46 | Chapter 3
First catch your immature seabird. I myself have caught many thou-
sands of seabirds by metal hook or nylon noose around the leg, by fleyg
(effectively a giant lacrosse net used especially by Faroese and Icelanders
to catch Atlantic Puffins for the pot), by mist net and, of course, by a
straightforward grab. Steve Votier, an ornithologist at the University
of Exeter, has a personal website that shows one of the other tricks of
the seabird trade, catching gannets by using a long pole to noose them
around the neck.^3 Using this technique, his team noosed gannets at the
world’s third largest colony on Grassholm, off south- west Wales. Each
of the captured birds, five immatures and 25 adults with chicks, was
released after the brief indignity, with a satellite tag, programmed to
obtain an hourly- GPS fix. The contrast in the tracks of the two groups
was striking. The average out- and- back journey of an adult was 370 km.
None went north into the Irish Sea and the furthest west reached by any
bird was south- west Ireland. The immatures travelled three times the
distance on their excursions from Grassholm, and showed considerable
variety in their tracks. Two rounded Brittany to enter the Bay of Biscay
while another once did a circuit of Ireland and once ventured among
the Scottish Hebrides.^4 (See Map 1.)
Not only did the tracks of the immatures tell of exploratory behaviour,
so did the fact that two of the five visited other gannet colonies on their
excursions. One bird called at no less than three Irish colonies while an-
other made a prospecting visit to the Rouzic colony off the northern
coast of Brittany. It would be fascinating to know more about whether
and in what circumstances these pre- breeding visits led to eventual set-
tlement as a breeder in later years.
Although the picture was slightly clouded by technical issues, Voti-
er’s analysis of the stable isotopes in the gannets’ blood suggested that,
compared to adults, the young birds were either eating larger fish or
fishery discards, the fish caught but not brought ashore by fishers. It is
at least a possibility that they were feeding in different areas. Not only
is that compatible with the different tracks, but it would also enable the
younger gannets to avoid feeding alongside the potentially more skilled
adults.
Another study, this time in the turquoise Mediterranean rather than
the drabber Irish Sea, matched Votier’s work in showing that immature