Latitudinal variations in incubation behaviour among uniparental incubating birds

Uniparental incubating birds must resolve the trade-off between self-maintenance and incubation. This balance manifests through diverse incubation behaviours that vary significantly among species and geographic regions. However, limited research has examined the variability of incubation behaviours across species and regions. Using Bayesian phylogenetic mixed models, we investigated how three incubation behaviours (off-bout frequency, off-bout duration, and incubation constancy) vary with latitude across 201 uniparental incubating bird species. Our findings reveal distinct incubation strategies adopted by uniparental birds across latitudes. Species at lower latitudes exhibit fewer off-bouts and, meanwhile, have longer off-bout duration. Conversely, those at higher latitudes exhibit more frequent but shorter off-bouts. Notably, a clear latitude-dependent pattern emerges in incubation constancy, with higher latitudes showing greater incubation constancy. Additionally, smaller-bodied birds tend to take more frequent off-bouts. Significant variations in off-bout frequency were observed across different habitats. Herbivorous species, in particular, show higher incubation constancy compared to omnivorous and carnivorous birds. These findings offer valuable insights into the association of latitudinal variation with evolutionary dynamics of life histories in uniparental incubating birds.