Status and habitat description of the globally threatened Udzungwa Forest PartridgeXenoperdix udzungwensisthirty years after discovery

Abstract

Summary The Udzungwa Forest Partridge Xenoperdix udzungwensis was discovered in 1991 in the geologically old and eco-climatically stable Udzungwa Mountains (hereafter the Udzungwas) in Tanzania - a global biodiversity hotspot in the Eastern Arc Mountains of East Africa. The partridge is categorised as globally ‘Endangered’ and this study aims at assessing its population status and habitat requirements in the two separate montane forests where it was discovered c.30 years ago and for the first time using systematic playback technique. We estimate the partridge population at c.2,800 individuals (1,680–3,860) confined to less than 150 km2 and now confined to a single forest and with a clearly declining distribution within the last few decades since its discovery. The species is confined to evergreen closed (semi-closed) canopy forest habitat with leaf litter and sedges on the forest floor for feeding and cover. The partridge has become an emblem for the high concentration of endemic species of the Udzungwa Mountains National Park. At the same time there is a risk that this species could go extinct without notice if the Tanzanian authorities do not tackle two envisaged main drivers, namely fragmentation of the evergreen forest area over the last few centuries and current illegal hunting. Hence it seems crucial to allow natural expansion of its forest habitat in the Udzungwas and to eliminate hunting in the other forest within its recently known distribution where the population has presumably been extirpated. The partridge is remarkable as its closest relatives are in South-east Asia and it is used as a flagship species for the Udzungwas, which has one of the highest concentrations of endemic species on earth.

Nature Forest Reserves in Tanzania and their importance for conservation

“…However, since its upgrading to NFR status in 2016, increased management efforts supported by local and international agencies and implemented in close partnership with TFS have led to a considerable reduction in some other threats to this reserve, like tree cutting and farmland encroachment [ 33 ]. Hunting pressure and long-term forest encroachment may have extirpated the Udzungwa forest partridge species, Xenoperdix udzungwensis , from the Nyumbanitu forest within the Kilombero NFR, where it was still at least until 2016 [ 34 ]. On ground insights from all other NFR would likely also contain important stories of success and remaining challenges for NFR management.…”

Decadienal afforestation and risks to montane grassland amphibians in the Udzungwa Plateau, Tanzania

“…Our estimates of plantation growth are “minimum” estimates, because we cannot be certain that gains on forest cover in remotely sensed data were pine plantations and not growth in naturally forested areas. Visits to the protected native forests on the Udzungwa Plateau have not witnessed growth in these forests (which are much better monitored than grasslands) and have instead seen these to be continuously declining except for the National Park (Cavada et al, 2019; Dinesen et al, 2023; Jones et al, 2019). Thus, we fear our estimates of expansion of trees through non‐natives may be an underestimate.…”

Nature Forest Reserves in Tanzania and their importance for conservation

“…A similar process has recently begun to show positive results in the Kilombero NFR. Hunting pressure and long-term forest encroachment may have wiped out the endemic Udzungwa forest partridge species from the Nyumbanitu forest within the Kilombero NFR, where it was present in 2016 [31]. This was one of the only two forest fragments globally where the species occurred, both in the Kilombero NFR.…”