(Following is a blog from our joint ABC/US Fish and Wildlife Service Millerbird Translocation Project Monitoring Team – Cameron Rutt and Robby Kohley. See the pictures at the end of the blog. It is an update on the project for the period September 10 through October 12. For background on the project, see: http://www.abcbirds.org/newsandreports/releases/110919.html)
Following their release here on 10 September, the Millerbirds translocated from Nihoa are off to a great start on Laysan, with one month already under-their-belts. Although it is premature to make any assessments of their long-term viability at this early juncture, we couldn’t be happier with the initial results. A full month in and we’ve already re-sighted each and every one of the 24 Millerbirds at least twice (for a total of 150 re-sightings), despite a last furtive female (color-banded Black over metal band on the left leg and Green over Yellow on the right leg, written Bk/S, G/Y on our data sheets) remaining out of sight until early October. In fact, we’ve managed to re-sight 22 of the 24 Millerbirds (11 of 12 birds carrying radio transmitters, and 11 of 12 carrying color bands only) within the past six days alone, a particularly successful stretch for us! During this span, we’ve noted no less than seven male-female pairings, and two pairs have been observed carrying nesting material, with preliminary nest structures already underway. Our early impression is that the Millerbirds are tending to cluster in regions of higher density, rather than spreading evenly across their newfound habitat. It also appears that these regions are in the sparser, more segregated clumps of naupaka (a native shrub, Scaevola taccada), with scattered bunchgrass (Eragrostris), rimming the vegetated exterior ring of the island in the north and northeast.
Prior to release, half (12) of our translocated cohort were outfitted with radio transmitters to allow tracking by telemetry. These signals helped us keep tabs on the birds during the first three to four weeks post-release, a critical time of increased mobility, prior to their eventual territory settlement. Although some birds have quickly found turf to proclaim their own, other individuals are still wandering. The most nomadic individual was most certainly Blue over metal left, Blue over Blue right (B/S, B/B), who managed to make it all the way to the southern tip of the island (23 September – 5 October; >1.25 miles from the release site), only to be seen the following day at the complete opposite end (6 October)! Tracking the 12 transmittered individuals is now behind us, as all of the batteries have since expired (the last pulse emitted on 7 October), which leaves us with only our eyes, ears, and a lot of hiking ahead.
Along the way, we were also able to document a few rarities that found their way to this speck of land amidst a sea of blue. These included a Lesser Frigatebird (3rd Laysan record), Wood Sandpiper (16 – 26 September; 6th record for Hawaii), Gray-tailed Tattler (25 – 26 September; 9th record for Hawaii), a probable first-cycle Hawaiian Coot (5th Laysan record; separation from similar American Coot difficult, but there are a number of records from the Northwestern Hawaiian Islands, so not completely unexpected). Additionally, two other more regular Asian shorebirds wound up among the many Pacific Golden-Plovers and Ruddy Turnstones: a juvenile Ruff (12 – 19 September) and as many as 23 Sharp-tailed Sandpipers (high count; 8 October).
Picture 1. The Laysan Millerbird monitoring team – Robby Kohley (L) and Cameron Rutt (R). Radio telemetry was used during the first three weeks as a tool for tracking 12 of the 24 Millerbirds released. Photo credit: Chris Farmer.
Picture 2. Laysan is shaped like an elongated donut with a hyper-saline lagoon in the middle and vegetated dunes around the perimeter. The lagoon is habitat for migratory shorebirds, especially Pacific Golden-Plover, Ruddy Turnstone, and Wandering Tattler. Photo credit: George E. Wallace.
Picture 3. A Millerbird on Laysan perched in naupaka, the dominant shrub in the release area at the north end of Laysan. Note the color bands. Each bird carries a unique color band combination which allows individual identification in the field. Photo credit: Robby Kohley.