Small bird, big surprise: a 140-km range extension of the River Prinia Prinia fluviatilis in northwestern Kenya, with the first record from the Elemi Triangle
Thomas M. Butynski and Yvonne A. de Jong
Eastern Africa Primate Diversity and Conservation Program, Nanyuki, Kenya
The River Prinia Prinia fluviatilis Chappuis, 1974, is a small passerine of the family Cisticolidae, restricted to waterside and water-logged, sometimes seasonally dry, vegetation in otherwise arid landscapes. Its distribution consists of a series of isolated wetland “islands” along the Sahelian belt, from northern Senegal in the west to northwestern Kenya (Urban et al. 1997; BirdLife International 2018; eBird 2026). The eastern-most record was obtained by Finch (2005) in 2001 near Nanam (520 m asl), 20 km southeast of Lokichokio, Turkana County, extreme northwestern Kenya. This was an eastward range extension of about 2,500 km from southwestern Chad, and the first record for Kenya and East Africa.
Within its large and fragmented range, the River Prinia (Figure 1) is typically confined to tall grass, reeds, and bushes along permanent and seasonally flooded rivers, streams, lakes, and marshes. Forages on invertebrates from stems and leaves of grasses, shrubs, and trees. Like other prinias, the River Prinia moves actively through dense cover, often in pairs or small groups (Urban et al. 1997; Birdsoftheworld 2026; Oiseaux 2026).
Figure 1. River Prinia Prinia fluviatilis on Mesquite Neltuma juliflora, Lotikipi Plains, Turkana Country, northwestern Kenya.
In December 2025, during Phase Three of our Horn of Africa Antelope Survey, we encountered River Prinia twice on the Lotikipi Plains of northwestern Kenya and once in the Elemi Triangle (420–480 metres above sea level). All encounters were east of Lokichokio, extending the range 140 km to the northeast (Figure 2). These records were confirmed by Adam Scott Kennedy and Brian Finch based on photographs. All three encounters with River Prinia were of single birds foraging at 2–6 metres above the ground in Mesquite Neltuma juliflora (formerly Prosopis juliflora) forest monoculture on water-logged soil (Figure 3).
Figure 2. Encounters with River Prinia Prinia fluviatilis in northern Turkana County, northwestern Kenya, in December 2025 depicted in yellow. Site of the first record of the River Prinia in Kenya is depicted in green (Finch 2005).
Mesquite is a widespread invasive species in Kenya, being native to Mexico, South America, and the Caribbean. This plant, introduced to Kenya in the 1970s (Mohamed et al. 2025), has probably created the only suitable habitat in the region for River Prinia (Figure 4). The ‘Mesquite forests’ of northern Turkana comprise trees as tall as 14 m and with a diameter at breast height of up to 30 cm (Figure 3).
Figure 3. One of the three Mesquite Neltuma juliflora forests on the Lotikipi Plains, Turkana County, northwestern Kenya, where the River Prinia was found.
The Lotikipi Plains of northwestern Kenya comprise an extensive semi-arid savanna ecosystem dominated by a mosaic of open grasslands, acacia–commiphora bushlands, dwarf shrublands, and localized riparian woodlands associated with seasonal drainage lines on black-cotton soil. Vegetation structure and productivity are primarily determined by a highly variable rainfall, soil characteristics, seasonal flooding, and drainage. The extensive grasslands are dominated by drought-tolerant perennial grasses interspersed with annual herbs following rainfall. The more common trees are in the genera Acacia (Vachellia), Commiphora, Balanites, Boscia, and Grewia, but nowhere do these trees occur in dense woodlands. In recent decades, large areas on the Lotikipi Plains have undergone substantial woody plant encroachment led by the rapid expansion of Mesquite and, to a lesser extent, the native, but aggressively spreading, False Umbrella Thorn Acacia (Vachellia) reficiens. This has resulted in a reduced grass cover, altered habitat structure, and diminished forage availability for grazing ungulates (Mohamed et al. 2025).
Figure 4. River Prinia Prinia fluviatilis on Mesquite Neltuma juliflora, Lotikipi Plains, Turkana County, northwestern Kenya.
The River Prinia is currently assessed as ‘Least Concern’ on The IUCN Red List of Threatened Species (BirdLife International 2018). Its dependence on riparian and wetland habitats, however, makes this bird potentially vulnerable to changes in water regimes, drainage of wetlands, over-grazing, over-browsing, and agricultural expansion along drainages. In northwestern Kenya, dense Mesquite bushlands and forests appear to be the stronghold, if not the only habitat, for River Prinia. It is likely that the River Prinia is now a resident bird in Kenya and that further research will find that it is a fairly common species across northern Turkana County. The geographic range of this bird is expected to expand in Kenya as Mesquite continues to spread.
River Prinia might not have been present in Kenya prior to the introduction of Mesquite in the 1970s. Some other bird species present in the Mesquite forests where we found River Prinia that were, likewise, probably not present at these sites prior to the establishment of Mesquite, include:
- Northern White-faced Scops Owl Ptilopsis leucotis
- Red-chested Cuckoo Cuculus solitarius
- Common Bulbul Pycnonotus barbatus
- Spotted Morning Thrush Cichladusa guttata (Figure 5)
- African Paradise Flycatcher Terpsiphone viridis
- Slate-coloured Boubou Laniarius funebris
- Lesser Masked Weaver (Ploceus intermedius)
Figure 5. Spotted Morning Thrush Cichladusa guttata on Mesquite Neltuma juliflora, Lotikipi Plains, Turkana Country, northwestern Kenya.
Northern Carmine Bee-eater Merops nubicus (Figure 6) and Blue-cheeked Bee-eater Merops persicus (Figure 7) were two of the more obvious bird species observed on the edge of the Mesquite forests where we found River Prinia.
Figure 6. Northern Carmine Bee-eater Merops nubicus on the edge of Mesquite Neltuma juliflora forest on the Lotikipi Plains, Turkana County, northwestern Kenya.
Figure 7. Blue-cheeked Bee-eater Merops persicus on the edge of Mesquite Neltuma juliflora forest on the Lotikipi Plains, Turkana County, northwestern Kenya.
References
BirdLife International. 2018. Prinia fluviatilis. The IUCN Red List of Threatened Species 2018: e.T22713618A132268388. Website: https://www.iucnredlist.org
BirdsoftheWorld. 2026. River Prinia Prinia fluviatilis. Cornell Lab of Ornithology. Website: https://birdsoftheworld.org/bow/species/rivpri1/cur/introduction
eBird. 2026. River Prinia Prinia fluviatilis. Website: https://ebird.org/
Finch, B. 2005. River prinia Prinia fluviatilis near Lokichokio: a new species for Kenya and East Africa. Scopus 25: 55–59.
Mohamed, A. M., Hassan, E., Maalim, A. A., Kagombe, J., Hanshi, N. S., Osman, A. A. and Bile, Y. A. 2025. Control and management of Neltuma juliflora (formerly Prosopis juliflora) invasive weed: a boon for communities in drylands of Kenya. Policy Brief No. 2. Kenya Forestry Research Institute, Muguga, Kenya.
Oiseaux. 2026. River Prinia Prinia fluviatilis. Website: https://www.oiseaux.net/en/oiseaux/river.prinia.html
Urban, E. K., Fry, C. H. & Keith, S. (eds.) 1997. The Birds of Africa. Volume V. Academic Press, London.
Tags: east Africa, Elemi triangle, Kenya, Lotikipi, Prosopis, River prinia, Turkana