Regional‐scale and life‐history drivers of breeding timing and nest success in subtropical South American passerines

Life‐history theory predicts covariation among reproductive traits that maximize lifetime reproductive success. In birds, broad‐scale patterns including latitudinal gradients and the fast–slow pace‐of‐life continuum support this idea. Yet, most research has focused on tropical and northern temperate species, while subtropical regions remain poorly studied and are often less predictable than expected from these general patterns. We tested whether breeding timing and nest success exhibit interspecific convergence (i.e. sympatric species with similar life‐history patterns due to shared macro‐environmental conditions at intermediate latitude), as expected from ecogeographical gradients, or whether these traits are primarily shaped by local ecological filters and species‐specific traits. We analysed nest initiation dates from 1202 nests of 85 species using linear mixed‐effects models, and daily nest survival rates (DSRs) from 605 nests of 68 species using nest survival models. We found that community‐wide breeding season length was intermediate between tropical and temperate latitudes, but timing varied with ecoregion, diet, annual cycle strategy and clutch size. Overall DSR (0.957/day) was also intermediate, varying with ecoregion, nest habitat, nest age and seasonal timing. Our findings indicate that local ecological conditions and species' life‐history strategies shape breeding patterns, deviating from the primary predictions of broad‐scale gradients in subtropical South America. By providing the most comprehensive nesting dataset for the region, our results complement the limited regional literature and establish a baseline for long‐term monitoring of subtropical avian reproductive strategies under a changing climate.