Chokpak Pass is the narrowest place between Talas Alatau and Karatau, Tian-Shan ranges, having heights of 2500 – 4200 meters. The height of this pass is up to 1200 meters above sea level. It is here that a huge number of birds migrate annually from north to south and south to north. Due to the fact that the Tien Shan is located in the meridional direction, the birds fly around these mountains. Accordingly, in the spring they fly from west to east, and in the fall – from east to west. This phenomenon has long been noticed by scientists and since the 60s of the last century they have been regularly observing bird migrations through the Chokpak Pass. Here, in the season of migrations, ornithologists of the ringing center set traps for catching birds. These traps are called “Helgolland”, named after the place where they were first used (island Helgoland in the North Sea, Germany).
These traps have the appearance of large venterey with an entrance width of 35 and a height of up to 12 meters. The length of this “Venter” 50 meters. The trap ends with a receiving chamber, from which birds enter the replaceable cages, which change as birds accumulate. Birds are best caught in headwinds, they tend to fly lower. So in the spring – this is the east wind, in the fall – the west. In calm weather, the catchability of networks is much lower and a visit to the station is not so interesting. This should be considered when planning excursions. During multi-day ornithological tours, the wind direction is determined in the morning, before planning a day excursion.
In addition to the Helgoland traps at the Chokpak banding station, birds are caught in spider webs. As a rule, small dendrophilous species, which stop to rest and feed in the forest belts on Chokpak Pass, fall into them. The catchability of these networks is higher in calm weather.
Over the years, the station has been caught and ringed over 280 species. The total number of birds caught is about 2 million birds. There are days when more than 10 thousand birds are caught per day. In spring, two species of sparrows make up the bulk of the birds: the black-chested and Indian swallows, and in the autumn, corvids (rooks and daws).