Sunday 13 September 2015

Building for Bumblies

Our crawl of the internet for the optimum construction of a bumblebee nest returned this NERC article 'Bumblebee nest boxes don't work'. It reviews the dismal outcomes of a 4 year study on 6 different types of nest box by researchers from the University of Stirling and the Game and Wildlife Conservation Trust, where of the 736 nest boxes installed only 23 were occupied by bumblebees.

However as all gardeners will recognise, we are a people of hope, more often than not we garden with our finger's crossed. No matter how we rail against the indiscriminate randomness of elemental powers greater than our own, we have an indefatigable belief in the serendipity of nature as a constant. We cede to the slowness of garden-time, despite it passing concurrently with the contradictory rapid proliferation of weeds.

So, we were particularly delighted to read the numerous comments posted in addendum to the article which proved that contrarily bumblebees do make nests in man-made shelters in gardens. Gabriel Broaders from Devon posts that bumblebees are nesting in an upcycled fur-lined boot after a robin had nested in it the previous year. In fact many people attest to bumblebees nesting in disused bird boxes, perhaps because of a dearth of abandoned mice nests. We might remember to save the detritus when we clean out our bird box and use it in one of our bumblebee nests - of course we were going to build them ...and of course the bumblebees would come. Fingers crossed.

We chose this construction method as it seems to mimic a disused mouse nest, the preferred home of a houseproud bumblebee. It was easy to purchase the materials, we were able to build three nests for under a tenner and our experience in obtaining the used hamster bedding was priceless. We concede it is a little less attractive than having an incidental post-artisanal megalopolitan-crofter curated rhubarb forcer knocking about perhaps, though there is the chance that once the plants get established around them they'll be more easy to pass off as "gardenalia-n". For this project you will need:

  • 1 terracotta pot size EV27
  • 1 terracotta pot tray/saucer size EV23
  • galvanised (not pvc coated) 1.2mm garden wire or chicken mesh
  • 30mm length, 20mm (minimum) inner diameter tubing
  • a means to make some holes in the tubing - we used a drill
  • used hamster/or mouse bedding
  • nesting materials - ideally dried leaves, we improvised with straw and dry sphagnum moss
  • a couple of flat pebbles, we had broken quarry tile to hand

Using garden wire or chicken mesh make a grille to fit up inside the mouth of the pot. Make sure it has feet to lift it a good 25mm off the ground. The grille will keep the nesting material dry by lifting it above the soil.

The tubing curves which will cause condensation to pool, drill holes on the outside of the curve to allow it to drain.

This food grade silicon tubing can be bought by the meter on ebay, for those nearby ♥ W.P Wakefield Ltd.♥ (682 Lea Bridge Rd, London, E10 6AP)sell it - just look up when you enter the shop, there is a coil of it amongst the product suspended from the ceiling.

Trace the diameter of the upturned terracotta pot and dig a shallow pit, scour out a shallow trench to hold the tubing. Line the pit with pebbles. Position the grille (feet down) into the pit. Insert the tubing up through the grille to ensure the entrance way is firmly secured into the nest. We also supported the entrance at the far end of the tubing by propping it between pebbles before covering it over with soil. Make sure the drainage holes in the tubing are pointing down so that condensation will drain down into the soil.

Our local pet shop was happy to supply us with a handful of used hamster bedding; we took the strange looks we received from those earwigging our request to mean we were deemed eco-futurists, just a little out of sync. We didn't have very much to divide between the three nests we built but we reckon the odor de hamster Cuddles McGee is pretty pongiferous as the neighbourhood fox made a detour from its rounds to topple the saucers off all three nests last night.

We didn't have sufficient dry leaves to fill three pots so we used dry Sphagnum moss, here we may have made a mistake because the moss is specifically adapted with hyaline cells in its leaves that die on maturation to form receptacles for absorbing and retaining water from the atmosphere. In other words it acts as a sponge - we were hoping that it would wick condensation from the inner nest but it may well act just as effectively as a sink for all the rain we've been getting.

Line the pot with the nesting materials then up-end it onto the grille.

Place flat pebbles on the pot before balancing the saucer on top, this allows air to circulate and the saucer prevents rain getting into the nest.

We're holding thumbs and crossing our fingers and toes.

The Bumblebee Conservation Trust

Buglife

The Bumblebee Conservation Trust

References:
T. Jones, Bumblebee nest boxes don't work, 13 January 2014,NERC Science of the Environment, Available online 13 September 2015
Gillian C. Lye, Kirsty J. Park, John M. CHolland and Dave Goulson, Assessing the efficacy of artificial domiciles for bumblebees, Journal for Nature Conservation, Available online 21 April 2011, doi:10.1016/j.jnc.2010.11.001

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