Geographical Distribution and Sympatry of Tufted and Plain-Mantled Tit-Spinetails (Leptasthenura Platensis and Leptasthenura Aegithaloides) in Argentina
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Volume 8 1997 No.2 ORNITOLOGIA NEOTROPICAL 8: 113-120, 1997 ltJ The Neotropical Ornithological Society GEOGRAPHICAL DISTRIBUTION AND SYMPATRY OF TUFTED AND PLAIN-MANTLED TIT-SPINETAILS (LEPTASTHENURA PLATENSIS AND LEPTASTHENURA AEGITHALOIDES) IN ARGENTINA Victor A. Cueto1, Javier Lopez de Casenave2 & Luis Marone3 1 División Ornitología, Museo Argentino de Ciencias Naturales "Bernardino Aivadavia", Avenida Angel Gallardo 470, 1405 Buenos Aires, Argentina. 2 Departamento de Biología, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Piso 4, Pabellón 2, Ciudad Universitaria, 1428 Buenos Aires, Argentina. 3Ecofisiología Vegetal, Instituto Argentino de Investigaciones de las Zonas Aridas, Casilla de Correos 507, 5500 Mendoza, Argentina. Resumen. Analizamos la distribuci6n geográfica de Leptasthenura platensis y L. aegithaloides en Argentina, con especial referencia a aquellas localidades en donde han sido encontradas juntas ambas especies.La distribuci6n geo- gráfica es presentada en un mapa de puntos que muestra las localidades conocidas para L. platensis (185 localidades) y para L. aegithaloides (160). Ambas especiesse distribuyen en ambientes secosy xéricos. Presentamos el segundo registro de L. platensis en la provincia de Mendoza, identificando a la especie mediante el examen de individuos capturados en redes de niebla y el análisis de sus vocalizaciones. Confirmamos informaci6n previa sobre cuatro localidades simpátricas y reportamos un nuevo sitio de simpatna. También presentamos otras localidades donde las especiesson probablemente simpátricas. Leptasthenura platensis y L. aegithaloides son simpátricas o potencial- mente simpátricas en algunas áreas de vegetaci6n correspondientes a las formaciones del Espinal y del Monte, especialmente en el centro y centro-este de Argentina. Abstract. We analyze the geographical distribution ofLeptasthenura platensis and L. aegithaloides in Argentina, with special reference to localities where these two species are sympatric. We map the geographical distribution showing known localities of occurrence for L. platensis (185 localities) and for L. aegithaloides (160). Both species are distributed in dry and xeric environments. A second record of L. platensis for Mendoza Province is reported, where the species was mist-netted. We confirm previous information of four sympatric localities, and report a new sympatric site. Further, other localities in which these speciesare probably sympatric are discussed. We found that L. platensis and L. aegithaloides are sympatric or potentially sympatric in vegetation corresponding to the Espinal and Monte formations, especially in central and east-central Argentina. Accepted 24 January 1997. Key words: Furnariidae, geographical distribution, sympatry, Leptasthenura platensis, L. aegithaloides, tit-spinetails, Nacuñán, Argentina. INTRODUCTION of their ranges (Narosky & Yzurieta 1987, Cane- vari et al. 1991), but Vaurie (1980) pointed out The Tufted Tit-Spinetail Leptasthenura platensis that these two species overlap in the steppes of (Reichenbach, 1853), and the Plain-mantled Tit- north-eastern Patagonia and in some areas of Spinetail, Leptasthenura aegithaloides (Kittlitz, central Argentina. Maps in Ridgely & Tudor 1830), are two closely related speciesof Furnarii- (1994) show a broad area of overlap. Vuilleumier dae (Wetmore 1926). They are allopatric in most (1993), however, did not observe actual sympatry 113 along a transect in northern Chubut Province, Most localities cited prior to 1925 were taken although he sighted the two species near each from Cory & Hellmayr (1925). Severa1localities other in two areas, concluding that they are for Buenos Aires Province were taken from the potentially sympatric. Therefore, the geogra- maps in Narosky & Di Giacomo (1993). Some phical distribution of these two speciesis in need records for La Pampa, Rio Negro, Chubut, and of further study (Vuilleumier 1993: 22). For Santa Cruz Provinces were kindly provided by example, Olrog (1963, 1979) and Meyer de F. Vuilleumier (unpublished data, 1992 and Schauensee(1970) gave Chubut Province as the 1993). Severa1localities for Neuquén Province southern limit of L. platensis, but Humphrey & were given by M. Babarskas,J. Veiga, and F. Fili- Bridge (1970) reported one specimen from Santa berto (pers. comm.), and M. Babarskas provided Cruz Province, much further south. data for other provinces as well. C. Ludwig kind- Differences in the plumage of these two ly informed on specimens of Leptasthenura stored species include the presence of a crest in L. pla- in the collections of the u. S. National Museum tensis (absent in L. aegithaloides), fourth pair of