Justification of Red List Category
This species is listed as Vulnerable owing to its very small range on a few tiny islands, where it is especially at risk from unpredictable climatic events.
The species's population fluctuates widely, probably averaging around 5,000 birds. Carrying capacity for the species has been estimated at 10,000 individuals (M. Morin in litt. 2012), and so its population is best placed in the band 2,500-9,999 individuals. This equates to 1,667-6,666 mature individuals, rounded here to 1,500-7,000 mature individuals.
The current trend is unclear. Large fluctuations were recorded over the period 1968-1990, but this may be partly due to the varying methods and seasons of censuses (Morin and Conant 1994). There has been a dramatic increase in the numbers on Southeast Island, in Pearl and Hermes Reef Atoll, since the successful invasion of golden crown beard Verbesina encelioides, which provides nesting habitat and food. The negative impacts of Verbesina on seabirds dictates that it be removed from the atoll in spite of its benefits to the species (S. Conant in litt. 2003). The population of T. cantans crashed after the first efforts to control Verbesina, but the abundance of Verbesina has since increased (S. Conant in litt. 2007). The overall population is judged to have experienced unquantified fluctuations over the last ten years.
Telespiza cantans is confined to Laysan in the Northwestern Hawaiian Islands (U.S.A.), as well as on two very tiny islands in the Hermes and Pearl Atoll, with around 30-50 birds, down from 772 in 1986 (Morin and Conant 2002), persisting from an introduction in 1967 (S. Conant in litt. 2007). On Midway Island, an introduced population succumbed to rats during the 1940s (Fisher and Baldwin 1946). In 1903, the introduction of rabbits to Laysan led to a serious decline in population size, but the species recovered rapidly after the rabbits were exterminated in 1923. The population numbered 1,000 individuals in 1928, c.5,000 in 1951 (Berger 1972), and apparently fluctuated between 5,000 and 20,000 over the period 1968-1990, with a mean of 11,044 (M. Morin in litt. 1999, 2003); this apparent fluctuation may be due, at least in part, to differing methods and seasons of censuses (Morin and Conant 1994). There has been a dramatic increase in the numbers of Laysan Finch on Southeast Island, at Pearl and Hermes Reef, since the successful invasion of golden crown beard Verbesina encelioides, which provides sheltered nesting habitat and additional food. The negative impacts of Verbesina on seabirds, which become entangled in the plants when returning to nest sites, dictates however that it be removed from the atoll in spite of its apparent benefits for T. cantans (S. Conant in litt. 2003).
It is a primarily herbivorous omnivore (Berger 1972, Conant 1988), feeding on insects, flowers, fruits, stems, seedlings and roots (Morin and Conant 2002). It survived the defoliation of Laysan by introduced rabbits, apparently by feeding on bird eggs, persistent seeds and carrion (Berger 1972, M. Morin in litt. 1999, 2003). On Laysan Island it nests almost exclusively in bunchgrass Eragrostis variabilis, but on Pearl and Hermes Atoll where bunchgrass is uncommon, the introduced birds nest in other plants or in man-made debris that floats ashore (M. Morin in litt. 1999, 2003).
Today, the primary forces regulating this species's population are storms and drought, which can cause almost total nest failure (Morin 1992a). Global warming is a further cause for concern, given that the maximum altitude on Laysan is only 12 m and that, as well as predicted sea-level rises of 0.5-2.0 m by 2100, the frequency and severity of hurricanes and droughts are expected to increase as a consequence (McNeely et al. 1995, Moulton and Marshall 1996). In the past, invasive alien plants have reduced nesting habitat (Gagné 1988, Morin et al. 1997, M. Morin in litt. 1999, 2003). Additional potential threats include the accidental introduction of non-native plants, animals and diseases (M. Morin in litt. 1999, 2003). A population crash followed the first attempts at Verbesina eradication in the Pearl and Hermes Reef Atoll, although Verbesina is now recovering.
Conservation Actions Underway
Laysan is part of the Hawaiian Islands National Wildlife Refuge. The alien grass Cenchrus echinatus is believed to have been eradicated (M. Morin in litt. 1999, 2003) and native bunchgrass is recovering in response (M. Reynolds in litt. 1999).
19 cm. Large finch with heavy, slightly hooked bill. Male yellow on head and breast, yellow-tinged grey on back and rump, dull white underparts. Dark wing and tail feathers with golden-yellow edges. Female and juvenile similar, but greyer above and on hindneck with fine streaks on head and breast, heavier streaks and spots on back. Greyer edges to wing feathers. Voice Loud canary-like song. Call a chirp resembling that of House Finch Carpodacus mexicanus.
Text account compilers
Stattersfield, A., Derhé, M., Benstead, P., Stuart, T., Taylor, J., Isherwood, I., Khwaja, N.
Conant, S., Reynolds, M., Baker, H.C., Morin, M., Camp, R., VanderWerf, E., Baker, P.E., Fretz, S.
BirdLife International (2019) Species factsheet: Telespiza cantans. Downloaded from http://www.birdlife.org on 13/11/2019. Recommended citation for factsheets for more than one species: BirdLife International (2019) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 13/11/2019.