Lower reaches of the Sarysu River

Year of compilation: 2007

Site description
The lower reaches of the Sarysu river form part of the extensive clayey plains of the huge lowland semi-desert zone and are situated 150 km to the south of the district centre of Zhezkazgan and approximately 90 km to the north-east of the regional centre of Kyzyl-Orda where the Karaganda, Kyzyl-Orda and South-Kazakhstan regions abut. The lower reaches of the Sarysu are alluvial in origin. The main course flows through a ravine-like valley and there is a system of subsidiary ravines and gulleys extending far into the surrounding plateau. Within the IBA the river course forms a distinct flood-valley up to 1-1.5 km in width. The banks of the river vary in structure: the right side is higher and with a more rough terrain with frequent exposure of bedrock, the left one is rather smoothly sloping and shows evidence of ancient erosion only in its northern parts. Apart from scattered, poor qualirt woody and scrubby areas, the actual flood valley is covered by dense reedbeds. In the southern part of the site the left bank consists mainly of the sand cliffs/dunes, with some also on the right bank.

Key biodiversity
The site contains a high variety of habitats typical of the semi-desert zone and support a rather rich local avifauna. The heavily eroded slopes of the plateau has a healthy breeding population of Bubo bubo. Buteo rufinus and Aquila nipalensis also use these areas, but their numbers are quite low, especially the latter. Aquila heliaca appears to be distributed rather evenly along the river valley, except for the area of sand cliffs which are much lower. Judging by the number of old nests, it would appear that the Aquila helica population was formerly 3-4 times higher. The cause of this decline is thought to be the cessation of extensive grazing. Falco naumanni is common in all areas where the relief allows the establishment of nesting colonies, usually 2-3 pairs. Circus macrourus breeds along the entire Sarysu river vally, though the nesting density is not uniform. At the edge of the sandy areas, within the typical semi-desert habitat, Chlamydotis undulata occurs infrequently and, where the sand dunes encroach into the river valley, Tetrax tetrax is rather common. Phasianus colchicus is common in the scrub throughout the flood valley.

Pressure/threats to key biodiversity
One of the significant factors responsible for the deterioration of habitats, particularly those important by birds of prey, is the cessation of extensive cattle grazing in the region. This leads to a proliferation of tall weeds which, in due course, lead to a reduction in local roden populations and a decline in food supplies for birds of prey.

Recommended citation
BirdLife International (2023) Important Bird Areas factsheet: Lower reaches of the Sarysu River. Downloaded from on 29/03/2023.