Data Zone
Justification of Red List category
This species is confined to only two islands in the Lesser Antilles: Dominica and Martinique. Hurricane Maria devastated forests on Dominica in 2017, and is thought to have caused a concomitant reduction in this species' population. In addition, at least on Martinique the species occurs largely above 800 m, where densities are high but climate driven upslope habitat shifts are proceeding at pace. In combination, and noting that major hurricanes are predicted to occur at higher frequency due the increases in sea surface temperature, these threats indicate that there is an ongoing decline in the extent and quality of the species' habitat. However, this species has demonstrated some tolerance to past hurricanes, from which it can recover quickly, and the nature of threats means it is not found in few locations. despite the relatively small range. Additionally, the high densities of the species from montane areas indicate is still has a large population size. Accordingly it is listed as Near Threatened.
Population justification
The species is described as fairly common, but patchily distributed (Stotz et al. 1996, Kirwan et al. 2019). The density of this species has been calculated with very different outcomes, perhaps reflecting significant variation at different altitudes. On Martinique, density of 'at least 3-4 individuals/km2' noted at unknown elevations (Schuchmann and Boesman 2021), while surveys in 1996 found it the 7th commonest bird on Martinique in favoured montane forest, at a density of 3.5-7.7 individuals/ha (equivalent to 350-770 birds/km2) (De Mercey 1996). The lower estimate of Schuchmann and Boesman (2021) is suspected to be overly precautionary (P. Feldmann in litt. 2024) and at least at higher elevations the density calculated by De Mercey (1996) is probably more realistic. If the De Mercey (1996) density is used for high-elevation forests on Martinique, the population size on this island alone greatly exceeds 10,000 mature individuals with similar numbers from Dominica. These numbers do not account also for the species' (scarce) presence in the lowlands. Accordingly the global population size is estimated to number 25,000-150,000 mature individuals.
Trend justification
Difficult to interpret, but suspected to be declining in response to habitat loss and degradation, and potentially climate-induced shifts in habitat extent. There are reports that this species is particularly sensitive to hurricanes: it reportedly became substantially rarer on Dominica due to hurricanes in the 1980, from which it apparently recovered only slowly (Schuchmann and Boesman 2021). Likewise, in the aftermath of Hurricane Maria on Dominica in 2017, the species' abundance dropped drastically (Fairbairn et al. 2022, see also eBird 2023). However, hummingbirds on Guadeloupe recovered quickly after Hurricane Hugo in 1989 (P. Feldmann in litt. 2024) and given the Lesser Antilles is a region with a naturally high occurrence of hurricanes, it is assumed this species has some resistance to these threats. But it is projected that the intensity and probably the frequency of hurricanes will increase as a consequence of climate change (Knutson et al. 2010, Walsh et al. 2016). It can therefore not be ruled out that the rate of habitat loss and mortality may begin to rise faster than these recoveries take place, and the species may begin to decline in the long-term (rather than undergo fluctuations in response to hurricanes). It is also possible that climate change may induce habitat extent shifts upslope, thereby reducing the total area of suitable habitat available to this species, which evidently is much commoner at higher elevations.
Over the last ten years, 18-20% of tree cover has been lost in this species' range (Global Forest Watch 2023, using Hansen et al. [2013] data and methods disclosed therein). However, this high rate is largely driven by the impacts of Hurricane Maria on Dominica, which caused a total rate of tree cover loss of over 18% in 2017 (Global Forest Watch 2023). On Dominica alone, tree cover loss amounted to 36-37% over the past ten years (Global Forest Watch 2023). Forest cover on Martinique however has remained largely stable over the past two decades (Global Forest Watch 2023). In the years prior to and after Hurricane Maria, tree cover loss has been very low at <0.1% per year (Global Forest Watch 2023). Based on the overall rate of tree cover loss and reports of direct mortality, the rate of population decline is suspected to have been between 10-29% over the past ten years. It is however noted that this is largely driven by declines of the subpopulation on Dominica, while the subpopulation on Martinique is likely stable.
The species occurs on Dominica and Martinique. This restricted range results in a small extent of occurrence and a moderately small maximum area of occupancy, assuming all mapped area is occupied. Within this range forest cover loss totals 18-20% in the past ten years (Global Forest Watch 2023, using Hansen et al. [2013] data and methods disclosed therein), most due to the direct effects of Hurricane Maria. Although this species has demonstrated resistance and fast recovery to previous strong hurricanes, these impacts along with potential climate change driven altitudinal habitat shifts are inferred to be causing a decline in habitat extent and quality. It is common at higher elevations (De Mercey 1996, P. Feldmann in litt. 2024), but appears to be found widely on the islands (Kirwan et al. 2019, Schuchmann and Boesman 2021).
It inhabits humid forest, forest edges and second growth from sea-level to at least 1,300 m, basically the maximum elevation within the range (eBird 2023). It prefers the highlands above 800 m where high densities have been recorded on Martinique (De Mercey 1996), but is also found at sea level (Kirwan et al. 2019, Schuchmann and Boesman 2021).
Major hurricanes represent the most acute threat to the species. These storms can impact the population both directly by causing high rates of mortality immediately after the event, as well as indirectly by damaging forests within the range (Fairbairn et al. 2022, Global Forest Watch 2023). The effect on the population size is large, with severely reduced abundance over several years and at least following some storms, slow recovery (Schuchmann and Boesman 2021, Fairbairn et al. 2022). The projected increase in intensity and probably frequency of hurricanes in the Caribbean (see e.g. Knutson et al. 2010, Walsh et al. 2016) implies that the risk of these events occurring is increasing. However, the species has evolved in a region that has a high hurricane frequency and congeners have demonstrated resilience in recovering from major hurricanes in the past, notably in 1989 when Hurricane Hugo hit Guadeloupe, such that the impact of hurricanes is still not likely to represent a threat that can drive this species to extinction in a handful of events.
At least on Martinique, high densities of the species predominately occur above 800 m (De Mercey 1996, P. Feldmann in litt. 2024). As a result of temperature and precipitation changes due to climate changes montane habitats are already shifting upslope on other islands in the region (P. Feldmann in litt. 2024), with resulting ongoing degradation and loss of area of suitable or optimal habitat where the bulk of the population is found.
Conservation Actions Underway
The species is listed as Endangered at the national level in Martinique (UICN Comité français et al. 2020).
Conservation Actions Proposed
Research the species's ecology, biology and behaviour. Investigate the impact of habitat loss through hurricanes on the population size. Monitor the population trend.
Protect suitable habitat within the range. Establish forest restoration programmes to increase the area of habitat available to the species with the aims to facilitate population recovery and to buffer the impacts of future hurricanes.
Text account compilers
Hermes, C., Berryman, A., Martin, R.
Contributors
Feldmann, P.
Recommended citation
BirdLife International (2024) Species factsheet: Blue-headed Hummingbird Riccordia bicolor. Downloaded from
https://datazone.birdlife.org/species/factsheet/blue-headed-hummingbird-riccordia-bicolor on 23/11/2024.
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 23/11/2024.