Table 1 – Characteristics (mean and sd, shown in brackets) of the central place (long) foraging tracks undertaken by Pterodroma madeira and P. deserta during the incubation phase of their breeding season, considering the entire track and the search and transit sections separately. The sampling units are the foraging trips and the sample size (“n”, shown in brackets) reflects the number of trips considered. The duration, cumulative distance and maximum distance were calculated considering all tracks (both collected at 1 h and at 2 h temporal resolution); all the other parameters were calculated using the tracks collected at the same temporal resolution (1 h)
Parameter | Pterodroma madeira | Pterodroma deserta | ||
|---|---|---|---|---|
All tracks (n = 12) | All tracks (n = 41) | |||
Duration (days) | 11.19 (3.19) | 13.52 (3.58) | ||
Cumulative distance (km) | 5656 (1359) | 7864 (2212) | ||
Max distance from colony (km) | 2043 (352) | 2460 (579) | ||
Tracks 1 h resolution (n = 12) | Tracks 1 h resolution (n = 21) | |||
Ground speed (kmh-1) | 21.38 (2.82) | 24.61 (3.08) | ||
Time in search state (%) | 46 (9) | 42 (12) | ||
Wind speed (kmh-1) | 20.68 (2.62) | 24.60 (3.25) | ||
Tail wind component (kmh-1) | 4.65 (2.48) | 6.55 (3.00) | ||
Search | Transit | Search | Transit | |
Ground speed (kmh-1) | 10.25 (1.34) | 30.61 (2.86) | 14.24 (2.03) | 32.07 (1.63) |
Wind speed (kmh-1) | 20.49 (2.29) | 20.95 (3.86) | 25.85 (4.18) | 23.73 (3.33) |
Tail wind component (kmh-1) | 4.47 (3.28) | 4.70 (3.07) | 7.83 (4.40) | 5.64 (3.37) |
Wind Δangle (°) | 76.48 (8.38) | 77.93 (7.54) | 69.99 (11.99) | 74.69 (10.31) |
Sea surface temperature (°C) | 18.20 (1.50) | 19.44 (0.85) | 22.50 (1.55) | 22.50 (1.04) |
Bathymetry (m) | -3651 (436) | -3875 (284) | -3841 (549) | -3977 (248) |