132 | Chapter 7
This is not as stupid as it might seem. Perhaps the fact that the two trav-
ellers, or indeed travellers more generally, choose a variety of routes
means that no one route becomes clogged with traffic. Everyone bene-
fits from the multiple route choices that have been made.
I have been lucky enough to study Manx Shearwaters over many
years. Unfortunately for the birds, the studies have meant that they are
unceremoniously removed from their burrows time and again. Some are
stoical, some more rumbustious and aggressive. There are clear differ-
ences in character between the birds. And, as has emerged in other com-
parable seabird studies, a minority of pairs raise the majority of chicks.
This variation in quality bears comparison with the so- called Pareto
Principle which originated in the observation that 80 percent of Italy’s
wealth belonged to only 20 percent of the population. It has since been
extended to many aspects of organisations. For example, 20 percent of
the workers produce 80 percent of the results.*
With individual seabirds probably differing in quality and character
and certainly living long enough to develop individually consistent hab-
its, it is perhaps no surprise that individual consistency is a theme that
emerged once seabird tracking projects proliferated. This chapter will
describe examples of such consistency, now identified in over 10 percent
of all seabird species, and mull over whether it benefits the birds.
The consistency might operate over several timescales. An adult bird
might set forth from the colony to find food in a direction that is more
consistent than the various directions chosen by fellow colony members.
That is a short- term choice. On a longer timescale, habits acquired as a
youngster might be retained into adulthood. Over an entire lifetime,
migrants might return to the same non- breeding area year after year.
The consistent use of certain areas is conceptually distinct from
other possible manifestations of consistency. Some birds might regu-
larly choose to search for fish in cooler waters, others in warmer waters.
Some might choose to follow ships while others are more wary. In prac-
tice these alternative types of consistency may not be completely distinct
- (^) The principle also appears to apply to writing seabird books; about 80 percent of the useful
words come in 20 percent of the screen time, while the remaining 80 percent of time mysteri-
ously vanishes.