You may be surprised to see obviously immature (brown) gulls
at the waterside at this time of year vigorously begging from some nearby
adult. You can recognize begging by the bird's throwing its head back and
giving loud, high-pitched calls. You may be even more surprised to know that
the adult isn't necessarily the parent of that young bird. You may not be
surprised to see that the adult ignores the young or chases it away if it
remains persistent.
This begging behavior continues into the winter and even to the next spring in some
Glaucous-winged and Western Gulls and their hybrids. After all, they have
begged for food from their parents for several months, and the behavior is hard
to turn off—especially if they are hungry!
Extended parental care after the young have left the nest
area is rather rare in birds and seems to be restricted mostly to fish-eaters.
It is not easy to catch fish—no bird has evolved a rod, reel, hook and line for
the job—so a young bird just starting out to learn how to do this may have a
difficult time of it. So although we see these gulls trying to get a little
extra parental care, they don't usually get it.
However, young of some other types of birds are successful
beggars well after the breeding season. Several species of crested terns have
extraordinarily long dependence on their parents after fledging. Juvenile
Elegant Terns fly around with their parents for up to six months or more, beg
from them, and are fed.
Juvenile frigatebirds may return to their nesting colony for
as long as a year after leaving the nest, to be fed by one or both of their
parents. Frigatebirds forage by capturing squids and flying fishes at the sea
surface, and they have to be very effective at scooping one of these
fast-swimming fish from the water. Thus it takes a long time for the young
birds to be effective foragers.
Tropicbirds also feed in the open ocean and on the same types
of fishes and squids as frigatebirds, although they plunge into the water at
high speed to capture them rather than picking them up with a long bill.
Interestingly, tropicbird parents do not feed the young postfledging. Perhaps
they should, as frigatebirds are thought to have low juvenile mortality for a
seabird, presumably because of the extra help they get from their parents.
Dennis Paulson
3 comments:
What about other types of birds and not just sea birds? I don't know much about birds, but I remember watching all those childhood TV shows where the mamma bird comes back to the nest to feed her offspring.
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