Table 1 Foraging and breeding performance of Adélie penguins in four seasons.

Values shown are estimates (with 95% confidence interval) based on linear mixed-effect models for foraging behavior and means ± SD or single observations for others.

2010/112011/122012/132016/17
Sea-ice coverYesYesYesNo
Foraging behavior
  Trip duration (hours)19.3 (15.9–23.7)19.7 (12.4–31.4)15.0 (9.0–25.1)11.8 (7.6–18.4)
  Trip distance (km)2.1 (1.6–2.7)2.4 (1.4–4.3)2.4 (1.3–4.5)6.9 (4.1–11.9)
(N = 91 trips from 15 birds)(N = 92 trips from 28 birds)(N = 64 trips from 17 birds)(N = 260 trips from 27 birds)
  Dive duration intercept (s)*69 (58–80)74 (48–100)81 (56–106)54 (30–79)
(N = 531 dives from 8 birds)(N = 485 dives from 9 birds)(N = 1119 dives from 15 birds)(N = 2275 dives from 19 birds)
  No. of krill captured in a
100-s dive
4.1 (2.8–6.1)3.6 (1.4–9.2)5.2 (2.2–12.6)5.4 (2.2–13.2)
(N = 443 dives from 8 birds)(N = 374 dives from 9 birds)(N = 996 dives from 15 birds)(N = 1211 dives from 12 birds)
Body condition
  Adult female body mass (kg)3.8 ± 0.4 (N = 21 birds)4.0 ± 0.4 (N = 18 birds)4.2 ± 0.3 (N = 29 birds)4.4 ± 0.5 (N = 42 birds)
  Adult male body mass (kg)4.4 ± 0.3 (N = 21 birds)4.2 ± 0.4 (N = 28 birds)4.6 ± 0.4 (N = 42 birds)4.9 ± 0.5 (N = 31 birds)
Breeding status
  Chick growth rate (g day−1)67 ± 14 (N = 14 birds)69 ± 20 (N = 15 birds)76 ± 16 (N = 33 birds)102 ± 8 (N = 18 birds)
  No. of nests (in late
December)
70109181108
  No. of fledglings (in early
February)
3788219143
Stomach content
  Prey composition by mass†Krill 38 ± 46%Krill 37 ± 46%Krill 91 ± 19%Krill 94 ± 14%
Fish 62 ± 46%Fish 63 ± 46%Fish 9 ± 19%Fish, 6 ± 14%
Krill composition by massE. superba 32 ± 24%E. superba 73 ± 42%E. superba 81 ± 34%E. superba 100%
E. crystallorophias 68 ± 24%E. crystallorophias 27 ± 42%E. crystallorophias 19 ± 34%
(N = 10 birds)(N = 10 birds)(N = 11 birds)(N = 8 birds)

*Intercept of dive duration as a function of dive depth (i.e., dive duration of a hypothetical 0-m dive).

†In addition to krill and fish, a few amphipods (<1% by mass in most birds) were often found.