Data from: High predation risk decimates survival during the reproduction season

Predators attack conspicuous prey phenotypes that are present in the
environment. Male display behaviour of conspicuous nuptial colouration
becomes risky in the presence of a predator, and adult males face higher
predation risk. High predation risk in one sex will lead to low survival
and sex ratio bias in adult cohorts, unless the increased predation risk
is compensated by higher escape rate.  Here, we tested the
hypothesis that sand lizards (Lacerta agilis) have sex-specific predation
risk and escape rate. We expected the differences to manifest in changes
in sex ratio with age, differences in frequency of tail autotomy, and in
sex-specific survival rate. We developed a statistical model to estimate
predation risk and escape rate, combining the observed sex ratio and
frequency of tail autotomy with likelihood-based survival rate. Using a
Bayesian framework, we estimated the model parameters. We projected the
date of the tail autotomy events from growth rates derived from
capture-recapture data measurements. We found statistically stable sex
ratio in age groups, equal frequency of tail regenerates between sexes,
and similar survival rate. Predation risk is similar between sexes, and
escape rate increases survival by about 5%. We found low survival rate and
a low number of tail autotomy events in females during months when sand
lizards mate and lay eggs, indicating high predator pressure throughout
reproduction. Our data show that gravid females fail to escape
predation.  The risks of reproduction season in an ectotherm are
a convolution of morphological changes (conspicuous colouration in males,
body allometry changes in gravid females), behaviour (nuptial displays),
and environmental conditions which challenge lizard thermal performance.
Performance of endotherm predators in cold spring months endangers gravid
females more than displaying males in bright nuptial
colouration.