Data Zone
Justification of Red List category
This species is listed as Endangered, thus is perceived to be at a very high risk of extinction, because it has a very small population size of only 100-300 mature individuals. It was formerly considered to be Critically Endangered because of a declining population trend, but this has now been stabilised because of the protection of forests on Okinawa, and successful programmes to control invasive mongoose.
Population justification
The population size of this species has not recently been robustly estimated. BirdLife International (2001) estimated a population of 150–584 individuals, but only 75 mature individuals. Since this estimate, the range of this species has expanded more widely across Okinawa in response to active management of invasive mongoose (Yaghihashi et al. 2021) and localised forest regeneration (see Figure 2: Kotaka et al. 2021). In 2013 and 2016 respectively, this species was detected at 104 and 100 of 244 observation points, an increase on the 67 counted in 2007; the total number of birds observed across surveyed squares in 2010, 2013 and 2016 varied between 149–183 (Yagihashi et al. 2021). Two opposing considerations should be made when converting this into a population estimate of mature individuals: (1) not every bird will have been detected, despite the use of playback, thus these numbers should be considered absolute minimum values; but (2) not all birds will have been mature individuals. Accounting for these margins of error, these data suggest a total population of 75–200 mature individuals.
An alternative method of estimation is derived using nesting data from Kotaka et al. (2021), who found between 2017 and 2019 between 1–1.5 nests [= 2 mature individuals] per km2, albeit their sample size in each year was very small and not necessarily representative. In its occupied range there is approximately 200 km2 of suitable habitat (i.e. closed-canopy forest) not all of which, however, is likely to be occupied. Nonetheless, occupancy is likely high (Yagihashi et al. 2021, eBird 2024) and these data suggest a slightly higher population size of up to c.400 mature individuals.
Combining methods, a population size of 75–400 mature individuals is estimated, with a precautionary best estimate of 100–300.
Trend justification
Trend not well understood, but currently suspected to be stable following concerted conservation effort to create a mongoose-free area on Okinawa, and also protect a large area of this species' range as a national park.
Dendrocopos noguchii was already rare by 1928, with Kobayashi (1930) already commenting then that the species was in danger of extinction. It has remained rare, with the principal cause of its depleted population the widespread clearance of habitat throughout the 20th century (BirdLife International 2001) but there is increasing evidence that the species is negatively associated with the presence of the invasive Small Indian Mongoose Urva auropunctata (see Kotaka 2014), introduced to Okinawa in 1910 (Kishida 1931). Accordingly it has more recently undoubtedly benefited from concerted conservation effort to create a 'mongoose-free' area on the north of the island (Yagihashi et al. 2021, N. Kotaka in litt. 2024).
Repeat-effort playback surveys 2007-2016 recorded the following number (# of occupied squares out of 244, # of birds): 2007 (67, 120), 2010 (96, 165), 2013 (104, 183), 2016 (100, 149) (Yagihashi et al. 2021). Thus the number of occupied squares and counted individuals increased markedly between 2007 and 2010, after which it remained somewhat stable. The apparent increase in abundance in 2013 was also clearly detected by Kotaka et al. (2021), who found a sharp increase in the density of active nests in that year during monitoring 2005-2019. They attributed this to a temporary increase in nest availability caused by an outbreak of the pest beetle Plagiosterna formosana which first arrived on the island in 2010 (Kotaka 2014; see Figures 5 and 6c: Kotaka et al. 2021) and created a large number of temporary nest sites on dead trees.
While the declines in abundance (but note not occupied squares) between 2013 and 2016, and declines in nest density between 2015 and 2019, could be interpreted as reflecting a continuing population decline, Kotaka et al. (2021) considered them to be a temporary effect and not indicative of ongoing changes; the population trend is considered likely to be stable (N. Kotaka in litt. 2024).
