|Most recent IBA monitoring assessment|
|Year of assessment||Threat score (pressure)||Condition score (state)||Action score (response)|
|2015||not assessed||favourable||not assessed|
|For more information about IBA monitoring please click here|
Bolshoi Kak lake lies at the western edge of a group of widely separated waterbodies on the left bank of the upper middle reaches of the Ishym river valley. Administratively the site is located in the western corner of the Northern Kazakhstan region, very close to the interregional border. The lake is situated 280 km south-west of the regional centre of Petropavlovsk and 30 km south-west of the district centre of Timiryazevo. 25 kms from the eastern boundary of the site there is a railway running north-south. The site occupies a small part of the southern outer range of the West-Siberian Lowlands. The major type of land form and vegetation is forest-steppe, though within the site itself isolated forest stands are absent. More than half of the surrounding mesophylic steppe was converted to agriculture about half a century ago and now about 80-85% of the area are crop fields. Bolshoi Kak lake is a rather shallow waterbody of irregular oval form, stretching 9.3 km in length and 7.3 km in width, set in a shallow hollow. The lake is dependent on the intake of seasonal melt-water floods and, along with several associated waterbodies in the region, is subject to cyclic filling-up. The banks are void of any significant quantities of emergent vegetation. The central part of the lake, with a maximum depth of only about 1 m, is surrounded by a broad zone of muddy shoals. In years when water levels are low, the lake reduces in size by 20-40%.
Large numbers of waterfowl and shorebirds occur in both autumn and spring. In some years, for example 1995, 1997, 2000 and 2005, even in spring, one time aggregations of waterfowl totalled 20-25,000 birds. Whilst it is difficult to determine accurately individual species totals, the cumulative appraisal of several years data suggests the following annual numbers: Anser albifrons 25-30,000, Branta ruficollis 5-7,000, Cygnus cygnus up to 3,000. On passage, especially in autumn, there also occur impressive concentrations of Grus grus – 1.5-2,000 birds. Similarly, five Haliaeetus albicilla were recorded on 20.10.2007. Passage wader numbers are also high, for example in late May 2003, at one random vantage point 133 Numenius arquata were counted. Himantopus himantopus and Recurvirostra avosetta appear to be very common. In summer the lake supports breeding surface-feeding ducks. In mid-summer the site is known to be frequently visited by non-breeding flocks of Cygnus cygnus and Cygnus olor. Anser anser numbers begin to increase from the end of July.
Non-bird biodiversity: Of mammals several species of mustelid occur - Mustela nivalis, Mustela erminea, Mustela eversmanni, Meles meles and Mustela sibirica. Larger predators include Canis lupus, Vulpes vulpes, and more rarely encountered, Vulpes corsac and Nyctereutes procyonoides. Bordering the lake are a few areas of slightly modified steppic landscape still featuring an assortment of rich-herbage-motley-turf-grass associations.
BirdLife International (2023) Important Bird Areas factsheet: Bolshoy Kak Lake. Downloaded from http://www.birdlife.org on 28/01/2023.