Migration strategies, performance and annual activity budget in a short-distance migrant, the common starling Sturnus vulgaris

Migratory birds typically separate energetically demanding parts of the annual cycle like breeding, moult, and migration with some species engaging in so-called moult-migration. Moult-migration is known to occur in starlings from the northern breeding populations, however, little is known about the dynamics of this phenomenon and the costs and benefits for the involved individuals. Here, using state-of-the-art multi-sensor geolocators, we gathered information about the annual cycles of 10 starlings from two breeding sites in Latvia. We used a novel analytical approach based on atmospheric pressure measurements to reveal that all but one of the tracked individuals migrated to wintering sites in the British Isles. Tracking data exposed two separate migration strategies – (1) departure from the breeding grounds in mid-June soon after chick fledging with long stationary periods at moulting sites approx. 900 km westward (n = 5 of 10); (2) residing in close vicinity of the breeding sites up u..., In 2020, we set up two new study sites in Latvia to study Starlings. One in eastern Latvia in Zeltaleja (57.19°N 26.86°E) consisting of 100 nest boxes and the second in western Latvia near Lake Engure (57.27°N 23.10°E) consisting of two plots ca. 8 km apart with 100 nest boxes each. The distance between the two study sites was 230 km. During the breeding season from mid-April until mid-June all nest boxes were monitored at least once every four days and adult birds and chicks were ringed. Onset of egg laying at both study sites was highly synchronized among individuals with 90% of all recorded broods (n = 181) started between 19 and 29 April. No second brood was recorded at either of the two study sites. In 2020, we fitted 70 adult breeders (35 at each site; 34 males, 36 females) with multi-sensor archival data loggers (model: GDL3-PAM, Swiss Ornithological Institute,  Liechti et al. 2018), which were attached on the bird's back using nylon cord leg-loop harness. Adult birds were predom..., R-package ‘pamlr’ (Dhanjal-Adams et al. 2022)