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Providing evidence to improve practice

Action: Provide artificial nest sites for bumblebees Bee Conservation

Key messages

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  • We have captured 11 replicated trials of bumblebee nest boxes. Several different types of nest box have been shown to be acceptable to bumblebees, including wooden or brick and tile boxes at the ground surface, underground tin, wooden or terracotta boxes and boxes attached to trees.

 

  • Three replicated trials since 1989 in the UK have shown very low uptake rates (0-2.5%) of various nest box designs (not including underground nest boxes), while seven trials in previous decades in the UK, USA or Canada, and one recent trial in the USA, showed overall uptake rates between 10% and 48%.

 

  • Wooden surface or above ground nest boxes of the kind currently marketed for wildlife gardening are not the most effective design. Eight studies test this type of nest box. Five (pre-1978, USA or Canada) find 10-40% occupancy. Three (post-1989, UK) find very low occupancy of 0-1.5%. The four replicated trials that have directly compared wooden surface nest boxes with other types all report that underground, false underground or aerial boxes are more readily occupied.

 

  • Nest boxes entirely buried 5-10 cm underground, with a 30-80 cm long entrance pipe, are generally the most effective. Seven replicated trials in the USA, Canada or the UK have tested underground nest boxes and found between 6% and 58% occupancy.

 

  • We have captured no evidence for the effects of providing nest boxes on bumblebee populations.

 

Supporting evidence from individual studies

1 

Sladen (1912) placed 112 underground nest boxes for bumblebees in his garden near Dover, in Kent, England in 1910 and 1911. Boxes were buried cylinders of tin or terracotta, or holes in the ground with a wooden cover, and a 38-75 cm tunnel leading to them. They were occupied by six species of bumblebee, including the short-haired bumblebee Bombus subterraneus now extinct from Britain. Thriving colonies developed in 13-19% of nest sites provided.

2 

A trial of 36 underground bumblebee nest boxes in woodland and meadows near Urbana, Illinois, USA, found 48% of the boxes were occupied by a total of five species of bumblebee from 1915 to 1919 (Frison 1926). The boxes were made of tin or cypress wood, provided with grass from field mouse nests, and had an entrance spout or pipe at ground level. Some had a copper gauze base, to allow drainage.

3 

A trial of 172 nest boxes of six types (unequally replicated), carried out on farms in Wisconsin, USA in 1953, showed that bumblebees will nest in wooden nest boxes or half-buried flower pots at the surface, wooden boxes attached to buildings 1 m above ground, or in metal cans or roof tile enclosures buried underground (Fye & Medler 1954). Flax straw, old mouse nests or felt were added as bedding. Overall, 34% of the nest boxes were occupied, by five species of bumblebee, including three now thought to be declining in some parts of North America (Xerces Society 2008): the red-belted bumblebee Bombus rufocinctus, the yellow bumblebee B. fervidus and the half-black bumblebee B. vagans.

Additional reference

Xerces Society (2008) Bumblebees in decline. Invertebrate conservation fact sheet. Available at http://www.xerces.org/wp-content/uploads/2008/09/bumblebees_factsheet.pdf. Accessed 2 December 2009.

4 

A trial of 500 above ground wooden nest boxes near Lethbridge in southern Alberta, Canada, found that over 10% of boxes placed in uncultivated gardens, beside fence posts on prairie, or along copses were used (Hobbs et al. 1960). Upholsterer's cotton was used as bedding. Boxes placed in long grass were not used. Seven species used the nest boxes, including B. rufocinctus and B. fervidus, both thought to be declining in parts of North America, and the Western bumblebee B. occidentalis (one nest only),which has undergone dramatic range contraction recently (B. occidentalis may be a Western variant of another species Bombus terricola rather than a species in its own right - see www.nhm.ac.uk/research-curation/research/projects/bombus/bo.html).Two important alfalfa crop pollinators in Alberta - the yellow-banded bumblebee B. terricola and the red-belted or tri-colored bumblebee B. ternarius - did not use the boxes.

