In altricial birds. energy supply during growth is a major predictor of the physical condition and survival prospects of fledglings. A number of experimental studies have shown that nestling body mass and wing length can vary with particular extrinsic factors. but between-year observational data on this topic are scarce. https://www.roneverhart.com/Corvette-Taillight-Assembly-Inner-W-Backup-1980-1982/