4.3. Honey bee colony density estimations
It can be difficult to determine the number of honey bee colonies per unit area (colony density) due to the cryptic nature of honey bee nesting sites. Consequently, research involving data collection on colony density can be complex and time consuming. There are a number of instances where knowing colony density would be beneficial. For example, one can employ GIS technology (Geographic Information System, see the BEEBOOK paper on the topic, Rogers and Staub, 2013) to determine how colony density varies over land use patterns or within/between various ecosystems. Furthermore, one could track population size and health over time, monitor migration patterns, determine disease spread within a population, etc. Yet, these applications seem out-of-reach because of our inability to determine colony density accurately.
Currently, the only way to determine true colony density is to search a landscape thoroughly and locate all of the colonies in a given area by bee lining (identifying the direction of home flight and finding the colony on this line, see section 4.2.(Beelining) or extensive search for nests (e.g. Oldroyd et al., 1997). This seems challenging due to the cryptic nature of some nesting sites or in areas where accessing colonies is difficult or dangerous such as on cliff faces or high in trees. As a result, researchers have turned to indirect methods for assessing colony density.
Herein, we present two methods that can be used to
assess the density of honey bee colonies in an area. The first method (using
feeding stations) assesses the relative density of honey bee colonies in an
area through indexing while the second method (using genetic markers) provides
a direct estimate of colony density.