The following pieces of legislation apply to Protected Species and their habitats:

Planning Policy Statement 9 (2005), Key Principle 1.ii reads:

Plan policies and planning decisions should aim to maintain, and enhance, restore or add to biodiversity and geological conservation interests. In taking decisions, local planning authorities should ensure that appropriate weight is attached to designated sites of international, national and local importance; protected species; and to biodiversity and geological interests within the wider environment.

Paragraph 16 reads:

Local authorities should take measures to protect the habitats of these species from further decline through policies in local development documents. Planning authorities should ensure that these species are protected from the adverse effects of development, where appropriate, by using planning conditions or obligations. Planning authorities should refuse permission where harm to the species or their habitats would result unless the need for, and benefits of, the development clearly outweigh that harm.

Under the Natural Environment and Rural Communities Act, 2006

Every public authority must, in exercising its functions, have regard, so far as is consistent with the proper exercise of those functions, to the purpose of conserving biodiversity. 

Conserving biodiversity includes, in relation to a living organism or type of habitat, restoring or enhancing a population or habitat.