Those who closely follow recent conservation measures in the United States may have already heard about the historic reintroduction of the Millerbird to Laysan, an island in the northwest Hawaiian archipelago. But for many birders, this obscure Old World warbler is probably unfamiliar–the only member of its family endemic to Hawaii. In this article, we follow two eBirders–Cameron Rutt and Robby Kohley–as they provide a glimpse of the abundance of bird life that surrounds the Millerbird on its new-found home. For more information on the Millerbird, including the first successful fledgling (!), please visit see this website. Many thanks to Cameron for providing this exciting account of their visit to Laysan, the vagrants they found and documented, and how they used eBird to quantify the abundance of seabirds and other specialties on this remote Pacific island.
From Cameron Rutt:
As contractors for the American Bird Conservancy (ABC), the two of us were charged with spending the winter on Laysan, located in the northwestern Hawaiian Islands – an enviable or unenviable task, depending upon whom you might ask. Situated just north of the tropics, Laysan is on latitudinal par with the southern tip of Texas and longitudinally a straight shot south from Alaska’s Pribilof Islands. Laysan is not only remote, it is tiny, just over 8.5 kilometers (5 miles) in circumference, for a total area of only 414 hectares (1.4 square miles). It is a flat (maximum elevation, 15 meters (49 feet) above sea level), sandy island, with a hypersaline lake occupying a good chunk of the island’s interior.
ABC and the U.S. Fish and Wildlife Service combined forces for the translocation of Millerbirds (Acrocephalus familiaris) from Nihoa to Laysan, a distance of 1047 kilometers (628 miles). The critically endangered Millerbird once existed on Laysan, until rabbits were introduced just after the turn of the twentieth century. By 1923, the rabbits had already taken over the island and had nearly denuded it of vegetation. This devastation took with it the Laysan Rail, an endemic subspecies of the Apapane, and the nominate subspecies of Millerbird–all now extinct. In September 2011, the assembled team succeeded in capturing 24 Millerbirds on Nihoa (these from subspecies Acrocephalus familiaris kingi), then undertaking a placid three-day boat voyage, and finally releasing the birds on Laysan (Figure 1). With the rest of the team departing, the two of us were then responsible for shepherding the transplanted flock.
This unique opportunity also provided us with a chance to supply eBird with a novel dataset from a remote area. En route to and from Laysan, we were able to conduct one-and-a-half day’s worth of hourly transects. By taking GPS tracks each hour (for mileage covered) and then a representative coordinate for each respective midway point, these hourly traveling counts cover oceanic regions seldom cataloged.
Fig. 2. This image of Laysan base camp gives a sense for the living conditions and for the vast quantity of Laysan Albatrosses (foreground) that breed on the island. Photo by Cameron Rutt.
Additionally, while on Laysan, through the forethought of brainstorming with the eBird team, we devised standardized ways of recording the staggering numbers of seabirds throughout the changing seasons. Island-wide counts were simply out of the question, with estimated numbers of 134,000+ and 24,000+ adult Laysan and Black-footed Albatrosses respectively, present at any one time alone. The single adult Short-tailed Albatross was a bit easier to quantify (Figure 3).
Fig. 3. Adult Short-tailed Albatross on Laysan Island. In contrast to the other two species of albatross, this species was easy to count…one!
Over the first few weeks, we found a handful of locations for point counts and short traveling counts, which could be completed regularly and in a timely manner, as a way of monitoring the fluctuating numbers. Interspersed among these more feasible counts were bi-weekly or monthly counts conducted around the perimeter of the lake and simultaneously around the island’s circumference. In all, we averaged one complete checklist every other day for the 6.5 months on Laysan.
Throughout the six months, these counts revealed some interesting trends and startling high counts. We conducted two long simultaneous traveling counts where we tediously enumerated 27,894 Laysan and 12,953 Black-footed Albatrosses. A few weeks later, another point count – simply with the desire to count everything readily visible – ended an hour and fifteen minutes later with a bleary-eyed 24,032 Laysans. Additionally, largely throughout the course of these regular surveys, we amassed high counts for the following: 2,524 Bonin Petrels (Figure 3), 2,679 Wedge-tailed Shearwaters, 119 Tristram’s Storm-Petrels, 962 Great Frigatebirds, 648 Red-tailed Tropicbirds, 174 Laysan Ducks (Figure 4), 1,872 Pacific Golden-Plovers, 2,746 Ruddy Turnstones, 111 Wandering Tattlers, 1,194 Black Noddies, 559 Blue-gray Noddies (at Nihoa), and 165 Laysan Finches (Figure 5).
Fig. 4. Bonin Petrel. One of the common breeding seabirds on Laysan Island. Photo by Robby Kohley.
