ML129056891

Age

Not specified

Sex

Not specified

Observation details

Viewed with scopes from the beach at parking lot #3 from about 08:30 until about 14:00, and in view much of that time at distances over 400m to closer than 50m. We concluded at the time this bird was a dark juvenile Pomarine Jaeger, and photos later confirmed this, in my opinion. There was a group of birders at lot #1 (some 200m to the SE) concurrently, but we did not converse with them during the observation. I understand that there was some discussion regarding the ID (POJA vs PAJA), but I feel the evidence is strong for Pomarine: 1. Central pair of rectrices (R1) extended beyond the rest of the tail about 1 cm and were blunt, rounded (shaped like a thumb tip); this was noted repeatedly in the field and confirmed in several photos. 2. Outer primaries at rest were solid dark blackish brown, lacking any hint of pale fringes that characterize juvenile Parasitics. 3. At least as big in dimensions (wing span, length) as Ring-billed Gulls but bulkier, heavier. Flight was powerful and gull like; wings seemed broad at base. Bigger and thicker than adult Parasitics, seen in close proximity several times. 4. Behavior: the Ring-billed Gulls (RBGU) were frightened of this bird. It typically rested offshore several hundred meters and periodically would fly, often beachward. Virtually as soon as it left the water, dozens to hundreds of RBGUs even hundreds of meters away would immediately take flight. We witnessed this dozens of times. Two adult Parasitics that periodically passed near the gulls did not elicit this mass panic reaction, although the PAJAs did chase RBGUs. Several times we saw the Pomarine attack a RBGU from above, striking it and physically driving the gull into the water. This bird was mean and relentless in its attacks on the RBGUs. 5. Both upper and lower tail coverts were strongly, distinctly barred (dark brown and tan dorsally, creamy and dark brown ventrally). 6. Although we looked for the underwing “double flash” in the field, it was not evident. However, photos confirm that it was present (paler bases of the ventral primary coverts). In some photos the double flash is evident, less so in others. Ventral secondary coverts were paler than body. 7. Overall coloration was dark brown to gray brown, lacking cinnamon buff feather edges; nape was a bit paler brown, face was blackish brown right to the bill margin. Bill was distinctly two-toned, blackish from just anterior to nostril to tip, pale proximally.

Technical information

Model

NIKON D7000

ISO

800

Focal length

400 mm

Flash

Flash did not fire, auto

f-stop

f/10.0

Shutter speed

1/3200 sec

Dimensions

801 pixels x 784 pixels

Original file size

318.1 KB