I mentioned last week in my post about sea stars that beaches on Kodiak teem with an abundant variety of brightly colored sea stars. Sadly, though, sea stars are not as abundant here as they were a few years ago. I took a walk on the beach yesterday and was alarmed by how few sea stars I saw. Those I did see looked healthy, but the vast majority were wiped out by a deadly virus.
In June 2013, sea stars along the Pacific coast of the United States began dying in large numbers. Die-offs of sea stars have occurred before in the 1970s, 80s, and 90s but never of this magnitude. Within just three years, millions of sea stars from California to Alaska died from a disease called sea star wasting syndrome (SSWS). Sea stars with SSWS develop white lesions in the ectoderm quickly followed by decay of tissue surrounding the lesions which leads to fragmentation of the body and death. Biologists estimated 95% of some sea star populations were decimated by SSWS. While most species of sea stars were affected by SSWS, ochre stars (Pisaster ochraceus) and sunflower stars (Pycnopodia helianthoides) were especially hard hit.
The syndrome was first noticed in ochre stars in June 2013 along the coast of Washington state. In August 2013, divers reported a massive die-off of sunflower stars just north of Vancouver, British Columbia. In October and November 2013, large numbers of dead sea stars were noted in Monterrey, California, and by mid-December, SSWS had reached southern California. In the summer of 2014, the disease had spread to Mexico and parts of Oregon. SSWS was first reported in Alaska in Kachemak Bay in 2014, but it wasn’t until 2015 and 2016 that sea stars began dying in large numbers in Alaska.
Biologists are certain sea stars are dying from a virus, but when they isolated the virus, they realized this virus was present in preserved museum samples taken from as far back in the 1940s. They believe some other factor such as increased water temperature or a change in pH is stressing seas stars and allowing an otherwise dormant virus to rage through their populations. Researchers noted an increase in ocean water temperature preceded the outbreak of SSWS, and in areas where the water temperature rose the most, the disease was more widespread. To test the theory that increased water temperature played a big role in the breakout of the disease, scientists placed sea stars in aquarium tanks ranging in temperature from 54 degrees to 66 degrees Fahrenheit. The results were clear, the hotter the tank, the more quickly the sea stars succumbed to wasting.
The drastic reduction in sea star populations is evident on Kodiak Island, and biologists worry how the loss of sea stars will affect the intertidal community. Sea stars are considered a keystone species, important to maintaining diversity in the marine environment. Sea stars eat mussels and sea urchins whose numbers could now explode and decrease biodiversity in intertidal and subtidal communities.
Scientists consider the recent outbreak of SSWS the single largest, most geographically widespread disease ever recorded, and as ocean temperatures keep rising, they fear the outbreak of the disease will continue.
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Visitors to our lodge are often surprised by the large number of brightly colored sea stars inhabiting the low-tide zone on Kodiak Island. Sea stars are prolific throughout the Pacific Northwest and are critical to the health of intertidal and subtidal communities. Scientists have identified more than 120 species of sea stars in Alaska, including the sunflower sea star, one of the largest sea stars in the world.
Sea stars are often called starfish, but since they aren’t fish, biologists prefer the name sea star. Sea stars belong to the phylum Echinodermata. Other echinoderms include sea cucumbers, sea urchins, sand dollars, and brittle stars. Echinoderms usually have pentamerous radial symmetry, meaning the body can be divided into five parts around a central axis. This five-parted symmetry is easy to see in a sea star with five arms, but it is also apparent if you look at the bottom of a sand dollar or the pen of a sea urchin. Some sea stars have more than five arms. A sunflower sea star has twenty arms, but the animal is still divided into five equal parts around the central disk.
Sea Stars are flattened in appearance and may range in size from 1 inch (2.54 cm) to over a yard (1 meter) in width. A sea star has an internal skeleton which is somewhat flexible. The skeleton consists of small calcareous plates bound together with connective tissue. Sea stars may look rigid and sedentary, but the connective tissue between the plates allows them to bend to attack prey, flee predators, and right themselves when they are turned upside down.
A sea star’s anus is in the center of the top side, or the aboral surface of the animal. A circular madreporite is located just off center on the aboral surface, and this madreporite is a critical part of the circulation system of the sea star. Instead of a circulatory system, a sea star has a water vascular system, and the madreporite acts as a trap door through which water can move in and out in a controlled manner. The mouth of a sea star is located in the center of its underneath or oral surface. Open furrows containing tube feet extend from the mouth along the length of each leg.
