Data from: Proximity to roads, but not exposure to metal pollution, is associated with accelerated developmental telomere shortening in nestling great tits

Comprehensively understanding the factors affecting physiology and fitness
in urban wildlife requires concurrently considering multiple
stressors.  To this end, we simultaneously assessed how
metal pollution and proximity to roads affect body condition and telomere
shortening between days 8 and 15 of age in nestling great tits (Parus
major), a common urban bird.  We employed a
repeated-measures sampling design to compare telomere shortening and body
condition between nestlings from four urban study sites south of Antwerp,
Belgium, which are located at different distances from a metal pollution
point source.  In addition, we explored associations
between metal exposure and telomere dynamics on the individual level by
measuring blood concentrations of five metals/metalloids, of which lead,
copper and zinc were present at concentrations about the limit of
detection.  To assess whether roadway-associated
stressors (e.g. noise and air pollution) might affect nestling condition
and telomere shortening, we measured the proximity of nest boxes to
roads.  Metal exposure was not associated with nestling
telomere length or body condition, despite elevated blood lead
concentrations close to a metal pollution source
(mean ± SE = 0.270 ± 0.095 µg/g wet
weight at the most polluted study site), suggesting that nestlings may
have some capacity to detoxify metals.  However,
nestlings from nest boxes near roads exhibited more telomere shortening
between days 8 and 15 of age, and shorter telomeres at day
15. Nestlings in poorer condition also had shorter telomeres, but
proximity to the road was unrelated to body
condition.  Thus, nutritional stress is unlikely to
mediate the relationship between proximity to roads and telomere
length.  Rather, proximity to roads could have affected
telomere shortening by exposing nestlings to air or noise
pollution.  Our study highlights that traffic-related
pollution, which is implicated in human health problems, might also affect
urban wildlife.