138 | Chapter 7
habits are those more likely to die in their early years. If this was the
case, the survivors, the adults, would show more consistent habits than
younger birds. Again there is no evidence for this scenario. Thus the
front- running idea is that consistent habits develop over a bird’s early
years – and the limited evidence supports this.
Speaking at the 2nd World Seabird Conference, Steve Votier, a key
contributor to the Grassholm studies, described how gannets with chicks
undertook repeatable stereotyped journeys out of the colony. On the
other hand, immature birds, followed by satellite- tracking, showed
highly variable foraging locations and low route fidelity from one trip
to the next. There was next to no individual specialisation. This differ-
ence was not simply associated with having chicks to rear. Failed breed-
ers also showed considerable trip consistency (albeit less than breeding
adults with chicks). Consequently Votier concluded that consistent in-
dividual foraging habits are learned during seabirds’ long lives.
When in life is this consistency acquired? This remains a tricky ques-
tion because fledging birds may be tracked for the first year or two at
sea. Then there is a gap in knowledge, around the period when birds are
3– 4 years of age and, literally, beyond the grasp of researchers. These
difficulties notwithstanding, Tommy Clay has tackled the issue, using
the exceptional data available on the Wandering Albatrosses of South
Georgia, thanks to many years of effort by the British Antarctic Survey.
Some birds develop consistency in the sea areas utilised in the first two
years of life. Others take several years, but still achieve this characteris-
tic before they begin to breed. But this variation has few obvious reper-
cussions. Clay found little association between when a Wanderer devel-
oped consistent use of particular sea areas and either its likelihood of
joining the breeding population or the age at which it would do so.
If consistency develops during an individual’s lifetime, does that
imply that a consistent lifestyle brings detectable benefits? Actually it
might not. Suppose, very simply, that there was ten times as much food
available in area A as in area B. Then if ten times as many birds visited
A as visited B, the birds visiting the two areas would prosper equally,
and a bird consistently visiting A would fare as well as one visiting B.
A researcher would struggle to detect any advantages arising from the
birds’ consistency. Perhaps as a result of learning, the birds in my simple