Over 90% of bee species are solitary rather than colonial, and their welfare depends critically on access to nesting sites that urban development and intensive agriculture have dramatically reduced.
Solitary bees experience welfare in the context of their ability to nest, forage and reproduce successfully. Evidence for individual solitary bee sentience is uncertain, but their capacity for nociception and learning makes the precautionary principle applicable. More importantly, the dramatic population-level decline of solitary bees represents a conservation crisis with cascading ecological effects. Providing nesting habitat — which costs nothing beyond tolerance of less tidy gardens — is the most direct and cost-free action available to any garden owner. The welfare and conservation cases coincide: what benefits solitary bee populations benefits individual bees.