Age and reproduction in lesser spotted woodpeckers (Dendrocopos minor)

We examined the influence of female age, male age, and pair-bond duration o n start of egg-laying, clutch size, and number of young fledged in the Less er Spotted Woodpecker (Dendrocopos minor). We also attempted to disentangle the relative influence of individual age and pair-bond duration on reprodu ction, because the effect of those factors may be confounded. Brooding perf ormance improved with age in that old females started egg-laying earlier an d old males raised more young than yearlings, and old pairs both started eg g-laying earlier and raised more young than new pairs. Clutch size was not affected by age, but showed a strong negative relation with laying date. La te-laying yearling females experienced a lower survival, and the survival o f yearling males showed a positive relation with fledgling production. That differential survival was a likely mechanism explaining the differences in reproductive performance between yearling and old birds. Several analyses suggested that pair-bond duration had independent positive effects on repro duction. Benefit of long-term pair-bonds appeared to depend upon repeated b reeding with a particular partner. The mechanisms behind the benefit of rem ating with a particular partner remain unclear, however. We postulate that much of the patterns of age effects on reproduction in the Lesser Spotted W oodpecker may be caused by constraints posed by the territorial system and effects of territory quality, although effects of individual quality can no t be excluded.