Table 1.
Dates of capture, recapture and morphometrics of the nine Long-tailed Skuas fitted with geolocators in 2010–11 and recaptured in 2011–12.
Figure 1.
Flyways used by Long-tailed Skuas between their breeding grounds (red stars) and their wintering ground.
(a–c) three males from north-east Greenland, (d–f) three males and (g–h) two females from Svalbard. Autumn movements (August–November) are in blue, winter movements (December–March) in red and spring movements (April–June) in yellow. Dashed lines represent interpolations (linear or parallel to the continents) for periods (equinox) when latitude could not be estimated. Black lines: same interpolations close to breeding grounds due to permanent daylight. The last panel (i) presents all raw positions (two per 24 h) obtained for these eight birds over one year.
Figure 2.
Kernel density distribution estimated for the Long-tailed Skuas.
(a) from release to September 10th, (b) between October 10th and November 31st, (c) December and January and (d) after April 10th. Contours represent densities of 25% (red), 50% (orange) and 75% (yellow).
Table 2.
Annual cycle based on the eight monitored Long-tailed Skuas (median values followed by ranges in brackets).
Figure 3.
Staging areas (blue lines and symbols) used by Long-tailed Skuas.
(a) geographical distribution of the staging areas used in the Atlantic and Indian Oceans; red colour is used for migration (i.e. “non-staging”) periods, blue colour for staging and black for periods when status could not be defined (i.e. when less than three successive days with daily positions). (b) individual differences in timing and latitude of staging.
Figure 4.
Daily (full line) and weekly (dotted line) rates of travel estimated for Long-tailed Skuas (in km d−1 ±S.E.).
Table 3.
Distances travelled by Long-tailed Skuas (Greenland and Svalbard birds combined; n = 8).
Figure 5.
Major flyways and wintering grounds of the Long-tailed Skuas compared with two other sympatric seabirds.
(a) Long-tailed Skua, (b) Arctic Tern and (c) Sabine's Gull. Contours are graphically inferred from Figure 1 (panels 1–8), Egevang et al [29] and Stenhouse et al [25], respectively. Blue: autumn flyways; Red: wintering grounds; Yellow: spring flyways.