43 Bird Census News 2012, 25/2: 43-52 Introducion Winter condiions inluence signiicantly bird nest- ing success and the condiion of a populaion as a whole. The larger the number of birds that perish during harsh winters, the smaller the populaion that starts breeding in spring. Ater an excepion- ally long and severe winter, many birds are in bad condiion. Breeding starts later and clutches are in general smaller than usual. In paricular early spring cold spells with heavy snowfall, occurring ater the arrival of most migratory birds, have a se- vere effect on survival. In order to examine the trends of wintering birds, several countries started to organise speciic bird counts. In the USA, the so-called Christmas Bird Count is one of the oldest bird monitoring schemes in the world. It started in 1900 and is sill widely used all over the country (Naional Audubon So- ciety 2010). Finland has also a long tradiion of winter bird couning, using transects. This started in 1956/57 (Koskimies & Rajala 1957). In Sweden wintering mainland birds are tradiionally moni- tored by using a point count method (Vinterfågel- räkningen 2012). In Finland, with ime it became clear that the trend results obtained by one single winter count, could be substanially improved by addiional counts in November and February. In Estonia we started similar winter bird counts in 1987 to get a beter knowledge of the presence and abundance of terrestrial wintering birds. The winter of 2011/12 was our 25 th season. Combined breeding populaion trend indices of terrestrial birds are frequently used to provide general indicators for taxonomic species groups or habitat speciic species groups, e.g. the farmland and forest birds indicators (Gregory et al. 2005; Gregory et al. 2008). We tried to test if producing a “winter bird indicator” was possible, using our long-term data on winter counts of farmland birds in Estonia. Here we present and comment the long- term trends of the 25 most common winter birds in Estonia and the irst naional Winter Farmland Bird Index for the period 1987-2011. Material and Methods We use transect counts without distance belts and a length of 10 km. All birds seen and heard are counted. Each transect is visited three imes, during the Autumn Count (15 to 28 November), the Christmas Count (25 December to 7 January) and the Spring Count (15 to 28 February). Observaions are recorded on special forms and entered in a database (MS Access). This database contains now 42,660 records of the 56 most nu- merous winter bird species and a small number of occasionally wintering species: in total, 643,643 observed birds. The observaions collected during the winter bird counts are assigned to eight broad habitat cat- egories: a) Discharge sites: sites where waste has been disposed; A review of 25 years of mainland winter bird counts in Estonia Jaanus Elts Estonian Ornithological Society / University of Tartu, Veski 4, 51005 Tartu, Estonia Jaanus.Elts@eoy.ee Abstract. Estonia has a long-term monitoring programme for wintering land birds running since 1987. Permanent transect counts without using distance belts are conducted three imes during the winter and 30-40 transects are counted annually. During the last 25 years nine species showed a stable trend, while ive species were increasing and seven decreasing. In 2012 we calculated for the irst ime an Estonian winter farmland bird index (WFBI), using only those nine species of which an important part of the populaion has been observed in farmland and open landscape. The index shows a moderate decrease over the last 25 years.