A SHORTAGE of natural nest sites has led to the decline of some garden birds and so adding a bird box to your garden is an easy way to provide a safe place to breed.

The British Trust for Ornithology holds a National Nest Box Week each February to encourage people to put up boxes.

But actually you can put one up anytime since most bird species have more than one brood and continue to look for boxes throughout the breeding season.

My own garden is full of nest boxes and over the years I have put up more than 200 in surrounding countryside. In the past I have advised local landowners on the where to site boxes to attract barn owls and other species on their land.

The advantage of persuading birds to nest in your garden is that you get to watch their young as they grow, and eventually fledge, right on your doorstep.

For me, having nest boxes right outside the house means I can be there to photograph and paint the birds I see.

Many of the nest boxes in my garden are made from reclaimed tree stumps that I have carefully selected to provide backdrops for my paintings.

These look beautiful on the outside but they involve some work to get them right on the inside.

A good box that appeals to the widest range of common garden birds should be around 28cm high, 15cm wide and 13cm deep with a 32mm hole. Make sure the front or top of the box opens for cleaning.

If you want to attract a particular species then you need to tailor your box appropriately.

Blue, coal, marsh and willow tits choose a 25mm hole, which larger birds can’t get into.

House sparrows are communal birds and like to nest together. They usually build their own nests, but they can be attracted to nest in manmade boxes. A terrace of three boxes together, each 30cm high, 38cm wide with a 32mm entrance hole, is a close enough imitation of a natural site.

Meanwhile house martins build mud nests on the eaves of buildings, often in colonies averaging five nests. These nests are enclosed with small openings.

Swallows on the other hand prefer open nests on the inside of buildings such as a garages, porches or stables. Like house martins they return each year and it is worth attracting them so that you can watch them bring up their broods year after year.

I choose indestructible boxes made from wood-crete, a sawdust and concrete composite, because they are well insulated and don’t rot.

Most commercially available boxes are easy to put up and have been designed to attract specific bird species, but I do warn against diamond-shaped boxes which give birds less space to fill with nesting material. I also find that boxes designed to attract tawny owls don’t have enough room for the owls to feed their chicks or for the fledgling owls to flap their wings.

Some of the tawny owl boxes on the market are also designed with the nest cavity located at the bottom of a tall box and I don’t think tawny owls can get in and out of them without landing too forcefully on their eggs or chicks.

I would also warn against tube-shaped boxes designed to be strapped under a leaning branch. The openings of these are located at the top which means the owlets risk getting drenched in heavy spring showers. And if they get too wet, the bottoms of these boxes often rot.

Where you put your nest box is important. People often make the mistake of siting bird boxes where they can get a good view of the action. Unfortunately, this is the last thing most nesting birds want.

It is important to site your box out of prevailing winds and ideally out of full sun and in a sheltered spot to avoid being exposed to heavy rain.

Again if you are trying to attract a specific species then let their natural habitat be the deciding factor when choosing where to site your box. Close to trees, for instance, if the species you want is a woodland bird.

Once your box is up then you can look forward to a fun breeding season, waiting to find out whether a bird has chosen to use it and then watching to see if any chicks fledge. And if they do, you can also feel statisfied in the knowledge that you’ve done your bit to help.