Justification of Red List Category
This species is considered Critically Endangered because it has an extremely small and fragmented population which has declined owing to habitat loss and fragmentation caused by hurricanes, fire and clearance for tourism, industry, residential housing and roads, as well as grazing and predation by invasive species. A 2008 recovery plan aims to urgently prevent further population decline due to habitat loss and other threats, and increase the wild population through protection and restoration to allow for four self-sustaining subpopulations.
The global population is estimated at c. 160 individuals, roughly equivalent to 110 mature individuals (range 90 to 130) (Rivera-Milán et al. 2015).
The population was estimated at 100 individuals in 1998, climbing to 182 individuals by 2003-2004. However, the population declined following hurricane Ivan in 2004, with a maximum of 136 individuals estimated in 2007 (Rusk 2007). Although these figures suggest that the population may have increased between 1998 and 2007, this includes c. 30 new individuals discovered in 2003, and increases may reflect an improvement in sampling methods. The population is thought to be undergoing a continued decline (B. L. Rusk in litt. 2010), estimated here at 1-19% over 13 years (three generations).
The species is endemic to Grenada in the Lesser Antilles. Historically, it was more widespread in coastal and possibly offshore islands (Rusk et al. 1998), but may always have been rare (Devas 1943). The population declined by c.50% in 1987-1990 (Blockstein 1991), and by 1998 numbered only c. 100 individuals, with strongholds on the Mt Hartman estate, and on the Perseverance and adjacent Woodford estates in the west (Rusk et. al. 1998). The population increased to an estimated 182 individuals by 2003-2004 (Rusk and Clouse 2004), but in 2004 hurricane Ivan had a devastating impact upon the island and the dove's population. This resulted in declines, particularly severe along the west coast, where the population declined from 36 calling males to 3-12 calling males, but also within the Mt Hartman area, from 55 males to 30-48 males (Rusk 2005). Three years following hurricane Ivan the population was estimated at 68 calling males with 136 individuals in total (Rusk 2008), however this assumes an even sex ratio, and there is a tendency for such relict populations to be male-dominated. The total population may therefore be as small as 100 mature individuals or c. 30 reproductive pairs (N. J. Collar in litt. 2008). A survey in 2013 estimated the population to be approximately 160 (+/- 30) individuals using distance sampling, with 33 birds recorded (Rivera-Milán et al. 2015). This is equivalent to approximately 110 mature individuals (range 90-130). Of all remaining known territories, 28 are within protected areas, 11 on unprotected crown land and 29 on private land. Forty-three per cent of remaining birds are thought to occur in the Mt Hartman Estate (Rusk 2010).
It inhabits a successional stage of dry, coastal scrub-woodland in the south-west, which comprises a closed canopy of leguminous (often thorny) trees and shrubs c.3-6 m high, a sparse understorey of shrubs and saplings, sparse to absent ground-cover and much exposed soil (Blockstein 1991). The flowering tree Haematoxylum campechianum is dominant in these areas (Rusk 1992, Baptista et al. 2015). On the west coast, its habitat includes some mixed deciduous/evergreen vegetation. It may have been always confined to xeric, coastal areas where climax vegetation was deciduous, seasonal forest and thorn woodland, but frequent natural disturbances (particularly hurricanes) kept the vegetation in a sub-climax condition (Rusk et. al. 2008). This temporary occupation of ephemeral patches and recolonisation of developing patches may be the normal life history pattern. Breeding is limited to the rainy season in the south-west, but is more extended on the less xeric west coast (Rusk 1998).
Habitat loss due to clearing for small plantations and charcoal production has been replaced in recent years with chronic and continuing habitat loss for residential housing, roads, commercial and other development. Habitat on private land is vulnerable to development and high land prices mean that it is not practical for the government to purchase these areas to ensure their protection (Anon. 2012). Forest clearing was substantially reduced at the Mt Hartman Estate by the late 1990s due to the establishment of the Mt. Hartman National Park and Dove Sanctuary and the cessation of farming on the remainder of the estate (Rusk 1998) but, in 1995, 50% of Perseverance was clear-cut for a planned quarry, with half the site now a sanitary land-fill (Rusk and Temple 1995). A lease was granted for a new quarry at this site in 2008, but that was temporarily halted in 2009 (Rusk 2008, 2010). Increases in squatters and cattle in the 1990s resulted in more disturbance at Perseverance, though currently habitat degradation is due to garbage and toxic fumes invading the site from the garbage dump across the road as well as spillover from the adjacent hurricane debris site (Rusk 2008, 2010). Population declines are likely to be compounded by high numbers of introduced mongooses, cats, rats and opposum predating eggs and fledglings, of which mongoose were found to be the most abundant (Rusk 2015), but rats the most widespread (Twyman and Hyslette unpubl. data). It is possible that mongooses and cats are able to climb diagonal branches and trunks to reach the birds. By 2012, mongoose numbers had reached levels whereby they were found to occur daily across much of Grenada Dove habitat (Bolton et al. 2015). A resort development proposed in 2015 at Mt. Hartman poses a significant threat to, and would have serious impact on the adjacent protected critical habitat unless mitigation measures including a predator exclusion fence are put in place to protect the species (B. L. Rusk in litt. 2016). This development will displace all doves outside the national park. Expanded national park boundaries were agreed to by the developer but are not yet legally established. Resort planning was halted in 2016, but may resume (B. L. Rusk in litt. 2016). Hurricanes pose a pertinent threat now that the remaining population is so small. Following hurricane Ivan in 2004, calling frequency by males during the breeding season appeared to have fallen significantly, possibly as a result of stress owing to limited resources (Rusk 2005). The hurricane damaged habitat structure and allowed the invasion of alien vines into suitable dove habitat. In the Mount Hartman Estate the dove was found to use man-made wells, and one which the birds used frequently was threatened by development (Bolton et al. 2015). Spread of disease (e.g. trichomonosis) between other bird species using these water sources is also a threat (Bolton et al. 2015).
