In addition to viewing hump-back whales, and occasionally Orcas, we usually also view Steller Sea Lions and Bald Eagles!
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There are hundreds of humpback whales who make their summer home in the pristine, fish-filled, waters surrounding the vicinity of Juneau. These huge, but graceful, creatures have migrated from Hawaii (some 3,000 miles/5,000 km away) each Spring to feed on the rich ecosystem of our Alaskan waters. Each whale consumes on average a half–ton a day of mostly herring. These 50 foot/15 meter and 50 ton behemoths will feed nearly continuously for the summer months. This is all in preparation for the long Fall swim back to Hawaii where there is virtually no food, but the warm waters are supportive of birthing offspring.
Humpback whales are born during the winter months and weigh between one and two tons and are about 15 feet (5 meters) in length when they take their first breath. However they are very lean – virtually no fat. Thus they would perish from hypothermia if born in the cold northern latitudes of Alaska. They will gain the protection of warmth from blubber rapidly as they begin nursing from their mothers prior to the long journey north, and will continue to nurse until after return to their winter home off Hawaii. The following return to Alaska will find them over 20 tons in size.
As with all “little ones,” the baby whales have not a care in the world, and when they are not nursing (which is FORTY times per day), we are sometimes lucky to catch “play-time.” When we are lucky, we’ll see them do this over and over again, interrupted sometimes by “mama” showing how it’s REALLY done!
Normally during summer they are single (except, of course, a cow and calf), but sometimes group together for cooperative feeding. This is called “bubble-netting.” In this behavior one or two will swim in a deep circle while exhaling a near continuous stream of bubbles. This vertical column of bubbles acts much like a fish net. Small schooling fish, most often herring, become confused and will not swim through the bubbles. Meantime, the rest of the pod, does a lot of “singing” and begins a rapid ascent with each of their 12 foot jaws wide open, and break the surface nearly in unison. In addition to the awesome visual sight, SCANIA will normally deploy her hydrophone during these periods so all aboard can listen to the nearly continuous whale songs.
Closing their mouths, they force their tongues against the stringy baleen to get rid of excess water, and then slowly swallow their meal through their narrow (about 9 inches/25 cm diameter) throats. Gulls in the vicinity who will feast on the small fish that escape the whales but are too near the surface for too long.
As the whales swim on the surface, each inhale/exhale involves some 80% of lung capacity (compared to about 25% for humans and land mammals). Whales are very efficient at oxygen storage, as blood makes up to 15% of their body mass – which is double that of humans. Then when the whale dives, it slows its own heart rate substantially – further rationing oxygen depletion. They can rapidly swim to extreme depths, as increased pressure causes the whale’s lings to collapse, and forces any residual air into its blowhole, and thus are not subject to the “bends” as are human divers. Although a Humpback can remain submerged well over thirty minutes, five to ten minutes between dives is much more typical.
These beautiful creatures are commonly known as “killer whales.” However they belong to the dolphin family. They are the largest of all dolphins, are found in all of the Seas, and are one of the most widely distributed animal species on earth. As the top predator of the sea, their diet consists of hundreds of species – much more diverse than any other mammal. They even consume their close relatives – dolphins! They eat fish, turtles, stingrays, seals, sea lions, squid, birds, “baby” humpback whales, and even (as personally observed by a friend of mine) an occasional moose! Interestingly, there has never been a recorded instance of an Orca attacking a human.
The teeth of the Orca interlock top and bottom and fit tightly together when they chomp their prey. Once they have a mouthful they either swallow the whole chunk, or if small their entire prey. They consume about 130 pounds (about 50 kilos) a day, so hence are almost continuously on the hunt for food. Although researchers have found some 22 different types of mammals in the stomachs of transient Orcas, different groups tend to “specialize.” For example, transient groups that regularly transit local waters around Juneau “specialize” in Sea Lions.
“Resident” Orcas do not feed on mammals at all, but have preferences within the fish family. For example, resident Orcas of Alaska prefer Silver and King Salmon over Pink Salmon.
Orcas work as a team, and are often referred to as the “wolves of the sea.” They communicate effectively with one another, but are typically totally silent when on the hunt, becoming very “chatty” once prey has been located. They will stun their prey by leaping upon them and swatting or flinging them in the air with their flukes. On one occasion a full grown Stellar Sea Lion of about 600 to 800 pounds (about 250 – 350 kilos) was about a boat length from me when a huge Orca leapt from the water atop him. Some seconds later the Sea Lion was thrown like a rag doll about 15 – 20 feet (5 – 6 meters) in the air! They have been seen going on rocks and beaches to snatch seals and sea lions. A researcher in Alaska in a 15 foot Boston Whaler had a harbor seal jump aboard, and stay there as the Orcas called loudly, “spy-hopped,” and circled the boat for some time before giving up and leaving.
