Tag Archives: Birds of Kodiak Island

Black Oystercatcher (Haematopus bachmani)

Birds, Kodiak Wildlife, , , ,

ematopus bachmani

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.

 

Arctic Tern (Sterna paradisaea)

Birds, Kodiak Wildlife, , , ,

The Arctic tern (Sterna paradisaea) is one of three species of terns found in Alaska. The other two species are the Aleutian tern (Onychoprion aleutica) and the Caspian tern (Sterna caspia). Terns belong to the family Laridae, which also includes gulls.

Arctic terns have a circumpolar range. They breed in the Arctic and subarctic regions of North America, Europe, and Asia, and they winter at the southern tips of Africa and South America, all the way to the edge of the Antarctic ice. In the United States, Arctic terns nest as far south as New England on the east coast and Washington State on the west coast. In Alaska, the Arctic tern has the largest breeding range of any Alaskan water bird. Arctic terns nest from Point Barrow through the Southeast Panhandle, and everywhere in between those two points.

Since Arctic terns breed in Arctic and subarctic areas and then migrate as far as the edge of the Antarctic ice to spend the winter, biologists believe they have the longest migration of any animal. The only animal whose migration may rival that of the Arctic tern is the sooty shearwater which migrates between New Zealand and the North Pacific. In a 2010 study, biologist Carsten Egevang and his colleagues fitted 11 Arctic terns with miniature geolocators, and they learned Arctic terns migrate even further than was previously believed. Some individual terns in the study traveled nearly 50,000 miles (more than 80,000 km) round trip. Because Arctic terns spend summer in the high latitudes of the northern hemisphere and then travel to the high latitudes of the southern hemisphere for the summer there, they see more sunlight every year than any other animal species on the planet.

Arctic terns measure 14 to 17 inches (36-43 cm) in length and have a wingspan of 29 to 33 inches (74-84 cm). Their bodies are white or gray during the breeding season, and a black patch covers the head and forehead. They have a sharply pointed red bill and short red legs. Their deeply forked tail resembles the tail of a swallow and is the reason for their nickname, “Sea swallow.” Terns are agile and quick in the air and can even hover above the water while searching for food. Because they have small, webbed feet, terns do not swim well and do not remain in the water any longer than it takes to catch their prey. A tern flies with its bill pointed down toward the water, and when it sees a fish or other prey, it dives into the water, grasps the prey, and flies away with the fish in its beak. During the non-breeding season, a tern’s legs and beak turn black, and the black patch on the head shrinks. Also during the non-breeding season, terns molt and lose most of their feathers. If they lose their feathers faster than they can be replaced, they may be flightless for a short period.

Arctic terns mate for life, and in Alaska, they arrive at their breeding areas in early to late May. During their courtship, the male performs a “fish flight.” He carries a fish in his bill and flies low over the female on the ground. If she sees him, she will join him in a high climb and flight. Terns nest in solitary pairs or colonies of a few to several hundred pairs. A tern’s nest is little more than a shallow depression in the ground, and nests usually have little or no lining material. Terns nest near fresh or salt water on beaches, spits, and small islands. The female lays one to three eggs that are brown or green and lightly speckled. Both sexes incubate the eggs, and the eggs hatch in about 23 days. The young terns immediately leave the nest and hide in nearby vegetation. The parents catch small fish to feed the chicks for the next 25 days until the chicks have fledged. Arctic terns are very aggressive during the breeding season, and they will attack intruders by crying loudly and repeatedly diving at the intruder’s head. Less than three months after they arrive at their breeding colonies, Arctic terns begin their long migration south.

Arctic terns eat small fish, insects, and invertebrates. During the non-breeding season, they are pelagic and forage at the edges of the pack ice, icebergs, and ice floes near shore.

The worldwide population of Arctic terns is between one and two million breeding pairs. Several hundred thousand pairs nest in Alaska. Because terns nest on the ground, their eggs, and chicks are susceptible to predation by foxes, rats, raccoons, gulls, and other seabirds. Arctic terns are also susceptible to pollution, human disturbance, and decreased food availability due to warming ocean temperatures. Arctic terns may live into their late twenties or early thirties.

Next week, my post will be about one of the rarest of all shorebirds, the black oystercatcher.  If you haven’t signed up for my free, monthly Mystery Newsletter, be sure to do so.  This month I am profiling a triple homicide that occurred at the Arctic Circle in -50 degree weather.

