Assessor: Matthew Child
Off-take under controlled trophy hunting is not suspected to be high enough to have any effect on the population, especially if trophies are increasingly sourced from introduced captive-bred subpopulations.
However, Blue Duikers are suspected to be adversely affected by bushmeat hunting (Venter et al. 2016). Snare removal over most areas of its range is ongoing, which suggests continuous trapping effort within semiurban areas. Snaring within the rural and farming communities is a big problem, with continual snare removal on a bi-weekly basis necessary to keep poaching at bay. Often animals are left in snares, dead or dying, suggesting that the practice of snaring is not out of desperation. Snaring may be the major cause of a continuing decline in mature individuals. They are easily caught in snares as they create well-marked paths between bed sites and feeding sites, over which snares can be laid. For example, locals claim disappearance of Blue Duiker from Ingele Forest (Weza), KZN, and researchers have yet to confirm their presence in the forest after 30 km of transect surveys (Y. Ehlers-Smith pers. obs. 2015). Similarly, illegal dog hunting for sport is suspected to be causing localised subpopulation declines or extinctions (Venter et al. 2016).
In a recent survey of private landowners within Blue Duiker range (Jones 2015), respondents listed poaching and dogs as common threats.
Although hunting Blue Duiker is not suspected to be specifically targeted, the opportunistic hunting of this species across most of its range, and the edge effects of its habitat make it vulnerable.
Jones AL. 2015. The potential habitat space of caracal and blue duiker in KwaZulu-Natal. M.Sc. Thesis. University of KwaZuluNatal, Pietermaritzburg, South Africa.
Venter J, Seydack A, Ehlers-Smith Y, Uys R, Child MF. 2016. A conservation assessment of Philantomba monticola. In Child MF, Roxburgh L, Do Linh San E, Raimondo D, Davies-Mostert HT, editors. The Red List of Mammals of South Africa, Swaziland and Lesotho. South African National Biodiversity Institute and Endangered Wildlife Trust, South Africa.
https://www.ewt.org.za/Reddata/pdf/Artiodactyla%20(36%20assessments)/2016%20Mammal%20Red%20List_Philantomba%20monticola_VU.pdf
The estimated area of occupancy (AOO) ranges from 1,415–2,858 km2 , depending on whether we include only currently occupied forests or all potentially viable forests within the extent of occurrence (EOO). Population estimates range widely: using a density range of 5–35 individuals / km2 yields a total mature population estimate of 3,538–50,015 individuals (using a 50% mature population structure). Under a precautionary purview, we suspect the lower estimates are more realistic given the wide variation in density and occupancy between patches on fine spatial and temporal scale, combined with multiple ongoing threats that may be causing local subpopulation decline or extinction (Venter et al. 2016).
Even taking a precautionary outlook, the minimum mature population size is estimated to be >2,500.
Venter J, Seydack A, Ehlers-Smith Y, Uys R, Child MF. 2016. A conservation assessment of Philantomba monticola. In Child MF, Roxburgh L, Do Linh San E, Raimondo D, Davies-Mostert HT, editors. The Red List of Mammals of South Africa, Swaziland and Lesotho. South African National Biodiversity Institute and Endangered Wildlife Trust, South Africa.
https://www.ewt.org.za/Reddata/pdf/Artiodactyla%20(36%20assessments)/2016%20Mammal%20Red%20List_Philantomba%20monticola_VU.pdf
Animals are caught in snares and killed.
There is a large overlap in offspring due to relatively short lambing interval (265 days) and they have a gestation period of 207 days (range = 196–216) (Bowland 1990). This, however, may not be applicable for moderate to lower quality habitats with lower fertility rates (Venter et al. 2016). As growth rates are dependent on habitat quality, which is deteriorating across most of its range, we assume regeneration potential is low.
Bowland AE. 1990. The ecology and conservation of blue and red duiker in Natal. Ph.D. Thesis. University of KwaZulu-Natal, Pietermaritzburg, South Africa.
Venter J, Seydack A, Ehlers-Smith Y, Uys R, Child MF. 2016. A conservation assessment of Philantomba monticola. In Child MF, Roxburgh L, Do Linh San E, Raimondo D, Davies-Mostert HT, editors. The Red List of Mammals of South Africa, Swaziland and Lesotho. South African National Biodiversity Institute and Endangered Wildlife Trust, South Africa.
https://www.ewt.org.za/Reddata/pdf/Artiodactyla%20(36%20assessments)/2016%20Mammal%20Red%20List_Philantomba%20monticola_VU.pdf