Common swifts have declined by over 50 percent in the UK since the 1990s, driven largely by loss of nesting sites in renovated buildings, and urban architecture decisions have major welfare consequences.
Loss of nesting sites directly affects individual swift welfare — birds that return from Africa after a 9-month migration to find their nest site sealed lose their entire breeding opportunity for that year. Long-established breeding pairs separated from traditional sites spend the breeding season searching without success, experiencing the reproductive loss and energy expenditure of fruitless nesting attempts. The accumulated effect of millions of lost nest sites across UK building stock over decades has directly driven the population decline. Swift brick installation — which can be retrofitted to existing buildings or incorporated into new builds — directly restores breeding opportunities and reduces the annual welfare cost of failed nesting.