Swift Foraging Ecology and Aerial Welfare

wildlife

The swift's aerial lifestyle means its welfare depends entirely on the abundance of flying insects. Insect decline is the key threat to swift welfare and population recovery.

Aerial Foraging Ecology

The common swift (Apus apus) is entirely aerial when not at the nest, catching all food and water on the wing. It feeds exclusively on 'aerial plankton' — small flying insects and spiders ballooning on wind currents. A swift family needs approximately 20,000 small insects per day during chick-rearing. They forage at heights from 10-2000m depending on weather, following insect-rich air masses across hundreds of kilometres in a single day.

Flying Insect Decline and Welfare

Flying insect abundance has declined by 60-80% since the 1970s in many European studies. This catastrophic loss directly impacts swift welfare: longer foraging journeys, reduced food delivery to chicks, thinner body condition, and reduced breeding success when insects are scarce. The causes of insect decline — intensive agriculture, pesticides, light pollution, habitat loss — are also the causes of swift population decline. Reversing insect decline is central to swift welfare recovery.

Weather and Foraging Welfare

Swift foraging is highly weather-dependent: cold, wet weather grounds insects, forcing swifts to fly hundreds of kilometres to find food. During prolonged cold wet spells in the breeding season, chicks can starve within days. Swifts have evolved to leave Britain early (August-September) to avoid deteriorating autumn insect availability. Climate change is altering weather patterns and insect phenology with uncertain but potentially significant welfare consequences for swifts.

Urban Foraging Opportunities

Urban environments can support swift foraging: street lighting attracts insects, creating aerial feeding opportunities; urban heat islands extend insect activity periods; and green urban spaces provide insect habitat. However, insecticide use in gardens and greenspaces, glass buildings causing insect-killing light pollution, and impermeable surfaces reducing insect breeding habitat limit urban insect abundance. Wildlife-friendly urban gardening directly supports swift foraging welfare.

Supporting Swift Prey Availability

Actions to increase flying insect abundance and support swift foraging welfare: reducing pesticide use in gardens and farmland; planting native flowering plants (supporting invertebrate food chains); maintaining wild areas, long grass, and log piles; reducing light pollution (shielded downward-only lighting); supporting agri-environment measures that restore insect-rich habitats; and reducing artificial surfaces in urban areas. Every garden and urban space managed for wildlife contributes to the insect abundance on which swifts depend.