Age effects on survival of Amazon forest birds and the latitudinal gradient in bird survival

Auk

article

Alejandra Pizarro Muñoz¹  Marc Kéry²  Pedro Vitor Martins³  Gonçalo Ferraz¹ 

[1] Ecology Department, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil;Swiss Ornithological Institute, Sempach, Switzerland;Klamath Bird Observatory, Ashland, Oregon, USA

关键词: age-mixture survival model;    age-specific survival;    age uncertainty;    Amazon;    Cormack-Jolly-Seber;    hierarchical model;    tropical birds;   

DOI  :  10.1642/AUK-17-91.1

学科分类：动物科学

来源: Central Ornithology Publication Office

【 摘 要 】

The search for explanations of the well-documented positive relationship between latitude and avian clutch size has created the expectation that tropical birds should balance their smaller clutch sizes with relatively high survival probabilities. So far, efforts to detect a latitudinal gradient in survival have found no statistical support, leading to the hypothesis that a gradient may be present in the survival of juveniles alone. Such a gradient could be masked by the data on adults when field records make no distinction between ages. We aimed to (1) assess the effect of age on survival of tropical birds by estimating age-specific annual apparent survival probabilities for a set of 40 passerine understory species from the central Brazilian Amazon and (2) test the hypothesis of a latitudinal gradient in adult survival with a meta-analysis of tropical and temperate-zone forest passerine survival probabilities at study areas from Peru to Alaska. We estimated age-specific survival using a hierarchical, multispecies Cormack-Jolly-Seber (CJS) model that treats species-specific parameters as random effects. To extend our analysis to data on birds of unknown age at the time of banding, we developed a novel CJS model with a mixture component for the survival of birds of unknown age. We found a strong effect of age on survival at our site, with juveniles having lower survival than adults. The meta-analysis of 342 survival estimates from 175 species and a latitude span of >60 degrees revealed a negative effect of latitude on survival, which supports the widely accepted hypothesis that, on average, tropical birds have higher annual survival than their temperate counterparts. We conclude that there is no need for an alternative latitudinal trend in juvenile survival to account for the general trend in clutch size.

【 授权许可】

CC BY