Biology Reference
In-Depth Information
The voices of the two species are also totally dissimilar. As its name implies, the whooping crane has
a high-pitched, rather musical cry. In stark contrast, great blue herons generally manage nothing better
than harsh, dismal, and decidedly unmusical croaks. When nesting, they contrive to utter a much wider
variety of sounds, but these strange cries could hardly be described as musical, either.
The eating habits of the two species are quite different, too. Herons, although their diet can be quite
varied, are preeminently fish catchers. This trait has long been recognized. For example, an English
writer in 1579 stated, in charmingly quaint language, “Herones, Bitternes . . . These Fowles be Fishers.”
Indeed, so dependent are great blues on being able to catch and swallow large fish that the inability of
many juveniles to master this art is considered a major reason why only one in five survives to adult-
hood.
Patience is a virtue widely urged on would-be Izaak Waltons, and it's difficult to conjure up a better
mentor in this regard than the great blue. Observing this heron at work varies from something akin to
watching a video at its slowest possible speed to gazing intently at a still life for an hour or two. A wad-
ing heron moves forward, ever so slowly, barely moving one leg at a time, often standing poised on a
single leg while it surveys the water for prey. When standing still, the bird freezes into total immobility,
anchored stoically in one spot for improbably long periods of time.
There is nothing lethargic about a great blue when it centers a victim in its sights, however. Then,
with astonishing rapidity, the elongated neck uncoils, the long, sharp beak cleaves the water's surface
with lightning speed, and more often than not the triumphant heron successfully grasps or spears its
meal.
If the prey is small, the heron merely points its bill skyward and gulps it down. A large fish or other
sizable prey requires more cautious treatment, though. First the heron must totally vanquish the lively
and thoroughly uncooperative prey lately hoisted from its watery domain. In service of that goal, it may
repeatedly stab its prospective meal to render it more or less inert. This is by no means the only weapon
in the great blue's arsenal. While watching a great blue fishing in his pond, a friend saw the heron
dredge out a bullpout—a small catfish also known as a bullhead or horned pout—about a foot long. The
heron then waded to the bank and industriously pounded the fish on the hard ground. It repeated this
performance several times until the fish expired, and only then did the bird attempt to swallow it.
The great blue's seemingly slender neck has an amazing ability to expand so that large fish and other
sizable prey can travel from beak to stomach. Nonetheless, swallowing large fish presents a substantial
hazard to the inexperienced heron. If the bird attempts to swallow the fish tailfirst, the spiny fins are
likely to catch in the bird's throat, condemning it to a slow and thoroughly unpleasant death. This is
only one more of the many lessons the juvenile heron must learn successfully in order to survive.
Although large fish are ultimately the key to their long-term survival, great blue herons indulge in
a wide variety of other foods. These include frogs, salamanders, crayfish, and insects, but also encom-
pass more substantial fare, such as the occasional small muskrat or duck. At times, great blues will also
seek terrestrial food. Mice, voles, and gophers are typical of this cuisine, but they've also been known
to seize and devour Norway rats.
