Grebes and Loons, Part 2

Two species of loons frequent the winter waters off Halibut Point while they await the thawing of ice on the inland and northerly lakes where they breed, nest, and raise their families.

Common Loon, lower left, and Red-throated Loon, upper right

The winter plumage of these birds can be distinguished by subtle differences in the grey-white patterns on their necks. An easier field mark is the heavier build and straight conical bill of the Common Loon, compared to the more delicate outline and slim, upturned bill of the Red-throated Loon.

Common Loon

Loons trail their legs and feet behind them in flight, which separates them from all the other coastline waterfowl except grebes. They are larger than grebes and without wing patches.

Red-throated Loon

Their drooping neck and head silhouette tends to be more pronounced among Red-throated Loons.

Common Loon, beginning to take on breeding plumage

A good look reveals the more checkered pattern on the back of a Common Loon. When possible, loons swallow their prey before surfacing, which is more easily accomplished with a fish than a crab.

Juvenile Red-throated Loon

Red-throated Loons show a speckled rather than checkered pattern on their backs, giving a slimmer, greyer aspect than Common Loons especially when young.

Common Loon in breeding plumage

A few Common Loons get a late start in their spring departure, so we get a glimpse of their spectacular breeding plumage and eerie yodeling out on moonlit water. Unfortunately I've never seen a Red-throated Loon in its colorful phase.

Webbed feet

Unlike most birds whose bones are air-filled around a porous structure, loons have dense bones. This extra weight makes them float low in the water and helps them dive as deep as 250 feet to search for food, driven by those powerful legs placed to the rear that make them great swimmers but hopeless walkers.

These aspects make loons and grebes appear superficially similar, but the resemblance is considered a case of convergent evolution involving strong selective forces encountered by unrelated birds sharing the same lifestyle at different times and in different habitat. They are both foot-propelled but the loon's feet are webbed unlike the lobed toes of the grebe, among other anatomical differences.

Airborne

Another adaptation by these essentially fresh-water birds is their ability to change seasonally to a briny environment where they necessarily ingest large amounts of saltwater. They are able to excrete excess salt through glands near their eyes. 

Loons seem to push the limits of combining underwater success with the ability to fly. They need a long runway, literally, to reach liftoff, but once airborne they are strong flyers navigating gale headwinds above the waves, and covering hundreds of miles in a straight flight during migration at speeds up to 70 miles per hour.

Grebes and Loons, Part 1

Once deep winter sets in, the shoreline of Halibut Point tends to provide a greater variety of bird life than does the upland acreage. The ocean edge at this season, from a binocularist's point of view, is also more interesting than in summertime when most of the coastal species have departed for northern or inland breeding grounds. So it is with grebes and loons. 

The grebes you might encounter here are named for remarkable breeding plumage that you are unlikely to see, because they will mostly have left the area by the time of their spring molt. They should be considered fresh-water birds forced here by frozen conditions on continental water bodies. Two of these species adapt themselves to our maritime conditions in winter.

A Horned Grebe beside two female Red-breasted Mergansers

The Horned Grebe is small, buoyant, and duck-like but with a pointed bill and red eyes.

Horned Grebe afloat

It is the species more likely to be seen diving for food close to shore. A glimpse of its outsized legs suggests its advantage in chasing fish below the surface.

Horned Grebe in flight

In flight those long legs trail behind. The bird's plumage is more boldly patterned than it seems while swimming compactly on the water.

A Red-necked Grebe above a Razorbill in flight

The drooping neck and head of a Red-necked Grebe bear a resemblance to a loon in flight, but its wing patches distinguish it from that order of birds.

A Red-necked Grebe devouring prey

After a successful dive this grebe brought to the surface a ling fish.

Red-necked Grebe in breeding plumage

A late-to-depart bird evidences the breeding plumage for which it is named.

Red-necked Grebe on the quarry

Several years ago at the very beginning of spring a Red-necked Grebe spent a week on the quarry, before it molted to breeding plumage.

It found an abundance of small fish to pursue.

Characteristically it subdued its prey with violent thrashing head motions before swallowing.

Then it oriented the fish head first to keep the sharp dorsal fins pointed backwards on the way down its throat.

The lobed toes of a Red-necked Grebe

Like other diving birds in the business of out-swimming fish, grebes have large feet extending from legs placed at the very rear of their bodies, designed to maximize propulsion but of very limited use for walking. Grebes differ from all the rest by having broad lobed toes, which they can work individually and in concert like the hydrofoil blades of a propeller.

Marine Mammals

We've  come to think of life as originating in the sea, with many branches becoming more complex and purposeful as they evolved 'upward' to terrestrial habitats. Recently, by which I mean over the course of tens of millions of years, some of those leg-bearing land-based creatures have re-committed to life in the water, to the point where we call them marine mammals, meaning that the oceans are their obligatory environment. The term does include polar bears, but mostly refers to animals that have developed profound adaptations allowing them to thrive primarily or entirely offshore. Looking into their special anatomy and abilities makes fascinating reading in online explorations. 

From Halibut Point the only sure observations of marine mammals are seals in winter, if you walk along the Atlantic Path until approaching Andrews Cove, where they can be seen at a distance 'bottling" with snouts protruding vertically above the surface while they think things over.

Harbor seal

Once in awhile seals come close to shore but are likely to submerge quickly into the depths where they are so well adapted to fishing , with large eyes, torpedo-shaped bodies, super-sensitive long whiskers that help navigate and follow prey, and a remarkable tolerance of long, deep dives.