Sea stars do not have eyes, but they have eyespots that can detect light at the tip of each arm. Interestingly, scientific studies have shown some species of sea stars move toward light while others move away from the light. Neurosensory cells which are sensitive to both touch and chemical tastes cover the surface of a sea star and are particularly dense in the suckers of the tube feet. Many species of sea stars are covered by clusters of tiny, calcareous pincers. These tiny pincers deter predators and keep the surface of the sea star free of parasites and debris. Also on the surface, thin-walled gills protrude between the calcareous plates and serve to exchange respiratory gases and excrete liquid wastes.
The internal anatomy of a sea star includes the water vascular system, digestive tract, reproductive organs, and nervous system. The water vascular system uses muscles and hydraulics to power a sea star’s tube feet. The tube feet not only allow a sea star to move but are used to grasp prey, and the combined force of numerous tube feet is strong enough to pry apart a clam shell. Most seas stars move very slowly, and their pace is measured in inches per hour, but giant sunflower sea stars can travel at a speed of two feet per minute.
The mouth of a sea star opens into two stomachs connected to paired, lobed organs called pyloric caeca. The pyloric caeca extend into each arm and aid in the digestion of food. Sea stars are either male or female, and their reproductive organs, or gonads, lie between the pyloric caeca in each arm. In the spring, sea stars broadcast either eggs or sperm through pores in their arms into the water where chance fertilization occurs. Sea stars have no brain or central nervous system, but they have a nerve ring in the central disk connected to radial nerves running the length of each arm. The radial nerves are connected to a diffuse network of nerve cells scattered throughout the skin. Sea stars have the ability to regenerate lost arms.
Sea stars utilize a range of habitats and may be found from the shoreline to depths greater than 13,450 ft. (4,100 m). Sea stars consume a wide variety of prey, including sponges, snails, clams, mussels, sea cucumbers, barnacles, anemones, scallops, fishes, and even other sea stars. Some species of sea stars feed on plankton, while other species prefer dead organisms. Sea stars have few predators and are believed to have a lifespan of only a few years.
Next week, I will post about sea star wasting syndrome, a devastating disease that has killed millions of sea stars in the last few years from California to Alaska.
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One of the main reasons Kodiak bears grow so much larger than inland grizzly bears is due to the abundance of food on Kodiak. Not only can bears feast on protein-rich salmon in the summer, but the archipelago is loaded with nutritious vegetation and sugar-packed berries. A brown bear’s jaws have powerful muscles and teeth that have evolved to adapt to an omnivorous diet of both plants and animals. Kodiak bears are opportunistic feeders. They eat roots, berries, grasses, sedges, wildflowers, wild celery, and other plants, as well as rodents, insects, large mammals (including deer and mountain goats), fish, carrion, and yes, unfortunately, garbage and pet food.
Bears’ stomachs contract during hibernation, and when they first leave their dens, they aren’t hungry. They eat little at first, concentrating on emerging plants and their roots. As the spring progresses, Kodiak bears can be seen feeding in grassy meadows and look much like grazing cattle. Their diet switches to salmon in the summer months, when they chase and catch fish in shallow streams or on the tidal flats near the heads of the deep, narrow bays on Kodiak. Bears also consume dead salmon that have washed up on shore. When the salmonberries, elderberries, crowberries, blueberries and other berries begin to ripen on Kodiak in late July and August, most bears spend at least part of their day in berry thickets, pulling the berries from the bushes with their lips and mouths. Salmon provide bears with fat and protein, and berries are high in natural sugars, all of which are important for building up a fat reserve for hibernation. As fall progresses, bears increase their consumption of salmon and berries as they strive to build up their fat layer before entering the den for hibernation. A diet rich in berries has its downside, though. Bears are one of the few wild animals susceptible to tooth decay. Abscessed teeth are not uncommon, and rotten teeth may affect the bear’s ability to eat and may even lead to starvation.
One of the most enjoyable aspects of bear viewing is watching a bear chase and catch a salmon. Sows teach their cubs how to fish and will often corral a salmon toward the cub in shallow water and then encourage the cub to chase the fish. A sow with newborn cubs that are still nursing will only allow her cubs to eat a small part of her catch after she has had her fill because she needs the extra protein to produce the milk to nurse her cubs, and the cubs are receiving most of their nutrition from her. As the cubs age, they nurse less, and the sow shares more of her catch with them. Finally, when they are old enough, she encourages them to fish on their own, and by the time the cubs are two years old, they can usually chase and catch a few salmon without the help of their mother.
