Explaining variation in life expectancy between individuals of the same age is fundamental to our understanding of population ecology and life-history evolution. Variation in the length and rate of loss of the protective telomere chromosome caps has been linked to cellular lifespan. Yet, the extent to which telomere length and dynamics predict organismal lifespan in nature is still contentious. Using longitudinal samples taken from a closed population of Acrocephalus sechellensis (Seychelles warblers) studied for over 20 years, we describe the first study into life-long adult telomere dynamics (1 to 17 years) and their relationship to mortality in natural conditions (N=204 individuals). We show that telomeres shorten with increasing age and body mass, and that shorter telomeres and greater rates of telomere shortening predicted future mortality. Our results provide the first clear and unambiguous evidence of a relationship between telomere length and mortality in the wild, and substantiate the prediction that telomere length and shortening rate can act as an indicators of biological age further to chronological age when exploring life-history questions in natural conditions.

The data package contains one dataset:
- Longitudinal and cross-sectional data on telomere length, body mass and tarsus length of Seychelles warblers collected in the field. Telomere length estimates were measured using an absolute qPCR method. Please see README file for further details.