Wildlife houses?

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Myth: You must buy special homes to attract garden wildlife

This is certainly what commercial suppliers and garden centres would like you to believe. The idea is that these empty homes will encourage wildlife into your garden and to breed in there. This could be the case if suitable natural habitats and hiding places are not already available, provided of course that the creatures concerned are to be found in your area.

We have a page on “Garden products that do and don’t work” linking to a detailed pdf leaflet so this is just a summary of key points on garden wildlife refuges and boxes. Bird nest boxes (if correctly sited) really do work^1. for some song birds such as blue and great tits, robins, house and tree sparrows, house martins and starlings. It has also been shown recently^2. that putting bird boxes in apple orchards can help control commercially damaging pests. This should remind us that enhancing life for one ecosystem component isn’t good news for some of the others!

Left: "typical" songbird nest box. Right: owl nesting box by the River Ouse

With bird nest boxes it isn’t a case of “one size fits all”, and the size, shape and openings must be correct to be used by different species. Specialist boxes can even shelter owls, swallows, house martins and swifts. You can find an excellent practical introduction in Adrian Thomas’s “Gardening for Wildlife^”3.^, which also points out that nest boxes are pointless unless the food resources that the birds need can be found in your garden and its surrounds. Once installed, it may be some time before they are used, and they do need regular cleaning between years. See our "How to" leaflet.

Commonly sold bat boxes seem rarely to be occupied in gardens. Bats use more than one shelter for different purposes, so even if your box is used sometimes it may usually be empty. Furthermore, bats prefer aged boxes and it may be several years before they move in.

You can buy all sorts of hedgehog boxes, but trials have failed to find evidence that they are reliably occupied. Habitat piles and dense shrubs with ground debris are probably common enough that houses are unnecessary. Even more pointless are dormouse boxes, 3 varieties of which are available through Amazon (other suppliers are available) starting at £24.99. Dormice are uncommon and very patchily distributed in southern England only, so unless your garden backs on to a dormouse reserve it will be a waste of money. If you give one to a child as an exciting present you are dooming them to disappointment and disillusion.

Owl nest box Photo: By Sian Harrison, CC BY-SA 2.0, https://commons.wikimedia.org/w/index.php?curid=13229244

Insect houses and hotels are popular commercial products, with dozens available online from £9 to £184. The “hotels” contain several compartments with various sized shelter spaces, while the simple ones provide tubes for nesting solitary bees. The Sheffield BUGS project^4. looked at bee nests in some detail, with packs of straws, wood blocks with drilled holes of different sizes and hollow bamboo sections. Only 4mm drilled holes and bamboo sections were occupied in more than half of the gardens used. Nest blocks in the sun were more used than those hung in shade. Generally, bee nests are useful, but you don’t need to buy them, home-drilled blocks or bundles of bamboo sections work really well. We recommend Marc Carlton’s fact sheet for advice on making bee nests. It is also likely that large bee hotels may create such dense occupancy that parasites and predators will be attracted. Several small “bee bed-and-breakfasts” are probably better than one big hotel. Some of the drawbacks are explained in our leaflet here.

The same BUGS project tested three designs of bumblebee box, surface and buried terracotta pots and a recommended design of wooden box. Commercially bumblebee boxes cost between £25 and £60. None of the boxes tested by the Sheffield group ever attracted any bumblebees at all, despite the target species being present in the gardens. Other observations suggest these boxes are only likely to be used if set in parts of the garden where queen bumblebees routinely nest – where they probably aren’t needed anyway. Don’t bother!

Conclusion

It is a myth that wildlife gardeners have to spend money on wildlife homes. However, some, such as bird nest boxes will work if you have patience and install and manage them properly. Insect boxes aren’t worth buying, but it is fun and worthwhile to make your own simple drilled-wood nests, if only so you can observe what happens. In practice, typical gardens will already contain lots of suitable refuges for nesting or hibernating insects.

References

1. Conservation Evidence on artificial nesting sites. Available here

2. García, D. and Marcos , M. 2020 Enhancing ecosystem services in apple orchards: nest boxes increase pest control by insectivorous birds. J. Appl. Ecol. Abstract here

3. Thomas, A. (2017) Gardening for Wildlife. Bloomsbury Natural History pp 65-69

4. Gaston, K.J., Smith, R.M., Thompson, K. & Warren, P.H. 2005. Urban domestic gardens (II): experimental tests of methods for increasing biodiversity. Biodiversity and Conservation 14, 395-413. Available here

Page written by Steve Head: reviewed by Ken Thompson

Dormouse box sensibly sited as one of 500 at Briddlesford Nature Reserve, where they are used to monitor the resident dormouse population.

Putting one up in your garden is pointless unless your property adjoins a reserve with a resident population