We document seasonal changes in the ratio of phosphatidylcholine (PC) to phosphatidylethanolamine (PE) in pectoralis muscles of captive and wild White-throated Sparrows (Zonotrichia albicollis). We manipulated day length in captive sparrows to induce ‘winter’ or ‘migratory’ condition. The PC/PE ratio in these sparrows was 1.87 ± 0.11 (mean ± SE), and did not vary significantly between treatments. However, the PC/PE ratio was higher in wild adult sparrows in winter (1.90 ± 0.19) than those caught in migration (1.20 ± 0.13 in spring; 1.37 ± 0.14 in fall). No effect of migratory state on PC/PE ratio was found among wild juveniles (1.32 ± 0.09 in fall, 1.18 ± 0.14 in winter). Seasonal changes to PC/PE ratios may be a result of migratory exercise, rather than migratory condition per se.