Scientific Colloquium
December 7, 2007

"Honey Bees, Satellites, and Climate Change"

Honey bees are experiencing severe declines which are not yet resolved, and remain a concern to crop growers, beekeepers, and the public.  Terrestrial ecologists are also concerned about loss of pollinators and impacts of urbanization, climate and land use/cover change on the crucial ecosystem process of pollination, a complex evolved interaction of plants and animals with likely differing individual responses to change.  It is difficult to relate variations in plant-pollinator interaction to climate change on the 1-5 km scales of satellite climate records (e.g. MODIS, NPP VIIRS) and biosphere-climate models, because very little quantitative data exist to develop necessary linkages and general parameterizations.  Metrics of the timing of nectar flows, using honey bees as samplers and derived from daily weighing of honey bee colonies (scale-hive records), appear to be quite useful.  A 15 year time series indicates that the nectar flow in central MD occurs nearly a month earlier today than in historical records.  Earlier nectar flows (pollination periods) may have noticeable impact on local ecosystems, and on the availability of local honey bee colonies of sufficient strength for spring pollination.  In 2007 a local volunteer scale hive network at 14 different sites confirmed this advance, and demonstrated potential for more extensive surveys of nectar flows.  In central MD, the nectar flow is closely associated with the time of spring green-up seen in the satellite data, and is consistent with increases in local winter temperatures due to urbanization and warming, and with earlier blooming dates of major nectar plants.  Nectar flows often occur later in the season in other biogeographic regions, for which different relations to the satellite data records must be developed.  A web site has been established ( to facilitate collection of scale-hive data and satellite comparisons.  There is widespread supporting interest in surveying nectar flows using this approach within the apicultural and ecological communities.

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