Winter Loss Survey 2011 – 2012: Preliminary Results

Note: This is a preliminary analysis, and a more detailed final report is being prepared for publication at a later date.

April 25, 2012

Dennis vanEngelsdorp1, Jeffery Pettis2, Karen Rennich1, , Robyn Rose3 , Dewey Caron4, Keith S. Delaplane5, James T. Wilkes6, Eugene J. Lengerich7, Kathy Baylis8, and the Bee Informed Partnership.

The Bee Informed Partnership (, in collaboration with the Apiary Inspectors of America (AIA) and the United States Department of Agriculture (USDA) conducted an online survey to estimate honey bee colony losses for the 2011/2012 winter season. A total of 5,543 U.S. beekeepers responded, approximately 20% of the beekeepers in the United States. Collectively, responding beekeepers managed over 14.6% of the country’s estimated 2.49 million colonies.

Preliminary survey results indicate that 21.9% of managed honey bee colonies in the United States were lost during the 2011/2012 winter. This represents a substantial improvement in mortality compared to the previous 5 years when losses of approximately 30% were recorded. Previous survey results found a 30% total colony loss in the winters of 2010/2011, 34% in 2009/2010, 29% in 2008/2009, 36% in 2007/2008, and 32% in 2006/2007.

On average, beekeepers lost 25.3% of the colonies in their operation. This is a 13.1 percentage point or 34.0% decrease in the average operational loss experienced by U.S. beekeepers during the winter of 2010/2011 when they reported an average loss of 38.4%. Almost half of responding beekeepers (46%) reported losses greater than 13.6%, the level of loss that beekeepers stated would be acceptable.

Colony Collapse Disorder (CCD) is a phenomenon in which the entire colony of bees abruptly disappears from its hive. Of beekeepers surveyed who reported losing colonies, 37% lost at least some of their colonies without the presence of dead bees. While we cannot confirm that these colonies had CCD, these respondents reported higher average colony losses (47%) than respondents who lost colonies but did not report the absence of dead bees (19%).

The winter of 2011-2012 was unseasonably warm with NOAA ranking January as the fourth warmest in U.S. history. This could have favorably impacted colony survival this past year.

The Bee Informed Partnership is funded by the National Institute of Food and Agriculture, USDA.

1. University of Maryland; 717-884-2147;
2. USDA-ARS Bee Research Laboratory, Beltsville, MD
3. USDA APHIS Plant Protection and Quarantine, Riverdale, MD 20737
4. University of Oregon, Corvallis, OR
5. University of Georgia, Athens , GA
6. Appalachian State University, Boone, NC
7. The Pennsylvania State University, Hershey, PA
8. University of Illinois, Urbana-Champaign, IL

8 thoughts on “Winter Loss Survey 2011 – 2012: Preliminary Results

  1. Pingback: Winter Honey Bee Losses Decline «

  2. According to an article in the July 2012 issue of Bee Culture the scientists involved in the data collection analysis say they don’t know the reason for improved bee survival this winter, but that the unusually warm winter during 2011/2012 is one possible contributing factor. January 2012 ranks as the fourth warmest January in U.S. history.

    It seems that if winter losses are reduced in winters which are warmer than usual losses could be reduced in normal winters by protecting the bees from the cold weather. Protecting them from cold weather may not mean that they need to be warmer all winter. Winter protection could be as simple as protecting them from the extremes of lower temperatures which occur from strong winds, for short periods such as overnight or for just a week or two in January. Perhaps hive insulation which reduces the lowest winter temperature within the hive from ten degrees below zero to just five degrees below zero during a few days in the winter would make all the difference of whether the colony can survive the winter. Perhaps hive insulation could mean the winter survival of a few hundred bees which otherwise would have frozen and that in itself might make the difference of whether the colony survives the winter. Perhaps hive insulation could make just enough difference to allow the cluster to expand by an inch or so to reach a needed honey supply.

    Though the researchers and scientists have to wait to prove a connection between warmer winters and reduced winter losses in bee colonies there is no reason that we as beekeepers have to wait to make the connection ourselves and to do something about it. I encourage all beekeepers to insulate their hives now instead of waiting for the official recommendations.

    Do it yourself insulation recommendations are available at

    Good Luck,
    Bob Williams

  3. Are the effects of clothianidin on Apis mellifera reverseable?

    Also, I am a student of Human Sustainability and Environmental Design; what variables impact the chance for human survival if this trend continues. What should I be considering at this potentially momentous period in human history as a designer of human habitats?

    I look forward to as many despises and suggestions as possible,

  4. I suggest switching out at least 6 frames each year with new foundation. One chemical by itself may not be harmful, but mix it with another chemical and you may get a harmful chemical. Bees travel miles collecting pollen and nectar. We can not control what our neighbors are using on their garden, yards, etc. I suggest we come up with a way to test the foundation on the hives that died and see if there is a common link. Notice how the size of the cells are smaller on old foundation, could this have something to do with our loss? Does the small cells make smaller bees that may not be able to generate enough heat in the winter?

  5. Quote from article: “A total of 5,543 U.S. beekeepers responded, approximately 20% of the beekeepers in the United States.”

    I thought the total number of beekeepers in the US was around 250-300,000. Can you confirm? Did the article mean to say 2% instead of 20%?

    • Hi Laura,
      Thank you for your question. We need to use national statistics from a reputable source and thus rely on the National Agricultural Statistics Service (NASS) Honey Report. Due to the nature of how they collect their data (reporting only those beekeepers who manage 5 or more colonies), we realize that the number we use is probably underestimating the total number of beekeepers in the U.S. but we are constrained, at this point, to use the best estimate we have. Not all states require colony registration so we cannot reliably get a total from the states.

  6. Pingback:

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