A guide to nestboxes
In our increasingly urban world, nestboxes are vital little havens for birdlife. Sadly, climbing plants like Ivy and the gash-ridden covering houses where birds would’ve nested and roosted in have disappeared. In House Sparrows, we know a lack of nesting spaces is one of the main culprits behind their declines (of nearly 71% from 1977-2016). Nestboxes replace these natural spaces, and this blog is just an intro to the types you’ll see.
1. First, is your generic, four-sided nestbox, with an entrance/exit hole on the front. These are for our familiar, exotically coloured little songsters like Blue Tits. However, the size of the hole will dictate the species you’ll attract…
25mm (diameter) attracts: Blue and Coal Tit sized birds.
28mm: Great Tit, Pied Flycatcher and Tree Sparrows (plus above).
32mm: Nuthatches, House Sparrows and Redstart-sized birds (plus above).
45mm: Starling-sized birds, including Greater Spotted Woodpecker (and occasionally Wren).
Along with the main hole, if you’ve got a drill handy it’s a good idea to put in some drainage and ventilation holes. When watching a pair of Blue Tits tending to their chicks, you see them flitting to-and-fro the nestbox almost every few minutes! delivering juicy caterpillars. And all that food has to come out somewhere…and drilling 5 small holes in the floor (ideally 1.5cm across) gives it somewhere to go other than onto their siblings. Drilling two holes (about 2cm wide) on either side of the box will also help keep the feathered inhabitants cool.
(Also, worth mentioning there’s a new style of this birdbox, with an entrance/exit ‘slit’ instead of a hole, said to be more tempting for birds: https://www.bing.com/videos/search?view=detail&mid=159D1A9EC3B6AFF2D2F4159D1A9EC3B6AFF2D2F4&q=different+types+of+nestbox&shtp=GetUrl&shid=214c1808-3301-46ce-a2c3-af6bcc3bf8cb&shtk=SG93IHRvIHB1dCB1cCBhIG5lc3QgYm94IGluIHlvdXIgZ2FyZGVu&shdk=V2FudCB0byBhdHRyYWN0IG1vcmUgYmlyZHMgdG8geW91ciBnYXJkZW4gZHVyaW5nIHRoZSBicmVlZGluZyBzZWFzb24%2FIEhlcmUncyBteSB0aXBzIG9uIGhvdyB0byBwdXQgdXAgYSBuZXN0IGJveC4gVG8gYnV5IGEgbmVzdCBib3ggZnJvbSBTaW1vbiBLaW5nIFdpbGRsaWZlIGNsaWNrIGhlcmUgaHR0cHM6Ly93d3cuc2ltb25raW5nd2lsZGxpZmUuY29tL3Byb2R1Y3QtY2F0ZWdvcnkvd2lsZC1iaXJkcy9uZXN0Ym94ZXMtYW5kLW5lc3RpbmcvIFRvIHdhdGNoIG15IHZpZGVvIGFib3V0IHRoZSBSb2JpbiBOZXN0ZXIgbWVudGlvbmVkLCBjbGljayBoZXJlIGh0dHBzOi8vd3d3LnlvdXR1YmUuY29tL3dhdGNoIC4uLg%3D%3D&shhk=xJJ2rhbajJR9iGGXoM4EMUhYJ5jrTLZ9m0ASHZXm%2BRc%3D&form=VDSHOT&shth=OSH.8JPD0MQZ1n1wVUgjXxGTuw ).
2. Next, are open-fronted nestboxes. Identical to the generic one, apart from they have large, rectangular holes at the front, instead of a small round one. The species you can expect to attract to these are:
· Robins
· Wrens-They may also use ones with round holes 45mm+.
· Spotted Flycatchers-If you have these in your garden, treasure them! They’re beautiful little birds, with that speckled white and silver plumage, almost like marble.
. Pied + Grey Wagtail-They also have their very own ones (pictured right).
The only thing to remember with open-fronted nestboxes is they’re more vulnerable to predation, so ensure you situate them where it’s partially concealed, but still has good access (ideally amongst a nice wash of Ivy).
3. Colony Nestboxes. Three (or more!) birdboxes in one. They have one shared, long roof, front, base and backboard, but on the inside (usually) have dividers screwed in to make three ‘chambers’, each (ideally) with its own set of drainage holes. And whilst on holes, I really recommend drilling another small 1.5cm hole in each divider, to help with ventilation.
Colony nestboxes were made exclusively with House Sparrows in mind. Highly social birds, House Sparrows naturally live in bustling colonies. More sparrows, more eyes scouring for danger (and food). Their nests will even touch! However, if you have a colony nestbox that doesn’t have dividers in, I still recommend putting some in. One theory for House Sparrow decline is a deadly ‘bird Malaria’ so separating nests will (theoretically) reduce transmission. And of course, there are no booby traps to stop other birds from using the box. If two Blue Tit pairs decide to move in, they might not be so keen on sharing a house…
4. Swallow, House Martin and Swift nestboxes. Hypnotizing migrants from Africa, seeing these seemingly sky-bound creatures nesting, as opposed to tiny, sickled specks against a pale sky is phenomenal! Though Swallows might use large versions of a generic nestbox (with a 50mm+ hole) they and House Martins much prefer specialist domed nestboxes.
These replicate their natural nests, which they sculpt from a blend of wet mud and saliva-and consist of a clay sphere, screwed to two bits of wood which mimic the eaves of a house. Swifts on the other hand use a long, wooden construction with a small, tic-tac shaped entry hole. Both of these boxes should be placed as high as possible-the eaves is ideal.
5. Birds of Prey. Impressive structures made for suitably impressive birds! Generally, raptors don’t take to nestboxes, preferring to nest atop a colossal Pine or on the side of a cliff. However, Barn Owls, Tawny Owls and Kestrels buck this trend, living just as happily in either. Each box is specifically engineered for the species, for example, a barn owl one is triangular, to match the contours of the inside of a derelict barn they might opt to nest in naturally. Instead of describing each box here, I’ve linked them all side-by-side for those interested here: https://shopping.rspb.org.uk/bird-prey-nest-boxes/.
Whilst on the topic, the Hawk Conservancy Trust have started something called the ‘Raptor Nestbox Project”, a project where the trust builds and installs raptor nestboxes to see the affect it has on raptor populations. Definitely worth a look if you have a minute: https://www.hawk-conservancy.org/conservation-research/uk/rnbp/#:~:text=Nest%20boxes%20can%20be%20an%20effective%20conservation%20tool,nesting%20opportunities%20for%20cavity%20nesting%20birds%20of%20prey.
As always, feel free to comment or get in touch via social media etc if you have any questions or would like to know more.
Thank-you for reading!
House Martin nestbox credit: https://www.vinehousefarm.co.uk/media/catalog/product/cache/1/image/9df78eab33525d08d6e5fb8d27136e95/h/o/house_martin_double_nest_chmd_1_1.jpg
Swift nestbox credit: https://cdn.shopify.com/s/files/1/0955/9060/products/Swift_box_cladding_1024x1024.jpg?v=1480511622