honey consumption and late winter brood rearing

My 8-frame hive is wrapped in a hive cozy. On warm afternoons in December and January, bees flew vigorously and performed orientation flight. These 2021-2022 measurements show that bees are most likely consuming their honey stores and raising late winter brood.  

• Temperature measurements are taken at dawn at the top vent using an inexpensive RadioShack Waterproof Pocket IR Thermometer. The orange trend line is most likely an increase in total bee metabolism/respiration (bees covering late winter brood). Peak temperature top vent measurement of 78°F (25.6ºC) is not the expected 89.6-96.8°F (32-36ºC) brood nest temperature, so why? Cold air flows into the hive entrance and screened bottom board and mixes with warm moist bee respiration and exits the top vent - usually I discover the warm moist air condensed to the outside of the hive cover.
  
• Less frequently, I weigh the hive using an inexpensive luggage scale. The green trend line is most likely winter consumption of honey stores. I would prefer to connect densely sampled weight measurements (points) with a spline instead of the polynomial trend line.  However, extra hive weight measurements are not possible with my travel schedule. 
• Also shown are HoneyBeeNet 2012 hive weight measurements from Cowetta GA (40 miles from Atlanta). HoneyBeeNet is a NASA hive and climate citizen science project. The zoom into these end of year weight measurements show a similar sharp drop in hive weight. 

2019 - fall hive weight and water balance calculator

• graph 1 - dramatic 2019 fall hive weight gain
• graph 2 - flat to decreasing 2018 fall hive weight
• water balance calculator table - 2019 shows a slightly positive fall water balance compared to past years, while 2018 shows a dramatically wet fall water balance

Many factors contribute to fall hive weight gain, but I speculate that that dry conditions favored optimal goldenrod and aster honey bee forage; sadly these dry conditions stressed shrubs and trees.  Local fall water balance appears to slowly cycle with a period of 3 to 4 years, meaning that fall 2020 might also be dry - stay tuned.

hive weight - fall 2018 to spring 2019

I'm using an inexpensive luggage scale to weigh 4 box tall hives.  I attached the ends of a length of parachute cord to the front legs of my hive stand, then I pass the central part of the cord beneath the hive and towards the back of the hive.  This forms a V shape of cord beneath the hive.  I slowly pull on the cord with the luggage scale until the back edge of the bottom board slightly rises above the hive stand.

Scale readings are converted to total hive weight using a factor of 1.825 which I estimated using an unoccupied stack of 4 boxes with a similar total hive weight.

In the graph note:

• Hives loose weight between 30-Sep-2018 and 22-Dec-2018.  Hive #1 looses more weight than hive #2.
• No measurements during winter.
• On 24-Mar-2019 hive #1 gains more weight than hive #2.

Fall weight loss is greater for hive #1 which is most likely attributed to its larger population compared to hive #2.  Said another way, hive #1 consume their honey stores more rapidly due to a larger population.

During the winter, these hives are insulated with Bee Cozy hive wraps and I don't disturb the bees with hive weight measurements.

In a similar explanation, greater spring weight gain for hive #1 is most likely attributed to hive #1 having a larger population compared to hive #2.