Monday, July 15, 2013

Bee Hive Size

Honey bees live in cavities. In Ethiopia, natural cavities are hollow trees or crevices in volcanic rock walls. Ethiopian farmers also keep bees in three distinct styles of manmade hives. Traditional bee hives are long baskets, usually constructed from cane or strips of wood. Transitional bee hives, also known as “top bar hives,” are open baskets with strips of wood at the top to hold the bees’ combs. Modern bee hives are wooden boxes with removable frames to hold the bees’ combs. Honey bee colonies will generally maintain their brood nest in a hive as long as there is food available in the region and the hive remains suitable to the bees. To try to determine why the Amhara beekeepers are experiencing their bees' absconding and swarming, we look closely at each of the three manmade bee hives.

The first concern for a bee hive to be suitable for the bees is its size. For the farmers to build up a population of bees capable of producing a surplus of honey the hive must be large enough for the bees to greatly expand their brood nest. In nature, bees often select a cavity with a volume of about 40 liters. After the colony fills this volume, the colony divides; and half of the bees swarm in search of another cavity. We measure traditional and transitional hives and find them to have a volume of about 89 liters. A modern Zander hive with two brood nest boxes measures about 84 liters, probably a suitable volume. It appears that the use of a single Zander brood nest box by some farmers probably leads to brood nest congestion and swarming. The Amhara farmers recognize that they might be able to reduce swarming by adding more hive boxes and frames as bee populations grow. In today’s photo, seasoned Ethiopian beekeeper, Gebeyehu, brings one of his traditional bee hives to the Machakel training facility for us to examine. Hive size is important wherever we keep bees.


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