Justification of Red List Category
This species is listed as Critically Endangered because it is restricted to an extremely small range on a single island, within which the quality of habitat has been reduced as cyclones have caused the loss of suitable nesting trees. Any potential change in land management within this tiny range could prove catastrophic for the species.
Surveys in 2009 estimated 135 individuals, roughly equivalent to 90 mature individuals.
Approximately the same number of birds were detected annually in surveys from 2006-2008 (with a slight increase in 2009), and data from radio-marked and colour-banded birds do not indicate a major population crash or major population increase (D. Kesler in litt. 2009, 2010). However, studies of demography (Kesler et al. 2012a) indicate that the population may be declining substantially, and that juvenile survival and adult female survival may be the life history stages most compromised in the population.
Todiramphus gambieri is confined to the island of Niau in the Tuamotu Archipelago, French Polynesia, where the race niauensis was represented by 400-600 birds in 1974, and reported as common in 1990; the nominate gambieri having become extinct on Mangareva, Gambier Islands, probably prior to 1922 (Holyoak and Thibault 1984, Seitre and Seitre 1991, Seitre and Seitre 1992). Surveys in 2003 and 2004 estimated the total population as 39-51 individuals, significantly lower than previously supposed (Gouni and Sanford 2003, Gouni et al. 2004), but surveys in 2006-2008 suggested that the total population had remained relatively stable at around 125 individuals (Gouni et al. 2006, Gouni and Zysman 2007, D. Kesler in litt. 2008, 2009, 2010), with slight increases to 135 individuals in 2009 (Gouni et al. 2009) and 144 individuals in 2014 (SOP Manu 2015). However, studies of demography indicate that the population may be declining substantially (Kesler et al. 2012a).
This species prefers semi-open coconut plantation habitats (Gouni et al. 2006, Gouni and Zysman 2007, Coulombe et al. 2011), limestone forests, and cultivated areas around villages, and readily uses Niau's ephemeral wetlands and ocean coasts for foraging. In particular, the species selects agricultural coconut plantations with open understory, hunting perches, and exposed ground (Coulombe et al. 2011, Kesler et al. 2012). Breeding is primarily from September to January (although an active nest has been observed in July, R. van der Vliet in litt. 2012) in nest cavities excavated from dead and decaying coconut palms (thus its choice of nest-site is limited) (Holyoak and Thibault 1984, Gouni et al. 2007, Gouni and Zysman 2007). It feeds on insects (e.g. small coleoptera) and small lizards (Gouni et al. 2006). The main food source for chicks is lizards (Gouni et al. 2006).
The principal threat limiting population growth is considered to be predation by feral cats Felis catus (Gouni et al. 2006, Gouni and Zysman 2007, BEST Initiative 2016), with 25-50% of juveniles thought to disappear each year (Gouni et al. 2009), although a recent study has disputed this, based on the non-detection of T. gambieri in cat scat samples from Niau (Zarzoso-Lacoste 2013). Rats (Rattus rattus, Rattus exulans) may pose a threat through predation and through competition for food resources (Gouni and Sanford 2003, Gouni et al. 2004, 2006, Gouni and Zysman 2007, Kesler et al. 2012a, Zarzoso-Lacoste 2013). Since the cats on Niau largely prey on rats, the removal of cats in the absence of simultaneous control of rats could lead to a subsequent increase in the rat population (Zarzoso-Lacoste 2013). The removal of suitable nesting trees in 1984, following a hurricane in 1983, has reduced the availability of nesting sites (Gouni and Sanford 2003, Gouni et al. 2004, 2006, Gouni and Zysman 2007). The species may benefit from agricultural management, as it prefers coconut plantations managed with prescribed burning for hunting (Coulombe et al. 2011) and survival in those areas is enhanced (Kesler et al. 2012a). As such, any changes to the land management of the island could prove catastrophic for the species. However, more intensive management of coconut plantations with clearance of ground vegetation may reduce the availability of prey items (Zarzozo-Lacoste 2013). Cutting and burning of dead coconut trees may destroy nesting sites, and there is a risk of fire spreading to nesting trees or disturbance from smoke if fire is used to clean coconuts during the nesting season (Raust 2012).
Conservation Actions Underway
The species is legally protected in French Polynesia. Niau is included in the Fakarava Man and Biosphere Protected Area (P. Raust in litt. 1999). A species action plan has been produced for 2014-2018 (SOP Manu 2015). The plan contains the following conservation actions: monitoring of the species's breeding success and population; protection of nests and feeding habitat; control of cats; and raising awareness of the species in the local community (including children) (SOP-Manu 2015). From 2017-2018, a project has been underway to implement some of these actions (BEST Initiative 2016). Feral cats have been trapped and domestic cats have been neutered (Te Me Um, n.d.). Nesting trees have been marked with signs giving recommendations for their protection, and trunks of nesting trees are banded to prevent predation by rats (Raust 2012, Te Me Um, n.d.). Coconut farmers have been informed about habitat management, the use of fire and the preservation of dead coconut trees (Te Me Um, n.d.).
The natural history of the species was thoroughly investigated (Kesler 2011, Coulombe et al. 2011, Kesler et al. 2012a). Subsequently, an experimental translocation to the opposite side of Niau in 2010 provided a means of testing translocation methods and assessing the impact of harvest from the donor population (Kesler et al. 2012b). The Makatea and Anaa (Gambier Islands) have been assessed for their suitability for a translocated population, with the atoll complex of Anaa providing the best release option (D. Kessler in litt. 2012). Research is being conducted on the diet of invasive rats and cats to see whether they are predating chicks, or competing with adults (Vidal et al. 2010). Two studies have illustrated the birds' association with agricultural coconut plantations (Coulombe et al. 2011) and provide recommendations for managing coconut habitats to benefit the birds.
Conservation Actions Proposed
Research the impact of rats and cats on kingfisher survival and reproductive success. Research the impact of coconut plantation management practices on the abundance of prey such as lizards and arthropods and on the abundance of predators (Zarzoso-Laconte 2013). Research the genetic diversity of the population to assess the potential threat from inbreeding depression (Zarzoso-Laconte 2013). Test the effectiveness of bands around coconut palm trunks in preventing rats from climbing them (Zarzoso-Laconte 2013). Provide nest boxes to increase the availability of nest-sites (Gouni et al. 2004). Facilitate the establishment of a second supplementary population on Anaa through translocations (Fry et al. 1992, Gouni et al. 2006, D. Kesler in litt. 2008, 2009, 2010) and establish a captive-breeding programme to support future supplementations/reintroductions. Promote best practice with coconut farmers to reduce losses and disturbance to nesting trees (Raust 2012).
Buffy-cream head and neck. Variable amount of blue feathers on crown. Creamy-white forehead and broad, buffy neck-band. Dusky blue ear-coverts. White chin and underparts, often with rufous band across upper breast. Blue mantle, back, rump, wings and tail.
Text account compilers
Derhé, M., O'Brien, A., Shutes, S., Stattersfield, A., Symes, A., Wheatley, H., Butchart, S., Dutson, G., Bird, J., Harding, M.
Gouni, A., Kesler, D., Raust, P., van der Vliet, R. & O'Brien, M.
BirdLife International (2021) Species factsheet: Todiramphus gambieri. Downloaded from http://www.birdlife.org on 24/01/2021. Recommended citation for factsheets for more than one species: BirdLife International (2021) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 24/01/2021.