# 1.5.3 Summary of Section 1.5

1. Some annual plants and insects can spend the winter at juvenile stages, such as seed, egg, larva or pupa. Butterflies in Britain display a variety of juvenile overwintering strategies.

2. Migration often results in high mortality, but completion of the journey results in higher breeding success, due to increased availability of food and fewer competitors.

3. Birds increase their body mass, sometimes by up to 50%, prior to migration. The body mass increase is related to the power margin of the birds.

4. Early arrival of migratory birds at the breeding site confers important advantages on those individuals.

OpenLearn - Surviving the winter
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