Winter World_ The Ingenuity of Animal Survival - Bernd Heinrich [114]
No central control is required to achieve this communal response that automatically stabilizes the cluster microclimate. No chemical signal from the queen in the center serves as a thermoregulatory directive, since groups of bees with and without their queen react similarly. Neither do bees carry messages back and forth from outside to inside, because when the core bees are experimentally separated from the mantle bees by a thin gauze there is also no temperature change. That is, even when bees of the core are prevented from individually sampling the temperature surrounding the cluster, the core still maintains the same temperature. I also found no change in bee cluster temperature when I played back recordings of buzzing sounds generated by bees either in the core or the mantle at high or low temperature through a small speaker placed in a cluster core or its mantle. Additionally, I exchanged air by pumping it from the core to mantle, and vice versa, and also found no effect. Apparently, the bees in the core and the mantle do not inform each other about local temperature in order to coordinate a colony response. Instead, the high and relatively stable core temperature and the lower and more variable mantle temperatures can both be reasonably well explained by the response of the individual bees regulating their own temperature. The summed response, however, serves all in terms of energy economy.
Sometimes, however, the individual’s sacrifice is best for the colony, and given that bees are communal animals and the individual sterile workers (who are all female) produce offspring only indirectly through their siblings (new queens), that sacrifice is then selected through evolution. The most obvious sacrifice workers make is their attack on nest predators by stinging them. (When a honeybee worker stings just once, its barbed stinger is detached from its body along with the attached poison sac, and that bee soon dies.)
Worker bees may sacrifice their lives in another way. They may die not only by losing body parts, but also by quickly freezing to death. At least so it seemed to me when I watched my hives in the 2000–2001 winter. As is to be expected when examining something of sufficient complexity and interest, I made false starts, but learned along the way. Like the CIA.
During the Vietnam era, GIs discovered mysterious yellow spots on jungle foliage. The CIA was brought in to investigate the so-called mysterious “yellow rain,” which was soon suspected to be a new chemical weapon sprayed by the Vietcong. But entomologists later revealed that the smelly yellow mystery droplets came…[from bees.
Yellow spots are much more visible on white snow than on jungle foliage, and everyone can see them in the winter near their beehives here in northern climates. One also sees bees flying out of the hive in the winter whenever there is a thaw, and the prevailing wisdom is that they leave to take a poop if that is what they do. It made sense, just like yellow rain. But that didn’t make it true.
Forty thousand or so physically active honeybees exercising all winter to keep warm while crammed into one small space with lethally low temperatures outside face a hygiene problem, just like a bear does while in its winter den. But solutions are found. Bees won’t defecate within the hive any more than a bear will, which is to say never. The difference is that unlike a bear in winter, bees eat a lot, and they eat the same food a bear finds irresistible, honey and pollen. As the hive in winter is always clean of poop (although sometimes littered with corpses), we may see no problem at all, simply because the bees have solved it so well. But how long can they wait? Till spring? Do they die rather than poop? January 2001 provided a unique opportunity