Tag Archives: diver

Osprey (Pandion haliaetus)

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What lives in those exposed large, stick nests built on power poles, communication towers, and large trees? Most likely an Osprey.

Osprey image from Oregon Department of Fish & Wildlife

As you can imagine, a bird with a nearly 6-foot wingspan builds a big nest. Now imagine the bird adding a bit more to its nest each year. In the end, it is hard to imagine a nest becoming, over time, 10–13 feet deep and 3–6 feet in diameter!

Nest Challenges

Osprey build big nests and will build on any natural or man-made structure that meets its needs. Sometimes, what looked like a good choice doesn’t work out. Osprey nesting has caused power and service outages. There is always a risk of being electrocuted or collisions.

An Osprey’s nest contains more than just sticks we can see. Moss, bark, vines, grass, and lichen make the nest comfortable. But the birds will also add in other interesting things such as fishing line, baling wire, Styrofoam, and sometimes even plastic containers. Baling wire and fishing line can be fatal if the birds or young become entangled.

Nesting platforms and mitigation techniques reduce these conflicts and increase the number of birds and survival. The species is considered a conservation success story.

Where to see them

You can find Osprey nests near a lake, pond, swamp, reservoir, river, etc.  Live fish is key part of their diets unlike other raptors. They will also eat other smaller birds, snakes, voles, squirrels, muskrats, and salamanders.

Feet first!

Osprey are amazing fishers. Part of their fishing success, compared to other hawks, is undoubtedly due to an unusual toe/claw placement that helps them grip fish tightly. Their real success, however, is in technique.

The technique? Osprey dive feet first into shallow waters (up to about 3 feet) and grab a fish. They will also do this in deeper water where fish swim near the surface. Osprey have water-resistant feathers are the only raptors that dive.

Amazing Migration

In recent years, the number of Osprey residing year-around on the Pacific coast has increased. Normally, the birds would migrate as far south as Honduras. Researchers have found that some Osprey will migrate around 160,000 miles in their lifetimes. They are not sure what is causing this change.

Protection

Osprey are an amazing raptor and are protected by the Migratory Bird Treaty Act (MBTA) 16 U.S.C. Sections 703-712 of 1918 (as amended). All active nests (incubating adult, eggs, or young present) of migratory bird species are also protected by the MBTA. In Oregon, Osprey are protected by both state statute and Oregon Department of Fish and Wildlife administrative rules. Oregon Revised Statute (ORS 498) protects osprey from take, disturbance and harassment. Oregon Administrative Rule (OAR) 635-044 0130 categorizes osprey as Nongame Protected Wildlife. It is unlawful for a person to hunt, trap, pursue, kill, take, catch, or have in possession, either dead or alive, whole or in part, any Nongame Protected Wildlife.

References and where to find out more…Check the Oregon Department of Fish & Wildlife site at https://myodfw.com/wildlife-viewing/species/raptors and be sure to download their “Living with Wildlife” brochure at https://www.dfw.state.or.us/wildlife/living_with/docs/osprey.pdf. Another excellent resource is the All About Birds page by the Cornell Lab (see https://www.allaboutbirds.org/guide/Osprey/id).

Surf Scoter (Melanitta perspicillata)

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The most common scoter, or ocean duck, along the Pacific coast is the Surf scoter (Melanitta perspicillata). This salt water duck is found from Alaska south into north-central Canada, and all along the west and east coast of the U.S.

Surf scoter (courtesy of ODFW)

The Surf scoter overwinters by the thousands off the Oregon coast and are abundant here from fall through spring.

The bulk of this species overwinter in boreal forests in Alaska and Canada near freshwater lakes. Birds may also visit large lakes and reservoirs west of the Cascades in the fall.

Identification

Surf scoters are the smallest of three similar species (white-winged, black, and surf), which are often found in the same habitat.

Adult male Surf Scoters are around 19-inches in length and just over 2.3 lbs. Females come in just a bit shorter.

Adult male feathers are predominantly black with two white patches (forehead and nape). The colorful wedge-shaped bill is highly visible with white, yellow, red-orange, and black.

Adult females and subadults have a dark brown back, lighter brown belly, and light-colored patches on cheeks and nape.

Generally, compared to the other two species, the head profile is more flat, and bill heavier. The surf scoter has completely dark wings (visible in flight).  

Breeding

The species, however, does not breed in Oregon. Surf Scoters breed in Alaska and across north-central Canada.

Most form pairs before arriving at the breeding ground with males and females migrating together. Flight is strong and close to the waves.

Individuals appear to adjust their migration schedule so that they meet at the wintering and staging grounds at the same time. This helps the birds optimize reproduction.  

Females build nests that are bowl-shaped and lined with debris and down. Up to nine eggs in each nest are incubated for nearly a month by the female.

Nests are tucked into crowded breeding grounds and occasionally brood errors are made. The synchronous egg hatch must be a totally amazing event to witness.  

Food

Surf scoters forage in the surf, typically in open waters less than 33 feet deep. They dive in regularly flooded intertidal and subtidal zones.

While mussels are an important part of their diet these ducks will feed on any invertebrate found in or near the near shoreline sediments. This could include insects, crustaceans, herring spawn, coral, algae, shrimp, oysters, crabs, squid, clams, and more.

They generally capture and swallow their food whole under water. These birds will often form loose flocks to forage that move in irregular, wavy lines. They will often do this as a group, or loose flock.

Dive duration varies based on prey, water conditions, season, etc. This duck will also shift their diet as needed in winter and spring to more abundant prey.

The Matter of Molting

All waterfowl molt their feathers one or more times a year. For Surf scoters this process begins before migration in late July and lasts for about four weeks.

Surf scoter travels to a molting site (different than the wintering or nesting sites) in bays, inlets, or estuaries. These sites would most likely have easily available food and lower predation risk.

Sea ducks are vulnerable during the molt because they lose their flight feathers. Brightly-colored male plumage is also replaced by duller plumage.

Predators and Survival

These birds typically winter in marine habitats near rocky shores. Predators can include bald eagles, golden eagles, and carnivorous mammals.

Birds are particularly sensitive to oil spills. Spills impact food supplies and are known to kill many birds through starvation.

In the last 50 years, the population has somewhat declined but is not considered vulnerable.

REFERENCES:
–Oregon Dept. of Fish and Wildlife, Swans, Ducks, and Geese (https://myodfw.com/wildlife-viewing/species/swans-ducks-and-geese)
–USDI Fish and Wildlife Service (https://www.fws.gov/r5gomp/gom/habitatstudy/metadata/scoter_models.htm and https://www.fws.gov/birds/bird-enthusiasts/bird-watching/waterfowl-identification/surf-scoter.php)
–Wikipedia, Surf Scoter (https://en.wikipedia.org/wiki/Surf_scoter)