Canadian Journal of Zoology 81, 1249-1256 (2003)
Diving behavior of an epipelagically-feeding alcids, the Rhinoceros Auklets (Cerorhinca monocerata).
Kuroki M, Kato A, Watanuki Y, Niizuma Y, Takahashi A, Naito Y
The diving behavior of Rhinoceros Auklets (Cerorhinca monocerata) breeding at Teuri Island, Hokkaido, Japan,
was studied using small bird-borne time¡Vdepth dataloggers. The eight auklets made dives without an obvious horizontal
bottom phase to a median depth of 14.0 } 1.8 (mean } SD) m (maximum 57 m) for 53 } 8 s (maximum 148 s)
between the hours of 0300 and 2000. They made undulations (rapid depth changes), considered to represent prey pursuit,
in 35% of the dives. Of the undulations, 57% occurred during the deep (>80% of maximum depth) parts of the
dives and 26% during the ascent phase. The auklets performed 26 } 31 dives continuously during dive bouts of 32 }
34 min. Dive bouts at the end of the day were twice as long as in the morning and at midday. During dive bouts, the
auklets showed consistent trends in dive depth, decreasing (23% of bouts), increasing (32%), or stable (19%), but
sometimes they showed hectic depth changes (26%). V-shaped dives (with no horizontal bottom phase), potential prey
pursuit in both the deep parts and ascent phases of the dives, and variable depth changes within dive bouts indicate the
aukletsf epipelagic feeding habits.
BD03-2
|
