Thanks, Ghislain, for the interesting read.  Towards the end of the
document the authors wrote:
"It is unlikely that the availability of pollen is the only trigger that
induces the switch from brood-filled colonies of short-lived workers
to broodless colonies of long-lived workers because seasonal
changes in pollen supply clearly do not account for the resumption
of brood rearing that occurs before workers start foraging in spring."

I hadn't realised that Canada goes so far south - 43 degrees, which 
suggests that if people are going to record and share information they 
should include their latitude and longitude as they may cause the graph 
to curve in different ways.  I went across to my apprentice, Sarah's, 
Bee Happy Plants nursery this afternoon and, after I had placed the 
sensor of the aquarium thermometer in the hive, we discussed what she 
should record and the location was one item. She's 50 degrees and 50 
minutes north.  Also 330 feet above sea level.

She will record the hive temperature reading daily at 10am and will 
place another thermometer next to the hive shaded from sun and wind so 
the influence of ambient temperature will be apparent. Weather and 
entrance activity are also on the list but she, not I, was taking notes 
so I may have missed something.

Chris

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