Parental care trade-offs in the inter-brood phase in Barn Swallows Hirundo rustica

摘要: In seasonal environments with limited time and energy resources, double-brooded birds face trade-offs in the timing of their two reproductive attempts effort allocated to first second broods. Barn Swallow Hirundo rustica a long care period for brood enhances survival first-brood chicks, but also delays start brood, which turn reduces prospects second-brood chicks. Probably as response this trade-off, Swallows reduce post-fledging fledglings. By radiotracking whole families, we investigated determinants behaviour its consequences The end females’ investment was related beginning egg synthesis clutch. With synthesis, females significantly reduced provisioning rates firstbrood fledglings less than one-fifth previous rates, while proportion they spent foraging remained high. Assuming that success constant, conclude income production rather fledgling provision. Males did not compensate feeding rates. Thus clutch had marked effect on quantity food received by parallel changes parental observed drop daily rate These results support hypothesis strong tradeoff allocation subsequent Energy involves cost terms provisioning, result chicks is compromised. This probably outweighed improved an early brood.