April is a busy time for us at the Bee Informed Partnership. Many of our tech teams are sampling for the first time in some regions and it is also the month where we put much of our focus toward the launch and analysis of our Annual Loss and Management Survey. The preliminary loss results are in and, as usual, they are interesting.
For the 2016-2017 winter season, 4,963 beekeepers in the United States provided validated survey responses. Collectively, these beekeepers managed 363,987 colonies in October 2016, representing about 13% of the country’s estimated 2.78 million managed honey producing colonies. An estimated 21.1% of colonies managed in the United States were lost over the 2016-2017 winter. This represents an improvement of 5.8 percentage points compared to the previous 2015-2016 winter, and is below the 10-year average total winter loss rate of 28.4% (Figure 1). These winter losses were the lowest recorded since the survey began in 2006-07.
Beekeepers not only lose colonies in winter (October – March) but also throughout summer (April – September). The 2016 summer colony loss rate was 18.1%. When all the survey results were combined, beekeepers lost 33.2% of their colonies between April 2016 and March 2017. This is the second lowest rate of annual colony loss recorded over the last 7 years.
Figure 1: Summary of total overwintering colony losses in the United States across eleven years of conducting the winter loss survey (yellow bars; October 1 – April 1) and across six years of conducting the summer (April 1 – October 1) and annual loss survey. Total annual loss values (orange bars) include total winter and total summer losses. The acceptable winter loss rate (grey bars) is the average percentage of acceptable yearly colony losses declared by the survey participants in each year of the survey.
We did see, on average, lower Varroa mite levels last fall than in previous years and this may attribute to the lower recorded losses this year. You can read the full report at our website but we want to take this opportunity to explain the survey and the results. Before BIP started recording losses, there were no other numbers to compare what “normal” losses are for beekeepers and what is excessive. We are also trying to make the results more accessible every year by improving our website.
The Bee Informed Partnership reports total loss, or a weighted loss rate. Total loss treats each colony the same or more simply stated, “One colony one vote.” This means that the total loss rate is more representative of commercial beekeeper loss as they manage a large majority of the colonies in the survey. The average loss rate, which we no longer report in our preliminary summary, is an unweighted rate where we calculate the loss rate for each responding beekeeper and average these rates. So average loss, more simply stated is, “One beekeeper, one vote.” As there are many more backyard beekeepers than commercial beekeepers, average loss rates are more influenced by these smaller beekeepers.
Because the BIP winter loss results are presented as one number (21.1% total winter loss), it does not show the huge variability in what commercial beekeepers (and other operational sizes) report as their losses. Consistently across all BIP survey years, commercial beekeepers reported having fewer winter and annual losses compared to backyard beekeepers. For this year, Figure 2 illustrates the variation of losses across operation types from the BIP survey.