5 

A trial of 1,023 wooden nest boxes placed in grassland or woodland in southern Alberta, Canada (Hobbs et al. 1962) found an occupancy rate by bumblebees of 35% overall. Underground nest boxes were more often occupied (49%) than above ground (32%) or half-buried (36%) boxes.

6 

A trial of 1,233 surface boxes, 465 underground boxes, 500 false underground boxes and 100 above ground boxes in areas of mixed woodland and grassland in southern Alberta, Canada, from 1961 to 1966 (Hobbs 1967), found underground and false underground boxes were more often occupied by bumblebees (approximately 58% and 48% respectively) than surface boxes (approximately 26%) or above ground boxes attached to tree trunks (35%). False underground boxes were at the surface, but with a partially buried entrance pipe giving the appearance of a subterranean nest.

7 

A replicated trial carried out in 1970 and 1971 in southwestern Alberta, Canada, found that 23% and 43% of wooden nest boxes put out for bumblebees were occupied, in the respective years (Richards 1978). In total, 2,140 boxes were put out in a 1 km2 area, with equal numbers of underground, false underground, surface and above ground boxes. Upholsterer's cotton was added to each box as bedding. Fourteen different species of bumblebee Bombus sp. used the boxes. Preferred nest box locations were underground, buried 10 cm below the surface with a 30 cm plastic pipe to the entrance (38.5% occupied), and above ground, with the box wired to a tree trunk at chest height (38.7% occupied). False underground and surface nest boxes were also readily occupied (22.6% and 32.7% respectively).

8 

A trial (unequally replicated) of 654 bumblebee nest boxes over three years (1989-1991) in farmland, gardens and fenland in Cambridgeshire, UK, found only 10 boxes were occupied (1.5%) (Fussell & Corbet 1992). The nest boxes tested were wooden boxes raised 10 cm or 1 m above ground, or nest sites constructed with bricks and concrete tiles on the ground. Dry moss, felt or shredded textiles were added as bedding. Two common and widespread bumblebee species used boxes of both types, the early bumblebee Bombus pratorum and the common carder bee B. pascuorum.

9 

During a three‐year study in Sheffield, UK, no artificial nest chambers of any design (above ground terracotta plant pots, buried terracotta plant pots with entrance holes at the top (no pipe) and wooden boxes) were occupied by bumblebees Bombus spp. (Gaston et al. 2005). Between 52 and 72 nest boxes were put out each year, in 20 domestic gardens.

10 

Elliott (2009) reports putting out 100 wooden nest boxes in subalpine meadows in Gunnison National Forest, Colorado, USA, of which approximately 10% were occupied by the Bombus appositus, a long tongued bumblebee and one of the three most abundant bumblebee species in the study area. These nest boxes were lined with cotton for insulation, but no further detail of their design is given.

11 

Lye (2009) tested six different bumblebee nest box designs in gardens and farmland in England and Scotland: aerial wicker nest boxes (120), dug holes covered with concrete slabs or upturned flower pots (100 each), semi‐underground wooden nest boxes (100), wooden surface boxes (26) and a buried nest box design made with two pairs of flower pots placed mouth to mouth (170). She found very low uptake rates of 0‐2% for all designs except the underground flowerpot design, which incorporated drainage, ventilation and a 30 cm entrance pipe. For this design, 2% of 150 were used on Scottish farmland, but 40% (eight of 20) of those put out in an English botanic garden supported bumblebee colonies. Two of 20 aerial wicker nest boxes (10%) were occupied at the same site and one of 100 placed at a site in Scotland.

Referenced papers

Please cite as:

Dicks, L.V., Showler, D.A. & Sutherland, W.J. (2010) Bee conservation: evidence for the effects of interventions. Pelagic Publishing, Exeter, UK