Winter dispersal and activity patterns of post-breeding black-legged kittiwakes Rissa tridactyla from Prince William Sound, Alaska

Abstract

As colony-specific wintering ecology of small and medium-sized seabirds is poorly understood, it has been generally assumed that winter conditions have the same effect on all individuals from any given colony. However, advances in global positioning technology now allow researchers to investigate movements of smaller seabirds. We tracked black-legged kittiwakes Rissa tridactyla using geolocator tags during the non-breeding season. Although kittiwakes as a group appear to be generalists with respect to overwintering strategy, our data indicate that individual birds are more specialized in their use of wintering habitat. Among birds tagged in the Gulf of Alaska, we identified 3 groups employing different wintering strategies: (1) resident birds that remain in the northern Gulf of Alaska; (2) coastal birds that remain within coastal and shelf waters but move as far south as California; and (3) pelagic birds that travel up to 1700 km offshore. Given that wintering conditions differ in widely spaced areas, the effects of winter on bird survival and body condition are likely not the same on all birds in a colony, as is often assumed. Activity data revealed that kittiwakes are almost entirely diurnal during the non-breeding season. We found significant differences in time allocation among wintering groups: birds that remained in the colony region spent less time loafing during the day and engaged in longer daytime flying and foraging bouts than birds that wintered farther from the colony. These differences suggest that wintering birds make trade-offs among travel distance, metabolic demands, and foraging quality.

Combination of At-Sea Activity, Geolocation and Feather Stable Isotopes Documents Where and When Seabirds Molt

“…These methods involve actively transitioning from air to water; accordingly, foraging time was here identified as intermittent wet and dry states for at least one 10 min period. Although such records probably include non-foraging behaviors (e.g., preening, stretching), we believe that they represent a reasonable indicator of foraging activity of the birds (McKnight et al, 2011). Note that in most previous studies using wet/dry recorders, only two activities were quantified, corresponding to the total time per day either when the sensor was wet (on water) or dry (in flight/on land; Afanasyev, 2004;Catry et al, 2009).…”

‘Stepping stone’ pattern in Pacific Arctic tern migration reveals the importance of upwelling areas

“…We identified 3 types of behavior from the saltwater immersion data: (1) 'floating,' which occurred when the logger was submerged for at least one 10 min period, indicating that the bird was sitting on the water; (2) 'flying/standing,' which occurred when the logger was entirely dry for at least one 10 min period, as would occur when a bird was flying or standing on land or on floating ice or debris; and (3) 'possible foraging,' which occurred when the logger recorded intermittent wet and dry states for at least one 10 min period (McKnight et al 2011).…”

Consistent variation in individual migration strategies of brown skuas

“…Values of 0 (entirely dry), 1 to 199, and 200 (entirely wet) in each 10 min period were categorised as either 'flight' (as skuas remain at sea during the non-breeding period), 'foraging' or 'sitting on water', respectively, assigned to daylight or darkness periods based on nautical twilight hours and summarised accordingly (see Mattern et al 2015). Although some intermediate values (from 1 to 199) will reflect non-foraging behaviour, in general this categorisation is assumed to provide a reasonable indication of foraging activity among seabirds (McKnight et al 2011, Cherel et al 2016.…”