Fishing is a skill bears learn with much practice over time, so young bears are often clumsy fishermen. A sub-adult bear may gallop back and forth in a stream for thirty minutes without successfully landing a salmon, while an older bear walks slowly downstream and pounces on a passing salmon with little effort. A bear may also develop his own unique fishing technique. One bear may sit on a fallen log hanging low over a stream and attempt to grab fish as they swim past. A second bear may “submarine” by dunking his head under water to watch for fish, and a third may obtain his fish by chasing another bear and stealing that bear’s catch.
A Kodiak bear’s coat may range from dark brown to nearly blonde. Bears are typically darker in the fall when they begin growing their winter coat, and older bears are often darker than younger bears, but these are just generalizations. One cub from a litter may be light, while his brother is dark brown.
Cubs often have a natal collar, a white band around the neck and shoulder. Some cubs have no natal collar, and others have a collar that is bright and distinct. This band gradually fades over time, and it has usually disappeared by the age of three, but occasionally, you will see a four-or-five-year-old bear that still has remnants of a collar.
A bear’s fur is an excellent insulator. It is dense and oily, keeping the bear warm and preventing water from penetrating. The fur consists of two types of hair, the “guard hair” and the “under-fur.” Bears shed both the guard hair and underfur annually. In the summer, Kodiak bears often appear shaggy and matted. The bear in the photo below looks as if she is sporting dreadlocks. To help remove their fur, bears rub against trees and rocks, often standing on their hind legs, backing up to a tree and rubbing up and down. It is humorous to watch a bear “scratch his back” in this manner. While the old coat is shedding, a new coat is growing, and by September on Kodiak, most bears appear darker in color and well-groomed. The old, loose fur is gone, and only the new fur remains.
Brown bears have non-retractable claws up to four-inches long. The claws of young bears are typically dark brown and then lighten with age. Although some young bears have light-colored claws, beautiful, pearly-white claws are usually seen on an old sow or boar. Look at the photos and notice the difference in claw coloration between the sub-adult bear and the old sow.
Brown bears use their claws to defend themselves and fight with other bears, but Kodiak bears primarily use their claws to dig for roots and other food and gripping food. Even though their claws look large and clumsy to us, they are quite dexterous and capable of manipulating small objects. Kodiak cubs use their claws to climb trees, but adult brown bears are poor climbers due to their body weight and the structure of their claws. It is not uncommon to see a sow send her small cubs up a tree if she senses danger, and they stay in the tree until she vocalizes the signal that it is safe for them to come down.
Bears, like all animals, depend on their senses to survive. They use their senses for many things, but especially to find food and detect possible threats. A bear’s sense of smell is its most important sense. A brown bear’s sense of smell is three to four times more sensitive than that of an average dog, and it is difficult for humans with our relatively poor sense of smell to comprehend what this means and how much a bear depends on this sense. A bear uses his nose to find food, locate a mate, and avoid danger. A bear downwind from you may smell your presence and run from you while you are still several hundred yards away from him.
A bear’s second most important sense is hearing. Brown bears have relatively small ears, but they can detect noises at a great distance. A bear can hear the click of a camera shutter over the sound of the wind, crashing waves, or a swiftly running river.
For a long time, biologists believed bears had poor eyesight, but scientific research has shown a bear’s eyesight is similar to that of a human’s. Bears are not nearsighted as was once believed, and they can see colors. Brown bears often stand on their hind legs to increase their sight distance and get a better look at an object. It is not a sign of aggression when a bear stands on its hind legs; the bear is just trying to gain more sensory input.
The important thing to remember is a bear does not use each one of these senses independent of the others. If a bear sees something unfamiliar in the distance, such as a person, a boat, or even another bear, he may stand on his hind legs to get a better look, raise his nose to attempt to smell the interloper, and pick up his ears to try to ascertain unfamiliar sounds. If he still cannot determine what the object is, he may approach it for a closer look or circle downwind from the object so that he can smell it better.
Next week, I’ll write about a bear’s fur and claws. Does a bear’s fur change with age? Why are some Kodiak bears blonde and others a chocolate-colored? What is the white ring some cubs have around their neck? How do the claws change with age?
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Summer Friends at Amook Pass is a post by my friend, Marcia Messier. I love this humorous story about her animal encounters while she worked for us at Munsey’s Bear Camp. What Marcia doesn’t tell you in this piece is that I named our goat visitor Marcie because the goat’s daring trip each summer from the mountains to the ocean, reminded me of Marcia’s adventurous spirit. Prepare to smile as you read about Marcia’s adventures!
