This species is listed as Critically Endangered because it is has a very small population (100-150 mature individuals) on a single small island, with extent of occurrence 68 km². There is thought to be an ongoing decline in habitat quality, and although the species is no longer declining in abundance, it remains extremely susceptible to stochastic events; any potential change in land management within its tiny range could prove catastrophic for the species.

Todiramphus gambieri is confined to the island of Niau in the Tuamotu Archipelago, French Polynesia. The nominate taxon, gambieri, from Mangareva Island is known only from the type specimen, and is thought to be extinct.

Surveys in 2019 estimated 173 individuals in total, and population monitoring in recent years indicate a stable (possibly increasing) trend overall (Igual and Ghestemme 2020). As such, assuming only a proportion refers to mature individuals and accounting for some uncertainty, the population is here placed in the band 100-150 mature individuals.

This species prefers semi-open coconut plantation habitats (Gouni et al. 2006, Coulombe et al. 2011), limestone forests, and cultivated areas around villages, and readily uses Niau's ephemeral wetlands and ocean coasts for foraging. The species rarely occurs in natural forest and primarily selects agricultural coconut plantations (the area of which on Niau was estimated at 8km² in 2006 [Butaud 2007]) with open understory, hunting perches, and exposed ground (Coulombe et al. 2011, Kesler et al. 2012), though historically probably occupied habitat formed by native palm Pritchardia mitiaroana which was likely more widespread before coconut plantations were developed at its expense (Thibault and Cibois 2017). 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). 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).

A principal threat limiting population growth is considered to be predation by feral cats Felis catus and rats (Rattus rattus and Rattus exulans) (Gouni et al. 2006, BEST Initiative 2016), with 25-50% of juveniles thought to disappear each year (Gouni et al. 2009). Studies on demography (Kesler et al. 2012b) indicate low female and extremely low juvenile survival (40 % and 12% respectively). However, recent studies have disputed such intense predation pressure, based on the non-detection of T. gambieri in cat and rat diet samples from Niau (Zarzoso-Lacoste 2013, Zarzoso-Lacoste et al. 2019). Rats may also pose a threat through competition for food resources (Gouni and Sanford 2003, Gouni et al. 2004, 2006; Kesler et al. 2012b; Zarzoso-Lacoste 2013; Zarzoso-Lacoste et al. 2019). 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, Zarzoso-Lacoste et al. 2019).

The species benefits from agricultural management as it prefers coconut plantations without understorey (Coulombe et al. 2011) and survival in those areas is enhanced (Kesler et al. 2012b); the abandonment of plantations therefore renders habitat unsuitable due to the development of an unfavourable understorey and as a result this species is now largely restricted to the eastern side of the island. However, more intensive management of coconut plantations is also thought to negatively impact this species: clearance of ground vegetation may reduce the availability of prey items (Zarzozo-Lacoste 2013), and fires may get out of control and destroy large areas of wooded habitat (Thibault and Cibois 2017). Cutting and burning of dead coconut trees may destroy nesting sites, and there is a risk of fire spreading to nesting trees and disturbance from smoke if fire is used to clear the ground beneath cultivated coconuts during the nesting season (Raust 2012). As such, any changes to the land management of the island could prove catastrophic for the species.

This species' restriction to a single atoll also renders it susceptible to extreme weather events: the removal of suitable nesting trees in 1984, following a hurricane in 1983, reduced the availability of nesting sites (Gouni and Sanford 2003; Gouni et al. 2004, 2006).

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 was produced for 2014-2018 (SOP Manu 2015). The plan contained the following conservation actions: monitoring of the species' 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). Population monitoring is ongoing to better assess the population trend and study the impact of conservation actions (Igual and Ghestemme 2020). Cat and rat control is ongoing and sterilisation campaigns of domestic cats have been carried out (Igual and Ghestemme 2020). 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, Igual and Ghestemme 2020). Coconut farmers have been informed about habitat management, the use of fire and the preservation of dead coconut trees (Igual and Ghestemme 2020). Awareness is regularly raised for the species in schools (Igual and Ghestemme 2020). 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. The natural history of the species was thoroughly investigated (Kesler 2011, Coulombe et al. 2011, Kesler et al. 2012b). 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. 2012a). 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. Kesler in litt. 2012).
 
Conservation Actions Proposed
Research the impact of rats and cats on kingfisher survival and reproductive success. Research survival, breeding success and dispersal through banding of birds, and monitor breeding pairs throughout the whole breeding season (Igual and Ghestemme 2020). 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). Continue to monitor the population (Igual and Ghestemme 2020). Continue and expand control measures control measures for invasive species (Igual and Ghestemme 2020). Provide nest boxes to increase the availability of nest sites (Gouni et al. 2004). Promote best practice with coconut farmers to reduce losses and disturbance to nesting trees (Raust 2012). Implement an alternative solution to fire management in order to manage coconut plantations sustainably (Igual and Ghestemme 2020). 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.