86 | Chapter 5
is that, however efficient is a seabird’s flight, large amounts of time and
effort will necessarily be devoted to, or one might say wasted on, travel
between breeding colony and feeding area. This is likely to restrict the
number of young that can be reared.
The second problem follows from the first. Since eggs or small chicks
would die if left unguarded for any significant period whilst an adult
was away at sea, a single-parent family is not an option for seabirds. At
no stage of the breeding cycle is this more true than during incubation.
Once one or several eggs are laid, more or less non- stop parental atten-
tion is crucial if the eggs are to hatch. This applies in Antarctica where
the threat may arise from fierce blizzards, and it applies equally in a cliff
colony of Common Guillemots in Great Britain where gulls are perpet-
ually circling in the hope of grabbing an unattended egg. It remains true
in the tropics where the predators might be crabs or frigatebirds.
Parental co- ordination between the two pair members is then a vital
element of successful breeding. It obviously starts well before laying.
Birds return to the colony. The One is sought and found. A bond is
formed, or re- formed since seabirds so very often retain the same mate
from one breeding attempt to the next. Then copulation occurs and in
due course an egg or eggs are laid, and incubation starts.
That overly brief account of the pre- laying period rushes past varia-
tion in its pattern between various seabirds groups. For some groups,
cormorants and gulls for example, it is a period that unfolds in a month
or thereabouts, broadly as described, and minimal extra knowledge has
arisen from modern devices. Other groups depart intriguingly from the
basic pattern.
Among some auks, the first return to the colony can be earlier than
might be anticipated, in September or October, well before the dark
depths of the northern winter.^1 This is true of southern populations of
the Common Guillemot while more northern populations do not return
until spring simply because the breeding cliffs are snow- clad through
the winter. As spring draws nearer, so a cyclic pattern develops among
several auk species: three days of colony attendance followed by 3– 5 days
of absence. Very early attendance at the colony perhaps helps the bird
secure ownership of a site when competition for a limited supply is
fierce, and perhaps helps ensure male and female are physiologically syn-
chronised for the forthcoming breeding effort.