During the summer months at Amook Pass, the animals were my friends. That sounds a bit corny, but they were amusing, startling, and comforting, all that friends should be. I looked forward and anticipated who might stop by for a visit during my busy days.
I was privileged to know Gizzy, Fletcher, Elsie, and Olive during my summers at Munsey’s Bear Camp. They were my very best animal friends. I thought it was interesting that Gizzy and Olive had similar personalities as did Fletcher and Elsie; even though, they had never met. Gizzy and Olive were the sweet ladies, soft-spoken, polite, accommodating for a photo, well groomed, and perhaps just a little bit shy of visitors. Fletcher and Elsie, on the other hand, were true wilderness cats. Fletcher was getting along in years when I first met him, but he told me many a hair-raising tale about his hunting skills as a younger gentleman. Elsie was in her prime, and she loved to stalk bears for days on end. Many a time as Robin and I were mourning her early demise, we would hear Mike yell, “Elsie’s back!”, and there she would be, dragging herself through the door, ragged, dirty and ravenously hungry after her latest adventure.
Fletcher and Elsie loved to hunt voles, the tiny mouse-like creatures close to the bottom of the Kodiak food chain. They must be a very tasty snack because twice daily I’d find their tiny blue and green left-over parts deposited on the front door step. I used to tell myself they were loving gifts, but then again, whoever left the pieces always seemed slightly amused when I reached down to pluck the bits off the doorstep while making slight gagging sounds.
Freddie the Weasel became a daily late-afternoon house guest. Maybe the sound of the old generator starting up interrupted his afternoon nap. He’d shoot in the backdoor, zip through the kitchen and take cover under the couch in the living room to watch and learn about life in the big house. At first, I jumped and shrieked thinking he must be some kind of Kodiak rat, but later in the day, Robin calmly explained about weasels.
Gizzy and Fletcher were still with us then but getting along in years. They knew their limitations, so they decided to pretend Freddie was just a figment of my over-active imagination. Not wanting to insult them, I went along with the game and soon we all looked forward to Freddie’s daily antics. I knew when he heard the boat motoring up to the mooring; I would see the tail end of Freddie flip out the front door.
Early in the summer season, the female Sitka deer would bring their fawns into the yard to nibble the bright green salad-like greens growing around the cabins. Sometimes there would be twins, and I would think happy thoughts as I watched them through the kitchen window while preparing breakfast.
One day I came nose to nose with a deer! I was hurrying to the cabin with a load of fresh laundry, and we met coming around the corner at the same instant. We were both startled and just stared dumbfounded into each other’s eyes for a moment. I’m not sure who moved first, but a hunter later told me I was lucky it hadn’t given me a good kick in the shins before it bolted off! I guess that happens, but ours was a peaceful meeting, and I will forever remember that instant.
I live in Arizona, so the first time I saw a fox on the pathway, I excitedly reported to Mike I had seen a coyote in the yard that day. Laughing, he looked at me like I was nuts and said, “There are no coyotes on Kodiak Island!”. I felt a little foolish but still maintain at a distance, a big healthy Kodiak fox looks very much like a thin Arizona coyote in the summertime!
I’ve seen Bald Eagles before, but in Arizona, they are a special sighting. On Kodiak, they are commonplace, and I was thrilled to see a nesting pair close to camp. On my mid-day break, if the weather was good, I’d sit in a lawn chair facing the bay and watch the eagles fish. It was entertaining; an eagle would fly over the water and scope out a fish, and then in an amazing feet-first dive, catch the fish in its talons. After this, it was usually impossible to get airborne once again, so it had to row itself and the fish, still clutched in its talons, ashore with its wings. There, after expending so much energy, it would devour the fish and do it all over again.
More than once, on a nice day, while taking a siesta in the hammock, enjoying the warm sun on my face, I’d hear and feel the strong wing beats of a very large bird flying close over me, and I’d know I had been checked out by a Bald Eagle!
Some of you may have read my “Encounter” with a bear. I was walking along the path up to the guest cottage one afternoon, my mind far away, when I heard a “horse” snort. The sound brought me back to the present in a flash, and I must say, I have never confused the sound of a bear with that of a horse again!
A secret I’d like to reveal is Mike used to make a bear playground out of old red mooring buoys a distance up behind the generator shed. I heard him and Robin laughing once about how much fun the bears had rolling, tossing and chewing these old red buoys. I never did venture up past the generator shed and burn barrel. Wearing a red jacket, I didn’t want the bears to make a mistake. I did wonder if mother bears warned their cubs, “never go near that playground as there is a dangerous human there who makes frightening loud, smoky blasts come out of the shed and soon after makes fire leap high into the sky out of a barrel!” Thinking back, I was probably quite safe.
