||Zapornia atra (North, 1908)
||Henderson Crake, Henderson Island Crake, Henderson Island Rail, Red-eyed Crake
Nesophylax ater (North, 1908) — Collar and Andrew (1988)
Porzana atra North, 1908
||del Hoyo, J., Collar, N.J., Christie, D.A., Elliott, A. and Fishpool, L.D.C. 2014. HBW and BirdLife International Illustrated Checklist of the Birds of the World. Volume 1: Non-passerines. Lynx Edicions BirdLife International, Barcelona, Spain and Cambridge, UK.
||Zapornia atra (del Hoyo and Collar 2014) was previously placed in the genus Porzana.
||17 cm. Small, flightless rail. Glossy black with red eyes and legs. Voice Clattering clackety-clack call.
|Red List Category & Criteria:
||Butchart, S. & Symes, A.
||Brooke, M., Hall, J., Bell, B., Oppel, S. & Bond, A.
||Benstead, P., Derhé, M., Mahood, S., O'Brien, A., Pilgrim, J., Stattersfield, A., Stringer, C.
This species qualifies as Vulnerable as it is only found on one small island. The accidental introduction of alien species could result in rapid population decline, or even extinction, as experienced by many other flightless island rails.
|Previously published Red List assessments:|
- 2012 – Vulnerable (VU)
- 2008 – Vulnerable (VU)
- 2004 – Vulnerable (VU)
- 2000 – Vulnerable (VU)
- 1996 – Vulnerable (VU)
- 1994 – Vulnerable (VU)
- 1988 – Threatened (T)
|Population:||Numbers were estimated at c.3,240 in 1987 (Graves 1992) and, using a different technique, c.6,200 birds in 1992; no major change in population size was evident in 2003 (Jones et al. 1995, M. Brooke pers. comm. 2007). A rat eradication attempt in 2011 reduced the population to probably <500 individuals, but because sufficient individuals were maintained in captivity during the eradication attempt, counts in 2013 and 2015 suggest that the population has largely recovered (S. Oppel and A. Bond in litt. 2016). In 2015, the estimated abundance of Henderson Crakes at 25 point count stations was 213 (95% CI 144-319) individuals, which would result in an overall population estimate of 8512 (95% CI 5755 - 12749) individuals assuming a survey radius of 100 m around each point (S. Oppel and A. Bond in litt. 2016). Although recruitment to the breeding population is not known, numbers of surviving chicks probably compensate for annual losses such that the population can be considered stable despite the continued presence of rats (Jones et al. 1995).|
Trend Justification: Studies indicate that predation rates are low and reproduction rates are sufficient to replace birds lost, thus the population is suspected to be stable.
|Current Population Trend:||Stable|
|♦ Number of mature individuals:||8200||♦ Continuing decline of mature individuals:||No|
|♦ Extreme fluctuations:||No||♦ Population severely fragmented:||No|
|♦ No. of subpopulations:||1||♦ Continuing decline in subpopulations:||Unknown|
|♦ Extreme fluctuations in subpopulations:||No||♦ All individuals in one subpopulation:||Yes|
|♦ No. of individuals in largest subpopulation:||100|