Bewick's Swan: An Ohio First

 

A quintet of Tundra Swans (Cygnus columbianus) prepares for landing.

I attended the annual Ohio Bluebird Society's annual meeting last Saturday, March 2, to speak about moths. Little known fact: The majority of the Eastern Bluebird's non-winter diet is moth caterpillars. Shauna and I had a great time, met lots of people, and I saw scads of friends that I haven't seen in a while. The Society is quite active and about 140 people were in attendance.

Afterwards, Shauna and I took the long way home, in order to visit Killbuck Marsh - one of the largest interior wetland complexes in Ohio. Killbuck lures scads of migratory waterfowl in spring, including large flocks of Tundra Swans (Cygnus columbianus). On February 23, Josh Yoder located a "Bewick's" Swan in a large flock of Tundra Swans, and I'd wanted to get up there to see it ever since. That bird was our primary target on this trip, and it wasn't hard to find, especially as many birders were on the scene.

The Bewick's Swan is now (mostly) considered to be a subspecies of the Tundra Swan (Cygnus columbianus bewickii). However, it has been considered a separate species in the past, and the American Ornithological Union didn't lump it into the Tundra Swan until 1983. While most authorities dealing with avian nomenclature and taxonomy consider it to be a subspecies at present, Avibase separates the two.

A pair of Tundra Swans drops in, landing gear extended. Don't expect National Geo-caliber imagery in this post. The flock of Tundra Swans that our target fraternized with was a LONG way across the marsh. Maybe 200 yards or so, so it took some photographic oomph to even get the documentary shots that I did. I used my Canon 800mm coupled with a 1.4x extender (1120mm) and that's generally not the ticket for sharp vibrant shots on a heavily overcast day. Nonetheless, the rig did allow me to capture diagnostic details of the bird in question.

As always, click the photo to enlarge

As a point of comparison for the bird to follow, here's the nominate subspecies of Tundra Swan - the subspecies that occupies North America and occurs in Ohio during migratory periods. That's an adult on the left, with a juvenile facing away from the camera. Note the classic small yellow teardrop on the bill, in front of the eye. While some individuals can have all black bills, a little fleck of yellow as on this bird is pretty typical.

One of these swans is not like the other. Specifically, the bird second from right. Even from afar, the big yellow blotch on the bill stands out. A typical Tundra Swan shouldn't (couldn't?) ever show that much yellow.

Here's the range map of the Tundra Swan, courtesy of the Cornell Lab of Ornithology Birds of the World website (I'm a longtime subscriber, and anyone with a serious interest in birds should consider a subscription, found HERE).

For the most part, all of the birds represented in America are Tundra Swans, and those in Eurasia are Bewick's Swans. A rub: The nominate subspecies of Tundra Swan (the North American birds) also breed in eastern Siberia, and hybridization between the two subspecies occurs there.

Here's the best that I could do to photographically capture the Ohio Bewick's Swan. While that big splotch of yellow exceeds anything that could, or at least should, be present on a Tundra Swan, classic Bewick's Swans can show even more yellow. On some/many/most Bewick's, that yellow forms an even larger blotch, and can extend across the top of the bill to connect the two side patches. Whether the yellow marks increase in size with age, I do not know.

Here is a germane quote from the Bird's of the World Tundra Swan account:

Birds appearing identical to the Palearctic form (C. c. bewickii) reported occasionally in w. North America (Alaska, Alberta, Saskatchewan, Oregon, and California). Some of these are likely true bewickii, but others may be bewickii x columbianus intergrades from e. Siberia, or even variants of columbianus with excess yellow on the bill. The occasional bewickii reported farther east in North America may represent escapees from captivity.

To address the latter point about escapees: While many species of waterfowl are kept - sometimes fairly commonly - in captivity, and occasionally escape, I don't think that's the case here. A search, less than comprehensive, admittedly, for Bewick's Swans for sale revealed nearly no sellers, and I've not personally heard of this subspecies being peddled by waterfowlers, at least in this part of the world. Also, the appearance of the Ohio bird syncs perfectly with the major northward push of Tundra Swans, and it is fraternizing with them. Presumably a wayward Bewick's Swan, prone to vagrancy, would also wander at this time of year. And more records have occurred in the east since that quoted paragraph above was written. eBird records about a dozen records to date from the eastern U.S. and Canada.