Marcie was my favorite yard animal. One warm July day, we spotted a solitary mountain goat strolling along the beach near camp. Mike and Robin reported this was indeed a rare sighting. We couldn’t help ourselves, Robin christened her Marcie, and we began to speculate about her life and why she was here on our beach. She was a rebel. Marcie was tired of billies, she had too many youngsters to raise, and the constant stress of all those steep icy mountain ledges was wearing her down. Maybe she had arthritis in her knees. Maybe she just wanted a vacation at the beach! We happily welcomed her, and for a number of years, she would appear for her annual July vacation at Munsey’s Bear Camp. One year she didn’t arrive. We looked and looked, but no Marcie. Right away we decided, instead of feeling sad, we would celebrate her life. We had a toast to Marcie, how brave she was to break away from the herd and dare to be different!
The sea otter is a zen-like sight floating on its back, paws pressed together as if in meditation pose. It’s a sweet maternal picture with mom floating on her back and a tiny baby resting on her belly. And how clever of them to use tools! They often are observed with a rock balanced on their belly, happily cracking open clams for lunch. Brilliant!
At Munsey’s Bear Camp, I often saw sea otters floating in the cove in front of the lodge, and the sea otters kept to themselves. Their cousins the river otters, however, were a different matter. A family of river otters took up residence under the dock. This dock was now their home, and no one else was welcome. The dock became their dining room and their toilet. A mop had to be stationed on the dock so that the horrid stinky mess could be swabbed away. The mop could also be used as a defensive tool.
With guests arriving and departing from the dock every five days, caution had to be observed. One day stands out in my mind. It was a beautiful, sunny Kodiak day, and we were all on deck welcoming new guests. As they were embarking from the float plane and luggage was being handed down, I took a step back and slid on an unseen mound of otter poo. I wanted to vaporize as I fell on my backside in an ungraceful plop! Afterward, we laughed about this incident, but I never forgot, and every time I saw a sweet little otter posing for pictures, I saw two little horns poking up through the top of its head.
I grew up near Cape Cod where everyone loved to fish. I didn’t. To me, the whole process from baiting the hook, to dragging the poor thing out of its natural habitat with a hook in its mouth, to butchering it, to stinking up the house with fried fish was cruel and disgusting. Fast forward 40 years and I’m a cook in a fishing camp. I politely listened and smiled at all the fish stories and quietly cooked the fish, wondering what all the commotion was about. One day my perception changed. Robin and Mike asked me if I’d like to go out on the boat with them for the day. We had only one guest, and it was a great day to get out of the house. Yes, I wanted to go! Like a good sport, I purchased my fishing license, and away we went. Mike anchored in a pretty cove, and as I sat down in the deck chair ready to enjoy the sunshine, Robin stuck a baited pole in my hands and showed me where to drop the line. Still not paying much attention, suddenly the pole was nearly yanked out of my hands, and the line was whizzing off the reel. “What’s going on?”, I hollered. Robin and Mike replied, “You’ve caught a fish.” They proceeded to give me instructions. Suddenly, the scenario was hilarious, like an old re-run of “I Love Lucy.” I couldn’t stop laughing which in turn made my arms weak and unable to reel in the line. In a second, Robin strapped a belt-like thing around me to support the fishing pole so that I could reel. Now we are all laughing hard, but with perseverance and aching arms, the fish finally emerged from the deep. I was leaned over the rail gasping in amazement at “my halibut” when all of sudden, Mike, with an expert jerk of his pliers, freed my fish from the hook and off it swam! Hey! At that moment I was totally conflicted. On the one hand, I proudly wanted to bring my halibut home for supper, but on the other, I wished it well and was happy it was able to live another day in Uyak Bay.
An eagle can rise on thermals and gain altitude until it is only a speck in the sky, and then it soars until it sees prey and can swoop down and make a kill. When an eagle spots a fish from the air, it begins to glide toward the water. As it nears its prey, it extends its legs and opens its talons. It soars just over the surface of the water and then plunges its legs into the water. The talons strike the fish, and the eagle immediately closes the talons, driving them deep into its prey. The eagle then flaps its wings to pull the fish out of the water and maintain enough speed to remain airborne. If the eagle cannot lift the fish, the bird may be dragged under water and forced to swim for shore. Eagles are strong swimmers, but if the water is cold, they may be overcome by hypothermia and drown.
