168 | Chapter 9
squid. They are. Information from attached magnetometers has revealed
that, in certain regions of the ocean, the albatrosses can be spinning on
the water for up to six hours of the night, in tiny circles of 1.5 metres
diameter. Although they cannot light up the water with electric light,
Wilson thinks that, during spinning, the birds are using their large feet
to agitate bioluminescent plankton, and create a light show which could
plausibly attract squid – just as a squid jigger’s light attracts them.
Two features of the Wanderers’ lifestyle might benefit from rapid
digestion. Firstly, the birds’ mobility places a premium on reducing
weight by digesting food quickly, and excreting surplus material. Sec-
ondly, Wanderers following ships show very little distaste for waste dis-
charged overboard that most readers would rightly view as distasteful.
To protect against the harmful bacteria associated with such food, an
acidic fast- digesting stomach would be useful, the very physiological tac-
tic of vultures. And a small study of the Wandering Albatrosses of the
Crozets discovered that their stomach acidity was greater than that of
other seabirds with a pH, a measure of acidity, comparable to that of
vultures at about 1.5.^7
The propensity of the Wandering Albatross to spend more time on
the water by night is widely true of other albatrosses. But it is not true
of smaller tracked petrels which may spend about the same time on the
water by day and by night (e.g. White- chinned Petrel) or actually more
time on the water by day (e.g. Chatham Petrel when not breeding).
Given that the Wandering Albatross catches most of its day’s food
during the daytime when flying, it is sensible to wonder whether the
species that are more active at night are night- time feeding specialists.
A strong candidate is Bulwer’s Petrel, a rather small all- dark species
found in all the world’s principal tropical oceans. Studied by Maria Dias
at the Salvage Islands, situated between Madeira and the Canaries, the
petrels, when at sea, spend in excess of 90 percent of the night- time
hours on the wing.^8 The day/night contrast is at its most extreme when
the petrels, friends of the infinite deep, reach their winter quarters. These
are tropical seas of the mid- Atlantic where the water is over 4,000 m
deep. There, Bulwer’s Petrels are 3– 4 times as likely to be flying by night
as by day. Since the proportion of night- time flying during winter barely
fluctuated with the phase of the moon, Dias reckoned the petrels were