Salton Sea Trumpeter Swan?

Continuing in the tradition of stumbling across some pretty cool rarities like a Nutting's Flycatcher in Arizona, a Common Cuckoo in downtown Watsonville, and a Magnificent Frigatebird over San Diego Bay, SDVO traveled to the Salton Sea over the weekend with some other hardy souls from Palomar Audubon Society with nothing in mind but a nice birding weekend with nice folks, and lots and lots of regular old birds.

Now, this trip had been in the works for weeks.  But when we left San Diego on Friday morning, there was some new chatter on the web about a Tundra Swan at Unit 1 of the Sonny Bono NWR.

Not fantastic, but a Tundra Swan would have been a county and year bird for us.

But by the time we got out to Unit 1 on Saturday morning and ran into Howard King and Curtis Marantz, the bird had been seen by Guy McKaskie, had had its mug shot passed around back east by Paul Lehman, and had morphed into a very likely Trumpeter Swan.

So what?  Well, the status of the Trumpeter Swan in California has long been a matter of considerable controversy.  In the late 1990s The Trumpeter Swan Society had suggested that as many as 200 birds may regularly winter in California. However, the only firm evidence was a mere 21 accepted records out of a total of 58 sightings reviewed by the California Bird Records Committee.  (As of writing date, sightings reviewed by CBRC has soared to a whopping 67.  And none of those birds reviewed were supposedly seen in Imperial County.)

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While we wait for the CBRC to annoint this bird (or not), here's what we know:

This bird has been in this area since at least 12-Jan-2013 when the San Bernardino Valley Audubon Goose and Crane trip tentatively listed it as a juvenile Tundra Swan, and when other listers posted it to eBird as a juvenile Trumpeter.

This large single bird was pointed out to us by Howard King and Curtis Marantz when the PAS group was headed back out of Unit 1. When King and Marantz first re-found it a few minutes earlier, it was in a large group of Snow Geese. However, by the time we arrived on the scene it was already standing alone in a field on the east side of Vendel Road about 0.80 miles south of the Unit 1 observation tower.

We studied the bird for about 10-15 minutes, but it never took wing while we were there. Nor did we get to hear it vocalize.

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As the Trumpeter Swan Society (HQ'ed in Plymouth, Minnesota) notes, there are three species of swans ordinarily found in North America. The Trumpeter Swan (Cygnus buccinator) and Tundra Swan (C. columbianus) are indigenous, while the Mute Swan (Cygnus olor) is a Eurasian species that has been introduced and now breeds in the wild in some areas. All three are very large all-white birds.

The bird was clearly a swan. Mute Swans are easily distinguished by the bright orange bill and distinctive knob on the forehead. The all black bill, and smoothly wedge-shaped head/bill, eliminates the Mute as a possibility here. (Mute Swans are easily distinguished by a bright orange bill and a distinctive 'knob' on the forehead.)

Trumpeters and Tundras are similar looking species that are more difficult to identify. Moreover, Trumpeters often mix with flocks of the relatively more common Tundra Swan throughout their migration and winter range. Distinguishing Trumpeters from Tundras is not easy, but it is possible by paying close attention to a few distinctive characteristics.

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While our light was poor, the swan's plumage appeared mostly white underneath, and mostly gray-brown on the upper areas (albeit with some lighter areas on the back and wings).

The head/bill was wedge-shaped. The bill appeared all black, but the distance (~0.253 km) and poor light made it difficult to see a lot of detail. However, we noted no red border on the lower mandible (but the red border may be present on some Tundras as well). We also saw no yellow spot in front of this bird's eye (but this tell-tale spot maybe absent on some Tundras).

The bird's neck appeared to rise from the forepart of the back, rather than from the front of the body as with Tundra Swans.

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Guy McCaskie and Matt Sadowski also re-found the swan the previous day, and got to see it fly. (Since Trumpeters usually hold their necks differently from Tundras during takeoff, it would be interesting to know if Guy and Matt noted any tendency of the bird to pull its neck into a shallow S-curve during its first few wing beats.)

Guy has reported it as a Trumpeter tenatively, and notes that "Steven Mlodinow and Bill Tweit, far more familiar with the separation of Trumpeter and Tundra swans than [Guy], have looked at photos of this swan and concluded it is a Trumpeter Swan."