The adult male Orca is distinguished by a tall (6 foot; 2 meters) dorsal fin that is very pointed at the top. The females, juveniles and babies all have smaller fins. Every orca has markings and scars that allow us to identify them as individuals.
Orcas are about 7 – 8 feet (2.5 m) and about 350 pounds (160 kg) at birth. Adults typically range between about 23 to 33 feet (10 m) and 4 tons (female) to 7 tons (male) pounds (3,500 – 5,600 kg) Males mature between 12 – 14 years, and females about 10 – 15 years. Females live about 50 – 60 years, while males live about half that long. In the Northern hemisphere they mate from July through September. Gestation periods are estimated between about 12 – 16 months, with births between October and March. The female gives birth to one calf at a time, and will bear a total of about 3 – 10 calves during her lifetime. Orcas nurse their young for about 16 months.
Though not an endangered species, they are protected by Federal Law.There are some 1500 Orcas (both resident and transient) in Alaska.
Although Orcas can stay undewater for as long as twenty minutes, and dive as deep as 800 feet (250 m), typically they dive for about five to ten minutes. Their exhalation “blows” are bushy in appearance and about 10 feet in height.
Transient pods of sizes up to 6-7 Orcas often travel through Juneau area waters.
Bald Eagles are fascinating birds. In addition to being large, graceful, and “tough,” they are rare among the animal kingdom in that they
- mate for life
- remain pretty much in the vicinity of their hatching
- take turns (male/female) nesting – warming and protecting eggs
- store up food in “nature’s refrigerator” to insure ample food upon hatching (Eagle parents lose almost a quarter of their body weight while awaiting hatching and storing food)
In 1963 the bald eagle population in the continental United States was reduced to just 417 known breeding pairs. Today, there are more than 7,678 pairs of bald eagles in the contiguous United States. As a result, although still protected, they have been removed from the “threatened” list.
The eyesight of eagles is legendary. The eagle can probably identify a rabbit moving almost a mile away. That means that an eagle flying at an altitude of 1000 feet over open country could spot prey over an area of almost 3 square miles from a fixed position.
Once an eagle spots a fish swimming or floating near the surface of the water, it approaches its prey in a shallow glide and snatches the fish out of the water with a quick swipe of its talons. Eagles can open and close their talons at will. If an eagle is dragged into the water by a fish too large for the eagle to lift, it is because the eagle refuses to release it. In some cases this is due to hunger. An eagle might drown during the encounter with the fish or if it’s unable to swim far enough to reach shore. The eagle can not fly again until it’s out of the water, so it uses its large wings to swim. The eagle is a strong swimmer, but iit may be overcome by hypothermia.
The eggs hatch in the order they were laid. Eaglets break through the shell by using their egg tooth, a pointed bump on the top of the beak. It can take from twelve to forty-eight hours to hatch after making the first break in the shell (pipping). Once the eggs begin to hatch, the female’s vigilance becomes nearly constant. The male provides the majority of the food needed by his rapidly growing family. Eventually the female will take up her share of the hunting, but in the early days, all of her attention is given to the young eaglets in the nest.
Chicks – Sometimes two chicks will survive, but it is not uncommon for the older eaglet to kill the smaller one, especially if the older is a female, as females are consistently larger than males. Should one chick decide to kill its sibling, neither parent will make the slightest effort to stop the fratricide.
Newly hatched, eaglets are soft, grayish-white down covers their small bodies, their wobbly legs are too weak to hold their weight, and their eyes are partially closed eyes, limiting vision. Their only protection is their parents.
Eagles feed their young by shredding pieces of meat from their prey with their beaks. The female gently coaxes her tiny chick to take a morsel of meat from her beak. She will offer food again and again, eating rejected morsels herself, and then tearing off another piece for the eaglet.
While on the nest with very young eaglets, parents move about with their talons balled into fists to avoid accidentally skewering their offspring.
Eaglet Growth – The young birds grow rapidly, they add one pound to their body weight every four or five days. At about two weeks, it is possible for them to hold their head up for feeding. By three weeks they are 1 foot high and their feet and beaks are very nearly adult size. Between four and five weeks, the birds are able to stand, at which time they can began tearing up their own food. At six weeks, the eaglets are very nearly as large as their parents. At eight weeks, the appetites of the young birds are at their greatest. While parents hunt almost continuous to feed them, back at the nest the eaglets are beginning to stretch their wings in response to gusts of wind and may even be lifted off their feet for short periods.