Conservation Actions Underway
Grenada Dove is the national bird of Grenada, has been a focus of environmental education in schools and ecotourism, and features on stamps. In 1996, parts of the Mt Hartman and Perseverance estates were declared a national park and a protected area, respectively. A recovery plan was drafted in 1998 and a four-year GEF/WB funded Dry Forest Biodiversity Conservation Project based on stakeholder input was implemented from 2001-2006. In 2008, an updated 10 year conservation and recovery plan was drafted (Rusk et. al. 2008). In 2011, critical dove habitat on crown lands at the Beauséjour Estate (c.100 acres) received Government of Grenada cabinet approval for its protection and addition to the Perseverance Protected Area (Rusk 2011), but a government housing development is planned for this site. This species is legally protected from hunting and egg-collecting, but these threats are insignificant. Dove habitats on private lands at Beauséjour, Grenville Vale and Woodford, all IBAs, are recommended for protection in the 2010 Conservation and Management Plan for Perseverance Protected/Beauséjour Area. All currently occupied dove habitat are IBAs and are included in Grenada's System Plan for Parks and Protected Areas. Currently, all remaining dove habitat is on unprotected, privately owned land. A legislative review to address private lands slated for protection has taken place (2013). The Grenada Dove Conservation Programme (GDCP), with the Forestry and National Parks Department (FNDP), is collaborating with BirdsCaribbean with the aim of developing eco-tourism activities in two of the key areas for the species (Mt Hartman and Beauséjour) (Anon. 2013). This collaboration has resulted in extensive interpretation at the Mt Hartman Visitor Center, a school outreach programme and increased student site visitation. Predator control measures at dove sites were initiated in 2014, with over 1,000 mongoose trapped and removed at Mt Hartman in an 18 month period. The Grenada Dove Conservation Programme and Forestry and National Parks Department collaborated with the University of Chester (2014-2015) to study tropical dry forest changes (including dove habitat) using historical and current data, and to look at possible future changes using climate change modelling scenarios.
Conservation Actions Proposed
Habitat protection and restoration and predator removal should be priorities for conservation of this species (Rivera-Milán et al. 2015). Eliminate/mitigate further habitat loss. Carry out regular surveys and establish a long-term monitoring programme (Bolton et al. 2016) to monitor population trends and determine the sex ratio (and therefore the actual population) of remaining birds. Monitor rates of habitat loss and degradation. Continue and expand control programme to reduce mongoose, rat and cat presence in dove habitat and monitor and manage numbers of other introduced predators (Bolton et al. 2016). Undertake research into the species's ecology, including home range size and habitat preferences (Bolton et al. 2016). Ensure that the Mt Hartman and Perseverance reserves are effectively protected. Formally protect important habitat that falls within private lands (Rusk 2011) and protect the Mt Hartman national park from development impacts and predation with a predator exclusion fence. Address other limiting factors and implement species management activities (supplemental food /water). Develop incentives/regulations for protection of dove habitat on private residential lots in the south-west (adjacent to Mt Hartman), and Beauséjour and Woodford on the west coast (B. L. Rusk unpubl. data). Restore habitat at existing and new sites. Implement the revised recovery plan (Rusk et al. 2008). Establish two new subpopulations (Rusk et al. 1998) and consider establishing a captive breeding population. Provide alternatives to standing water sources such as 'leaky' hose water stations to reduce the risk of disease (Bolton et al. 2015).
31 cm. Medium-sized, plump bicoloured dove. Brown upperparts, with white forehead and white breast feathers that extend around shoulder. White underparts with pinkish-brown breast, plain dark wings, tail tipped white, and pale eye. Shows cinnamon underwing in flight. Pinkish red legs, feet and bare skin around the eyes. Similar spp. Eared Dove Zenaida auriculata is smaller, more uniform brown with dark eye and auricular mark, black spots on scapulars and no white in tail. Voice Mournful descending hoooo, repeated at seven to eight-second intervals.
Text account compilers
Sharpe, C.J., Symes, A., Wege, D., Wheatley, H., Benstead, P., Butchart, S., Calvert, R., Ashpole, J, Bird, J., Capper, D., Hermes, C., Khwaja, N.
Rusk, B., Ellard, J., Wege, D., Collar, N., Blockstein, D.
BirdLife International (2021) Species factsheet: Leptotila wellsi. Downloaded from http://www.birdlife.org on 20/10/2021. Recommended citation for factsheets for more than one species: BirdLife International (2021) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 20/10/2021.