At 8:01am looking west with my binoculars from the Plum Hills parking pull off I picked up a single dark bird at considerable distance harassing a flock of 50-100 Herring, Laughing, Ring-billed and Great Black-backed Gulls that were actively feeding over the channel east of Clark's Island. The tide was unusually low (-1.8ft) due to the lunar cycle and so the rest of the bay was essentially mudflat. My immediate thought was a Peregrine as one has been around intermittently during the summer. I put the scope on the flock for a better look and picked up a second bird engaged in aerobatic jousting with one of the smaller gulls, but more importantly realized that it was not a Peregrine but a dark jaeger! I only had them for a few exhilarating seconds and they were gone (or at least I lost them).

About 5 minutes later I spotted a small group of gull-sized dark birds on the mud about 300 yds south of where I'd seen the aerial show. Hoping for large shorebirds I got my scope on them and realized that were not large shorebirds and thought perhaps juvenile Laughing Gulls. But that didn't feel right either so I started taking photos with my 400mm lens hoping to get enough pixels so that when enlarged the images would clear things up. As I took the shots I remembered the dark jaegers seen a few minutes earlier and realized that this could well be a group of 5 jaegers! I began clicking off photos hoping to get enough detail to confirm and if possible determine which species they were.

The distance was great and the light very poor, yet the images confirm that these were definitely Jaegers, but when it comes to determining which species, someone more expert than I will have to make the call if there's enough in the poor photos to enable it! The following photos show the sequence of the birds on the flat and then rising up to fly off to wherever was next - perhaps Plymouth Beach? I see no dark caps on the lighter individuals and so surmise that these are sub-adults. The lighter birds show a bulky belly and in a couple of cases zooming on the images seems to show a short pointed tail like that of a Parasitic. The 3rd photo (of all 5 in flight) leads me to conclude that two are dark phase or intermediate birds and three are light phase.
I have consulted several books for help in sorting these out, and after reading the incredibly informative chapter on the Jaegers in Kenn Kaufman's Field Guide to Advanced Birding I'm convinced there's no way to be certain about these birds beyond a reasonable doubt - at least based on what I can see in these photos. For what it’s worth, however, my gut says that if they are all the same species they are most likely Parasitics, because (1) when dogfighting with the gulls both birds seemed no bigger than the Laughing Gulls, (2) they don't have a the bulky feel the books attribute to the Pomarine, (3) when a couple of the blurry photos are zoomed to the max, the tail on one of the birds seems short and pointed, and (4) in this region they are much more likely to be seen this close the mainland.
Officially, though, I'm reporting Jaeger (species).