Mick Street: Do you know your nest boxes?

Valentine’s Day, February 14th is the start of National Nestbox Week, the perfect time to create a place for our feathered friends to get together.

The history of St. Valentine`s Day has links to the Roman fertility festival of Lupercalia on February 15th. On 14th February AD 269 the Christian preacher Valentine was executed by the Emperor Claudius which gave us that date as St. Valentine`s Day.

However, it was Geoffrey Chaucer who gave us the connection to love match making in his dream poem “The Parlement of Foules”. The birds hold a conference on St Valentine’s Day to choose their mates and this is said to have begun the custom.

Mid February is when many birds do pair up and, for over 20 years the British Trust for Ornithology has designated February 14th- 21st as National Nest Box Week to give the birds somewhere to raise their broods. To have a bird nest in your garden is a joy for a wildlife watcher and well worth the effort.

There are some important things to consider if you are buying a nest box.

The most commonly purchased and the one likely to have most success is that for hole nest nesting birds. The hole varies in size depending on species. A 28mm hole is needed for Blue tit and Great tit and a 32mm hole for a House sparrow. The overall volume of the box is also important, a Blue tit is a small bird but can often have a brood of twelve young. Many boxes that are sold are too small and so will never be used. The distance from the base plate to the hole should be at least 150mm(6 ins), the base plate should be 120mm x 150mm and the wood should be 15mm thick for good insulation.

The main predators of these smaller birds are Grey squirrels and Great spotted woodpeckers which will enlarge the hole to get at the chicks. A metal plate of the correct hole size can be screwed over the hole to prevent this.

Starlings need a different style. Imagine a conventional box turned through 90 degrees, with the sloping roof covering the long side and with the 45mm hole at one end to create a tunnel effect. Swift boxes are of this design and will also attract House sparrows. All these boxes should be tilted forwards slightly for drainage. Artificial nests for House martins are a special design, usually using woodcrete, a mixture of sawdust and concrete. You can buy nesting/roosting pockets but they are usually too small and made of perishable and poorly insulated materials so a waste of money. The only bird that might roost in one is a wren and then only if they are very well hidden.

Siting of nest boxes is also important. House martins prefer under the eaves of a house. House sparrows and Starlings feel safe up there too, but Starlings will also accept boxes on trees. Boxes for Blue and Great tits can be attached to trees or houses and should be placed higher than one and a half metres off the ground and with the hole facing North or East to avoid too much sun. Both these species depend on the caterpillars on oak trees to feed their young and so the box needs to be within reasonable flying distance of a mature oak tree, fortunately not a problem in the Sid Valley.

The are open fronted “Robin boxes”. Robins prefer ones boarded up at the front to just over half as the Robin likes to sit tight and hide from prey. They prefer low to the ground and well hidden. If you can see the box when you have sited it, then it is not hidden well enough. Pied wagtails and Spotted flycatchers prefer boxes boarded less than half way up as they like to look for predators and then fly off before they get too close.

You are very unlikely to attract a Spotted flycatcher to your garden, but if you are lucky enough to have any birds nesting in your garden, enjoy watching but please, from a safe distance so you do not disturb them.