Rat predation of puffin eggs and chicks is a significant welfare threat at island colonies, and successful rat eradication programmes have produced dramatic recovery in puffin breeding success.
Rat predation causes acute welfare harm to individual puffins — chicks and eggs are killed, and adult birds roosting in shallow burrows face nocturnal attack. The welfare of birds under chronic rat predation pressure is affected by the repeated breeding failures that force energy-costly re-laying or abandonment. Successful rat eradication eliminates this ongoing welfare threat permanently for the island population. The non-target welfare costs of rodenticide eradication programmes are managed through careful bait station design (excluding non-target species) and seasonal timing. The dramatic recovery in puffin numbers following successful eradications validates the welfare benefit — more birds breeding successfully represents individual welfare gains multiplied across the recovering population.