Bearing up

One of the things that we read about early on in our project was the fact that bumble bees will memorise their nest the first time they leave it by doing "navigation circles" around it. These are a series of circles of increasing size and distance, where the bee looks at the nest and observes the landmarks around it.

On a few occasions we had queens that we attempted to nest and when they left the nest we thought maybe they had shown this "navigation" behaviour. However, there is nothing like seeing the real thing for sure to know what you are looking at. 

I found a great piece of video on the DVR this morning that showed one of our bees in close up coming out of the nest for the first time and spending about 20 seconds up close memorising the entrance. After this, she would have circled at a further distance and height to take in the surroundings properly. (Of course, now she would have the benefit of our "runway" :-) )

So, I already had some iPhone footage attempting to show this circling from a longer distance. So, I've edited the two clips together so you can see what the entire behaviour looks like. It's unmistakable and the behaviour we had seen with earlier queens really did not come close - none of them really memorised the nest entrance like these workers do, even though they circled up to half a dozen times around the nest area. 

My own theory is that the circling we saw with the queens was more to do with them getting their own bearings - bearing in mind (no pun intended) that we'd transported them from the nest site they were hunting down, into our own nest box. Quite possibly a confusing process for them. It makes sense they would have to get a handle on their location once exiting our nest box.

Anyway, here's the video...

Although in the close-up segment our worker is out of shot for some of the duration, you can still see her shadow cast on the nestbox itself. She also moves very quickly so appears to dart about rather than move smoothly. 

Going Cuckoo

A beautiful day today, we thought we were definitely on for some bees today to test out the latest version of our boxes. There was some tidying up of the irrigation system to do - I consider this part of the project, as the irrigation is needed to cope with all the additional bee-friendly plants we've brough into the garden. 

The other job was to get the camera feed from the rear nestbox into the house. Yesterday was the first day it went live and for expediency I just wired it to a temporary TV in the garage. The infrared cameras I'm using in the nest boxes come with about 20 metres of cable, so there was plenty to run it round the edge of the garden. This camera is now routed into the house and main TV. This allows us to view the box with extreme convenience and we can even use "picture in picture" mode to keep an eye on things while watching other things.

rear nestbox cam shown PIP on main TVWhile I was doing the technical work, BCW was out looking for bees. Finally I was able to head out too and catch up with her. As we met she was excitedly to tell me she had just let one go. I couldn't believe what I was hearing! Then she explained she was certain it was a "cuckoo" bee - a cheap imitation of Redtail, with no pollen baskets on its legs. Rather cheekily, a "cuckoo" bee seeks out an existing nest and lays its eggs in there and does none of the work of rearing its young. So, there is no point trying to get one of these bees to nest, as they don't! However, their behaviour does give some pointers as to where they'd expect other bees to have their nest. We actually caught 2 today. 

BCW was standing at the corner of a field where she had seen lots of bees. Some of these appear to using the corner as a landmark for their journeys - they fly across the field to the corner, then zip off on the next leg of their journey. If you are standing in the corner at the time they will sway left to right as  they take you in (probably wondering what this strange tree-like thing that has appeared in their field), then swoop a few circles round you, then shoot off on their way. This behaviour is quite predictable and reliable.

The behaviour today seemed different - not so much outright nesting, but more foraging and "flying through" so although BCW had seen about half-a-dozen bees, it was only the cuckoos that had been in catchable situations. I guess some of the bees we are now seeing have already set up nest and are stocking up for a bit of child-rearing!

I went to the corner of the adjacent field, rather unhopeful of catching anything as it was dry and muddy and cracked, whereas we have seen the Bumbles searching in embankments. However, within 5 minutes I was rewarded with a redtail searching amongst the mudy cracks. I couldn't believe my luck and when she finally landed I was able to catch her with ease. She was quite placid and we decided to take her to the main nestbox at the front.

BB16 - redtailShe went into the box without any problem and the view on the two cameras in this box was amazing - the first time we have been able to test it. The infrared works a treat and the clarity is excellent. I'm really pleased with it. 

Unfortunately she only stayed about 5 minutes. She didn't really explore the box at all, even though we had hoped a redtail would be less fussy than a bufftail. When she left she did a wonderful set of landmarking circles; the best we had seen to date - about 4 circles at a lower level and 3 at a higher level. It really looked like she was taking her surroundings in.

