Quantifying an individual’s state as fitness proxy has proven
challenging, but accumulating evidence suggests that telomere length and
attrition may indicate individual somatic state and success at
self-maintenance, respectively. Sexual ornamentation is also thought to
signal phenotypic quality, but links between telomeres and sexual
ornamentation have been little explored. To address this issue, we
examined whether telomere length and dynamics are predicted by the
expression of a sexually selected ornament, the length of outermost tail
feathers (streamers), using longitudinal data from a population of
European barn swallows (Hirundo rustica). We further assessed
associations of telomere length with age, sex, breeding status and
survival. Telomere length showed high individual repeatability (R =
0.97) across years while shortening with age in both sexes. Telomere
length and dynamics were not significantly associated with survival to
the next year, remaining lifespan or reproduction status (comparing
breeding and non-breeding yearlings). Tail streamer length was
negatively associated with telomere length, independent of sex. Thus,
telomere length may reflect the costs of carrying an elaborated sexual
ornament, although ornament size did not significantly predict telomere
shortening. In conclusion, telomere length in adult barn swallows is a
highly consistent trait and shows a negative relationship with sexual
ornamentation, suggesting a trade-off between sexual ornamentation and
telomere length.
The effect of tail streamer length on aerodynamic performance in the barn swallow
