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What does a Hungry
Loon Eat?
Fresh and saltwater fish are the primary
diet of Common Loons. However, both adults and juveniles also regularly
eat crustaceans, especially crayfish, and aquatic invertebrates. During
the summer, adults eat many species of freshwater fish, including yellow
perch, suckers, shiners, and occasionally small trout. Loons typically eat
fish weighing 10-70 grams. Adult birds, especially large adult males,
occasionally catch large fish (up to 250-300 grams). A big fish, such as a
full-grown sucker, can take a several minutes for a loon to subdue and
swallow. The loon may drop the fish and dive after it repeatedly, stabbing
at it again and again with its beak, until the fish is no longer moving
and can be eaten.
Being visual hunters, loons need relatively
clear water conditions to find prey. Adults prefer to hunt in shallow
water, and eat whatever is easiest to catch and most abundant. Feeding
dives are usually less than a minute, although if prey is hard to find,
the dives can be longer. To help them digest fish bones and the shells of
crustaceans, loons also ingest small pea-sized stones. An average of 10-20
stones are maintained in the gizzard, which grinds down the hard items to
enable them to pass through the lower digestive tract easily.
Juvenile loons are fed fish appropriate to
their size. Adults offer black downy chicks small minnows and sunfish,
crayfish, and aquatic insects. Juvenile birds watch underwater as their
parents are hunting, and begin trying to catch small prey when they are
~4-6 weeks old. By the time they are in the immature feathered plumage,
juveniles are capable of catching and eating larger items, up to several
inches in length. They continue to beg for food from the parents until the
late fall when they become more and more independent.
In the winter, loons live in saltwater, and
so their diet is very different than in the summer freshwater habitats.
Fish such as flounder and herring, as well as crustaceans, are regular
components of their winter diet. Loons have a salt gland to excrete excess
salt that they ingest while feeding on the ocean.
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