DIVERGENCE BETWEEN NORHT TEMPERATE AND SOUTH TEMPERATE WRENS IN SOCIAL MATING SYSTEM

P. E. LLAMBIAS; M. M. JEFFERIES; P. G. CORIA; G. J. FERNANDEZ

Puerto Iguazú

Congreso; Ornithological Cogress of the Americas; 2017

Aves Argentinas en conjunto con la Association of Field Ornithologists (AFO) y Sociedade Brasileira de Ornitología (SBO).

Due to their broad distribution across the Americas, the House Wren (Troglodytes aedon) and the Sedge Wren (Cistothorus platensis) are ideal species to study geographic variation in mating systems. North and south temperate populations differ in environmental variables and life-history traits that may affect social mating systems. We compared social polygyny rates of north temperate and south temperate wrens using original and published data. We carried out field work on Sedge Wrens in Mendoza (Argentina), and on House Wrens breeding in tree cavities in Buenos Aires (Argentina) and in nest-boxes in Buenos Aires, Mendoza and New York (USA). We incorporated published data into the analyses from Sedge Wrens breeding in Iowa and Minnesota (USA) and of House Wrens breeding in tree cavities in Alberta (Canada) and Wyoming (USA). Social polygyny was more frequent in northern than in southern House Wrens breeding both in tree cavities (8.65% vs. 0.00%) and in nest-boxes (22.99% vs. 2.16%). Similarly, social polygyny rate was higher in northern than in southern Sedge Wrens (16.67% vs. 3.08%). While in the north social polygyny seem to be the consequence of attracting a secondary female to the territory (n=35), in the south was the consequence of usurpation of the territory of a neighbouring female (n=7). Differences between hemispheres in social polygyny rates and in how polygyny is achieved suggest that different selective forces may be operating in northern and southern populations. Future work in additional study sites is essential to stablish the generality of our results.