Page 381 - (DK) Ocean - The Definitive Visual Guide

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HUMAN IMPACT
SEA BIRDS UNDER
THREAT

Feeding Methods The inexorable increase in fishing
and shipping has had a significant
brown Marine birds have evolved several ways of hunting their impact on many coastal and
pelican 33 ft (10 m) food. Most spectacular are the plunge divers—birds such marine birds. Sea birds are often
as gannets, boobies, and brown pelicans—which slam into harmed directly, becoming
shoals of fish from heights of up to 100 ft (30 m). Diving entangled in nets or caught in oil
13 ft (4 m) sea birds also include many that operate from the surface, spills. They can also be harmed
160 ft (50 m) such as cormorants and penguins. Emperor penguins indirectly, when fishing reduces
their food supply. Global warming
typically dive to 500 ft (150 m), but can descend to more poses yet another threat: changing
murre
cormorant than 870 ft (265 m)—the greatest depth for any bird. sea temperatures can trigger
Many oceanic birds, such as albatrosses and petrels, hunt major changes in the fish stocks
on the wing, snatching animals or scraps from the surface. on which birds feed.
330 ft (100 m) Kleptoparasitic birds, such as frigatebirds, which harass COLLATERAL DAMAGE
other birds into disgorging their catch, also hunt on the Caught in a fishing net, this cormorant is one
33 ft (10 m) wing. Coastal birds often probe for food in the shallows of thousands of birds that drown every day.
Diving birds have difficulty seeing plastic
or along the tideline, but skimmers slice through the water,
netting underwater and often become trapped.
holding their lower bill
490 ft (150 m) underwater while in flight,
a remarkable technique
adelie penguin
that works only if the
surface is flat and calm.

660 ft (200 m) MAXIMUM FEEDING DEPTHS
Plunge divers (left), such as the
brown pelican, rarely reach more
emperor penguin than a few yards beneath the OCEAN LIFE
surface. Deeper divers, such as the DAWN PATROL
penguins, use their wings or feet to Trailing its beak in the water, a
820 ft (250 m) propel themselves, often staying skimmer searches for food in the
under for several minutes. calm waters of a lagoon.