It is a common misconception that once an eagle grasps its prey with its talons, it cannot let go. While eagles can lock their talons, it is a voluntary action. An eagle can release a fish that is too heavy for it to lift, but sometimes it holds on anyway, perhaps deciding the prize is worth the swim to shore.
Biologists estimate an eagle can only lift a maximum of four to five pounds, but since lift is dependent on both wing size and air speed, the faster the eagle flies, the greater its lift potential. An eagle that lands to grab a fish and then takes off again can manage less of a load than one that swoops down at a high rate of speed and plucks its prey from the water. Speed and momentum allow the eagle to carry more weight.
An adult bald eagle needs between 0.5 lbs (.23 kg.) and 1.5 lbs (.68 kg) of food per day. A study done in Washington State found an eagle needs to consume between 6% and 11% of its body weight per day. If an eagle eats a three-pound (1.4 kg) fish one day, though, it does not need to eat again for a few days. Bald eagles living in coastal Alaska feed mainly on fish such as herring, flounder, pollock, and salmon. They may also prey upon seabirds, small mammals, sea urchins, clams, crabs, and carrion.
In the summer and fall on Kodiak Island, eagles congregate along salmon streams or near the ocean where salmon are likely to school. Large numbers of eagles also gather near fish canneries where they feed on the fishy discharge from the processing plants. Both mature and immature eagles feed on carrion, but research indicates young eagles are more dependent on carrion, and they eat carrion while they develop and hone their hunting skills. Adults, on the other hand, more actively hunt live prey, particularly fish.
The bill and neck muscles of a bald eagle are adapted to allow the bird to gorge itself quickly. An eagle can eat a 1 lb. (.45 kg) fish in only four minutes, and it can hold onto a fish with one talon while it grips its perch with the other talon and tears apart the fish with its bill.
Eagles are the masters of their domain and consider any animal they can lift as a suitable meal. If an eagle flies over a seagull rookery, all the birds on the rookery take flight to chase away the menacing predator. Between fish, birds, voles, weasels, and hares, eagles on Kodiak Island have plenty to eat.
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If you look up on a windy day on Kodiak Island, you will likely see several eagles soaring high in the sky. Bald eagles are built for flight, particularly for soaring and gliding. An eagle expends a great deal of energy flapping its large wings, so to conserve energy when gaining and maintaining altitude, it utilizes thermal convection currents or “thermals,” which are columns of warm air generated by terrain such as mountain slopes. It has been estimated a bald eagle can reach flying speeds of 35-43 mph (56-70 kph) when gliding and flapping and 30 mph (48 kph) while carrying a fish. While not known as particularly fast fliers, eagles can soar and glide for hours at a time.
The construction of an eagle’s wings and tail make soaring and gliding possible. The wings are long and broad and are covered by a layer of lightweight feathers arranged to streamline the wing. The primary feathers, or primaries, provide lift and control an eagle’s flight during turning, diving, and braking. An eagle can tilt and rotate individual feathers to maneuver and brake. The tail also assists in braking and stabilizes the eagle when it dives toward prey. While soaring, tail feathers spread wide to maximize surface area and increase the effect of updrafts and thermals.
When an eagle finds an air current or a thermal, it can gain altitude without flapping its wings. If it is dead calm with no air currents moving up or down, eagles cannot soar, and that is why you see more eagles soaring on windy days or sunny afternoons and sitting on their perches on calm, cool mornings.
When a young eagle first leaves the nest, its wing and tail feathers are longer than those of an adult. As an eagle matures, its wing and tail feathers become shorter and narrower with each successive molt. The larger wings of a juvenile make it easier for the bird to catch an updraft or weak thermal and to fly slower and in tighter circles than an adult. The downside of the larger wings and tail is the juvenile rises slower, sinks faster, and cannot soar as far as the adult. Adult bald eagles can flap their wings faster and fly at a greater speed than immature eagles, making them more efficient at chasing down live prey.
Female bald eagles are larger than males, and while their wings are also slightly larger, the larger wing size does not make up for the increased weight of the female. Therefore, females require more wind or stronger thermals than males to be able to gain altitude and soar. Since thermals are weaker during the morning and evening hours, females are more likely to remain on their perches during these times and soar when it’s windy or in the afternoon when thermals are stronger.
An eagle’s large wings make landings and takeoffs tricky, and landing on a perch is something eagles manage to do gracefully only after much practice. A newly-fledged juvenile looks very awkward when it tries to land on a perch and may even crash land or swing upside down if it grabs the perch while it still has too much forward momentum.
