Survey Year
Loss Calculation
Operation Type
State Beekeepers Beekeepers Exclusive to State Colonies Colonies Exclusive to State


  • You may download the data used for this data explorer by clicking here and filling out the request form. You will be asked to create an account and login first.
  • For each operation participating in the survey, the loss rate was calculated as the total number of colonies lost divided by the number of colonies at risk during the season. Colonies at risk were composed of viable colonies, as well as new colonies made or acquired, while excluding colonies sold or parted with. We use two different methods to estimate the loss rate at the population level: weighted and unweighted average, which can be selected using the dropdown menu: "Loss Calculation".
  • Loss Calculation: "Weighted average" method: the estimate is calculated as the ratio of the number of colonies lost to the number of colonies managed over a defined period across all participants in the population. This means that each operation is weighted in the population estimate according to the number of colonies they manage. "Unweighted average" method: the estimate is calculated as the average of all operational loss rates. This means that each operation has the same weight in the population estimate. This "unweighted average" is usually more representative of what smaller-scale beekeepers experienced, while the "weighted estimate" tends to represent better large-scale beekeepers, and be a better picture of the estimate of the number of colonies lost at the population level.
  • We obtained the 95% confidence interval from a bootstrap resampling of the data (n-out-of-n, 1000 rep). The confidence intervals for the loss estimates were adjusted in August 2020 for all years of data to utilize the bootstrap method which reduces the effect of outliers and generally provides a better representation of the degree of variation in the data.
  • Annual loss covers the whole period from one 1 April to the next 1 April ; Summer (1 April – 1 October); Winter (1 October – 1 April).
  • Loss rates should not be interpreted as a change in population size because beekeepers can replace lost colonies throughout the year. Therefore, colony loss rates are best interpreted as a turn-over rate, as high levels of losses do not necessarily result in a decrease in the total number of colonies managed in the United States.
  • Slight variations, resulting from additional analyses, may occur between reported losses in publications and those shown on this map.
  • Responses for beekeepers that manage colonies in more than one state are included in the loss calculation for each state they keep bees in. You can toggle this setting with the dropdown menu: "Operation Type" and select an alternative table showing multi-states operations only or single-state operations only.
  • Columns "Beekeepers exclusive to State" (and "Colonies exclusive to State"): shows the percentage of beekeepers (and their colonies) who do NOT keep bees in other state(s) outside of the selected state.
  • For the protection of privacy, losses are reported as N/A if 10 or fewer beekeepers responded in that state. These beekeepers' losses are included in the national statistics.

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