Common swifts are almost entirely aerial, sleeping, feeding and drinking on the wing across their 10,000km migration to sub-Saharan Africa, where they spend the northern winter in areas facing increasing drought stress.
Swift welfare challenges exist across their entire annual cycle. On migration, aerial insect availability is critical for refuelling stops. Periods of prolonged adverse weather during migration grounds cause mass mortality events when aerial insect populations collapse. The cumulative effect of habitat degradation at both breeding and wintering sites is reflected in population declines.