Ohio Birds and Biodiversity: double-crested cormorant

Showing posts with label double-crested cormorant. Show all posts

Saturday, September 28, 2019

Two birds, mostly unloved

I encountered this large congress of rock pigeons, Columba livia, convening on a wire yesterday. The cinnamon-colored bird especially caught my eye. A stop was in order, to attempt to capture the animals as they conferred with each other in undiagnosable pigeon-speak.

Classic "blue-bar" pigeons bookend this set of birds - this is the wild phenotype. A glance down the wire revealed all manner of color variants among the 100+ members of the avian colloquium, although the bird clad in cinnamon was the one that really drew my eye.

Homo sapiens brought pigeons over from the Old World in the 17th century, and it goes without saying that they took. I share none of my fellow primates' common disdain for this species. Pigeons are quite showy, and masters of the air. Their powers of flight are renowned. Homing pigeons display an incredible orientation to their cote, sometimes beating their masters back home. Feral urban pigeons seem to organize pleasure flights, especially early in the morning or towards dusk. A squadron will head aloft, and race about the ether in well-organized packs, seemingly enjoying their incredible aeronautic abilities.

Mark Zuckerberg and Facebook reminded me of this photo, which I took and posted to the social media mega-site one year ago today. I had intended to post the image here, then, but never got around to it.

That morning, before first light, I headed to a local hotspot, Pickerington Ponds Metro Park. A very rare (for Ohio) roseate spoonbill had been hanging out there, and I wanted to see and perhaps photograph the pink visitor from the Deep South.

Upon my arrival, I found the wetlands socked in with thick pea soup fog. The overall ambience was stunning, but not good for finding or photographing birds. As the sun's rays began to thin the mist, these double-crested cormorants slowly materialized. I sometimes recognize a good shot when I see it, and I knew this was a photogenic opportunity.

I was armed for bear - or distant spoonbills - with my Canon 800mm f/5.6 lens. Needless to say, that optical tank was mounted on a tripod, and I quickly plugged a remote shutter release into the camera, and threw the latter into live view mode. After framing a composition, I watched the birds closely as they preened and prepped for a day of fishing. When their collective postures looked interesting, I'd hold the trigger down and fire away. The beautiful juxtaposition of fog and light lasted only a few minutes, and I'm glad that I was there to live in that moment.

Like the aforementioned pigeons, double-crested cormorants are often held in low regard. Where cormorants are plentiful, such as on the Great Lakes, fishermen especially want to wage war on the piscivorous birds. The rod and reel set view them as competition, even though cormorants probably take few fish species, such as perch and walleye, coveted by fishermen.

Monday, October 31, 2011

Double-crested Cormorants, writ large

The not always placid waters of Lake Erie lap at the Huron jetty, which encloses a large spoil impoundment. Back in the day, when the dredged muck was still being sprayed into this basin, the impoundment was a huge mudflat and a beacon for birds. Many a rarity was found, including Ohio's only Spotted Redshank (1979), and our first record of Arctic Tern (1980). Even though the impoundment has been swallowed up by a luxuriant cloak of giant reed, Phragmites australis, the Huron Pier and its environs remain one of the most interesting and productive locales on Lake Erie, especially in the fall.

I was here Sunday, on a whirlwind trip from Huron to Magee Marsh. My dream? Discover Ohio's first Ash-throated Flycatcher. I didn't, or this blog would be titled differently. Ash-throated Flycatcher is WAY overdue, with scores of records in eastern North America, including, I believe, every state around Ohio. I figure the inaugural specimen will be found at the tail end of October or in November, and likely at a place such as Huron.

In spite of the Ash-throated choke, I saw lots of interesting birds at Huron. First of season Snow Buntings. Flyover Pine Siskins. Three flyby Surf Scoters. Hundreds of delicate little Bonaparte's Gulls. Six species of sparrows lurking in the Phragmites. And much more.

But the dominant bird, bar none, was Double-crested Cormorant, Phalacrocorax auritus. Great platoons of the fish-eaters constantly streamed by, nearly all of them on a west to east trajectory. In my 2.5 hours at the Huron Pier and nearby Nickel Plate Beach, I estimated that 4-5,000 birds winged by, assuming they were all different and that the flocks weren't circling around.

Of the cormorants that were close enough to see well, nearly all were juveniles with their dusty brown throats and breasts. Less than 10% and probably well under that percentage were adults.

There is no question that Double-crested Cormorants are being cranked out in record numbers on the Great Lakes; perhaps unprecedented numbers. Like some other fish-eating predatorial birds such as Bald Eagle and Osprey, Double-crested Cormorant populations plummeted from the 1950's through the 1970's, as the effects of unregulated use of DDT wreaked havoc on the food chain. Spurred by Rachel Carson's landmark book Silent Spring, environmentalists began railing against DDT and demanding it be banned. President Richard Nixon's newly created Environmental Protection Agency reviewed the issue in 1971 and rejected a ban, declaring that the chemical was not harmful to wildlife or people.

Confronted by overwhelming scientific evidence as to the dangers of DDT, the EPA's hand was forced and in 1972 the agency disallowed nearly all uses of the chemical. Not surprisingly, chemical companies sued over this decision, but a U.S. Appellate Court upheld the ban.

And birds began to recover.

Part of a cormorant concentration that numbered into the thousands skitters across Sandusky Bay, Ottawa County, Ohio yesterday.

I recall from my early days of venturing to Lake Erie, in the mid to late 1970's, that spotting a Double-crested Cormorant was a momentous occasion. There just weren't that many around. According to Bruce Peterjohn's book Birds of Ohio (2001), by the mid-60's observers noted fewer than ten sightings of cormorants annually, and nearly all reports were of fewer than ten birds.

By the 1980's Great Lakes Double-crested Cormorants were booming, and Canadian biologist Chip Weseloh documented increases of nearly 30% annually in breeding populations. While this nearly exponential growth has slowed, cormorants are still thriving.

While crossing the State Route 2 bridge over Sandusky Bay, I glanced over at a rocky islet on the north side of the bridge and saw it was carpeted with probably 1,000+ cormorants. What's more, hundreds and hundreds of others were swimming and flying about, even more birds than I usually see here. I made a detour to a good vantage point and made the video above. It shows but a snippet of the birds that were present. Based on my observations, I would say that as many as 5,000 cormorants were around the mouth of Sandusky Bay yesterday, maybe even far more than that.

Not everyone accepts the presence of all of these fish-eating birds. Fishermen, especially, get their dander up over cormorants. The rod and reel crowd, perhaps understandably, tends to think that the cormorants compete for prized yellow perch and walleye. But the scientific evidence suggests that they don't. A 1997 study, HERE, analyzed the stomach contents of 302 cormorants and found that the primary prey were gizzard shad, freshwater drum, and emerald shiners - fish species of little interest to Lake Erie fishermen.

In recent years, the health of Lake Erie has nose-dived, and that's a topic I hope to find time to write about soon. I wonder if the Double-crested Cormorant population will also begin to fade, as the big birds once again serve as a barometer of Man's ravages to our ecosystems.