Abstract
Estimations of honeybee colony winter losses in Poland have been carried out at Warsaw University of Life Sciences since 2008 (in 2008 they concerned the two winters of 2006/07 and 2007/08), using a preliminary questionnaire in 2008 and the standardized COLOSS questionnaire since 2009. During the first years of the survey, concerning the period of autumn 2006 - spring 2012, the multimode method of data collection was used, and beekeepers sent in between 393 and 769 questionnaires a year. Overall, the number of participants increased, but in particular voivodeships it fluctuated. The estimated overall winter colony loss in Poland was low during the winter of 2006/07 (10%) and quite low during the winter of 2008/09 (11.5%). In other years it was substantially higher reaching 15.2% in 2007/08, 14.8% 2009/10, as much as 18.3% in 2010/11 and then down to 15.8% in 2011/12. A similar pattern of average losses was observed, but each year, excluding the winter of 2010/11, at least 50% of beekeepers reported acceptable losses of only up to 10%. During the analysis of the spatial pattern of overall losses, some data which could blur the pattern were eliminated. The results suggest that such climatic factors as a warm autumn but also high summer precipitation, followed by low winter temperatures influenced the spatial distribution of the losses.