We analysed the use of three-dimensional space by 13 freely diving ringed s
eals, Phoca hispida, to distinguish between local search, presumably within
prey patches, and travel or exploration between prey patches. We subdivide
d the three-dimensional home ranges of ringed seals into 3 x 3 x 3 m grid c
ells. For each dive, we determined the time spent swimming through each gri
d cell and the frequency of grid cell revisits. The seals generally spent 1
-3 s in each cell and rarely revisited cells. During 34% of all dives, howe
ver, ringed seals focused their effort within a reduced volume, suggesting
local search within patches of prey. The disproportionate effort within res
tricted volumes resulted from seals revisiting cells (18% of dives), reduci
ng speed within cells (9% of dives), or both reducing speed and revisiting
cells (7% of dives). Ringed seals searched locally in less than 10% of desc
ents and ascents but did so in 41% of bottom phases (time spent at depth be
tween the end of descent and the beginning of ascent). (C) 2001 The Associa
tion for the Study of Animal Behaviour.