The Bouillon Nest Box has a 28mm entrance hole making it ideal for birds such as Blue Tits and Great Tits. Made from robust timber up to 18mm thick and left untreated so you can add a wildlife friendly colour stain or treatment of your choice. There is a shortage of natural nesting sites, which is thought to be one of the major factors behind the decline of some of our once most-common birds. By putting up nest boxes, such as this, which replicates a bird\'s natural nesting preferences, you can encourage them to breed near your home. This nest box is also available with 32mm entrance (Malmedy 32mm Nest Box - 90805) hole so you can attract more wildlife to your garden.