After a pause to catch our breath and get a much needed cuppa, BCW went out again on the hunt. This time she found a bufftail, more-or-less in the same location. We decided we'd try this one in the box at the back. Although the front nestbox is the best-equipped from a technical point of view, that doesn't mean it suits the bees best. It is noiser and less surrounded by greenery for example. 

BB17 - bufftailIt was now about 3.30pm - still about 15 - 15 degrees C outside, though it had been threatening rain on and off. She went into the box very happily and in the end stayed for 50 mins. She followed the typical pattern of scratching and shuffling for a few minutes at a time then resting. All of this time she was unfortunately off-camera, somewhere just below it and she never really explored the box. It's frustrating when the bees decide to inhabit a zone that the camera can't see; but at least the audio gives us a clue what they're up to! We sensed she was going to leave after about 50 minutes and she too delighted us with a wonderful set of circles rising from the box. She even outclassed BB16 doing perhaps a dozen circles rising from ground level up to about 2 storeys high, circling wider and wider and drifting over the neighbours garden a little. This was the best evidence we have had to date of a bumblebee setting her "navigation" - i.e. memorising the landmarks around the nest site.

Of course, this always raises hopes that they are planning to return, but we have learnt from experience that even these signs are not a guarantee. Sadly this has proven to be the case again tonight - neither BB16 nor BB17 have come back to the nestboxes despite our best hopes. However, they thoroughly entertained and delighted us in the process and we can hope they will perhaps return another day. 

Flying visit

I wasn't at home today but BCW was out and busy on the hunt for more bees!

Around about lunchtime BCW reported she thought she could hear scratching from inside the box with the camera/mic; and possibly some movement of the nesting material near the entrance. It wasn't totally conclusive though, as it was possible the wind was causing the movement and the lid to rattle a little bit. Tantalising!

Then between 2 and 2.15 BCW caught another redtail (Bb12). (While out she also saw a Carder and a Bufftail). BB12 went into the box without too much trouble and went straight to the back left corner - which is different to all the others, who have gone to the front left corner. She didn't stay still at all like all the others, but just explored a little. But she only stayed about 2 minutes before coming out. 

When she left she walked out onto the new grass outside and then when she took off she hovered back and forth over the box and flowers, gradually getting higher and higher. Then she flew off quite gently.

This is completely different behaviour to what we have seen before. The shortest any bee has stayed to date has been 20 mins, so this is a new "fastest exit" time! And, although the bees have left in a spiral, today's behaviour seems much more like the "landmarking" movements that bees make when, for example, they encounter humans in a field (see our research papers). In such scenarios they fly within about 2 metres of the human, then swing back and forth from left to right at a height of between 2 and 4 metres, and then perform a couple of circles. This is thought to be the Bumble taking a navigational note of what they see - and it's really amazing to experience when you are out in the fields: they all do it!

So, was little redtail getting her bearings for the nestbox? Again, we shan't know unless she returns, but this is probably the best behaviour we have seen so far.

So, this also begs the question about the 2 minutes inside the box; what was going on there? Here are a few theories:

• She was very frightened/stressed and so left immediately - this doesn't seem to fit, she was calm and co-operative, more than many of the others; and the most agitated bees have actually stayed still inside the box after entering.
• She thought maybe there was another animal in the box or that it was in use - there is perhaps a risk that the small amount of grass we have put in the box smells a bit fresh and she thinks an animal has placed it there recently (well, a human has!) 
• Maybe there was another animal in there - perhaps there was a bee in there already, that BCW heard earlier?
• She really liked it, knew it was a great nest, and decided to make a mental note of it and go out foraging

So, again, until some time has passed we cannot know what was going on in little BB12's head!

This is the new layout in the boxes by the way, with a small amount of cut grass inside.

 new box layout with cut grass and less bedding overall

An hour later, between 3 and 3.15pm, BCW then reported catching another redtail in the back garden! This is amazing to see them actually in the garden. However, BB13 was not very co-oeprative and she just refused to go into the front nest box. Maybe this was the same bee as BB11! In the end, BCW let her go rather than stress her too much. 

Again we applied a bit of "bee thinking" and had the brainwave of putting grass down between the lawn and the rear box. Since we have now seen 5 redtails searching the back lawn (which needs cutting!) we thought it made sense to "extend" the lawn across the narrow gravel border to the box. This way they might actually just explore all the way up to the box. And with the grass now around the front of the box to make it look more like a little nesting hole in a grassy mound, you never know, they might just be fooled inside it!

That's the theory anyway!