ML474337751

Age

Not specified

Sex

Not specified

Observation details

***First ever hybrid combination, not supported in eBird taxonomy: White-rumped Sandpiper x Semipalmated Sandpiper (hybrid). First seen through the windshield of the car at a distance of ~50 meters, thought to be a weirdly plumaged White-rumped Sandpiper (WRSA). When we got closer to the flock, there was a normal WRSA in the location, and so we wrote it off as a WRSA. 15 minutes later we saw the bird again at point blank range, and immediately knew it was a hybrid of some sort. The bird overall feels structurally similar to a WRSA, but with plumage mostly that of a Semipalmated Sandpiper (SESA). Key structural elements Size is similar to a WRSA (larger than SESA, almost the size of a Sanderling), with long wings creating a slim attenuated appearance at the rear of the bird. Beak heftier than a SESA, especially thick at base (structured more like WRSA). Webbing between base of toes absent, as in WRSA, as opposed to the partial webbing (semi-palmation) of a SESA. Key plumage elements Overall plumage patterning and coloration quite similar to SESA: pale gray background overall; pure white flanks (which would show some form of streaking in any plumage of WRSA); retained back feathers from breeding plumage similar to SESA. Rump intermediate between SESA and WRSA: SESA normally has a fully dark rump from the tail to the back, and WRSA has a broad white rump—this bird has a thin line of white bisecting a dark rump, and white mottling in the remaining dark. Key behavioral elements One of the strong supporting characters for SESA parentage to me is the 'rear-up aggressive' posture that's shown in ML474337711, where the bird gives a chatter call and tilts up like this. This bird was doing that regularly. The combination of intermediate elements between these two species supports the identification of the first ever White-rumped Sandpiper x Semipalmated Sandpiper (hybrid). White-rumped Sandpiper hybrids have been documented with Dunlin and Buff-breasted Sandpiper before. To my knowledge this is the first ever hybridization documented for Semipalmated Sandpiper with any other species.

Technical information

Model

Canon EOS R5

Lens

RF100-500mm F4.5-7.1 L IS USM

ISO

800

Focal length

500 mm

Flash

Flash did not fire

f-stop

f/7.1

Shutter speed

1/2500 sec

Dimensions

2621 pixels x 1650 pixels

Original file size

2.62 MB