of Natura1 History, Washington D. C. rectrices cinnamon in L. platensis but pale gray to We present a map of the Phytogeographic buffy in L. aegithaloides, dark crown usually Provinces of Argentina. The comparison of this heavily streaked in L. aegithaloides (almost un- map with that of the geographic distribution of streaked in L. platensis), and throat streaked in the speciespermits one to obtain data of the type L. platensis but unstreaked or less streaked in of vegetation that these birds inhabit. L. aegithaloides. Taken together, these characters From April1993 to December 1995 we car- are distinctive on study skins, but can be difficult ried out eleven visits to the Biosphere Reserve of to appreciate in the field (Vuilleumier 1993). Nacuñán (34°02'S, 67°58'W, Fig. 1). Nacuñán Although Wetmore (1926), Narosky & Yzurieta (1987), Canevari et al. (1991), and Ridgely & is located in an intermediate latitude of the Mon- Tudor (1994) described the vocalizations of these te desert (Morello 1958). The prevailing habitat species,these are in need of further comparative in the reserve is an open woodland of algarrobo study (Vuilleumier 1993: 39). (Prosopisjlexuosa) with high shrub (Larrea diva. In this paper we analyze the biogeography of ricata, Capparis atamisquea, Condalia microphyl. L. platensis and L. aegithaloides in Argentina, la) and grasscover. Isolated patches with high co- with special reference to localities where these ver of chañar ( Geojfroea decorticans) and shrub- two speciesare sympatric. We confirm previous- lands of Larrea cuneifolia also prevail in some ly known sympatric localities, report a new areas.In October 1994 we tape-recorded individ- sympatric site (which also constitutes the second uals in the field. Sonagrams were obtained from record of L. platensis for Mendoza Province, these recordings, as well as from previous Argentina), and present other localities in which recordings of both species at other locations. these species are probably sympatric. Sound analyses were carried out at the Laborato- rio de Investigaciones Bioacústicas de la Funda- METHODS ción "Federico Wildermuth", Gálvez, Santa Fe Province. We present the geographic distribution of tit-spi- netails on a map, showing known localities of oc- RESULTS AND DISCUSSION currence of these two species.Research to compi- le this map involved an extensive survey of the Geographic di5tribution. We were able to obtain literature (see Appendix). In addition, we exami- a list of 185 localities for L. platen5i5 and of 160 ned specimens in the collections of the Museo localities for L. aegithaloide5 in Argentina (Fig. Argentino de Ciencias Naturales "Bernardino 1). We did not use unprecise localities, such as Rivadavia" (MACN), the Facultad de Ciencias "A lo largo del Río Chico de Chubut", or "Cór- Naturales y Museo de La Plata (MLP), and the doba Province", as well as those localities in Instituto Argentino de Investigaciones de las Zo- which the specific identity of tit-spinetails was nas Aridas (IADIZA). Finally, we carried out either dubious or not reported. A complete list field work to further elucidate the distribution of these localities is available from the authors of these two tit-spinetails. upon request. 114 TI1'SPINETAIL DISTRIBUTION IN ARGENTINA The two speciesof Leptasthenura are distribu- Espina!, and Puna Phytogeographic Provinces ted in dry and xeric environments (seeFig. 1 and (Cabrera 1976). 2). In Argentina, Leptasthenura platensis occurs Some locality records appear to be outside mostly from central to northern, northeastern, the main ranges as outlined above. Por L. aegitha- and eastern regions, inhabiting areas with xero- loides these outlying records could represent mi- philous trees and shrubs, belonging to the Chaco gratory movements, as suggestedby Olrog (1979) and Espinal Phytogeographic Provinces (Cabrera and Nores et al. (1983) for Lo aegithaloides palli- 1976). Leptasthenura aegithaloides ranges from da. These records are in southern Santiago del the south northwestward toward the extreme Estero Province, in Córdoba Province, and in .northwest of the country, and is found in shrub- eastern Buenos Aires Province. The loca!ity steppes, shrublands, and zones with xerophilous records for Lo platensis in Chubut and north- t~ees, belonging to the Patagonian, Monte, western Santa Cruz may indicate a southward FIG. 1. Geographical distribution of Leptasthenura FIG. 2. Phytogeographic Provinces of Argentina, platensis (black dots) and L. aegithaloides (circles) in according to Cabrera (1976) and modified by Canevari Argentina. The 19 localities where the two species et al. (1991). Province nomenclature follows Cabrera occur together appear as triangles. The Biosphere (1976). Localities where Leptasthenura platensis and Reserve of Nacuñán is indicated byan arrow. L. aegithaloides occur together appear as black