They try to swallow what they catch immediately. If they have to bring it to the surface, gulls are waiting to harass them into releasing the prize by pecking their head and face. When gulls approach they duck back underwater.

Resting seals look both ridiculous and blissful outside the aqueous environment for which they are supremely designed.

Grey seal

Grey seals known a "horseheads" also frequent New England waters, though less commonly than harbor seals.

Minke Whale

Fairly far out in the Bay you might have a lucky moment spotting a whale going by, if you happen to be looking in just the right place. The few I've seen were traveling determinedly and covered perhaps half a mile between breaths, surfacing every 6-12 minutes.

Minkes at 30 or so feet are the smallest of the local baleen whales. Long, flat keratin plates hang from its mouth in place of teeth to enable it to filter crustaceans, plankton and small schooling fish from great gulps of seawater.

Humpback whale

Much less frequently the larger baleen whales come within sight of land in the Ipswich Bay, mostly during the warmer month when they build up fat stores for fall migration to southern calving and nursery grounds.

Atlantic white-sided dolphins

Fast-swimming Atlantic white-sided dolphins are usually found in social groups that can range from five to fifty. They often engage in acrobatic activity, breaching and jumping at the surface in pursuit of fish, or apparently for the pleasure of athletic play and entertainment in front of power boats.

Gannets and dolphins attacking a school of fish

This species is not considered migratory but has seasonal movements, moving closer inshore and north in the summers, and offshore and south in the winters.

The Pogey-Plankton Ecosystem

Considering that I haven't directly encountered either pogies or plankton, I'm astounded to learn how influential they are in the makeup of our biosphere.

Phytoplankton

Plankton escape our notice because they are microscopic though super-abundant in the ocean. Some are plants, the phytoplankton, and some are animals, the zooplankton. Zooplankton ultimately depend on phytoplankton because they are the ones that turn sunlight into organic life and form the very foundation of the food chain. Marine animals diversify up from zooplankton through a complex of carnivorous predators that eat other flesh. 

Pogies are one of the relatively few vegetarian species of fish. As adults they prosper almost exclusively on phytoplankton. They don't bite anything. They're able to harvest those myriad algae and other miniscule drifting plants by passing them through a filtering system in their gills. They are able to digest celluloids profitably perhaps like our grazing ruminants which rely symbiotically on gut bacteria. Pogies have nearly cornered the market on their food source, although oysters and mussels in the estuaries, and some huge marine mammals like basking sharks and baleen whales are also filter feeders, though these creatures don't appear to discriminate between phytoplankton and zooplankton. 

Operating with a seemingly limitless food source and tremendous individual fecundity, pogies became far and away the most prolific fish along the Atlantic coast, despite being devoured by almost everything that could swim, fly or dive where they congregated. We've seen how, despite being prodigiously netted for farming soil enrichment, they still sustained the multitudes of fisheries dependent on menhaden in their diet. Even in fairly modern times author and observer Bruce Franklin refers to "that living river of menhaden [that] flowed with the seasons north and south...many miles wide along the coast, [yet filling] bays and estuaries from Florida to Maine with almost solid flesh." He relates the testimony of a sea captain in the 1870s who reported to the Fisheries Commission that "I saw a school of menhaden out at sea, when I was going to Portland, that was two miles wide and forty miles long." ¹ 

As capital investment and technology rendered the pursuit of menhaden into an industrial commodity, the species was annihilated in the northern part of its range. Eben Phillips' fish oil factories closed. Fleet operations necessarily shifted South and are now almost entirely owned by a single corporation located in the Chesapeake Bay. One of the complications to management of the fishery is that menhaden spend much of their lives within three miles of the shore, where waters are supervised by State agencies with parochial interests.  The incentives, particularly with regard to migratory fish, are to catch all you can when they pass by, and blame other regions for the demise. The National Marine Fisheries Service tries to coordinate policy beyond inshore territories out to the 200-mile limit.

Trends in Menhaden catch, 1940 to 1967 ¹

One consequence of the decimation of menhaden is the unchecked growth of phytoplankton, "that inconceivable mass of rootless plants that drift about in the sea with little or no control of their own locomotion." The phytoplankton take different forms, much of it one-celled algae. Nutrients flowing from continental land and rivers make estuaries and coastal waters especially rich environments for phytoplankton. Left unchecked‒as has occurred periodically in the North Atlantic and is now threatening the Chesapeake Bay‒the dense bloom of phytoplankton growth can block sunlight, reduce oxygen, toxify waters, smother bottom-dwelling shellfish, and lead to eutrophication of coastal zones.

The tragedy of the commons was formulated as an economics problem, but it portends an ecological problem as well with consequences for the livability of the planet. The tragedy of the commons reveals an outcome where individual incentives to consume a resource, acting in their apparent own self-interest, results in harmful over-consumption to the depletion and detriment of all. Solutions to the tragedy of the commons include the imposition of private property rights, government regulation, or the development of a collective action arrangement.

Advocacy for federal intervention in the United States has of course collided with a very strong inclination toward individual freedom. Since the beginning of resource administration in the 1870s, fisheries management has been assigned to the Department of Commerce rather than the Department of the Interior, with an orientation to sustaining harvests. Advocacy has featured many voices with competing perspectives and interpretations of data. One principle is clear about ecological relationships: pressure on any one part affects others. Human activity and welfare are very much part of the equation.

The Ipswich Bay and Folly Point, looking west from Halibut Point 

¹ Chart and information derived from Bruce Franklin's The Most Important Fish in the Sea, 2007.