In the future, the population trend of this species will recover further if the area of suitable habitat can be expanded, and mongoose control measures remain implemented. However, if mongoose control measures cease or fail, this species may decline (rapidly) again in the near-future (N. Kotaka in litt. 2024), and its extinction risk will appropriately increase. This should be very closely monitored.
Dendreocopos noguchii is endemic to Okinawa Island, Japan, where it is confined to Kunigami-gun (=Yambaru) with the main breeding areas along the mountain ridges between Mt Nishime-take and Mt Iyu-take (BirdLife International 2001, Yagihashi et al. 2021, eBird 2024).
It occurs in subtropical, evergreen broadleaved forest at least 30 years old, with tall trees more than 20 cm in diameter, much of which is now confined to hill-tops. Foraging takes place in old-growth forest. Nesting is between late February-May, often in hollow Castanopsis cuspidata trees. There is an extraordinary difference in the foraging niches of males and females (Kotaka et al. 2006). Although both forage on dead and live trunks, males have also adapted to feed on the ground on soil-dwelling arthropods, as well as berries, seeds, acorns and other nuts (Kotaka et al. 2006).
Historical declines are principally attributable to deforestation, but this has effectively ceased and is unlikely to return given the establishment of the Yambaru National Park by the Ministry of the Environment Japan in 2016 and its subsequent registration as a UNESCO World Natural Heritage site in 2021 (N. Kotaka in litt. 2024). Perhaps the greatest threat to the species now is that posed by Small Indian Mongoose Urva auropunctata (see Kotaka 2014), introduced to Okinawa in 1910 (Kishida 1931). Recent efforts to create a 'mongoose-free' area on the north of the island (Yagihashi et al. 2021, N. Kotaka in litt. 2024) have now meant this threat is unlikely to be causing declines in this species, but this outcome depends on the continuation of action. An outbreak of the pest beetle Plagiosterna formosana which first arrived on the island in 2010 (Kotaka 2013; see Figures 5 and 6c: Kotaka et al. 2021) created a large number of temporary nest sites on dead trees but may longer term have slightly reduced habitat availability; nonetheless, threats such as this (including pine wilt disease, first introduced in the 1970s) are considered temporary and not a cause of declines. Typhoons represent a plausible future threat, particularly in response to climate change.
Conservation Actions Underway
It is legally protected in Japan. The Yambaru area was protected by some local administrations since 2007, but not until 2016 did it formally become a national park. In 2021, it was registered as a UNESCO World Natural Heritage Site. There is a large-scale control effort of Small Indian Mongoose Urva auropunctata, which has been going from the late 1990s (Yamada and Sugimura 2004, Yagihashi et al. 2021) and now aims to eradicate the invasive species north of a line stretching from Shioya to Fukuchi (N. Kotaka in litt. 2024).
Conservation Actions Proposed
The principal conservation action needed is the continuation of efforts to control H. javanicus, with an eventual goal of eradication on the whole island highly desirable. A more robust quantification of the population size would be a useful task, as would the continuation of data collection akin to that summarised by Yagihashi et al. (2021). Ensure that the Yambaru National Park is well protected and old growth forest remains.
31 cm. Medium-sized, dark woodpecker. Generally deep brown with reddish tips to feathers, brightest on lower rump and uppertail-coverts. White spots on primaries. Tan-brown lores, malar area and ear-coverts and paler brown throat. Male has dark red crown and nape streaked with blackish-brown and female has blackish-brown crown. Voice Sharp whit call and a variable kyu-kyu kup kup kup or kyu kyu kup.
Text account compilers
Berryman, A.
Contributors
Kotaka, N.
Recommended citation
BirdLife International (2024) Species factsheet: Okinawa Woodpecker Dendrocopos noguchii. Downloaded from
https://datazone.birdlife.org/species/factsheet/okinawa-woodpecker-dendrocopos-noguchii on 23/12/2024.
Recommended citation for factsheets for more than one species: BirdLife International (2024) IUCN Red List for birds. Downloaded from
https://datazone.birdlife.org/species/search on 23/12/2024.