EN
Lord Howe Woodhen Hypotaenidia sylvestris



Justification

Justification of Red List category
This species is listed as Endangered as it has an extremely small population of less than 250 mature individuals which is restricted to a tiny area of available habitat on one island. 

Population justification

In the 2016 island-wide survey, 250 Lord Howe Woodhens were recorded, and the population was estimated to be 286 (Lord Howe Island Board 2016). These totals, which include juveniles, exceed the estimated carrying capacity of the island of 220 individuals (Brook et al. 1997), probably because some birds are fed by residents and many benefit from access to artificial habitats like the golf course and waste management facility; there were actually fewer at Grey Face, Boat Harbour and Far Flats than in the 1990s (Lord Howe Island Board 2016). More recent population estimates are slightly lower than in 2016: the November 2018 survey recorded 212 individuals (Portelli and Carlile 2019), with an estimated total population of 245 individuals (Major et al. 2021); in 2019, 219 adults and juveniles were temporarily held in captivity to avoid primary poisoning during the Rodent Eradication Program (Lord Howe Island Board unpublished) with at least 10 remaining at large (N. Carlile unpublished). There were fewer than ten pairs of Lord Howe Woodhens in the 1970s and the entire population is derived from a single pair in the lowlands, up to five pairs in the southern mountains and three pairs on the southern slopes (Miller and Mullette 1985, Major et al. 2021).

Trend justification
The population was estimated to be stable (NSW National Parks and Wildlife Service 2002) but conservation efforts have resulted in the population experiencing continued growth over at least the last decade (D. Portelli in litt. 2016). Ongoing population monitoring has demonstrated a steady increase of approximately 4.5 birds per year since 2004 (Lord Howe Island Board unpubl. data via D. Portelli in litt. 2016).

Distribution and population

Hypotaenidia sylvestris is endemic to Lord Howe Island (Australia). In 1788, it was found from sea-level to the tops of the two mountains on the island, but from the mid-19th century, it became restricted to the summits. In the 1970s the population comprised 10 breeding pairs and 3 singletons (Miller & Mullette 1985). In the 1980s, following the eradication of introduced pigs Sus domesticus, birds were reintroduced to two lowland sites (Boat Harbour and Little Slope), and two elevated sites (Goat House and Erskine Valley). Three birds were released within the settlement (Salmon Beach and Kings property) and a fourth was released at the site of capture at Salmon Beach after 66 days in captivity (D. Portelli in litt. 2016). They now occur on the summit of Mt Gower, at Big and Little Slopes, Grey face, Far Flats and around the settlement (Frith 2013). They have also been recorded on Mt Lidgbird (Miller and Mullette 1985). A comparison of the contemporary population and historic specimens has demonstrated a decline in genetic diversity over the past century (Major et al. 2021).

Ecology

Hypotaenidia sylvestris is sedentary and highly territorial (Marchant and Higgins 1993). On Mt Gower, it occurs in gnarled mossy forest. At lower altitudes, the species occurs in a wide range of Oceanic Rainforest communities. It also occurs in vegetation associated with residences where supplementary food is available. It forages amongst leaf litter, rotten logs, moss and lichens, feeding on worms, molluscs and invertebrates (Marchant and Higgins 1993). The species is also known to scavenge on residential waste, and prey upon providence petrel chicks and eggs, and rodents (Department of Environment and Climate Change [NSW] 2007). It is monogamous and usually occurs in pairs. Pairs build 3-4 nursery nests on the ground under thick vegetation, in/under root cavities, in petrel burrows and under domestic debris. The breeding season varies between years but females generally lay between August and January and continue raising young until April. However, breeding can occur at any time of year when conditions are suitable. They lay 1–4 eggs in nests in dense vegetation or petrel burrows (Miller and Kingston 1980). Both parents incubate eggs for 20-23 days, and brood and feed chicks. Chicks fledge at 28 days. Females may lay another clutch as soon as 30 days after the initial clutch. Juveniles reach adult size at 12 months, but may start breeding at nine months (Marchant and Higgins 1993, Department of Environment and Climate Change [NSW] 2007). Maximum longevity is fourteen years (D. Portelli pers comm., Lord Howe Island Board unpublished data, Brook et al. 1997).

