What Wild Things Where?

Gabion pillar with bee logs by plastic fence and tree trunk

Gabions are “units of wildlife habitat”, chokka full with different homeliness

I had a brilliant email reply from Linda at Buzz Club answering some of my habitat questions

John Little is one of my favourite gardeners and hole diggers, as he is constantly experiments with wildlife habitat and aesthetic designs (see his Tiktok channel).

We suggest structural complexity and topography is overlooked in landscape design and is more important than plant choice for driving biodiversity.

Trouble is, he still hasn’t written the book.

Another champion of wildlife habitat is The Buzz Club, and they are on fire recently with a whole load of brilliant entoLIVE webinars on Eventbrite together with the Biological Research Centre. There was an opportunity to email in questions which Linda very kindly answered at length. For my own reference, as it’s such good advice, I’m posting them here.

  1. Are bee logs with variety of hole sizes okay as long-term habitat, or do they also need cleaning out each year like constructed bee logs

“There is debate on this one, to be honest!

Commercial bee hotels that are made with plastic parts (like viewing windows) do seem to build up debris / pests (e.g. flies) and need cleaning out, although it isn’t clear if this is a specific problem or if it just that the observational design of those hotels means it can be seen more easily. Some hotels are designed to have removable cardboard or paper tubes, so you can keep the cocoons somewhere safe over winter and also clean out the holes while you’re at it. But again, these are hotels that are designed to have more observations / active maintenance elements to them.

Drilled logs are a more ’natural’ style of habitat, since finding holes in trees / logs is something that cavity nesting bees would do, and there is an argument that they simply won’t use ones that are too gross, and that natural processes would clear out the unused tubes ready for next year.

There is also a question of density of nesting spaces. Very big bee hotels probably present a situation that would not be naturally found very often = lots of nesting holes all in one place, used for multiple years. While we do see big nesting aggregations of solitary bees in wild spaces, these are more usually of the ground nesting kind. Those won’t be reusing tubes from last year because the tunnels collapse over winter and new ones are excavated, so any debris and rubbish present in the old tunnels won’t be brought forward to the new ones.

I tend to go with what seems the most natural situation with what I’m working with. E.g. if I’m setting up a drilled block / bamboo tube bundle bee hotel on the side of my house where I can observe the bees, then it’s a useful habitat but not the most natural setup. I also probably want it to last for several years. So multiple spaced-out small hotels are better than one massive crowded one. I may take filled ones down to put them somewhere sheltered for bees to develop and emerge in spring (but not go back into), with fresh ones up for next year. I’m not totally sure how long you should leave a hotel out of rotation (since some solitary bees take more time to emerge than others), but it’s something we’re looking into.

If I were creating a more natural setup, like bundles of dry plant stems that bees can use, but aren’t really expecting to last multiple years, then I wouldn’t worry really about clearing it out since the tubes will probably be too broken down for the bees to want for next year anyway. If I want that habitat again it would need replacing.new the nxt year, but I’d be fairly certain it wouldn’t be building up problems.

If you’re setting up bee logs that aren’t going to be easy to clean, then I’d think about it in terms of infection control. Avoid putting in too many holes or clustering them tightly (no bee slums!) - so if there is disease in one tube, it won’t be able to easily spread to neighbours. Holes that aren’t suitable for bees to nest in anymore still can provide shelter for insects or overwintering space, so inspecting logs as spring approaches and replacing any that look rotten, or adding a new one nearby so bees have a choice, seem like good ideas.”

  1. What inverterbrates do self-binding gravel paths provide habitat for, and are there any specific techniques to create better habitat (eg loosening gravel around edges of path)?

“I haven’t heard much about this, to be honest! Looking up ‘self binding gravel’, it basically seems to be gravel that has different sizes pieces in it, so it jigsaw’s together better when pressed. That’s a more natural surface types than a lot of paths, so I wouldn’t be surprised if insects that normally dig into hard rocky soils might be interested, but it’s not something I am familiar with.”

  1. Are there any ecological studies on benefits of gabions as habitat for inverterbrates?

“A quick literature search didn’t pull up a lot about gabions specifically (journals.co.za/doi/pdf/10.10520/AJA00423203_1935 <- was main one I found), but there is a fair amount about the ecological benefits of dry stone walls, particularly in the UK where we have been using them for a very long time. A gabion and a dry stone wall seem like they are probably ecologically very similar, both basically being a vertical stack of rocky nooks and crannies (which sounds great!):

Are gabions a thing you install a lot in gardens? I wonder if anyone has compared them to drystone wall habitats…?

A big thank you to Linda.