Garden Birds. Mike Toms

because the control birds – those without access to additional food – were under heavy competitive pressure, suppressing clutch size and other measures of breeding success. They found, for example, that fed birds laid 18 days earlier, on average, than control birds and were also more synchronous. One of the challenges to unravelling these effects is the difficulty in studying wild birds, of following individuals throughout their entire life cycle and in dealing with populations that may move between habitats and over significant distances.