This is part of the 2020 Digital Seaside Center. For more Digital Seaside Center content, click here.

Hello everyone! Welcome back to local wildlife weekly.

This week, we’re back to birds (cue the trombone wah). I know, I know– I’m getting predictable. I am trying to keep these posts as relevant as possible, fashioning them in real-time based on what I happen to observe and photograph during the week. It just so happens that, this time of year, I find myself looking at birds and bugs more than anything else. On the coast of the Long Island Sound these are the most diverse and obvious taxa: mammals are few and far between, reptiles similarly scarce, amphibians nonexistent in saline habitats. My access to fish is limited. I don’t have the means to photograph most other marine life. I am looking to break this bird/bug stranglehold in the coming weeks— it will force me to get creative— but in the meantime I thought I’d counterbalance my last bird post with a profile of the species I believe to be the piping plover’s antithesis: the double-crested cormorant. Exceedingly common, increasing, large and grotesque, our cormorants are everything the plovers are not. Their only similarity, it seems, is their ability to be hated– for wildly different reasons, of course. Just as I promised a defense of the the plover (“they are not the enemy!”) I will now defend the cormorant with similar gusto. All local wildlife is deserving of our admiration, if we know where and how to look.

Introducing: The Double-crested Cormorant!

Two Double-crested Cormorant watch me kayak past. Photo by Brendan Murtha.

The double-crested cormorant, Phalacrocorax auritus, is one of our most common waterbirds. Even the most disinterested people on the shore tend to notice these birds, classed among “seagulls” for their ubiquity. Standing atop pilings and buoys, black wings spread like some fallen angel, cormorants do not receive the admiration egrets, osprey, and other coastal species do: one could call them the “dark horse” of our local avifauna. They are, by all accounts, strange, and live an alien lifestyle far removed from what most people expect of birds. This is no genteel songbird, no majestic raptor. This is a greasy marine weasel, snaking through the algal gloom with an insatiable appetite for fish: wet, slimy, smelly.

Am I being too hard on these birds? If so, I don’t mean it— I find cormorants charming and fascinating, and I rag on them only to prove a point. I’ve always had a soft-spot for the underdog, the proverbial “other,” and am obligated to first address the causes of their alienation before I jump to solutions.

Let’s familiarize ourselves with the cormorants’ natural history. Cormorants are today placed in the Suliformes order, although their evolutionary history has been historically contested. Long thought related to pelicans, the latter are now believed to share closer ancestry with herons, and cormorants (family Phalacrocoracidae, with 40 species worldwide) are classed in a separate order alongside boobies, frigatebirds, and darters. All the birds mentioned here are specialized fish-hunters, employing various tactics to do so. The range of extant strategies mirrors the diversity of fish available for taking. Boobies, for example, are open-water “plunge-divers,” zipping through the waves like harpoons after schooling baitfish. Eel-like darters such as the anhinga (common in Florida) navigate densely weeded areas, pursuing solitary fish taking shelter in the reeds.

Cormorants occupy a niche somewhere between these two extremes. The six species of cormorant in North America are all open-water hunters, and most are salt-water specialists. Cormorant diversity on the east coast is lacking; the Sound plays host to only two. The great cormorant (Phalacrocorax carbo) visits only in the winter, and is an exclusive denizen of rocky North Atlantic shores. Throughout the rest of the year double-crested is the default, the most widespread species of the group and a postcard generalist.

Double-crested cormorants are equally at home in fresh and saltwater, but stick close to shore regardless. They’ll take a wide variety of small to mid-sized fish, whatever they can catch and swallow, although certain species make up large proportions of their diet during seasonal runs. Individual cormorants may take as many as 60 fish species throughout the year, and across their range over 250 species have been documented as prey. Because cormorants like to hunt along the bottom, they are generally restricted to shallow waters, and rarely descend more than 10 meters beneath the surface. They do show preference for clear water when it is available, but their ability to catch prey in remarkably turbid waters (think of muddy marsh channels) indicates both powerful eyesight and some degree of tactile sensitivity (non-visual response to movement in the water). One of the more interesting cormorant foraging behaviors involves teamwork, where bands of birds will “herd” schooling fish into traps and shallows (think sheepdogs or teams of lioness). This behavior is more frequently observed in clear water, when pursuit of schooling fish is feasible; murky waters drive individual cormorants to lurk along the bottom, picking off what they can get.