At three or four weeks, this eaglet is covered in its secondary coat of gray down. In another two weeks or so, black juvenile feathers will begin to grow in. While downy feathers are excellent insulators, they are useless as air foils, and must be replaced with juvenile feathers before an eaglet can take its first flight, some 10 to 13 weeks after hatching. Unfortunately, approximately 40% of young eagles do not survive their first flight.The young eagle stays near the nest, practicing its abilities to fly and to hunt. The parents cannot tell juveniles how to hunt, they have to learn by watching the parents and by practicing. During this time they seem to spend more time looking at prey than they do actually attacking it.
Over the next month, they meet with their parents to be fed, but have little other contact with them. They learn to soar and to spot prey. Until the first winter after their fledging, young eagles near the nest are often still fed by their parents. Although a young eagle has the instincts to hunt, it lacks the skills. If food is scarce during the winter, it may die.
Six to nine weeks after fledging, juvenile eagles leave the nesting.
Nesting cycle – From the time the parents build the nest and the young are on their own, takes about 20 weeks. During the nesting cycle the parents remain within one to two miles of the nest. Juvenile bald eagles are a mixture of brown and white; with a black bill in young birds. The adult plumage develops when they’re sexually mature, at about 4 or 5 years of age.
Size – The female bald eagle is 35 to 37 inches, slightly larger than the male. With a wingspan which varies from 79 to 90 inches.The male bald eagle has a body length from 30 to 34 inches. The wingspan ranges from 72 to 85 inches.Bald eagles weigh from ten to fourteen pounds. Alaskan eagles are significantly larger than their southern relatives.
Longevity – Wild bald eagles may live as long as thirty years, but the average lifespan is probably about fifteen to twenty years.
Body Temperature – 102 degrees Fahrenheit (38.8 degrees Celsius)
Tolerance to cold temperatures – A bald eagle’s skin is protected by feathers lined with down. The feet are cold resistance because they are mostly tendon. The outside of the bill is mostly nonliving material, with little blood supply.
Fidelity – Once paired, bald eagles remain together until one dies. Once “widowed” the survivor will not hesitate to accept a new mate.
Voice – Shrill, high pitched, and twittering are common descriptions used for bald eagle vocalizations. Eagles do not have vocal cords. Sound is produced in the syrinx, a bony chamber located where the trachea divides to go to the lungs. Bald eagle calls may be a way of reinforcing the bond between the male and female, and to warn other eagles and predators that an area is defended.
Near Juneau, eagles are extremely plentiful and visible. They feed predominantly on the plentiful fish (salmon and herring) that venture too near the surface. They can soar such that they almost appear still, or fly and dive at speeds over 40 miles an hour!
The Sea Lions in the vicinity of Juneau are quite different from those seen – for example – languishing on docks in San Francisco.
“Steller” Sea Lions are named after Dr. Wilhelm Steller, a Dutch Medical Doctor who accompanied the expedition the Vitus Bering expedition in1741 as a passenger-Botanist. It is characterized by by an external ear (which can be closed on entering water) and by hind flippers that face forward. (True seals have internal ears and hind flippers face backward)
About 70% of the world-wide population of “Stellers” (about 80,000) call Alaska home. Males are about ten feet (3 meters) and weigh about a ton (1,000 kilos). Females are about seven feet (2 meters) and about 700 pounds (300 kilos). Thus the males are bigger than any bears. Stellers live about 20 years. They are fast swimmers and can swim over 15 knots for short bursts. Their principal predator is the Orca, or “Killer Whale.”
Stellers have been classified a “threatened” species in the Juneau area, where they are proliferating. A few hundred miles west of Juneau they are classified as “endangered.” (Studies as to why these Sea Lions are “endangered” are focusing on their dietary choices, although stock depletion may also be due to increasing predator populations and disease.)
The picture below catches a Stellar Sea Lion in the act of swallowing a Coho (“Silver”) salmon in one gulp! This is the ONLY time we have ever observed this. Normally the Sea Lion holds the salmon “sideways” in its teeth, and shakes the fish back and forth until a chunk breaks off, and then repeats the procedure. In the instance below, unfortunately out of the picture, two Bald Eagles were swooping down like bullets to “steal” the fish, so the Sea Lion flipped the fish, caught it in his mouth, and swallowed it whole – and then dove!
The Steller Sea Lions have no predator in nature other than the Orca (Killer Whale). “Resident” Orcas however eat only fish. Some of the Stellers in the vicinity of Juneau bear branded numbers for identification for scientific research.
About twenty miles north of Juneau there exists two large “rookeries.”