Understanding your climate
As we know beekeeping is very climate dependent. Local climate will affect everything from brooding cycles, available forage (plants and forage) and the bloom dates as well as bee foraging behaviour. Adequate amount of rain and the correct range of temperature will dictate nectar flow. A drought will cause a pollen dearth. An early frost could cut short a the perfect nectar flow.
To assist us in understanding our local climates I am in the process of developing some basic indicators to help measure differences between beekeeping areas (Foraging Intensity, Nectar Flow and Winter Harshness Factors). These methods will then allow beekeepers to chose the most effective practices (Spring management, Honey Production and Overwintering methods) best suited to their climates and areas.
**Interesting BC Apiculture Bulletin #111 of Bee Behaviour During Foraging
Here is weather filtered through some bee behaviours.
-Bees start actively foraging at +8C (46F) (Pollen)
-Some nectars only flow at higher temps (Clovers) – best from 16C to 30C (61F to 86F)
-Hard to collect nectar and pollen when raining
-Plants need rain to produce good nectar/pollen (i.e. Fireweed)
-Bees will stop foraging in winds above 40km/h (25mph)
-Experience tells me very poor above 20km/h (13mph) especially if cooler.
FDH - Forage degree hours >8C / 46F
NDH - Nectar degree hours >16C / 61F
CDH - Cluster degree hours <8C / 46F
I use a similar logic to GDD and HDD (Growing degree days/heating degree days but using hourly data)
The advantage of using Degree Hours is that it eliminates the impact of cool evenings on the calculation. For example our place usually get 5-10C cooler nights than Whitehorse but with the same daily highs.
Abbotsford BC - Climate that many of our Nucs and queen stock come from; How long will the bees take to adjust to there new climate? How does moving bees 2000km north affect their annual cycle? What are the wintering implications?
Below are monthly Charts based on Daily Degree Days
Ranking of both northern and southern location in North America (above is sorted by CDD intensity)
Interpretation: Dawson City "winter" has 4309 degreeC Days of cumulative temperature below 5C (Think Heating Degree Days). Therefore bees in Dawson City will require twice as much energy as Edmonton to maintain an effective cluster (assuming the same hive setup).
Internal hive monitoring can be used to measure energy produced to maintain hive temperatures for given external temperatures. Hive R-Value, and both internal/external temperature are known. Reference: The Biology and Management of Colonies in Winter
Diurnal = daily (Tmax - Tmin)
Diurnal temperature swings impacts hives mostly during spring when brood nests are small and during the winter months when bees are clustered (brood nest size is limited by number of bees able to maintain the ideal brood rearing temperature of 35C/95F; the winter cluster is designed to help maintain the center of the cluster at 35C/95F to ensure the queen survives the long winter. Occasionally bees will get caught outside of the clusters when temperatures suddenly drop and bees are not able to re-establish an effective cluster)
FDD (Forage Deg Days) =abs(Tave-10) if less than 0 = 0
Forage Degree Days measure the cumulative intensity degrees) over time (daily) throughout the season when temperature are above typical temperatures 10C/50F when bees will be out foraging pollen, nectar and propolis.
FDD Days (Forage Deg Days) =number of days where value is above 0
This indicator counts the actual days when the daily average temperature was above 10C/50F
NDD (Nectar Deg Days) =abs(Tave-15) if less than 0 = 0
Nectar Degree Days measure the cumulative intensity (degrees) over time (daily) throughout the season when temperature are above typical temperatures when bees will be out foraging nectar sources (flowers will start releasing nectar above 15C/59F).
NDD Days (Nectar Deg Days) =number of days where value is above 0
This indicator counts the actual days when the daily average temperature was above 15C/59F
CDD (Cluster Deg Days) =abs(Tave-5) if less than 0 = 0
Cluster Degree Days measure the cumulative intensity (degrees) over time throughout the season when temperatures are below typical temperatures when bees are clustered. The factor can then be used to calculate energy requirements based on the various hive wintering methods (supplemental heating, wraps, venting, etc...)
CDD Days (Cluster Deg Days) =number of days where value is below 0
This indicator counts the actual days when the daily average temperature was below 5C/41F.
- Develop a moisture (rain) factor indicator (very important of coastal areas and areas with little rain)
- Wind Factor to improve wind protection and better understand wind effect on bee foraging behaviours)
30C = 86F / 20C = 68F / 15C = 59F / 10C = 50F / 5C = 41F / 0C = 32F / -10C = 14F / -20C = -4F / -30C = -22F / -40C = -40F
Simplified Calculation Approach:
Remember the surface area is equal to the area of all sides (and top) exposed to the elements
(1 BTU/hr = 0.293 W/hr)
1 Kg of honey is equivalent to 330 Watts of energy (at 100% conversion rate)
0.68 kg of water per kg of honey (Remember we need to get rid of this moisture but also if we reduce the energy requirements we reduce the moisture created)
Interesting Article on why you should Insulate - http://beecosy.com/why-insulate/
R-Values for Typical Hive Components or insulation material
Poly Hive 100EPS =7.9R (Bee Box); Wood Hive = 1.21R (22mm)
Polystyrene = 5.0R /inch; Wood = 1.4R / inch; Foil Bubble Wrap = 1.0R; Felt Paper = 0.06R
Chart showing energy requirements to maintain 8C inside the hive based on their typical R-Value. Energy requirement was converted into honey and potential water moisture generated based on 18% water content.