 

 

 

 

 

 

Bald Eagle (Haliaeetus leucocephalus)

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Bald Eagle

The bald eagle (Haliaeetus leucocephalus) is only found in North America. Its range stretches from northern Mexico to Canada and Alaska and covers all the continental United States. Due to a variety of factors, including the use of the pesticide DDT, bald eagles nearly became extinct in the contiguous United States by the 1950s. The 1940 Bald Eagle Protection Act prohibited commercial trapping and killing of bald and golden eagles, and more significantly, DDT was banned in 1972 when it was proven the pesticide interfered with the eagle’s calcium metabolism, causing either sterility or unhealthy eggs with brittle shells. In 1973, Congress passed the Endangered Species Act, and the bald eagle was listed as an endangered species. In 1995, when eagle populations in the continental U.S. began to rebound, the bald eagle was removed from the endangered species list and transferred to the threatened species list. On June 28, 2007, bald eagles were removed from the List of Endangered and Threatened Wildlife.dsc_0005-2

While Alaska’s eagles were never threatened by the use of DDT, Alaska has its own nefarious history with bald eagles. In 1917, commercial salmon fishermen convinced the Alaska Territorial Legislature that eagles killed large numbers of salmon and were competing with the fishermen’s livelihoods. This claim was later shown to be false, but the legislature enacted a bounty system on eagles that paid two dollars to anyone who turned in a pair of eagle legs. This bounty system lasted for thirty-six years and led to the killing of a confirmed 120,195 eagles, plus countless others that were never turned in for a bounty. The bounty system ended in 1953, and when Alaska became a state in 1959, its bald eagles were officially protected under the Federal Bald Eagle Protection Act of 1940. Alaska’s eagle population is now considered healthy, and one-half of the world’s 70,000 bald eagles live in Alaska. Twenty-five-hundred bald eagles reside on the Kodiak National Wildlife Refuge.

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The genus Haliaeetus, the sea eagles (in Latin, hali means salt and aeetus means eagle), includes eight of the sixty species of eagles. The sea eagles live along sea coasts, lakes, and river shores. The species Haliaeetus leucocephalus (leuco means white and cephalus means head) consists of two subspecies. The southern bald eagle, Haliaeetus leucocephalus leucocephalus, is found from Baja California and Texas to South Carolina and Florida, south of 40 degrees north latitude. The northern bald eagle, Haliaeetus leucocephalus alascanus occurs north of 40 degrees north latitude. Northern bald eagles are larger than their southern cousins

Eagles are well-insulated by their feathers and are good at regulating their body temperature. Unlike many birds, they do not need to migrate to warmer areas each winter, but in many parts of the country they do migrate, sometimes long distances, in response to varying food supplies. Due to its abundant year-round food supply, Kodiak has a non-migratory eagle population. Furthermore, hundreds of eagles from the Alaskan mainland migrate to Kodiak for the winter months. Effluent from canneries and fish processing plants in the town of Kodiak provides a consistent source of food for these birds in the winter months, and hundreds of eagles can be seen in town perched in trees, on cannery rooftops, on the edges of dumpsters, and even on pickup trucks. In Uyak Bay and other remote bays on Kodiak, eagles stay near their nests all winter, feeding on fish and winter-killed deer among other things.

Since the ban on DDT and related pesticides in 1972, bald eagle populations around the country have rebounded to some degree. The bald eagle population in Alaska is healthy and stable and has never been listed as endangered or threatened by the Federal Government. Eagles in Alaska never suffered the scourge of DDT poisoning, and even now in most areas, they live in a relatively contaminant-free environment.dsc_0099-2

The Bald Eagle Protection Act imposes a fine of $10,000 and two years imprisonment for anyone who harms a bald or golden eagle. It is illegal to even have an eagle feather in your possession without a proper permit. Nevertheless, humans are still responsible for many bald eagle deaths. On Kodiak, Refuge biologists have recovered eagles that have starved to death, been killed by airplanes and cars, caught in traps, and oiled by fish slime or fossil fuels. The Exxon Valdez oil spill killed hundreds of eagles in Alaska. In January 2008, fifty eagles swooped down on a dump truck filled with fish guts outside a Kodiak seafood processing plant. Twenty of the eagles were drowned or crushed, and the rest were so slimed they had to be cleaned. Bait left unattended on a fishing boat can cause a frenzy when eagles land and start fighting over their find. If their feathers become oiled by fish slime, they become less-waterproof, and then if the eagle falls into the water, it is more susceptible to hypothermia.kodiak_alaska_microgrid_508

In 2009, the Kodiak Electric Association (KEA) erected three wind turbines on Pillar Mountain near the town of Kodiak and added an additional three turbines in 2012. Many people worried the turbines would be a danger to eagles since turbines elsewhere in the U.S. kill an estimated 573,000 birds a year. KEA funded a study to address the concerns, and researchers determined that eagles went out of their way to avoid crossing the ridge among the turbines. No eagles were killed during the study, and according to avian biologist, Robin Corcoran, she has never received a report of a dead eagle near the turbines.

Eagles do die from electrocution on Kodiak. Many of the power poles near town are fitted with devices designed to protect eagles, but in January 2011, an eagle was electrocuted when she landed on the lowest of three cross bars on a power pole. That particular crossbar did not have a protective device because utility authorities believed there was not enough room for an eagle to land on it. The dead eagle had been banded years earlier by the Alaska Department of Fish and Game, so biologists knew she was 25 years old, the second-oldest bald eagle documented in Alaska, and one of the oldest-documented eagles in the country.

