Plum Island Safari

Looking across the Ipswich Bay from Halibut Point a great stretch of sand marks the horizon, some of which is preserved as the Parker River National Wildlife Refuge on Plum Island and adjacent estuaries. I decided it was time to take a look.

Egrets, ducks, and wading birds

The inner side of the refuge offers both salt water and fresh water habitat. Its great advantage over Halibut Point as a food producer for wildlife is the prevalence of mud.

Dunes and ocean

The outer side looks back at Halibut Point's rocky shoreline and quarry ponds. The environments could scarcely be more different. Plum Island's sand dunes continuing into shallow water form another part of its distinctive ecology.

Near the entrance to the Refuge is a tribute to legendary naturalist Ludlow Griscom of Harvard's Museum of Comparative Zoology. I was gratified to read on the plaque that he played a leading role in establishing the 4,700 acre sanctuary. Eleven years ago in these Notes I reported on a conversation I had with Roland Clement, aged 101, concerning a birding trip to Halibut Point with the charismatic Griscom in 1941. Here is an excerpt: People were either awed by him, or hated him. I was a lucky protégé for a year or so....It was our aim to outdo our guru in first spotting some rare find. Or, heavenly luck, catch him in some hasty misidentification. But he almost always took a second look before speaking out, so we remained empty-handed.

Cormorants, gulls, and egrets in a feeding frenzy
on small fish driven to the surface by larger fish

The Refuge is simultaneously a place of serenity and of existential tumult.

Harrier, or Marsh Hawk

A visitor might well get a sense of being on safari in a distant, exotic landscape.

Osprey

Given the richness of these estuaries in supporting colonies of wildlife, it is not surprising that Plum Island attracts a wide range of birds of prey.

Red-tailed Hawk

Fierce raptors patrol the air eyeing the teeming flocks of shorebirds and rodents scurrying in the uplands.

Sandpipers and plovers take flight

Here the appearance of a falcon overhead panics waders feeding on the mud flats.

Merlin (falcon)

The falcon circled and burst into the flock as it veered distractingly in hopes of collective safety.

The Merlin and a Semipalmated Plover

The falcon succeeded in knocking down one of the shorebirds to its demise.

Greater Yellowlegs and Short-billed Dowitcher

Of course those mild-mannered mud probers are also carnivorous in their appetites as they insert their bills into the mud for tiny invertebrates.

Common Tern with fish

So are the graceful terns patrolling the waters off the beach.

Great Egrets and Snowy Egrets rising

This refuge at the edge of the continent sustains not only its resident wildlife but as a critical staging area in the Atlantic flyway for countless songbirds arriving and departing on migration flights across thousands of miles of ocean.

The U. S. Fish & Wildlife Service manages the preserve with a nice balance of primal sanctuary and recreational access and vistas for visitors. Even for those of us lucky enough to frequent Halibut Point, a trip to Plum Island feels like a safari to an exotic but accessible destination.

Swallows on the Wing

Swallows move fast and spend most of their waking hours hunting in the air. Their insect prey is invisible to us yet these birds spot it and catch it in flight. As they hurtle, loop and glide overhead swallows seem more like a concept than something with definite features, more like a verb than a noun. Swallows extend the romance of the aerial sphere beyond our knowing.

Three Tree Swallows and a Barn Swallow (top center)

And yet occasionally they alight on an observable perch. With the right light and the aid of binoculars their sleek beauty comes to the eye.

Barn Swallow over the quarry pond

One understands that swallows are able to catch more calories than they expend in their energetic pursuit of prey.

Barn Swallow feeding young

They also have to keep up with the demands of their brood. When fledglings leave the nest they line up around the quarry to observe and practice their difficult trade, while still being provisioned by adults.

This transfer of food usually comes as a bolus, a mouthful comprising many insects rather than one at a time.

Male Tree Swallow

Swallows have adapted to hunting insects on the wing by developing a slender, streamlined body and long, pointed wings, which allow great maneuverability and endurance, as well as frequent periods of gliding. Their body shapes allow for very efficient flight; the metabolic rate of swallows in flight is 49–72% lower than equivalent song birds of the same size.¹

 The impression is falcon-like scaled down to smaller prey.

