Migration strategies, performance and annual activity budget in a short‐distance migrant, the common starlingSturnus vulgaris

Abstract

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 until the end of October (n = 5 of 10). Accelerometer data revealed significantly higher activity budgets during moult for the individuals exhibiting moult‐migration. Furthermore, birds that underwent moult‐migration arrived at the breeding sites in the following year on average 10 days later and showed significantly higher activity levels during the pre‐breeding period compared to birds without moult‐migration. Activity tracking also showed that 67% of all migratory flights were performed during the night, contradicting previous assumptions of starlings being predominantly diurnal migrants. Maximum recorded flight altitudes reached 2500 m a.s.l. and the longest uninterrupted flight lasted 22.5 h. Our results highlight energetic trade‐offs of moult‐migration in starling, but their downstream consequences remain to be tested.

Revisiting Perdeck's massive avian migration experiments debunks alternative social interpretations

“…However, our data debunk the possibility that juveniles copied the distances and directions of conspecifics encountered in the social environment of the translocation sites. These results may be partly explained by recent tracking data showing that for actual migration flights, starlings resorted to nocturnality, and may thereby be more lonesome travellers than previously thought [ 45 ]. Although nocturnality does not necessarily exclude social behaviour, we suggest that this is unlikely since the majority of nocturnally migrating birds travel solo [ 46 ], and to the best of our knowledge, starlings do not produce nocturnal flight calls like, for instance, American wood warblers ( Parulidae ) [ 47 ] and European thrushes ( Turdidae ) [ 48 ].…”

Sex-specific migration strategies and underlying physiology contribute to spring arrival protandry in a songbird

“…Assuming that the circadian pattern of migratory activity might re ect actual behaviour in the wild (Schmaljohann et al 2015;Ilieva et al 2023), the observed dynamics of circadian activity suggest that, in the wild, male reed buntings start their migration shortly before sunrise and continue migratory ight some hours during daytime, while females migrate mainly during the second half of the night and cease migration around sunrise. The possibility of continuing the nocturnal migratory ight into the daytime was recently reported in another short-distance migrant, European starling (Sturnus vulgaris), which had been previously assumed to migrate primarily during the day (Vīgants et al 2023). In captive conditions, a similar explanation was recently proposed for circadian activity dynamics in Sedge warblers (Acrocephalus schoenobaenus) in autumn (Ilieva et al 2023).…”

Avian migration clocks in a changing world

“…Juvenile Reed warblers displayed nocturnal flights in the wild well in advance of migration, presumably to form memory for navigation, and corresponding nocturnal restlessness in captivity (Mukhin et al 2005 ). In late summer birds may undertake post-breeding movements, for example for dispersal or to reach moulting locations (Pillar et al 2015 ; Vīgants et al 2023 ).…”