The bigger question involves hybridization between the subspecies, and definitively answering that is well beyond my paygrade. While I've seen many thousands of the nominate Tundra Swan subspecies, I've got next to no experience with Bewick's Swan. I think it would be very helpful to get images of this bird to someone who sees lots of Bewick's Swans and understands their variability, and especially the appearance of hybrids between the subspecies.

NOTE: It is always helpful to remember that "species" are merely a human compartmentalization scheme. All species are in a constant state of evolution and where one draws the line of separation between two very similar "species" or especially "subspecies" is almost always somewhat arbitrary.

Any way one slices this swan, it was a great find by Josh Yoder, and the bird offers interesting food for thought, in addition to its undeniable curb appeal. It is an apparent first state record for Ohio, and one of very few reports anywhere in eastern North America.

Nature: Giant swans make yearly visit on long migration

A pair of adult tundra swans against a frosty November sky/Jim McCormac

Columbus Dispatch

December 3, 2018

NATURE

Jim McCormac

Like avian clockwork, the first icy northern winds of late November and early December sweep in flocks of migratory tundra swans. The exuberant war-whoop calls of flocks high aloft evokes a sense of untamed wilderness and sparks the listener to scan the ether seeking the source.

Eventually the giant birds materialize; glimmering flecks of ivory shimmering in V-formation.

A tundra swan is massive. Measuring nearly 4½ feet in length, with a wingspan pushing 7 feet, a well-fed male (males are slightly larger than females) can weigh 23 pounds.

By comparison, a bald eagle averages about 2½ feet in length and weighs 10 pounds, although the wingspan is about the same. Trivia: It would take over 3,000 ruby-throated hummingbirds to equal the mass of a big tundra swan.

On a recent trip to the former Sandusky Plains of north-central Ohio, I encountered hundreds of swans. Flocks were plentiful in the collective 15,000 acres of Big Island and Killdeer Plains wildlife areas, and in flooded fields between these sites.

The two wildlife areas are about all that’s left of the wetlands of the Sandusky Plains. The former wet-prairie region once blanketed much of Crawford, Marion and Wyandot counties, but nearly all of its rich soil has been converted to beans, corn and wheat.

Nonetheless, ancestral instinct is strong and the swans still use the Sandusky Plains as a migratory way station, in spite of the prairie largely being swept away in the past century or so.

The giant birds are an on epic journey. Well-named tundra swans breed in the Arctic, the nearest nesters at least 1,100 miles to our north. Some that pass through Ohio might have bred over 2,000 miles north — nearly the distance from Columbus to Los Angeles.

Most of the swans that visit Ohio will travel to coastal areas along the eastern seaboard, mostly from New Jersey to the Carolinas. In total, these powerful flyers will have made a one-way flight of up to 2,500 miles.

Many of the swans that I observed were family units: snowy white adults accompanying dusky-necked juveniles. The youngsters must be shown the migratory ropes. Unlike many songbirds, which have built-in GPS and can make inaugural migrations unaided, swan cygnets require coaching. The adults remain with their offspring until they return to tundra nesting grounds the following spring. By then, migratory corridors are firmly stamped into the youngsters.

Tundra swans commence breeding when they are 2 to 3 years old. Once a pair bond is established the swans remain monogamous, although new mates might be taken if one of the pair dies. These relationships can be long-lived. The oldest documented wild tundra swan was nearly 24 years old, a female that was banded and later recaptured in Ohio.

Lewis and Clark first described the tundra swan on their western expedition of 1804-06. Struck by the peculiar fluting hum created by the swan’s wings in flight, they dubbed this species the “whistling swan.”

That charismatic name stuck until 1982, when ornithologists rebranded it. The scientific name, Cygnus columbianus, remains, the specific epithet recognizing the Columbia River of the Pacific Northwest, where Lewis and Clark’s team obtained the first specimen.

White swans, swirling in like giant snowflakes on Arctic breezes, serve as elegant reminders of a natural world that doesn’t recognize political boundaries.

Naturalist Jim McCormac writes a column for The Dispatch on the first, third and fifth Sundays of the month. He also writes about nature at www.jimmccormac.blogspot.com.