the meandering years of immatUrity | 43years without ever putting webbed foot on terra firma. Then, as the years
pass and the bird matures, colonies are visited, and one colony is even-
tually chosen as the breeding place. A mate is found and breeding com-
mences. This extended pre- breeding period has long puzzled biologists,
especially as some species seem physiologically able to breed years be-
fore they do so. For example, a team from the British Antarctic Survey
peered laproscopically at the testes of five- year- old Wandering Alba-
trosses on Bird Island, South Georgia. Despite this species rarely breed-
ing before the age of eight, the testes of these non- breeding males aged
five or older were as large as those of many breeding males, and levels of
testosterone in blood samples were in line with the range of breeding
males.^1 Why do they delay so long?
The answer could be linked to the risks and benefits of breeding.
There is likely to be a risk of predation when visiting the colony, there
could be risks associated with flying substantial distances between the
colony and the prime feeding regions, and parenthood itself may be
physiologically exhausting. On the other hand the benefits, measured in
terms of fledglings hatched and despatched, hinge inter alia on the bird
knowing where to find food and catch it efficiently. Possibly several
years are needed before this know- how becomes sufficiently refined for
the potential benefits of breeding to outweigh the likely risks.
This life- history pattern means there is a time gap between a bird’s
first flight and its return to the colony months or, more likely, years
later. Even with the availability of modern devices, this poses problems
for the researcher seeking to track a bird’s location and activity. The
batteries of devices deployed at fledging may expire. Gadgets attached
to the plumage will fall off when the bird moults. And, of course, the
bird has to survive those immature years if its device is ever to be re-
trieved. No wonder scientists refer slightly forlornly to this period as
the ‘lost years’. Yet it is also the period when the seabird is likely to ex-
plore the oceans, discover the best feeding areas, and perhaps develop
the individually- consistent habits that are a feature of so many adult
seabirds, a fascinating topic to which I shall return in Chapter 7. With-
out better understanding of the pressures on seabirds during those miss-
ing years, our ability to improve their lot is severely compromised. The
urgency is only compounded by the observation that, in species with a