Millerbird (Acrocephalus familiaris)

Avifaunal inventory of Laysan Island, Hawaii, USA

“…The released birds primarily remained within the nearly contiguous patch of Scaveola taccada towards the north and northeast of the island, although one individual traveled at least 8.72 km during a stretch of 37 days from the time of its release until mid-October (Rutt & Kohley 2012). Two periods of breeding were recorded during our survey; the first occurred from early October to early December 2011, outside of the published breeding season for this species (January-September; Morin et al 1997). During this period, females from three pairs laid eggs but, of these, only one clutch hatched and the nestling was eventually found dead in the nest (Rutt & Kohley 2012).…”

Long-distance translocations to create a second millerbird population and reduce extinction risk

“…We did a rapid assessment of Laysan's habitat suitability for millerbirds by mapping low, dense shrubs and bunchgrasses, the type of vegetation most commonly used by millerbirds on Nihoa (Conant, 1983;Morin et al, 1997). The resulting area on Laysan was at least 180 ha, more than twice the entire vegetated area of Nihoa.…”

“…The unbanded proportion of the population grew in the nine-month gap between 2013 and 2014 monitoring periods, and population estimation was thus more complex in 2014. Because territorial millerbirds are more visible and vocal than non-territorial birds (Morin et al, 1997), and because they seldom travel far (MacDonald, 2012), intensive monitoring in specific areas allowed discovery of unique, unbanded adults that held territories (in addition to banded territory-holders). Unbanded, non-territorial birds are more cryptic and nomadic; counting them was more difficult and raised the potential for double-counting individuals.…”

“…Owing to Nihoa's remoteness (located 250 km northwest of Kauai and accessible only by boat), monitoring of the millerbird and potential threats has long been intermittent. Surveys between 1967 and 2012 yielded highly variable millerbird population estimates ranging from 31 to 800 birds (Morin et al, 1997;USFWS, unpublished data). Population viability analysis suggested that extinction probability was very high (Conant and Morin, 2001).…”

“…The Nihoa and (extinct) Laysan millerbirds were genetically separable at the subspecies and perhaps species level (Fleischer et al, 2007). However, in light of their ecological similarity-similar size, foraging behavior, diet, habitat selection, and breeding behavior-their taxonomic distinctness was not considered an impediment to moving millerbirds from Nihoa to Laysan (Fisher, 1903;Morin et al, 1997, Morin and. Laysan has no known alien pathogens affecting passerines, no mammalian or other nonnative predators, and it has habitat structure suitable for millerbirds (Morin and Conant, 2007).…”