Breeding-site fidelity of an obligate grassland bird in the Northern Great Plains

Many migratory birds show breeding-site fidelity, but research has focused primarily on shrubland and forest species, with grassland birds largely overlooked. Fidelity is typically higher in woody systems because of the greater predictability and stability of these environments. Furthermore, breeding-site fidelity has been shown to influence territory size, with returning birds occupying higher-quality habitat in familiar landscapes and maintaining smaller territories. We investigated Western Meadowlark (Sturnella neglecta) breeding-site fidelity in the Northern Great Plains from 2022 to 2024, with objectives to (1) quantify breeding-site fidelity in grasslands managed with fire and grazing, and (2) characterize the relationship between individual breeding-site fidelity and territory size. We observed high breeding-site fidelity, with annual return rates of 61% in 2023 and 60% in 2024, and 33% of birds banded in 2022 returning in both subsequent years. Territory sizes declined over time regardless of return status (2022: mean = 7.80 ha; 2024: mean = 5.50 ha; χ²₂ = 7.86, p = 0.02). Mean territory size did not differ by return status (χ²₂ = 0.53, p = 0.77) and variability in territory size was not different between returning and non-returning birds (F1,68 = 3.39, p = 0.07). We documented strong breeding-site fidelity in Western Meadowlarks. Although the drivers of this fidelity remain uncertain, several non-exclusive mechanisms may contribute, including stable habitat maintained through fire and grazing, individual experience, and landscape configuration that limits dispersal. Declines in meadowlark territory size over time may reflect interannual variation in precipitation. Precipitation likely influences resource availability, with wetter years allowing birds to establish smaller, more resource-rich territories. Our findings contribute additional evidence that grassland birds can exhibit strong breeding-site fidelity despite dynamic management and environmental conditions and highlight the need for future research explicitly linking management regimes, environmental variability, and individual behavior.