Devising the best approaches to count birds and then actually performing the counts provides a more intimate knowledge of the birds, which could otherwise pass unnoticed. For instance, in attempting to count Tristram’s Storm-Petrels, you quickly realize that their daily arrival is too late for any sort of evening or twilight count. However, their generally silent departure in the morning continues into the visible section of dawn’s twilight, where small numbers can be seen heading out to sea up until about 25 minutes before sunrise (alternatively, the earliest detection in the evening is roughly 45 minutes after sunset, despite more vocalizations at night). Nevertheless, nocturnal auditory point counts to listen for their distinctive call notes produce only negligible numbers. By far the best strategy, we found, was to conduct short nocturnal traveling counts to listen and spotlight for them near their nest burrows.
Fig. 5. Many burrow-nesting seabirds–including storm-petrels, Pterodroma petrels, and shearwaters–make their trips to and from the island only at night. This dusk swarm involves mostly Bonin Petrels and Wedge-tailed Shearwaters. Photo by Cameron Rutt.
Along the way, we were also able to document a few rarities that found their way here amidst a sea of odds: Lesser Frigatebird (3rd Laysan record), three “Brewster’s” Brown Boobies, a probable first-cycle Hawaiian Coot (5th Laysan record; separation from similarly-aged American Coot is tenuous and not currently resolved), Wood Sandpiper (16 September – 13 January; 6th record for Hawaii; Figure 6), Gray-tailed Tattler (25 September – 17 March; 8th record for Hawaii; Figure 11), Glaucous Gull (8 February; ~17th record for Hawaii), and Black Tern (12–13 December; ~18th record for Hawaii). Additionally, two other more regular Asian shorebirds wound up among the many Pacific Golden-Plovers and Ruddy Turnstones: two Ruffs and as many as 105 Sharp-tailed Sandpipers (high count, 30 October; Fig. 12), among the highest all-time Hawaiian tallies. Hawk migration, although quite unlike its mainland counterpart, was particularly exciting this year, with a whopping total of three raptors (of two species)! Two juvenile Peregrine Falcons gave the shorebirds a regular workout and a surprise Northern Harrier stopped in for a ten-day stint in mid-October, only to be harried by Brown Noddies and Sooty Terns–an odd combination.
Fig. 6. This Wood Sandpiper spent half the winter on the island, marking the 6th record for Hawaii. It looks something like a small, dull-legged Lesser Yellowlegs with larger back spots and a prominent supercilium.
Lastly, another benefit of eBirding regularly is the motivation to stave off the complacency that comes from the monotony of a largely unchanging bird scene. It was only through the nudge of entering regular eBird checklists that we wound up discovering two special one-day wonders: a Green-winged Teal and the Glaucous Gull.
The results of the intense eBirding is best seen on the Midway Island bar chart in the U.S. Minor Outlying Islands “country” in eBird, visible here. While many of these species and records are from Laysan, remember that some of these records are from Midway Island.
Contributed by Cameron Rutt and Robby Kohley
*Statistics on Laysan and state records were garnered from the comprehensive Pyle and Pyle monograph and do not reflect sightings since 2009.
Below is a selection of photos of the island and its endemic and interesting species from the voyage, including a few more vagrants.
Fig. 7. Laysan Duck is a Mallard relative restricted to the northwest Hawaiian Islands. In this striking image, one hunts brine flies alongside the central lagoon. Photo by Cameron Rutt.
Fig. 8. Laysan Finch, the only remaining endemic landbird on the island, following the extinction of the rail, Apapane, and native Millerbird subspecies. Photo by Robby Kohley.
Fig. 9. Gray-backed Tern breeds during the summer months, so was scarce during the time the team was on this island, with returnees beginning in January. Very like Bridled Tern, but with a gray back, this is a specialty of the central Pacific islands. Photo by Cameron Rutt.
Fig. 10. Perhaps the raptor best-equipped to cross water. Peregrine Falcons were seen a couple times by the team. This juvenile is very dark and molted into more adult-like plumage by spring. For many species, determining the subspecies can help to determine if the origins are American or Asian. This bird was believed to be Falco peregrinus japonensis, and thus an Asian bird. Photo by Cameron Rutt.
Fig. 11. Gray-tailed Tattler is a dream bird for many of us, but identifying a silent one would be a challenge on the Pacific coast where the very similar Wandering Tattler is common. No need to check the length of the nasal groove on a bird like this though–in direct comparison Gray-tailed is strikingly paler and also has a more-even width and more extensive supercilium. This bird marked just the 8th for Hawaii. Photo by Cameron Rutt.
Fig. 12. One of the more common migrant shorebirds in the Hawaiian islands, interestingly, is the Sharp-tailed Sandpiper. This fresh juvenile is distinctive with its bright red cap, bold supercilium, and buffy breast with very fine streaking, all of which help separate it from the similar Pectoral Sandpiper, which is actually rarer in Hawaii. Photo by Robby Kohley.
Fig. 13. A real rarity for Hawaii was this Northern Harrier, which stopped over for 10 days on the island, much to the chagrin of the nesting terns that regularly harassed it. As with Peregrines, subspecies ID is important here–this one appears to be the American subspecies Circus cyaneus hudsonia. Photo by Cameron Rutt.