Contrasting latitudinal patterns of life‐history divergence in two genera of new world thrushes (Turdinae)

Abstract

Several long‐standing hypotheses have been proposed to explain latitudinal patterns of life‐history strategies. Here, we test predictions of four such hypotheses (seasonality, food limitation, nest predation and adult survival probability) by examining life‐history traits and age‐specific mortality rates of several species of thrushes (Turdinae) based on field studies at temperate and tropical sites and data gathered from the literature. Thrushes in the genus Catharus showed the typical pattern of slower life‐history strategies in the tropics while co‐occuring Turdus thrushes differed much less across latitudes. Seasonality is a broadly accepted hypothesis for latitudinal patterns, but the lack of concordance in latitudinal patterns between co‐existing genera that experience the same seasonal patterns suggests seasonality cannot fully explain latitudinal trait variation in thrushes. Nest‐predation also could not explain patterns based on our field data and literature data for these two genera. Total feeding rates were similar, and per‐nestling feeding rates were higher at tropical latitudes in both genera, suggesting food limitation does not explain trait differences in thrushes. Latitudinal patterns of life histories in these two genera were closely associated with adult survival probability. Thus, our data suggest that environmental influences on adult survival probability may play a particularly strong role in shaping latitudinal patterns of life‐history traits.

Metabolic rate is negatively linked to adult survival but does not explain latitudinal differences in songbirds

“…Furthermore, using latitude as a proxy for survival rate is problematic because survival rates vary extensively among species within latitudes, with overlap among temperate and tropical groups (reviewed in Martin et al ). In addition, patterns of latitudinal variation in survival can differ dramatically among clades (Boyce & Martin ). Metabolic rate and adult survival appeared to be negatively correlated across latitudes in songbirds in one study (Williams et al ).…”

Apparent survival of tropical birds in a wet, premontane forest in Costa Rica

“…A prevailing view is that tropical species typically have slow life history strategies where individuals prioritize future reproductive efforts over success in a given year, have lower fecundity, extensive parental care, and high adult survival (Skutch 1967, Ghalambor and Martin 2001, Lloyd and Martin 2016, Pizzaro Muñoz et al 2018. However, few demographic data for testing these predictions are available for most tropical taxa (Martin et al 2011, Boyle et al 2016, Boyce and Martin 2017. In particular, estimates of apparent survival of tropical birds vary widely and are often lower than expected (Karr et al 1990, Sandercock et al 2000, Blake and Loiselle 2013.…”

“…, Martin , Boyle et al. , Boyce and Martin ). In particular, estimates of apparent survival of tropical birds vary widely and are often lower than expected (Karr et al.…”

Is the distribution of the Acorn Woodpecker (Melanerpes formicivorus flavigula) associated with oaks and granaries? A local study in an urban area in northern South America

“…For instance, some species might be better competitors than others or are more generalist in their diets. Although there are local studies on native and introduced species in urban environments, such as foraging behavior (Delgado et al 2005, Delgado 2007, Delgado & Calderón 2007, Osorio & Marín 2016); nesting biology (Sedano et al 2008); interactions with other species (Garcés et al 2012); or abundance and reproduction (Sánchez et al 2016), there are a lack of studies examining how species who are widely distributed have modified their behavior and use of habitat to thrive in local conditions (Boyce & Martin 2017).…”