It has been raining, windy and cold this week. From Monday 10th June to Thursday 13th June the number of flying hours may have only been 12 hours out of a possible 66 hours*. The constrain on flying hours is only hours above a minimum temperature:
|date||site||day length||10C or more||11C or more||12C or more||13C or more||14C or more||15C or more|
|2019-06-09||Headington||16.6 hours||14.5 hours||14.3 hours||14.0 hours||12.8 hours||11.3 hours||10.0 hours|
|2019-06-10||Headington||16.6 hours||8.5 hours||6.8 hours||2.8 hours||2.2 hours||1.0 hours||0.0 hours|
|2019-06-11||Headington||16.6 hours||9.8 hours||0.8 hours||0.0 hours||0.0 hours||0.0 hours||0.0 hours|
|2019-06-12||Headington||16.6 hours||14.3 hours||12.3 hours||9.0 hours||6.2 hours||3.5 hours||0.0 hours|
|2019-06-13||Headington||16.6 hours||15.5 hours||12.8 hours||8.8 hours||3.5 hours||0.0 hours||0.0 hours|
|2019-06-14||Headington||16.6 hours||16.3 hours||16.3 hours||13.8 hours||10.8 hours||10.0 hours||8.3 hours|
The rain and wind would have been additional constraints.
On Thursday lunchtime I went to check on the bees. I was concerned that Colony 17 might be starving. While I was there a swarm was pointed out to me. It was clinging to a tree about 6m up.
The weather had been so poor that they must have swarmed on Sunday or early on Monday. There were small mounds of bees on the floor looking very cold and wet. There were very few flying bees.
After some thought I decided to catch them. I reasoned that they had probably used up the honey in their stomachs. In this starved state there was a low probability that they'd be able to find a new nest site, occupy it and forage enough to survive. Stuck on a tree in the rain they might fall and cause a hazard for passing pedestrians.
On Friday morning I called the Oxford University Parks department. They were great. They arranged a team with a cherry-picker to come out. I really appreciate their help.
Once there I went up; shook the branch twice to get the bees into the box; and came down again. The catch couldn't have taken more than 5 minutes once the cherry picker was in place.
I had a hive ready. It had some comb from a previous colony. I also put in a tub of thick (but not fully set) honey. I tipped the bees into the top of the hive. There was no prospect of them walking in. I then did something unusual. I completely shut them in. It was a lock-in.
This morning I checked on them. They had moved up onto the comb. I removed the honey and opened their door. We'll see how they fare.
* Flying hours assume that the minimum temperature for flying bees is at least 13C when measured in Headington. The Headington weather station is a little over 4.5km away from my out-apiary site. The climate in Headington is noticeably warmer than in the valley where my out-apiary is sited. This apparent temperature difference is caused by humidity from the river. I do not have the data to support exact number of flying hours at a particular hive.