Time to nest

MANY birds will be building their nests in March. Some start from scratch, while others will use a nest from previous years, or perhaps one started by another species. Apart from most ground-nesters, which have a simple scrape and little material, many birds build complex nests. These can require precise materials; finding these and building the nest can take a considerable amount of time and effort.

The simplest tree nest probably belongs to one of the pigeons. Woodpigeon, for example, makes a simple platform of about 200 twigs, with a lining of thinner ones.

The male provides the female with materials and she does the construction, taking a week or so. Common Starlings can rapidly build a nest in a suitable cavity and may take only one to three days, but they will add materials later in the form of fresh leaves and flowers, which may keep the nest free from parasites. Male Eurasian Wrens can be busy making several nests from which the female chooses one to embellish and complete. The most intricate nest of any British bird must be that of Long-tailed Tit, which may take three to four weeks to complete, containing as many as 200-300 sprigs of moss, 600 spider cocoons, 2,000 feathers and 3,000 flakes of lichen.

While larger birds will tend to build the biggest nests, studies of nests of Palearctic passerines have shown other factors are involved. Nests which are built by both parents tend to be larger than those built by just one, birds in colder regions tend to build larger nests and birds with less risk of predation will also build bigger ones. One of the largest nests in Britain was built by a Golden Eagle and was almost 5 m deep, being used by many families of eagles over the years. Corvids can build quite bulky nests and Jackdaws are known for filling a chosen nesting space with twigs – one was more than 3 m high and

2 m wide, and it was thought to have taken four years to complete.