Parasitic Jaeger at Lake McConaughy

• Main Authors: Dinsmore, Stephen J, Silcock, W. Ross
• Format: Text
• Language: unknown
• Published: DigitalCommons@University of Nebraska - Lincoln 1998
• Subjects: Poultry or Avian Science; Zoology; Sullivan; Parasitic Jaeger; Pomarine Jaeger; Sabine's Gull
• Online Access: https://digitalcommons.unl.edu/nebbirdrev/204; https://digitalcommons.unl.edu/context/nebbirdrev/article/1203/viewcontent/Nebraska_Bird_Review_66_4_Dec_1998_Parasitic_Jaeger_at_Lake_McConaughy_p114_115.pdf

On 5 October, 1997, we joined Joel G. Jorgensen and John Sullivan for a pelagic trip on Lake McConaughy. A similar trip in late September 1996 yielded a Sabine's Gull, but we were really hoping to see a jaeger. From 7:00 to 8:30 a.m. we gradually worked our way from the dam towards the western end of the lake. Besides moderate numbers of Franklin's and Ring-billed Gulls, there were few birds on the lake. At approximately 8:45 a.m. Dinsmore noticed that all of the gulls at the western end of the lake had suddenly taken flight. Less than a minute later, we simultaneously spotted a jaeger soaring directly overhead. The size, dark coloration, and prominent white flashes in the Wings identified the bird as a jaeger. The bird made a couple of attacks on Franklin Gulls and then flew east down the lake. We chased the jaeger for more than ten miles before losing it. We relocated the bird a short time later just above the dam. This time, the bird attacked a couple of Ring-billed Gulls before flying west up the lake. We again took chase, but lost the bird before reaching Lemoyne. The gull-like shape, generally brown coloration, and prominent white bases to the primaries identified the bird as a jaeger. The bird was smaller but longer-winged than a Ring-billed Gull and larger and slimmer than a Franklin's Gull. The overall coloration was dark brown, except for some warmer rufous tones on the underparts. We saw no visible barring on the underparts. The bill was straight and slender, but the color pattern was not noted. The upperwing was dark brown except for white at the base of at least the outermost four primaries. The underwing was also dark except for a prominent white area on the undersides of the bases of the primaries. The rectrices were dark and the central feathers were slightly elongated with pointed tips. We all agreed on the identification as a juvenile Parasitic Jaeger. Careful size comparisons to Franklin and Ring-billed Gulls eliminated juvenile Pomarine Jaeger, which also generally shows more white color on ...