An eagle’s acute vision allows it to see prey while soaring high in the air. The eyes of an eagle are larger than those of an adult human, and an eagle’s eyesight is at least four times sharper than that of a human with perfect vision. An eagle flying at an altitude of several hundred feet can spot a fish under water. The eyes are protected by a nictating membrane, and each eye has two fovae or centers of focus, letting the bird see both forward and to the side at the same time. Eagles have binocular vision, so they can perceive depth, allowing them to judge how far away their prey is when they begin a dive.
Next week, I’ll write about what bald eagles eat and how they hunt. Once again, I want to remind you to sign up for my free monthly Mystery Newsletter and read about true crime in Alaska.
Two species of squirrels live on the islands of the Kodiak Archipelago. The Arctic ground squirrel (Spermophilus parryii) was introduced a few hundred years ago, and the more common red squirrel (Tamiasciurus hudsonicus) was introduced in 1952. The red squirrel population is slowly spreading across Kodiak Island, and biologists estimate at least 10,000 to 15,000 red squirrels now live on Kodiak.
Red squirrels range across Canada and Alaska and south into the North Central and Northeastern United States, west to the Rocky Mountains. Their range in Alaska extends through most of the forested areas, from the Brooks Range through south central and southeast Alaska.
Red squirrels are members of the rodent family, and the species Tamiasciurus hudsonicus has been divided into 25 subspecies. A red squirrel is small, measuring approximately 12 inches (30 cm) in length, with its long, bushy tail accounting for a third of the total length. A large adult may weigh 8.4 ounces (240 g). In the summer, it has a pale red to olive-gray coat with a black line along each side. It is creamy white or buff-colored on its underside. In the winter, it has reddish-brown ear tufts and a bright rusty red strip along the back, while the black stripes along the side fade or disappear. In all seasons, a red squirrel has a white ring around each eye.
Red squirrels are territorial and vigorously defend their territories. A squirrel’s territory can range in size one-half acre to six acres, and each squirrel knows its territory well and may have several nests and food caches within the boundaries of its territory. Red squirrels build their nests in trees. The nests are usually between 10 to 60 ft. (3-18 m) above the ground and are either constructed inside a tree cavity or out of a mass of twigs, leaves, moss, and lichens inside the dense foliage of a branch.[4,5}
Red squirrels mainly eat the seeds of conifer cones. A spruce forest covers the north side of Kodiak Island, and the squirrels living in this forest eat the seeds of spruce cones. Since few spruce trees grow on the rest of the island, though, squirrels in other areas eat and cache alder cones. When collecting cones, a red squirrel cuts green cones from a tree and allows them to fall to the ground. The squirrel then gathers the fallen cones and buries them in one or several caches in its territory. By collecting only green cones, the squirrel knows the seeds are still in the cones.
A squirrel may collect several bushels of cones in a cache, and a cache may be as big as 15 by 18 ft. with a depth of 3 ft. (5 x 6 x 1 m). In addition to one large cache, a squirrel often has several smaller caches in its territory. Besides seeds, red squirrels also eat berries, buds, fungi, insects and bird eggs. They do most of their food collecting during the day but may also be active on moonlit nights. Red squirrels do not hibernate but instead depend on their stored food caches to make it through the winter. In regions with heavy snow, they may dig elaborate snow tunnels to reach their caches.
Red squirrels can climb trees with ease. They run up and down the trunks and along branches and can jump as far as 8 ft. (2.4 m) from one branch to another. On the ground, they walk or run and can run as fast as 14 mph (22.5 km/hr) over short distances.
Red squirrels are solitary animals except during the breeding season, when males leave their territories, and females allow males to enter their territories. A female has a one-day estrous period, and one to ten males may pursue her during that time. The dominant male will approach the female while uttering quiet vocalizations. Copulation is brief but may be repeated several times until the female becomes aggressive. After a gestation of 36 to 40 days, the female gives birth to three to seven young. The young are blind and hairless at birth and weigh only ¼ oz. (7 g). The young develop slowly and do not open their eyes until they are 27 days old. By 30 days of age, they are fully furred and begin to leave the nest. When young red squirrels are 9 to 11 weeks old, they begin to establish their territories.
A red squirrel will emit a long rattling buzz when another squirrel enters its territory, and this call is often accompanied by tail-jerking and foot stamping. Neighboring squirrels may respond with similar calls. A slowly repeated “whuuk” call is an alarm call announcing the approach of a predator. Biologists have noted red squirrels often produce a high-frequency alarm call when they detect an avian predator and a low, barking call when they sense the approach of a land predator. In addition to vocalizations, red squirrels use posturing and chemical signals to communicate.
