Justification of Red List Category
Although the species has a restricted range, it does not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence <20,000 km2 combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). The population is considered stable and hence does not approach the thresholds for Vulnerable under the population trend criterion (>30% decline over ten years or three generations). The population size is fairly large, and hence does not approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). For these reasons the species is evaluated as Least Concern.
The species is described as fairly common within its small range (Cheke et al. 2001). Assuming that it occurs at similar densities to a congener, Lovely Sunbird (Aethopyga shelleyi), at 49.1 individuals/km2 (Santini et al. 2018), with 10% of the mapped range likely occupied, the population may thus number 37,000 individuals, roughly equating to 25,000 mature individuals. However, the species is thought to occur at lower densities than congeners across its suitable habitat (P. Simpson in litt. 2020). Assuming that this value is a maximum therefore, the population is tentatively placed in the band of 15,000-24,999 mature individuals.
Forests within the range of the species are not thought to be under imminent threat. Recent fores loss estimates remain low at <5% (Tracewski et al. 2016, Global Forest Watch 2020) over a 3-generation period (10 years; Bird et al. 2020). The population is therefore suspected to be stable in the absence of evidence for any substantial declines or threats.
This species is endemic to Mindanao, Philippines, where it is fairly common at sites including on Mt Malindang (race malindangensis at 1,600 m; Nuñeza et al. 2006), Mt Kitanglad, Mt Apo (at 1,900-2000 m; Mohagan et al. 2015), Mt. Hilong-hilong (at 1,115-1,810 m; Paz et al. 2013), Mt Pasian and Lake Sebu (nominate boltoni), and Mt Busa and Mt Matutum (race tibolii); this latter taxon ranging on Busa from 1,300 m upwards and on Matutum from 820 m upwards. The species is seldom recorded below 1,800 m on Mt. Apo and Mt. Kitanglad (P. Simpson in litt. 2020).
It generally occurs in flowering trees and shrubs in stunted (and mossy) forest above 1,500 m. The species has also been recorded in upper montane forests of Mt. Apo (Mohagan et al. 2015) and in the mossy forests of Mt. Malindang (Nuñeza et al. 2006). It has been recorded breeding in January-July. The species is known to forage singly, in pairs, and occasionally in mixed-species flocks (Cheke and Mann 2020).
Although its area of occupancy must be very small, forest loss remains low (Tracewski et al. 2016, Global Forest Watch 2020). Thus, its habitat is considered fairly secure.
Conservation Actions Underway
Restrictive management in Mt. Hilong-hilong has been imposed by the Department of Environment and Natural Resources-Caraga (Paz et al. 2013).
Text account compilers
Benstead, P., Bird, J., Nuñeza, O.M., Simpson, P. & Taylor, J.
BirdLife International (2021) Species factsheet: Aethopyga boltoni. Downloaded from http://www.birdlife.org on 09/05/2021. Recommended citation for factsheets for more than one species: BirdLife International (2021) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 09/05/2021.