Justification of Red List Category
There are no robust population estimates for this species (Brink and Whitecross in prep. 2021). However, the species has a limited range (del Hoyo et al. 1994) and usually occurs at low densities (Seddon et al. 1999). The population is therefore suspected to fall into the band of 1,000-3,000 individuals, roughly equivalent to 670-2,000 mature individuals.
The population is inferred to be in decline owing to ongoing habitat destruction (Global Forest Watch 2021; Brink and Whitecross in prep. 2021).
Modelling by Brink and Whitecross (in prep. 2021) estimated that habitat loss since 2000 ranged from 5.3% in areas with a probability of occurrence of >10%, to 19.3% loss in areas with a probability of occurrence of >80%. Assuming that the population declines at a similar rate to habitat loss, this is equivalent to a rate of decline of 6.4-23% over three generations (24.21 years [Bird et al. 2020]). The models used by Brink and Whitecross (in prep. 2021) did not account for land-use, and therefore may include suboptimal habitats such as plantations. The resulting calculations of percentage habitat loss are therefore likely to be underestimated, however there is currently no evidence suggesting that habitat loss or the consequent population decline is exceeding 30% over three generations. The rate of decline is therefore placed in the band 6-29% over three generations, and based on the current threats, it is suspected to continue at the same rate into the future.
Circaetus fasciolatus occurs from southern Somalia, Kenya, Tanzania, Mozambique to north-eastern South Africa, extending up the Save River (Mozambique) to south-eastern Zimbabwe (Brown et al. 1982). It is generally found within 20 km of the coast, except along major rivers (del Hoyo et al. 1994), in the lower Tana River forests in Kenya, the Usambara Mountains in Tanzania, and in Zimbabwe (Brown et al. 1982). It is uncommon, occurring at low densities, over most of its range (Brown et al. 1982; Seddon et al. 1999) but is locally common in the East Usambara Mountains (Stuart and Hutton 1977; L. Borghesio in litt. 2016). In South Africa, where it has suffered a range reduction (no longer found in the southerly part of its former range), the total population is only 40-50 pairs (Harrison et al. 1997), and between Southern African Bird Atlas Projects (SABAP1 1987-1992; SABAP2 2007-present) it has suffered a possible 16% decline in range in South Africa (Cooper 2015). In the early 1990s it was recorded in only 16 out of 31 coastal forest blocks in Kenya and Tanzania (Burgess and Muir 1994), and a more recent survey recorded it in only 24 out of 41 forests (L. Bennun in litt. 1999).
It is a secretive raptor feeding almost exclusively on snakes and lizards (Brown et al. 1982), but also taking rodents, amphibia, arthropods and birds (del Hoyo et al. 1994). It is confined mainly to dense coastal and riverine forest, also ranging into adjacent marshes and floodplains (del Hoyo et al. 1994), and also further inland in similar forest patches to riverine habitats (D. Parkes in litt. 2016). Anthropogenic habitats adjacent to forest are used for foraging and the species may nest in plantations of introduced Eucalyptus spp. (Borghesio et al. 2008). In fact its range decline in South Africa may be attributable to a loss of plantations and cultivated land (Cooper 2015). The species is sedentary and resident throughout much of its range, except for some movement north into Kenya during the dry season (May-September). Egg-laying occurs in July-October in East Africa and September-October in southern Africa. Its small nest is constructed from sticks, well-hidden amongst and supported by creeping plants (Parkes 2007; D. Parkes in litt. 2016). The clutch-size is one (del Hoyo et al. 1994). Breeding territories are between 2 and 3 km2, though there can be some overlap between pairs (D. Parkes in litt. 2016). When not breeding it will spread further away from the forest patches and hunting territories will be much larger (D. Parkes in litt. 2016).
Coastal forest is threatened with degradation and fragmentation (particularly along rivers) (del Hoyo et al. 1994) as a result of the extraction of wood for use as timber, charcoal, poles and firewood (Burgess and Muir 1994). Slash and burn agriculture threatens its forest habitat (although recently some practitioners of this were moved away from a known area for this species; D. Parkes in litt. 2016), and the loss of cultivated land and plantations has created local range declines (Cooper 2015). In Mozambique, it probably no longer occurs on the coast between the Limpopo and Save rivers due to human population pressure and deforestation, while the population south of the Save river is probably fewer than 50 birds (V. Parker in litt. 1999). In South Africa, much of its former range has been lost to the expansion of plantations, agricultural activities and other anthropogenic developments. More than 80% of the Indian Ocean Coastal Belt Forest has already been lost and fragmented due to these pressures, whilst the remaining habitat is projected to undergo significant changes due to climate change (Colyn et al. 2020).
Conservation Actions Underway
CITES Appendix II. Research into the distribution and rates of habitat loss is currently being conducted by BirdLife South Africa.
60cm. A small snake-eagle with barred underparts and three white bars on the relatively long tail. Dark brown upperparts and rufous brown underparts barred white below breast. Greyish face. Juvenile white below streaked with black. Yellow cere and legs. Similar spp. Western Banded Snake-eagle C. cinerascens has a single pale bar across a short tail, and has less barring on the underparts.
Text account compilers
Bennun, L., Borghesio, L., Brink, C., Colyn, R., Evans, M., Martin, R., O'Brien, A., Parker, V., Parkes, D., Robertson, P., Symes, A., Taylor, J. & Westrip, J.R.S.
BirdLife International (2022) Species factsheet: Circaetus fasciolatus. Downloaded from http://www.birdlife.org on 04/07/2022. Recommended citation for factsheets for more than one species: BirdLife International (2022) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 04/07/2022.