States like Montana do not have buffer zones to mitigate overstocking. The regulations are a legacy of protection from the spread of AFB. And when CCD occurred, it was clear that at least in MT the buffer zones worked.
I have done research for DARPA on how far we can get bees to fly and search. I also did some work along this line when I was working for EPA on delineating distributions of pollutants. One mile radius from the hive is seemingly nothing to a honey bee. Two miles apparently is an easy flight, but when we pushed past two miles, nearing three, we saw an obvious fall-off. Bees at 4-5 miles near a point where the amount of energy expended equals or exceeds what they can gather from floral resources. However, there are reports of bees, under severe dearth conditions, going as far as 13 miles.
J.E. Eckert did a classic study of how far can a bee fly via trials in Wyoming. Joe Traynor provided a nice study and his own observations. His articles was published in Bee Culture in 2002
How Far Do Bees Fly? One Mile, Two, Seven? And Why?
Jump to Latestchitwnbry16 · Feb 24, 2016 · Edited by Moderator Mar 14, 2016Bee Culture - June, 2002
Joe Traynor
With growing concern about pollen transfer from genetically modified crops and with continued concern about pesticide poisoning of bees, it is becoming increasingly important to know the answer to the question posed above.
The flip answer, "as far as they have to" is also the best answer.
Imagine a large wreath of flowers, encircling a hive (or an apiary) in a barren desert. Gradually expand that wreath and you will find that bees will forage up to seven miles, but that the law of diminishing returns (where hives lose weight) kicks in at about four miles.
In what has been termed a "classic experiment", J. E. Eckert essentially did the "wreath experiment" in a three year study (1927-1929) that was published in 1933(1). This study should answer the title question for all time. Eckert picked two irrigated areas in Wyoming that were separated by a 17 mile stretch of barren badlands, then placed colonies at increasing distances from the irrigated wares. Roger Morse summed up his study in the table on the next page.
What's striking about this experiment is that colonies can make a living when the nearest food source is four miles away. From this, it is easy to see that a two mile buffer zone is not sufficient to protect bees from pesticides (or to prevent pollen transfer from two different varieties of plants grown several miles apart).
The area covered by bees increases exponentially with distance from the apiary since the area of a circle is a function of the square of the radius:
See Graphic.
I have had personal experience learning about the flight range of honey bees as determined by pesticide applications. Around 1981, bee colonies in an almond orchard in Kern county suffered severe poisoning from a spray (parathion) on blooming nectarines well over two miles away. There were approximately 5,000 bee colonies on 2,500 acres of almonds located over two miles south of about 200 acres of nectarines that were in full bloom. The poisoning occurred at the tail end of the almond bloom when pollination was essentially completed and when almond bees greatly expand their foraging radius. The bee kill pattern in the almonds conformed exactly to the distance from the nectarines: the closest bees, a little over two miles from the nectarines, showed a severe kill while bees four miles away suffered what would be considered a "light" kill.
Bees placed on alfalfa seed pollination will travel great distances to get pollen rather than work alfalfa flowers for pollen(2). In an extensive test in the 1980's, David Chaney (U. C., Davis) found that bees placed for alfalfa pollination collected 10 times as much safflower pollen as alfalfa pollen even though the nearest safflower field was five miles away!(3) a distance greater than the breadth of Celine Dion's ego!(4).
California laws (and laws in some other states) require pesticide notification to beekeepers within a mile of hazardous spray. Since the nectarine incident described above, I have requested notification for sprays on blooming crops up to two miles away; my request has not been fulfilled and probably never will be although I have made it every year since the incident (saying, essentially, "attention must be paid").
A number of variables affect the hazard of a given pesticide application including the attractiveness of the sprayed crop, the total acreage to be sprayed and the dilution of bees (on other flower sources) in the area. When all conditions are right ("wrong" from the beekeeper's standpoint) severe pesticide kills can occur from sprays applied well over a mile from apiaries.
It is probably not practical to inform beekeepers of sprays within four miles, or even two miles of apiaries, but area-wide restrictions on pesticide applications could be made. These restrictions could ban the use of a few extremely hazardous materials (e.g., Penncap-M, Sevin, Furadan) in bee "areas" and restrict the use of others.
How far do bees fly? The answer still is . . as far as they have to.
Joe Traynor is a crop consultant and pollination specialist from Bakersfield, CA. He is afrequent contributor to these pages.
References
1. Eckert, J. E. 1933. The flight range of the honeybee. J. of Agricultural Research 47:257-285.
2. Morse, Roger 1984. Research Review (How far will bees fly?). Gleanings in Bee Culture, September 1984, p. 474.
3. Chaney, David circa 1985. Bloom dynamics in alfalfa: Implications for pollination and seed production. M. S. Thesis, International Agricultural Development, University of CA. Davis, CA.
4. Carroll, Jon. San Francisco Chronicle, April 9, 2002. Carroll estimated Dion's ego at more than a mile, but gave no exact figure.
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