journal Article Feeding Ecology of Central Chilean Foxes, Dusicyon culpaeus and Dusicyon griseus Get access Fabian M. Jaksić, Fabian M. Jaksić Museum of Vertebrate Zoology and Department of Zoology, University of California, Berkeley, CA 94720Instituto de Zoología, Universidad Austral de ChileMuseo Nacional de Historia Natural, Chile Search for other works by this author on: Oxford Academic Google Scholar Roberto P. Schlatter, Roberto P. Schlatter Museum of Vertebrate Zoology and Department of Zoology, University of California, Berkeley, CA 94720Instituto de Zoología, Universidad Austral de ChileMuseo Nacional de Historia Natural, Chile Search for other works by this author on: Oxford Academic Google Scholar José L. Yáñez José L. Yáñez Museum of Vertebrate Zoology and Department of Zoology, University of California, Berkeley, CA 94720Instituto de Zoología, Universidad Austral de ChileMuseo Nacional de Historia Natural, Chile Search for other works by this author on: Oxford Academic Google Scholar Journal of Mammalogy, Volume 61, Issue 2, 20 May 1980, Pages 254–260, https://doi.org/10.2307/1380046 Published: 20 May 1980 Article history Received: 15 January 1979 Accepted: 27 November 1979 Published: 20 May 1980