Red squirrels have a high mortality rate, and only 22% survive to one year of age. Females that survive their first year have a life expectancy of 2.3 years and a maximum lifespan of 8 years. Red squirrels may be preyed upon by hawks, owls, eagles, bobcats, coyotes, weasels, minks, foxes, raccoons, and fishers. In the long term, habitat loss is the biggest threat to red squirrels.[4,5}
Beginning next week, I’ll write a few posts about bald eagles. As always, I appreciate you stopping by to read my blog and would love hearing from you. Please leave a comment!
The black oystercatcher (Haematopus bachmani) with its black body and bright orange bill is a familiar sight on Kodiak Island beaches, but it is one of the least abundant shorebird species in North America. The total world population of oystercatchers is believed to be less than 11,000 birds, but oystercatchers never have been accurately counted, so their population size is unknown. It is also not known whether their population is stable, increasing or decreasing. When the Exxon-Valdez oil spill directly killed a large number of oystercatchers and damaged the intertidal area where black oystercatchers feed, biologists realized how little we know, not only about the population size of these birds, but also about their biology and behavior. We don’t know how long they live, how old they are when they first mate, or what their migratory habits are. Black oystercatchers have been identified as a species of high concern throughout their range in the U.S. and Canada, and federal and state agencies are now working together to learn more about these fascinating birds.
Black oystercatchers range from Baja California to the western Aleutian Islands. Over 65% of the world population resides in Alaska, and more than 1700 oystercatchers live on Kodiak Island.
The black oystercatcher is a large shorebird, approximately 15 inches (38 centimeters) in length. It has a long, heavy, bright orange-red bill, yellow eyes encircled by orange rings, pink legs, and black plumage. its dark feathers often make it hard to see against the black rocks in the intertidal zone, but its loud shrill call announces its presence. In addition to its loud wheep-wheep call, it also has a softer hew-hew-hew call it uses when it is alarmed.
Black oystercatchers live in the upper end of the intertidal zone. They live and nest near an available food source, and if possible, they live near mussel beds, their food of choice. They are territorial during the nesting season, but they often aggregate in groups of tens to hundreds in the winter months. Kodiak Island is the only documented area in Alaska that supports large winter aggregations of black oystercatchers. Winter flocks of twenty to three hundred birds have been counted in the Kodiak Harbor, as well as in Kalsin Bay, Cape Chiniak, Uganik Bay, and Uyak Bay.
Black oystercatchers forage on low-sloping gravel or rock beaches, where prey is abundant. They eat mussels when they are available but also eat other intertidal creatures such as limpets, chitons, crabs, barnacles, clams, and other small animals. An oystercatcher uses one of two methods to eat mussels and clams. If it finds a bivalve with a partially-opened shell, it jabs its bill into the opening, cuts the muscles that hold the shells closed, and consumes the animal. If the shells of the bivalve are closed when the oystercatcher finds it, the bird hammers on the shell to break it open.
Black oystercatchers nest on the shoreline just above the high-tide mark. They may nest on bare rock, sand, gravel, tufts of grass, or among logs. They often nest on small islands, where they are better protected from predators. Nests are built by both parents and are simply a shallow, circular depression lined with shell fragments, rock flakes, or pebbles. Pairs often build more than one nest in their territory, and then the female chooses which nest to use.
Biologists believe black oystercatchers mate for life, and they return to the same nesting territory year after year. In Alaska, they arrive at their nesting sites in March and leave in September. A female lays one to three eggs. The eggs are pale buff or olive and are spotted and marked with brown and black. Both parents incubate the eggs for 24 to 29 days. When the chicks hatch, they are covered with down and stay near the nest at first. Parents take turns guarding the chicks and procuring food. When the chicks are a little older, they follow their parents to the feeding areas, and the parents feed them there. Chicks can fly when they are approximately five weeks old, and they slowly begin to feed themselves. Biologists are not sure how old a black oystercatcher must be before it is sexually mature and can reproduce, but limited evidence suggests they may not be able to reproduce until they are five-years-old. Biologists know black oystercatchers are long-lived birds, but there is little data on how long they live. Some banded birds have lived nearly 16 years.
Next week I’ll tell you more about recent and current research on black oystercatchers and why these birds are considered an indicator species. Don’t forget to sign up for my Mystery Newsletter.