Arctic Tern (Sterna paradisaea) at Potter's Marsh on the outskirts of Anchorage. Photograph copyright of Angus Wilson©.
During the late morning we ran up against a long column of migrating Short-tailed Shearwaters, moving NNW at the phenomenal rate of 500 or so per minute!!! The column of birds streched from horizon to horizon and showed no signs of slowing up. They may have been following the 'Alaskan Stream Current'. As we were to discover during the next day, this was just a small part of their phenomenal globe-spanning migration. An abundant breeder around Southern Australia, Tasmania and New Zealand, the majority of the world's population spend the northern summer on rich feeding grounds around the Aleutian Islands and within Bering Sea as far as the permanent ice. We remained with the shearwaters for about thirty minutes and then veered northwest towards the Aleut fishing community of Sand Point, and rounded the north end of Unga Island where we found our first Aleutian Terns and Tony spotted an adult Common Black-Headed Gull.
We landed at Unga Spit where the remains of a petrified forest lay exposed on the sandy shore. As we clambered out of our life jackets Andy suggested keeping an eye out for shorebirds along the beach, and within a few seconds we discovered a beautiful female MONGOLIAN PLOVER feeding amongst the dried kelp and driftwood of the wrack line. The whole shore party, birders and non-birders alike, had a chance to view the bird through a battery of telescopes at a distance of 50 meters or so. For the most part the bird feed in a typical plover manner, taking a few short steps and peering ahead, sometimes tilting its head to look more closely with one eye. A couple of times it crouched down amongst the debris to snooze for a few minutes before starting to hunt again. The whole time we were on the island, the plover kept to a fairly small feeding territory, only flying a short distance onto some freshly exposed mud moments before we returned to the ship. The plover was also very confiding, allowing several of us to crawl up relatively close to take photographs without interrupting its feeding.
A female Mongolian Plover (Charadrius mongolus) peeking over a sand bar at the prostrate photographer. Taken on Unga Spit in the eastern Aleutians. Photograph copyright of Angus Wilson©.
Not to be out done, Dick and John pushed further along the beach and soon found a pair of adult KAMCHATKA GULLS standing on the water's edge. This distinctive form is considered a mere eastern Asiatic race of the Mew Gull; a species found throughout the Holarctic Region. In the flesh, Larus canus kamtschatschensis differs rather strikingly from both L. c. brachyrhynchus found in Alaska and western North America, and nominate L. canus canus of western Europe. Although their was a clear size difference between the two birds (presumably male and female) both resembled Ringed-billed Gull rather than Mew Gull in stature and bulk. The lemon yellow bills were unmarked and appeared heavier than in typical Mew Gulls. Both birds showed an fairly obvious pale straw-yellow iris - in stark contrast to the dark eyes of the adult Mew Gulls we had been watching in Anchorage. A couple of times the birds faced each other and made a brief display or head raising suggesting that the may attempt breeding in the area. As we understand it, there are few well documented records from North America and do not as yet know whether breeding has been documented. It is difficult to comment on the mantle color without birds to compare with but we did notice an obvious difference from the general shade seen on Anchorage Mew Gulls.
A small stream ran across the beach attracting ten or so adult Least Sandpipers and a pair of displaying Semipalmated Plovers. In an attempt to pick up some passerines, we followed the stream gully which was lined with short willows, catching brief glimpses of a male Aleutian Green-winged Teal and a Bank Swallow (a.k.a Sand Martin). Although we couldn't find any notable passerines along the stream, we managed to flush a male Willow Ptarmigan, which displayed angrily for us at close range while a pair of Parasitic Jaeger coursed over the Lapland Longspur-filled tundra. Mary Jean Hage spotted two unidentified swans land some way ahead of us, but there was not enough time to search them out.
Early moring in the Aleutians. Photograph copyright of Angus Wilson©.
Later in the day we made a landing near Cape Pankof at the southeastern end of Unimak, the largest island of the Aleutian Chain. A strenuous hike produced typical tundra species such as Rock Sandpipers (the race Calidris ptilocnemis coesi), Lapland Longspurs, Buff-bellied Pipits, Song Sparrows (along small watercourses) and Gray-crowned Rosyfinches. Given the rugged topography, the four of us split up so that we could check an interesting looking freshwater lake to the north and a fairly birdy saltwater lagoon to the northwest, each being a couple of miles from the landing site. Unfortunately over this rough and hilly terrain and with very limited time, neither could be reached properly and we were forced to scan from a distance. The freshwater lake produced a few Greater Scaup and Bald Eagles but could easily have held more surprises. The salt water bay and adjacent lagoon had several Kittlitz's and Marbled Murrelets, two Pacific Loons, more scaup and a number of other unidentified waterbirds. Luckily we encountered no bears on this exposed landscape but did flush a Red Fox that scampered along a well worn trail before vanishing into the tundra.
During the latter part of the day and evening we sailed through the Unimak Pass, a broad channel connecting the Bering Sea with the Pacific. This is one of the eastern most breaks in the Aleutian Chain and provides a migratory corridor for large numbers of seabirds. Entering the pass, we again hit the stream of Short-tailed Shearwaters that we had seen the day before south of Unga Island. For several hours we ran alongside this incredible column of shearwaters passing at a rate of 500-800 per minute (conservative but careful estimate). Once again, the line of birds stretched from horizon to horizon. In fact, there seemed to be additional parallel lines of birds further to the east and west, doubling or tripling the numbers. A couple of times the ship tried to cross the stream of birds, but on each occasion the river of shearwaters snaked away from us keeping a safe distance, while birds coming up on the rear would cut across the stern to reestablish the path. The vast majority of the Short-tailed Shearwaters were heavily worn and showed an extensive off-white strip along the top surface of the wing produced by the exposed bases of the flight feathers. Somewhat confusingly, most of the birds showed an extensive dull grey wash to the underwing, suggesting the broad silvery underwing patches of Sooty Shearwaters. We were later to notice good numbers of fresh plumaged birds once we were in the Bering Sea itself - perhaps nonbreeders that had already had sufficient time to molt?
Hundreds of thousands of Short-tailed Shearwaters (Puffinus tenuirostris) and Sooty Shearwaters (Puffinus griseus) pass through the narrow breaks in the central and eastern Aleutians to reach their feeding and molting grounds in the Bering Sea. Photograph copyright of Angus Wilson©.
Much smaller numbers of Sooty Shearwaters were mixed in with the Short-tails, allowing extremely useful direct comparison. The Sooties could be distinguished by their slightly larger size, slower and less flicky wingbeats, and lack of a dark-capped appearance - the size and shape of the pale underwing coverts being less useful given the very worn state of the Short-tails. We also observed huge numbers of Red Phalaropes, often in flocks of hundreds. Dwarfing the shearwaters, our first Laysan Albatross of the trip lumbered purposefully along the portside, seeming to ignore the ship altogether. Mixed in with this mass tubenose migration were 8 Aleutian Terns, 15 immaculate adult Sabine's Gulls (groups of 5, 4 and 6) and a distant pod of Orca. The awe-inspiring spectacle continued for more than four and a half hours until our pre-plotted course pulled us slowly away from the river of birds. In this period alone we must easily have seen a quarter of a million Short-tailed Shearwaters and nearly eight thousand Red Phalarope.
Pacific-race of Northern Fulmar. Photograph copyright of Angus Wilson©.
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