wind and waves | 121to Crozet latitudes. They necessarily face headwinds on either the out-
ward or homeward journey, during which they tack like sailing ships.
While the Southern Ocean is certainly dominated by westerly winds
pushing a bird east, there are periods, time slots, when movement to the
west is potentially easier. One such period is after the passage of a low
pressure system. As the cold front trailing the system passes an island,
so the wind swings quite abruptly from north- west to south- west. Eric
Woehler, a Tasmania- based biologist with some 30 years of experience
of southern hemisphere seabirds, tells me that this is when prions and
diving petrels leave Marion Island to embark on a foraging trip. Simi-
larly, it is in the aftermath of the cold front that Wandering Albatrosses
in the southern Indian Ocean seize the opportunity to make progress
westward, flying north- west at right angles to the south- west wind.^15 This
takes them north of any high pressure system following in the wake of
the low. There the wind is easterly, allowing further progress westward.
Although these studies show how breeding seabirds exploit prevail-
ing wind patterns to reduce travel costs, they shed no light on how the
birds would fare were wind patterns to change. We might reasonably
guess that albatrosses could become becalmed, were the wind to fade
away. But consider the alternative. Since albatrosses need winds of at
least 30 km/h to allow dynamic soaring, might not winds stronger than
those currently prevailing reduce their travel costs and enhance breed-
ing success?
This possibility has been given credence by the hugely- informative
long- term French study of Wandering Albatrosses on the Crozets.^16
Over the study’s 40 years, winds have strengthened in this part of the
Southern Ocean, both towards the north where breeding females con-
centrate their feeding, and further south where males feed (see Chap-
ter 3). Stronger winds have allowed the birds to travel faster. Since their
feeding success depends principally on distance covered, faster travel
allows the albatrosses to gather the same quantity of food, mostly squid,
in less time and arrive back at the nest more rapidly. This is especially
advantageous during incubation since a major cause of breeding failure
is abandonment of the egg by the sitting parent, urgently awaiting the
return of the mate from its squid hunt. Associated with the improved
breeding success and stronger winds, the birds have become about one