What are effective impediments to discourage birds from nesting?

Choosing overhead wires and metal spines as effective impediments to discourage birds from nesting is correct because these methods create physical barriers that limit the birds' ability to land and construct nests in particular areas. Overhead wires make it difficult for birds to perch, reducing their chances of nesting on ledges, roofs, or other structures. Metal spines serve a similar purpose by providing an uncomfortable or unstable surface for birds, deterring them from settling in those locations.

In managing bird populations and preventing the complications that arise from nesting, utilizing physically designed barriers is often preferred as it does not harm the birds and is generally a long-lasting solution. Other methods, while they may have their merits, do not provide the same level of structural deterrence that these physical impediments offer.