Almond pollination triggers the world's largest mass migration of managed pollinators to a single flowering crop (Somerville, 2007). The University of California, Davis, advises that honey bee hives should be removed from almond pollination when 90% of flowers of the latest blooming variety are at petal fall (Mussen, 2014), but this advice relies entirely on anecdotal evidence and, in Australia, it appears to be unduly conservative.
Almond orchards containing apiaries of commercial hives were used to trap bee-collected pollen (Somerville, 2011) at the hive level and to track bloom progression of three almond varieties (Nonpareil, Carmel and Price) using tagged branches. Bloom progression was correlated with bee-collected almond pollen. Tracking bloom progression is a more practical, and no less accurate, field measurement to ensure hives are removed at an appropriate time, to the mutual benefit of beekeeper and orchardist.