The differences in Juvenile Pomerine and Parasitic Jaegers can be difficult to discern but I believe that if you are looking at a fairly close photo of the two you should be able to make the proper identification. While I was at Wisconsin Point there was debate about the juvenile birds that we were looking at. I later took a look at the photos that another birder was kind enough to send to me and found that we had seen all three species. The consensus that morning was that we were seeing the adult Long-tailed Jaeger and the juvenile Pomerine over and over but I had my doubts about this and photos confirmed my doubts. I studied the Peterson Advanced birding guide and many photos taken from coastal pelagic trips along with photos from fellow Minnesota birders. Here is what I found: One aspect that seems to be little talked about between the two is the head size. The Pomarine has a noticeably larger head that bulges out past the wings and I think this can be one of the better characteristics. In direct comparison this can be quite noticeable and the most recent posted photos of the Parasitic show this quite well (it has a relatively small head). Pomarines have a much more noticeable bi-colored bill than a Parasitic although both can show this characteristic. Even in poor light the Pomarines bill should typically show bi-colored when a Parasitic's bill may appear black. The barring on the Pomarine is more distinct. There is barring on the Parasitic but it is more even throughout the underwing and far less contrasting on the undertail coverts. The Pomarine typically has an almost black and white contrast where the Parasitic will have a more light brown to cinnamon and black contrast. The Parasitic usually has more cinnamon coloring and the coloring is less contrasting and more uniform than the Pomarine. Both seem to have darker heads than bodies. Pomarines may have a dark brown coloration but it does not have the warm tone of the Parasitic. Wing size can be subtle but the Pomarine has a chunkier wing more reminiscent of a skua and I find that the white wing patch is slightly more elongated on the Parasitic (this would be hard to analyze unless there was a direct photo comparison). Unfortunately since I did not know which was the Pomarine and which was the Parasitic when I was actually looking at the birds I can not comment on flight style. All of the juvenile birds to me looked to be about the size of an adult Ring-billed Gull or slightly smaller (I had fantastic side by side views of this on multiple occasions). One aspect that I think can sometimes be misleading is the tail extension. On an obvious individual the sharper tail extension can be very useful for the Parasitic but I found that in many photos it was difficult to tell if there was a small rounded extension or a slightly longer pointed extension. Because of this I found that if the bird has a short tail extension the photo needs to be extremely close and at the correct angle to make the distinction between the two and could lead a person in the wrong direction if this is used for identification without looking at all other characteristics. Another photo that to me looks like a Parasitic and not a Pomarine is the juvenile bird that Erik Bruhnke posted on 10/15/10. The bottom photo I believe to be a Parasitic based on the above observations but this analysis could be wrong. I do not pretend to be an expert on the above species and these are just personal observations. As with any of the more difficult species it is best to look at a combination of characteristics. Just the fact that that we are able to analyze all three species in detail is a great experience and shows how fun and challenging birding can be! Any comments are appreciated. Thanks, Jason Caddy South Minneapolis [email protected] ---- Join or Leave mou-net: http://lists.umn.edu/cgi-bin/wa?SUBED1=mou-net Archives: http://lists.umn.edu/archives/mou-net.html
