A meta‐analysis of global avian survival across species and latitude

Abstract

Tropical birds are purported to be longer lived than their temperate counterparts, but it has not been shown whether avian survival rates covary with latitude worldwide. Here, we perform a global-scale meta-analysis of 949 estimates from 204 studies of avian survival and demonstrate that a latitudinal survival gradient exists in the northern hemisphere, is dampened or absent for southern hemisphere species, and that differences between passerines and nonpasserines largely drive these trends. We also show that while extrinsic factors related to climate were poor predictors of apparent survival compared to latitude alone, the relationship between apparent survival and latitude is strongly mediated by intrinsic traitslarge-bodied species and species with smaller clutch size had the highest apparent survival. Our findings reveal that differences among intrinsic traits and whether species were passerines or nonpasserines surpass latitude and its underlying climatic factors in explaining global patterns of apparent avian survival.

Bridging gaps in demographic analysis with phylogenetic imputation

“…Although geographical variation in demographic traits (e.g. differences in clutch size and survival across latitudes) could create different patterns of covariance among vital rates, including phylogeny, life history traits, and latitude may be sufficient to control for such variation (Jetz et al 2008, Scholer et al 2020. Future studies could use a broader coverage of avian life history to investigate how biases in the availability of demographic data affect imputation accuracy and could assess imputation of vital rates in other taxonomic groups.…”

Do avian species survive better on islands?

“…I focused on year-round resident species, as most island species are not migratory. I first consulted earlier extensive reviews of survival rates in birds [15,18,[20][21][22]. I complemented this set by performing online database searches using key words such as 'adult', 'survival', 'annual' and 'birds'.…”

“…One study compared birds on islands and continents but focused on maximum longevity rather than adult survival [14]. The most recent synthesis of adult survival rates excluded island species [15]. A broadscale analysis of island shifts in adult survival has yet to be performed to fully characterize the life-history island syndrome.…”

“…While the prediction that living on islands improves adult survival is simple, several mitigating factors must be considered. In addition to traits such as body mass and clutch size, which are closely associated with adult survival [15], it is important to consider differences between the Hemispheres in life-history strategies [15], as well as latitudinal effects on survival. Indeed, many studies have documented a decrease in survival with increasing latitude in birds [15][16][17][18].…”

“…In addition to traits such as body mass and clutch size, which are closely associated with adult survival [15], it is important to consider differences between the Hemispheres in life-history strategies [15], as well as latitudinal effects on survival. Indeed, many studies have documented a decrease in survival with increasing latitude in birds [15][16][17][18]. Island species also tend to breed cooperatively more often [2].…”