172 | Chapter 9
long (longer than 12 min). Of 137364 dives recorded by 93 penguins
264 dives [0.2%] reached depths greater than 400 m and 48 lasted longer
than 12 min [0.03%]. Most (65%) very long dives occurred in winter
(May– August) while 83% of the very deep dives took place in spring
(September– November). The two most extreme dives (564 m depth,
21.8 min duration) were separate dives and were performed by different
individual penguins. Penguins diving extremely deeply may have done
so as part of their foraging strategy whereas penguins diving for very
long times may have been forced to do so by changes in the sea- ice con-
ditions.”^19 No wonder Wienecke’s face is one characterised by raised eye-
brows expressing surprise and delight at the dives of penguins, and life
in general.
Once information about these impressive depths is to hand, all man-
ner of questions surface. One is how the birds detect prey before actu-
ally catching it. In some cases, there is little doubt that vision is the
primary sense. I have already mentioned the Imperial Shag swinging its
head from side to side as it scours the sea bed. Among penguins catch-
Emperor Penguins are probably the deepest- diving of all seabirds, sometimes
plumbing depths in excess of 500 m in pursuit of fish and squid.