While these manmade disasters are tragic, they are uncommon and do not appear to be a threat to Alaska’s bald eagle population. A greater and less-obvious threat is the destruction of eagle-nesting habitat by logging and commercial and residential development. Eagles tend to nest in large, old trees that are not easily or quickly replaced once they are removed.

Once an eagle attains its adult plumage, it is impossible to determine its age unless it has been leg-banded by biologists. For this reason, we have limited data on the life span of bald eagles. Biologists believe 50-70% of all juvenile bald eagles die in their first year, and as many as 90% die before they are fully mature. Eagles in captivity may live 40 to 50 years. The oldest documented eagle resided in Stephentown, New York and lived to be 48-years old. On average, eagles live 15 to 20 years in the wild, and the oldest documented wild eagle was a 32-year-old bird from Maine. Alaska’s oldest eagle was a 28-year-old from the Chilkat Valley.

Eagles are fascinating birds and have been studied a great deal. Later this winter, I will dedicate more posts to eagle biology. Please leave a comment if you have a question or anything you would like to share about eagles.

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Arctic Tern (Sterna paradisaea)

Birds, Kodiak Wildlife, , , , ,

The Arctic tern (Sterna paradisaea) is one of three species of terns found in Alaska. The other two species are the Aleutian tern (Onychoprion aleutica) and the Caspian tern (Sterna caspia). Terns belong to the family Laridae, which also includes gulls.

Arctic terns have a circumpolar range. They breed in the Arctic and subarctic regions of North America, Europe, and Asia, and they winter at the southern tips of Africa and South America, all the way to the edge of the Antarctic ice. In the United States, Arctic terns nest as far south as New England on the east coast and Washington State on the west coast. In Alaska, the Arctic tern has the largest breeding range of any Alaskan water bird. Arctic terns nest from Point Barrow through the Southeast Panhandle, and everywhere in between those two points.

Since Arctic terns breed in Arctic and subarctic areas and then migrate as far as the edge of the Antarctic ice to spend the winter, biologists believe they have the longest migration of any animal. The only animal whose migration may rival that of the Arctic tern is the sooty shearwater which migrates between New Zealand and the North Pacific. In a 2010 study, biologist Carsten Egevang and his colleagues fitted 11 Arctic terns with miniature geolocators, and they learned Arctic terns migrate even further than was previously believed. Some individual terns in the study traveled nearly 50,000 miles (more than 80,000 km) round trip. Because Arctic terns spend summer in the high latitudes of the northern hemisphere and then travel to the high latitudes of the southern hemisphere for the summer there, they see more sunlight every year than any other animal species on the planet.

Arctic terns measure 14 to 17 inches (36-43 cm) in length and have a wingspan of 29 to 33 inches (74-84 cm). Their bodies are white or gray during the breeding season, and a black patch covers the head and forehead. They have a sharply pointed red bill and short red legs. Their deeply forked tail resembles the tail of a swallow and is the reason for their nickname, “Sea swallow.” Terns are agile and quick in the air and can even hover above the water while searching for food. Because they have small, webbed feet, terns do not swim well and do not remain in the water any longer than it takes to catch their prey. A tern flies with its bill pointed down toward the water, and when it sees a fish or other prey, it dives into the water, grasps the prey, and flies away with the fish in its beak. During the non-breeding season, a tern’s legs and beak turn black, and the black patch on the head shrinks. Also during the non-breeding season, terns molt and lose most of their feathers. If they lose their feathers faster than they can be replaced, they may be flightless for a short period.

Arctic terns mate for life, and in Alaska, they arrive at their breeding areas in early to late May. During their courtship, the male performs a “fish flight.” He carries a fish in his bill and flies low over the female on the ground. If she sees him, she will join him in a high climb and flight. Terns nest in solitary pairs or colonies of a few to several hundred pairs. A tern’s nest is little more than a shallow depression in the ground, and nests usually have little or no lining material. Terns nest near fresh or salt water on beaches, spits, and small islands. The female lays one to three eggs that are brown or green and lightly speckled. Both sexes incubate the eggs, and the eggs hatch in about 23 days. The young terns immediately leave the nest and hide in nearby vegetation. The parents catch small fish to feed the chicks for the next 25 days until the chicks have fledged. Arctic terns are very aggressive during the breeding season, and they will attack intruders by crying loudly and repeatedly diving at the intruder’s head. Less than three months after they arrive at their breeding colonies, Arctic terns begin their long migration south.

Arctic terns eat small fish, insects, and invertebrates. During the non-breeding season, they are pelagic and forage at the edges of the pack ice, icebergs, and ice floes near shore.

The worldwide population of Arctic terns is between one and two million breeding pairs. Several hundred thousand pairs nest in Alaska. Because terns nest on the ground, their eggs, and chicks are susceptible to predation by foxes, rats, raccoons, gulls, and other seabirds. Arctic terns are also susceptible to pollution, human disturbance, and decreased food availability due to warming ocean temperatures. Arctic terns may live into their late twenties or early thirties.

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