the meandering years of immatUrity | 49extent to which this inferior performance of the young birds was due to
lower efficiency, and to what extent it was because their southward
track from Skomer took them to waters less productive than those used
by the adults.
A picture is emerging of immature and breeding seabirds using dif-
ferent sea areas, possibly in part because the young birds are less effi-
cient foragers. If correct, we might expect that, through the several years
of immaturity, the young bird’s behaviour at sea would progressively
converge on that of the adults. An example where this might be so is
provided by the Wandering Albatrosses tracked from the colonies on
Iles Kerguelen and the Crozets in the Southern Ocean.^7 In their first
five months after fledging, young Wanderers are as well able to take
advantage of tail and side winds as adults. This aspect of flight appar-
ently needs little learning. However they spend progressively less of
their time on the water and more on the wing, covering greater daily
distances. This is almost certainly associated with developing the flying
skills described in Chapter 2. Then, following that tiresome gap when
the birds are beyond reach, immatures between four and eight years of
It is pitch- black on Skomer Island off the coast of Wales. Clamorous Manx
Shearwaters are present in their thousands. The challenge for researchers:
find the handful of birds carrying GPS devices.