Vegetation structure - nest concealment relationship affects the nest survival in the Warbling Doradito

DA CARDONI; NM CHIARADIA; AV BALADRÓN; MG PRETELLI; JP ISACCH

Puerto Iguazú

Congreso; Ornithological Congress of the Americas; 2017

Association of Field Ornithologists, Aves Argentinas, Sociedade Brasileira de Ornitologia

Choice of the breeding site may strongly affect survival rate in birds. At nest-site scale, factors related to vegetation structure, are commonly thought to be crucial factors that modulate the probability of nest predation. The Warbling Doradito (Pseudocolopteryx flaviventris) is an austral migrant that breeds in several types of marsh and grassland-like habitats. Our aim was evaluate the breeding performance of P. flaviventris nesting in different habitats. We specifically considered the role of vegetation structure on the Daily Survival Rate (DSR) by comparing four physiognomically different plant communities: (1-Grass) grasslands of Cortaderia selloana; (2-Marsh) marshes of Juncus acutus; (3-Wet-grass) wetlands of Zizaniopsis bonariensis; and (4-Wet-shrub) wetlands of Solanum glaucophyllum. The vegetation structure at nest site and the degree of nest concealment differed among nesting habitats. DSR was higher in Grass (DSR=0.966, n=36) and Marsh (DSR=0.947, n=7) than Wet-grass (DSR=0.919, n=17) and Wet-shrub (DSR=0.878, n=14). We recorded brood-parasitism only in nests located in Wet-grass (12% of nest) and Wet-shrub habitats (36%). DSR was mainly explained by the Vegetation Obstruction Rate (vegetation density), indicating that nests with higher concealment had higher DSR values, which were recorded in Grass habitat. The results show that in spite of being all native environments there would be suboptimal habitats in terms of survival and fitness, indicating that at the population level this system would be behaving with a source-sink dynamics.