A global latitudinal decline in breeding site fidelity emerges from a single biome

Abstract

Species that breed in multiple years can either return to the same location to reproduce between seasons or disperse to a different location. Previous studies have shown that breeding site fidelity varies with species‐ and individual‐specific traits, but much of the observed variation remains unexplained. Breeding site fidelity may also vary latitudinally, given that key ecological factors relevant for breeding such as seasonality, resource availability, and habitat stability show strong latitudinal gradients. We examined variation in breeding site fidelity among shorebirds, using 189 estimates of local return rate from 120 populations of 55 species. We first show that there is a strong non‐linear latitudinal pattern in breeding site fidelity, with return rates being stable at lower latitudes and progressively decreasing towards higher latitudes. We then show that this effect is driven entirely by the tundra biome: in the tundra – but not in other biomes – return rates decrease sharply with latitude, resulting in overall lower return rates in the tundra compared to other biomes. We suggest that the high inter‐annual variability in local breeding conditions and short window for reproduction that characterize the tundra, especially at higher latitudes, favor breeding dispersal and hence lead to low site fidelity. Our findings show that an apparent global latitudinal trend in a life‐history trait can be driven by a single biome.