Transmitters were attached to four adult male Gory's Shearwaters (Calonectr
is diomedea) caught at their breeding sites off Crete, Greece, in autumn 19
98. The birds had left the Mediterranean by the beginning of December. Two
were last recorded in the eastern tropical Atlantic in January/February. Th
e other two wintered east of the Mid-Atlantic Ridge, one at about 10 degree
s N, the other one in equatorial waters, and could be tracked until return
migration in March/April. The seasonal variation in travel speed is in acco
rdance with a conventional pattern of migration with phases of migration an
d wintering, rather than continuous movement throughout the nonbreeding cyc
le. The birds left the Mediterranean later and wintered farther north than
expected. We suggest that the known longitudinal dine in body size, morphol
ogy, and vocalizations of Gory's Shearwater may also be found in migration
behavior.