NOTES ON GEOGRAPHICAL VARIATION AND THE ANNUAL CYCLE IN PATAGONIAN POPULATIONS OF THE RUFOUS‐COLLARED SPARROW ZONOTRICHIA CAPENSIS

Abstract

Summary Zonotrichia capensis australis inhabits Argentina from the northernmost limits of the Patagonian steppe south through Tierra del Fuego, and extends westward to the Pacific slope in southern Chile. At least part of the population has a north‐south migration along the Andean foothills of Argentina as far north as southwestern Bolivia. The breeding range of australis is bounded on the north and northwest by subspecies of Z. capensis (chilensis, choraules, and possibly hypoleuca) having conspicuous black lateral crown‐stripes. Topotypical australis (Tierra del Fuego) have plain grey crowns, but the frequency of black nuchal markings and faint lateral crown‐lines increases northward in the coastal populations. In inland populations (Andean piedmont) the frequency of black crown markings is apparently reversed, increasing southward. The size (wing‐length, tarsus, bill, and probably body‐weight) of australis decreases northward in both coastal and inland samples.The nesting season of australis begins in late November and early December and extends to mid January and early February. Postnuptial moult begins from mid December to early January. Moult proceeds while the testes are apparently still functional. Postnuptial moult terminates from late January through mid March. There is no evidence in the current data of geographical trends in the chronology of nesting and postnuptial moult. The calendars appear to be about the same throughout the range of australis.Postjuvenal moult begins about 4–5 weeks later than the onset of postnuptial moult and terminates in the latest birds in about mid March. Northward migration begins at about this time.