Krankesjöns Ringing Station

Location

Krankesjön is a well known birding location in southern Sweden: a shallow, bird-rich lake surrounded by a narrow belt of reeds and woodland. It is located in a military area, which has kept it pretty well conserved, and is also where Lund University's field station (Stensoffa) is based. A lot of research on all kinds of animals and plants (including bird ringing) takes place at this location, but this is the first attempt to undertake constant-effort ringing.

Methods

Ringing is an old method to individually mark birds for scientific purposes. Here, it is undertaken under license issued by the Swedish Ringing Centre (Natural History Museum, Stockolm). The most basic procedure involves capturing birds with mist-nets, recording species, age and sex, measuring size (wing length) and condition (weight) and releasing the birds, unharmed, with a metal ring bearing a unique number and the address of the ringing centre. When carried out by experienced ringers, the impact on the birds is negligible and the benefits can be important for fundamental as well as applied research, including conservation. The constant-effort procedure allows comparability of the number of birds caught.

Objectives

Constant-effort sites are used throughout Europe, with very similar procedures, to monitor bird populations. In addition to the changes in abundance, the ringing data allows to determine changes in productivity (measured as juvenile to adult ratio), as well as changes in survival (using between-year recoveries). Furthermore, the ringing procedure allows to monitor bird species that are difficult to census using other methods such as transects, point counts and territory mapping. Bird monitoring provide information on the overall health of the environment (birds as indicators), and can also be important for particular, threatened species and to assess the effect of conservation measures and environmental changes. Ringing birds at this station also contributes to other scientific projects and to train students.