Beekeepers and the Weather

Swarm Predictor

2013 Swarm
2013 Swarm

As I was thinking ahead to next spring and summer, and reflecting on seasons past, I decided to check my records to look at swarming. In the season just gone swarming kicked off much earlier than I’d seen before. I have detailed records going back to 2013, which isn’t that long really, but it’s better than nothing. I made a list of when I found the earliest queen cells in my hives going back seven years. Sure enough, last year they were building cells on 21st April, which is unusual for me. Before that, the next earliest had been 10th May, in 2014 and 2017. The latest was on 4th June in 2018.

Spreadsheets and Charts

Next, I dug out records of average monthly temperatures (maximum and minimum), rainfall and sunlight hours. I love spreadsheets and charts; I used to make a good living from playing with such things, so within a few hours, I had data tables and graphs galore. It wasn’t immediately apparent that there was a pattern at all, which was vexing. Surely there must have been something in the weather to foretell the building of queen cells in April last year if nothing else.

Luckily I remembered conversations with very experienced bee farmers about their good and bad years, and how the weather influenced that. I also looked up some phenology sites because surely the sooner plants are in flower, the sooner the bees can build up their numbers. This led to me looking closer at the weather in March/April. Sure enough, there seems to be a correlation between a warmer spring and earlier swarming. The picture became more apparent when I looked at both temperature and rainfall for March/April (spring build-up) and June – September in the preceding year.

Spring Temperature is Key

I ranked the spring and summer temperatures (average tmax) from 1 (hottest) to 7 (coldest) and did the same for rainfall (wettest to driest). For last year, BOTH the preceding year’s summer AND the current spring were the hottest of my records to date. The summer was also the wettest; we had a very wet June and September, but that didn’t seem to matter. The warmest summer followed by the warmest spring led to the earliest swarming, which makes sense.

Spring Weather vs Swarm Cell Dates
Spring Weather vs Swarm Cell Dates

The spring temperature seems to have a stronger effect than the summer of the previous year. I’m just scratching around with very little data but, hey, it’s only a bit of fun. When I looked at the year when swarming was latest (2018) I found that the spring of 2018 was the coolest on record (7th out of 7 years). It wasn’t especially wet, but it was cold. The preceding summer had been the 5th coolest out of 7. So we had one of the coldest summers followed by the coldest spring, which led to the latest swarming.

Balls of Crystal

Weather Impacts Swarm Dates
Weather Impacts Swarm Dates

Based on these tenuous findings, I can have a look in my crystal ball towards 2020. Last summer was ranked 4th out of 7 for temperature, and it was the wettest summer of the previous 7 years for me. Rain does not seem to be anywhere near as important as temperature, but that could change if we got really extreme weather such a drought or non-stop rainfall. I reckon from a swarm prediction perspective last summer was about average; not unusually warm nor cold. It all depends on what we get in March/April 2020 now. If it’s hot, I would expect swarming in the first half of May. If spring is relatively average, then I predict swarm cells will start around late May, and if we get a cold one, it might slip into early June.

What was the point of all that then? It is a window into the crazed mind of a beekeeping walrus who has no beekeeping to do because it’s mid-winter. The madness has set in.

Cupboard Therapy

Yesterday I performed the hugely therapeutic task of tidying many of my kitchen cupboards. Humans probably do this every few weeks, but for the walrus, it’s more of an annual event. There is something incredibly satisfying about emptying cupboards, cleaning all of the shelves with an antibacterial spray, then putting back items that are not out of date. As I had expected, the vast majority of cans of food, packets of pasta and rice, sauces, spices and so forth had expiry dates going back to the Jurassic Period.

Clean Cupboards!
Clean Cupboards!

I even found what looked like a dead mouse, but it turned out to be an old potato that had grown fur. Aside from that, I saw no signs of mice which was a relief. Last year I had an epic war with mice involving traps and various poisons. Eventually, the walrus emerged victorious, but it took a couple of months and much determination. A cat would have solved the problem much quicker, but I don’t believe that my beagle would take kindly to sharing her space with a sharp-clawed imposter.

The Circle of Life

After Christmas, I shall have to tidy up my bee sheds and light a sulphur candle in each, which will hopefully kill off anything lurking inside. I always start the season with neat stacks of organised boxes, floors and rooves. By the time I get to June, it looks like a tornado has swept by, and it stays that way until the cycle resumes after Christmas.

Speaking of which, seasons greetings and warm wishes to all. May your queens be prolific and her workers gentle, industrious and disease-free.

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