Orcas of Southeast Alaska
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Many who visit Alaska do so just for the opportunity to see a pod of wild Orca or "Killer whales". Their striking black-and-white coloration combined with their huge dorsal fins make them hard to confuse with any other whale (although Dall's porpoise are sometimes mistaken for killer whales by inexperienced observers). Orcas have captivated the imagination of the native people of southeast Alaska (the Tlingit and Haida people) and their likeness can be seen in much of their beautiful artwork. Orcas also figure prominently in their stories which have been passed down through generations (the Tlingit and Haida have no written language so story telling connects each generation to their past). Thus when you see a pod of Orca plying their way through the fjords that serves as the only real roads through the wilderness of southeast Alaska you are witnessing a sight that has changed little for 20,000 or more years... and it will no doubt have an affect on you, just as it did the first human inhabitants of Alaska.
Did you know that Orcas are actually the largest member of the dolphin family? That doesn't mean that they are not whales. All the worlds whales, dolphins, and porpoises (along with other groups of whales such as Belugas and Narwhals) are classified in the order "Cetacea". So saying "whales and dolphins" is a lot like saying "birds and sparrows"... sparrows are just another type of bird. It's probably just that the word "whale" has become synonymous with the word "big" (when you say something is "whale-sized" you probably mean that it is quite large) and most dolphins are quite small compared to their larger relatives such as Humpback whales or Blue whales and the like. So it's not surprising that people have called this particular dolphin species "whales". Orcas can reach lengths of 30 or more feet and they come equipped with a mouth full of pointed teeth that they sometimes use to tear the flesh off larger whales. This is what earned them their other name of "killer whales". Whalers used to call them the "whale killers" because they were the only whales known to hunt and eat other whales (now we know that a few other species also will also kill other whales though). Like all dolphins, Orcas travel in family groups called pods that stay together for their entire lives (usually). Orca pods are matriarchal societies that are led by the oldest female in the group. Should the matriarch pass away, it is her next oldest sister that will assume the leadership role in the pod. Because Orcas can live for over sixty years (in the wild anyway), as many as five generations can inhabit a single pod. Despite their fearsome reputation, there has never been a credible account of a Killer whale attacking a human in the wild. Killer whales have attacked their trainers in captivity, but that's different. Remember these whales are highly social creatures that live with their brothers, sisters, cousins, parents, aunts, and uncles for their whole lives. It's not hard to imaging that an animal suddenly plucked from that environment and placed in a shallow tank all alone and forced to jump for fish would be stressed, agitated and prone to violence.
Orcas, however, didn't get their gruesome
reputation for no reason. Pods of Orca work together, much like
wolves, to bring down prey which is much larger and more powerful than
they are. Being toothed whales,
Orcas have the ability to echolocate
and they use this ability to detect the presence of one of Alaska's other
whales such as a migrating Humpback.
Then, after locating the whale by sonar, the whales will go silent.
They don't need to communicate with one another because their hunting
strategy is a highly choreographed, well-rehearsed event. One Orca
will surprise the Humpback whale by exploding out of the dark sea and
perhaps taking a bite out of the whale's side. Then, just a moment
later, another orca will hit the whale from the opposite side. Then
one from below, then above, and so on. The Humpback doesn't know
where to turn. The Orcas may bite off the Humpbacks dorsal fin or
tail flukes (the Humpback's only real defense). Eventually the
Humpback tires and a number of Orcas may force it below the surface and
drown it. After the Humpback is dead they will often consume only a
small portion of the whale (the tongue for example) before moving on.
(At right is shown the badly damaged flukes of a young Humpback whale that
was attacked by orcas)
Here you see a few Steller's sea lions hauled out an a buoy in Lynn Canal between Juneau and Skagway. One year when my mother came up to visit me she went on a whale watch and saw a pod of Orca circling some very panicked sea lions on this very buoy! I can't believe I didn't go out on that trip! Aaarrgh!
Not all "Killer" whales, however, are killers
of large whales like Humpback whales. In fact, most orcas in Alaska
never eat meat! Scientists have discovered that at least two very
different "types" of Orca inhabit the waters of Southeast Alaska... the
"residents" and the "transients". The residents are so called
because they tent to inhabit a relatively small area for much of the
year... they are resident. Transients, on the other hand, roam
widely over vast regions of Alaska. Why might this be? It's
because the residents only eat fish such as Salmon.
Since
Salmon is so abundant in Alaska for much of the year, they do not need to
travel to far-off areas to find new food resources. The transients,
however, don't eat fish at all. Instead they have developed a taste
for meat and thus they will prey upon a Harbor seal of Steller's sea lion
colony, for example, until the seals or sea lions become wary of the danger
and spend more time ashore. The transients will then move on to
search for a new, unsuspecting seal colony. What determines whether
a newborn Orca become a resident of transient depends on the pod in which
that calf is born. Calves born in resident pods learn to fish by
watching older whales while they grow, whereas calves born into pods of
transients are inducted into the hunt at a young age and never develop a
love of fish. (At left is shown a Orca calf.
The "orangey" tint to the white parts of the whale are a clear indication
that it is a calf)
There are more differences between residents and transients, however, than just diet. There are physical as well as behavioral differences. For example, transients have smaller but more pointed dorsal fins than residents do. The dorsal fins of residents are also slightly more hooked at their tip. The shape of the "saddle patch" (the gray patch behind the whale's dorsal fin) also differs between the two "types" of Orca. Genetic research has shown that residents and transients have not interbred for upwards of 7,000 years which has led some to believe that the residents and transients should be considered different species. But, as those of you who study biology already know, the very idea of species is a human construct that we superimpose on the natural world. Nature is not confined by rigid rules or parameters. Nature is fluid, with changes constantly occurring over time... and the orcas of Alaska are simply a piece of a much larger, interconnected puzzle.
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