ML129508081

Age and sex

Unknown age, Male - X

Media notes

Despite the unlikely location, this male Mallard appears to show characters suggestive of a Mexican Duck given the female-like plumage combined with an entirely greenish-yellow bill. The dark uppertail coverts and upward curl to the central rectrices may suggest hybridization with Mallard, but it appears that some young male Mexican Ducks also show this character. Photograph taken by Curtis A. Marantz along San Luis Obispo Creek in downtown San Luis Obispo, San Luis Obispo County, California.

Observation details

While wandering down the trail along the creek just below the mission I happened to look down to see four Mallards in the creek. Three of these birds looked like typical female Mallards, but the fourth bird stood out conspicuously as a result of its female-like plumage combined with an unmarked, greenish-yellow bill that was like that of an adult male Mallard despite the female-like plumage. Although I must admit that I did not spend an extended period of time studying this bird, I did make sure to take several photos before continuing on my way. To my eye, this bird appeared similar to the female Mallards in its overall size and shape given a short and relatively stout bill with a blunt tip, a sloping forehead and a rounded crown on a head that was unremarkable in size for a dabbling duck, a medium-length neck, a plump body that sat high in the water, and a short tail and wings that appeared to be short when held closed. I never saw the legs or feet and I never saw the spread wing on a bird that was seen exclusively as it swam at the surface and picked at various items. My impression was that this bird’s plumage looked much like that of the female Mallards. I noted that the forehead and crown, back at least to the nape, were dusky in color and seemingly without any suggestion of green iridescence. Contrasting with the dark cap was a pale buff face that seemed to have some fine streaking, but I do not think this bird had as conspicuous an eyeline as did the female Mallards. The pale color of the face also appeared to extend at least a short way down the sides and front of the neck, but I think the breast was dark (though I cannot now remember its pattern). What I did note was that the body was boldly marked with wavy bands of dusky-brown on a paler and more reddish to cinnamon background. To me the pattern looked similar to that of a female Mallard, but this bird may have been slightly darker overall, and my impression was that the dark brown and paler bands were of roughly equal width. I was also confident that each feather had at least one (and possibly more than one) internal band, so the pattern was unlike the coarse scaling of an American Black Duck. I did not note obvious white edges to the tail, but I also cannot be sure that they were lacking, and I never saw the speculum even though I thought the inner tertials were dark brown and seemingly unmarked. I looked briefly at the base of the tail and was pretty sure that both the uppertail and undertail coverts were dark brown as opposed to black or even blackish. Something that is visible in my photos, but which I did not notice in the field was that the distal uppertail-coverts curved upward but they did not appear to loop back down. As noted above, the first thing that drew my attention to this bird was the clear, greenish-yellow color of a bill that a dark saddle on the upper mandible. I thought the eyes were dark, but I did not check them all that carefully, and I never saw this bird’s legs or feet.

Technical information

Model

Canon EOS 7D Mark II

Lens

EF100-400mm f/4.5-5.6L IS II USM

ISO

1600

Focal length

214 mm

Flash

Flash did not fire, auto

f-stop

f/6.3

Shutter speed

0.01 sec

Dimensions

4457 pixels x 2741 pixels

Original file size

9.57 MB