Lucia Bernad

Winter Population Size Estimations of Three Migratory Sheldgeese in the Southern Pampas, Argentina

Abstract. Sheldgeese [Upland Goose (Chloephaga picta picta), Ashy-headed Goose (C. poliocephala) and Ruddyheaded Goose (C. rubidiceps)] have similar migratory patterns, breeding in Patagonia (Argentina and Chile) and wintering mainly in the southern Pampas, Argentina. All of them are species of conservation concern in Argentina. The objective of this study was to estimate species densities using distance sampling and to calculate population sizes over three categories of habitat quality in the southeast of Buenos Aires Province, Argentina. Road surveys (9,200 km) were performed from a vehicle during two consecutive wintering seasons (13 June to 6 July 2011 and 9 June to 4 July 2012). Predicted probabilities of sheldgeese occurrence were divided into three classes of habitat quality. Upland Goose mean density was estimated at 3.72 individuals/km2, Ashy-headed Goose at 1.62 individuals/km2 and Ruddy-headed Goose at 0.04 individuals/km2. Consequently, Upland Goose numbers were estimated at 348,255 individuals, Ashy-headed Goose at 151,803 individuals and Ruddy-headed Goose at 498 individuals in the southeast of Buenos Aires Province. The results confirm former studies regarding the small population sizes of these species in comparison with historic data and suggest a decline in sheldgeese populations.

Natural infection in Pampas fox (Lycalopex gymnocercus) by Lagochilascaris major Leiper, 1910 (Nematoda: Ascarididae) in Buenos Aires, Argentina

AbstractLagochilascariosis is an emerging parasitic disease limited to the American continent, caused by nematodes of the genus Lagochilascaris. Its life cycle is heteroxenous, involving natural definitive hosts (wild carnivores), accidental hosts (domestic carnivores and humans), and intermediate hosts (rodents). Here we report, for the first time, the occurrence of Lagochilascaris major in female of a Pampas fox (Lycalopex gymnocercus) which was found in the Mar Chiquita basin, Buenos Aires province, Argentina. At necropsy, multiple Lagochilascaris larvae and several adults (1 female and 5 male) were observed inserted in the mucosa of the trachea and a male was also collected in the stomach. The diagnosis was made by observing the different stages with optical microscopy, by scanning electron microscopy of adult males and coproparasitological analysis. Although cases of lagochilascariosis have been reported in wildlife in different countries of the American continent, in Argentina, cases are really rare and were only found in domestic cats. Graphical abstractᅟLagochilascariosis is an emerging parasitic disease limited to the American continent. In Argentina, sporadic cases of Lagochilascariosis were reported in domestic cats but this work represents the first record in a wild carnivore (L. gymnocercus) naturally infected with L. major.

Niche Overlap Determination Through Habitat Suitability Models: A Management Tool for Native Birds of the Argentinean Pampas

Summary. In Argentina, predominantly in the Pampas ecoregion, the natural rangelands have increasingly been replaced by crops. Avifaunal studies have shown that the population density of several species decreased as the proportion of cropland in the landscape increased. The Greater Rhea Rhea americana and two migratory sheldgeese: the Upland Goose Chloephaga picta and Ashy-headed Goose Chloephaga poliocephala, are medium-large native species that have been common and sympatric inhabitants of the Pampas ecoregion. We aimed to analyse and compare the current ecological niches occupied by the three species during the non-breeding season in the southern Pampas of Argentina, the region where their original distributions overlapped, using Ecological Niche Factor Analysis. The three species showed high global marginality values, indicating that they occupied only a specific subset of environmental conditions of those available across the region. Suitable areas for Greater Rhea were located in the west and south of the study area, overlapping grazing lands and native habitats. The three species responded to landscape composition and configuration, as indicated by the low proportion of areas with suitable conditions for these medium-large birds. Suitable areas for Ashyheaded and Upland Geese were especially concentrated in the eastern part of the area and suitable areas for Upland Goose were more widespread than those suitable for the Ashy-headed Goose. We provide compelling evidence of low overlap between the ecological niches of the three species in the southern Pampas, which highlights the need for specific management strategies to ensure the conservation of these emblematic species. —Pedrana, J., Bernad, L., Maceira, N.O. & Isacch, J.P. (2018). Niche overlap determination through habitat suitability models: a management tool for native birds of the Argentinean Pampas. Ardeola, 65: 25–40.