Juvenile Tree Swallows

In late summer the Halibut Point quarry and shoreline provide good hunting prospects both high and low over water.

Gleaning from the water surface

The juveniles especially are attracted to picking bugs from the surface of the quarry.

Tree Swallow and the blue moon

Not surprisingly, swallows resemble falcons in their visual acuity as well as in their body and flight characteristics. They have a bifoveate retina that provides sharp lateral and frontal vision, an unusually long eye that enhances spatial resolution, a large posterior blind area, and a narrow binocular field.²

Their relatively long eyes allow for an increase in visual acuity without competing with the brain for space inside of the head.¹

Tree Swallows feeding on bayberry berries

In preparation for their fall migration southward swallows pluck extra calories from bayberry bushes along the Halibut Point shoreline.

Migrating swallows en route south

They are among the minority of songbirds that migrate primarily during the daylight hours. Although day migrants are more exposed to avian predators there are some advantages.  Day migrants are able to navigate using land formations they can see easily, such river valleys, coastlines, and mountain ranges. And, unlike night migrants, those that migrate by day can feed as they go. For Tree Swallows this means they can hunt both flying insects and their favorite berries.³  

Swallows form just one branch of the diverse winged world but they seem to have taken the achievement of flight to its ultimate degree.

1. Wikipedia. 

2. "We also show that swallows and diurnal raptors (hawks and falcons) have converged on a similar visual configuration but that, interestingly, predatory songbirds that ambush prey (flycatchers) have not converged on the same suite of traits. Despite the commonly held belief that predators rely on binocular vision, the temporal (frontally projecting) fovea present in swallows—but not present in other songbirds—is likely not involved in binocular vision. Instead, swallows have four nonoverlapping foveae in a 100° arc around the beak, which can improve the tracking of frontally located aerial prey that are engaging in evasive maneuvers."

Tyrrell, Fernández-Juricic and McPeek, "The Hawk-Eyed Songbird: Retinal Morphology, Eye Shape, and Visual Fields of an Aerial Insectivore," The American Naturalist, vol. 189 # 6, June 2017.

3. Treeswallows.com

Meadow Report

The reconstructed meadow at Halibut Point has continued to evolve through its third season. 

Bobolink

In a new sign of habitat maturity a male Bobolink scouted out nesting territory in the springtime. It apparently found the sanctuary too small for its requirements and stayed only briefly.

Goldfinch

Goldfinches, on the other hand, have found the varied ecology and the ripening seeds of coreopsis much to their liking.

Coreopsis flower buds

Because Coreopsis lanceolata is a perennial many of the plants that got a start in earlier years have strengthened to produce a strong show of flowers in 2024.

Coreopsis and Crown Vetch

Last year, in the new meadow's first truly floriferous season, Gloriosa Daisies predominated. Their blazing presence was much diminished this summer. Being an annual they need to keep reseeding and find their way into the long-term blooming cycle of the meadow. 

Wild Indigo Duskywing on Coreopsis

Coreopsis did provide eye-catching swathes of yellow, though without the multi-hued impact of the Gloriosa Daisies.

White-tailed Deer in Coreopsis

Their sunny discs gave the meadow a sustained cheeriness over the summer.

Eastern Smooth Beardtongue

Late developers in the wildflower seeding mix planted during the renovation are finally contributing to the floral diversity.

New York Ironweed (foreground) and Purple-headed Helenium

While it can't be said that all these plants would have grown on Cape Ann originally, the various North American natives have woven a gardenesque beauty among the grasses.

Ryegrass

The great variety of grasses in the meadow reflects a long history of introductions by human activity whether agricultural or accidental.

Yellow Foxtail

Ecological restorations are approximations where the possibilities of beauty if not purity can always be found.

Goldenrod, Indiangrass, and the old barn

in morning light

It is tempting to think in terms of successions leading toward a climax state, to a virtue of stable permanence, to fulfillment of an ultimate design. but it is change itself that characterizes our condition and newness that shapes reality.