ML354322721

Age

Not specified

Sex

Not specified

Behaviors

Flying

Media notes

The first of three dark-rumped Leach's Storm-Petrels seen in the southwestern corner of San Diego County waters photographed by Curtis A. Marantz at 9:15 am on 11 July 2021 over offshore waters approximately 53¼ kilometers west-southwest of Point Loma [32° 37’ 47” N, 117° 48’ 23” W], San Diego County, California.

Observation details

Three additional Leach’s Storm-Petrels were all dark-rumped birds that presumably represented O. l. chapmani, but with one of these birds having a somewhat darker rump than the other two. All three dark-rumped Leach’s Storm-Petrels were seen in the same general area as the white-rumped bird, and the first of these birds was seen at the same time as the white-rumped bird approximately 53¼ kilometers west-southwest of Point Loma at 32° 37’ 47” N, 117° 48’ 23” W. The other two were seen approximately 52¾ kilometers west-southwest of Point Loma at 32° 37’ 53” N, 117° 48’ 14” W, and approximately 52½ kilometers west-southwest of Point Loma at 32° 37’ 59” N, 117° 48’ 04” W. All three dark-rumped birds appeared relatively similar to one another, in that all three were somewhat smaller than the Black Storm-Petrels that we had been seeing, with one or two seen in direct comparison with Black Storm-Petrels, and with the first of the three seen in direct comparison with the white-rumped Leach’s Storm-Petrel. Further apparent was the different flight by these birds relative to that of the Black Storm-Petrels seen under similar conditions, with these birds having a more bounding and buoyant flight that gave them a different appearance despite their relatively similar coloration. I thought these birds had shorter tails than the Black Storm-Petrels, yet they had relatively long wings that tapered to pointed tips, and they flew with relatively deep wingbeats. Although these birds were almost entirely dark, they did not appear to be quite as black as the Black Storm-Petrels, with at least one or two birds clearly having a more grayish cast to the back and paler underparts. All three birds had relatively bold carpal-bars that were buffy to light gray in color, and all three had some suggestion of a paler rump. Two of the dark-rumped birds had rounded spots of white on either side of the rump just behind the wings that were relatively conspicuous and contrasting with a rather dark, grayish rump, but the third bird had an even darker rump and very little paler coloration on either side. My photos also show that these birds all lacked the paler band across the tips of the primary coverts that is often shown by Black Storm-Petrels, and that they had dark eyes and a short and relatively slim bill that was black in color, all of which I likely saw but failed to notice in the field, and photos of at least one of these birds show a moderate notch to the tail.

Technical information

Model

Canon EOS 7D Mark II

Lens

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

ISO

500

Focal length

400 mm

Flash

Flash did not fire

f-stop

f/8.0

Shutter speed

1/1250 sec

Dimensions

1749 pixels x 1189 pixels

Original file size

2.58 MB