Vancouver, WA area (Lat 45.9 N 122.7 W; elevation 167 feet)
July 4, 2013
Actual high 75 degrees. Actual low 51 degrees
Actual humidity 63 (range: 46 to 86).
In preparation for a few days of 90 to 100 degrees F weather earlier this month, I changed all of my inner covers to double-screened inner covers (15 inches by 12 inches), and opened up the back access panel of my screened IPM bottom boards (2 inches by 12 inches) to give my colonies plenty of ventilation. Early this morning, two robust colonies (2 brood box, 1 super) had beards. The low overnight was 51 degrees, and temperature when I was out there was 56 degrees. (I did not measure internal hive temperature.)
Of my 15 hives, the two hives with beards were the ones in which I also had propped up the outer cover by about an inch.
Is it possible the bees are bearding to WARM the hive (by blocking the front entrance airflow (the only gap they can actually control) and not to COOL it?