Hernández, N., Oro, D and Sanz-Aguilar, A., Environmental conditions, age and senescence differentially influence survival and reproduction in the Storm Petrel. 2017. Journal of Ornithology. Volume 158, pp 113–123. DOI:
10.1007/s10336-016-1367-x
Abstract: Demographic parameters in wild populations are expected to be shaped by
individual covariates and environmental variability. Thus, the
understanding of the effects of age and/or environmental conditions on
variability in vital rates is of special importance in ecological and
evolutionary studies. Early age-related improvements in survival and
reproduction and later declines due to senescence are expected, above
all in long-lived species. Survival in these species is predicted to be a
more conservative parameter than reproduction, thereby giving rise to
less temporal variability. We studied age-dependent patterns of survival
and breeding success in a long-lived seabird, the Mediterranean Storm
Petrel
Hydrobates pelagicus melitensis,
and the additive influence of individual heterogeneity and
environmental climatic variables using 22 years of individual-based data
(1993–2014). The North Atlantic Oscillation index (NAO) and sea surface
temperature (SST) were selected as proxies of environmental conditions
in both breeding and wintering areas. Our results show that vital rates
improved with age for both survival and breeding success. A slow effect
of senescence at older ages was detected for breeding success, whereas
models did not disentangle the occurrence or the absence of actuarial
senescence. Reproduction was also influenced by the age of first
observed reproduction: at the same age, more experienced birds that
recruited earlier had a higher breeding success than less experienced
ones. Breeding success (but not survival) also showed great temporal
variability in accordance with theoretical predictions. Neither the NAO
nor the SST explained this variability, probably because petrels feed on
lower trophic levels than most pelagic seabirds and other physical
features such as river runoffs and winds may be involved, as well as
other environmental stressors such as predation by sympatric gulls.
Dr. Ana Sanz-Aguilar and Ana Payo-Payo from the GEP have participated a the International Day of Women and Girls in Science 2017 to "achieve full and equal access to and participation in science for women and
girls, and further achieve gender equality and the empowerment of women
and girls". 