Cormorants must strike terror– or some piscine equivalent– into the hearts of fish. What a meticulously designed predator a cormorant is! Of course, most people don’t view them with such veneration. Why? We all love a good “bird of prey,” after all: eagles, hawks, owls and falcons are generally heralded as the pinnacle of predatory prowess. We venerate their cunning, their patience: we see blood on talons and feel our own hearts pumping it within, sense our own mortality. There’s just something familiar, primal, exhilarating about the hawk’s hunt– such an innate response is lacking when we face down a cormorant. They deal in an inaccessible world of impulse, of murky gloom, of silver flashes and stinging salt: their talents remain invisible, and alien, to us. Taken out of context, drying their oily wings on a guano-stained rock, cormorants can seem grotesque— it’s hard to see ourselves reflected in their brilliant turquoise eyes. It’s almost the “uncanny valley” of vertebrate camaraderie.

Of course, the perceived distance is on us. Birds have been hunting fish beneath the waves for millions of years: Cormorant-like predators such as Hesperornis long predate anything resembling today’s “raptors” in the fossil record. The sheer diversity in form and function among avian fish-eaters today speaks to this long evolutionary history. Cormorants, and their ecology, are not an anomaly.

Green’s Ledge Lighthouse (Norwalk/Darien) in the background. Photo by Brendan Murtha.

The double-crested cormorant has surpassed “novelty” level in some areas, however, and proceeded straight to nuisance. Their role as a generalist has given them much room for expansion in the constantly-changing Anthropocene, and since 1980 this bird has seen population increases across many areas of its range. The causes of the increase are varied, and debated. Part of this increase was simply a rebound from the ravages wrought on many waterbirds by DDT and other chemicals during the ‘60s and ‘70s. Yet, beyond population recovery, the cormorants enjoyed a unique boon as fisheries changed: impoundments stocked with sport fish became bonanzas, and fish-farms / aquaculture opened up new sources upon which populations could sustain themselves. Cormorants are voracious, and nest colonially— where you find one, you’ll often find many more. As a result, the birds have become a serious opponent of fisherman and fish farmers, stalwart competition and a drain on resources. They have made enemies, and unlike piping plovers (whose scarcity conflicts with our leisure) cormorants’ abundance conflicts with our livelihoods. The contrast could not be more stark.

Of course, the birds’ true impact on fisheries remains contentious. There is little agreement in the literature about the magnitude of their influence, and whether action is needed. Still, this has not stopped policymakers and fishery managers from cherry-picking the crop; conservation guidelines for double-crested cormorant have changed wildly over the last several years and drastic measures— including culling– have been taken to curb the birds’ numbers.

A particular contentious cull occurred a few years ago along the Columbia River in Oregon, to “protect” the area’s salmon industry. Thousands of cormorants on the lower Columbia River were methodically killed, and entire breeding colonies were wiped out by federal and state management. The move sparked outrage among bird-lovers and conservationists alike, especially as it became clear the cull did little to increase salmon numbers. In fact, in an ironic twist, the cull seemed to drive many cormorants upriver, away from the violence, where they began feeding almost exclusively on spawning salmon— at lower elevations salmon made up just a portion of their diet. There are many examples of mismanagement like this occurring, a classic pitfall of our “playing god” with species who are much more resilient and adaptable than we give them credit for. Of course, this at-times brutal rivalry also flies in the face of historical cooperation between man and cormorant: the birds are famous for their “domestic” partnerships with fisherman in traditional Chinese, Japanese and European fishing communities. Our departure from such a relationship speaks volumes: such is the nature of resource commodification and its corrosion of all things good.

Around here double-crested cormorants are generally not viewed as a nuisance– they remain in the realm of cautious curiosity. So they should remain, I think. Once we get over our squeamish discomfort, we can find in them an interesting mix of the ancient and the new, the familiar and the alien.

We can also find humility. As cormorants dry their wings next to our beaches and bars, marinas and motor-boats, they offer us a glimpse of vulnerability we generally don’t associate with “perfectly adapted” creatures: their flight feathers, not water-resistant, get water-logged and heavy after foraging. These soaked feathers trap little air and make the birds less buoyant, able to pursue prey along the bottom, but come with a sizable trade-off. Before embarking on any long flights the birds must dry out their wings, waiting patiently. They are at the mercy of the elements, temporarily immobilized. Yet, despite this obstacle, these birds have managed to thrive. If we must search for some camaraderie with them, this may be our golden-ticket— we too need to take a breather sometimes. We’re all out here, in this big web of life, just trying to make it through the day– what’s more foundational than that?

Food for thought. Or maybe just the nonsensical ramblings of a bird-lover. You choose!

Til next week!

- Brendan Murtha, 2020 Seaside Center Naturalist