Threats

No threats currently pose more than a negligible risk. Historical losses were due to hunting by people, predation by cats Felis catus and pigs Sus scrofa, and habitat degradation caused by pigs and goats Capra hircus. All these threats have ceased (Miller and Mullette 1985). Masked Owls Tyto novaehollandiae, introduced to control introduced black rats Rattus rattus may have caused local losses, but the owls are currently being eradicated. Further introductions of exotic predators or the introduction of chronic disease could have serious consequences (Taylor and van Perlo 1998). During the period of exposed bait on the ground or active bait stations, all accessible woodhens were captured before baiting commenced and held temporarily in captivity to avoid primary poisoning (Lord Howe Island Board 2009). Self-introduced Buff-banded Rails Hypotaenidia philippensis may outcompete woodhens, but the two species co-existed historically (McAllan et al. 2004). Natural catastrophes are an additional threat. Population Viability Analysis using VORTEX suggests that the species remains highly susceptible to changes in survival or fecundity (Brook et al. 1997).

Conservation actions

Conservation Actions Underway
CITES Appendix I. The species is successfully bred in captivity. Predation and disturbance by dogs is minimised by community support for conservation efforts and any problem dogs are deported (H. Bower in litt. 2016). Goats, cats and pigs have been eradicated (C. Haselden in litt. 2016). Most habitat conserved as World Heritage Area. Listed as threatened under appropriate legislation. Quarantine procedures minimise the probability of alien invasions. Rodent eradication completed and monitoring continues to be a priority.

Conservation Actions Proposed
Continue to undertake the Lord Howe Island Rodent Eradication Program using proven baiting methods to eradicate black rats and house mouse on Lord Howe Island. The introduced Masked Owls Tyto novaehollandiae is to be eradicated coincident with the rodent eradication program. Track population recovery following removal of rodents. Collar and Butchart (2013) suggested that captive breeding should be considered but there is limited support by zoos for holding an ex-situ population off Lord Howe Island as they have limited appeal for display and their ongoing husbandry is considered too expensive. Implement measures to prevent further introductions of exotic predators to Lord Howe Island. Maintain quarantine procedures. Continue to monitor trends in the population. 

Identification

34-42 cm (male), 32-37 cm (female). Large, olive-brown, flightless rail with bright chestnut wings. Olive-brown body, duller on underside. Indistinct, paler supercilium. Bright chestnut wings with narrow, dark brown bars on primaries and primary coverts. Long, decurved, pink bill, more brown towards tip. Red iris. Light pink-brown legs. Juvenile similar, but iris initially dark. Similar spp. Confusion unlikely. Buff-banded Rail G. philippensis is smaller, has bold black-and-white barring on underside, buff breast-band and clear white supercilium. Voice Loud, piercing, repeated whistle, often as duet. Hints Confiding. Spreads wings to sunbathe.

Acknowledgements

Text account compilers
Dutson, G., Pilgrim, J., Allinson, T, North, A., McClellan, R., Garnett, S., Stattersfield, A., Vine, J., Symes, A., Taylor, J.

Contributors
Bower, H., Carlile, N., Frith, C., Haselden, C. & Portelli, D.


Recommended citation
BirdLife International (2024) Species factsheet: Hypotaenidia sylvestris. Downloaded from https://datazone.birdlife.org/species/factsheet/lord-howe-woodhen-hypotaenidia-sylvestris on 26/02/2024.
Recommended citation for factsheets for more than one species: BirdLife International (2024) IUCN Red List for birds. Downloaded from https://datazone.birdlife.org on 26/02/2024.