The battle for nesting sites among the birds and the bees

Competition for nesting sites could explain why some birds and bumblebees are declining faster than others.

Research suggest animals that build their nests in early spring may win the fight for available habitat at the expense of late breeders, according to BBC.

Conservation efforts should focus on ensuring rare species have enough places to nest, say scientists.

For example, areas could be left to grow wild between spring and summer to help bumblebees establish nests.

Habitats such as hedgerows and hay meadows are being lost in many countries, meaning that fewer nesting sites are available.

Competition among animals for a suitable place to nest could explain why some species are struggling to survive.

"Ecologists understand why some groups of species are declining more, such as why farmland species are declining more than woodland species," said Dr Andrew Higginson of the University of Exeter.

"But an enduring mystery is the big variation in the declines of closely related species. Fighting over nest sites may be part of the reason - when nest sites are hard to come by, the species that will suffer most are those that nest later in the year."