This journal provides immediate access to some articles. Volume 363(1490); January 27, 2008 Introduction. Adaptation to the annual cycle Research Articles Optimal moult strategies in migratory birds PMCID: PMC2606747 Travelling on a budget: predictions and ecological evidence for bottlenecks in the annual cycle of long-distance migrants PMCID: PMC2606749 Adaptive specialization, conditional plasticity and phylogenetic history in the reproductive cue response systems of birds PMCID: PMC2606750 Optimal annual routines: behaviour in the context of physiology and ecology PMCID: PMC2606752 Avian circannual clocks: adaptive significance and possible involvement of energy turnover in their proximate control PMCID: PMC2606758 | ||