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Photo M Cabrera |
Abstract: Many species only show sexual dimorphism at the age of maturity, such
that juveniles typically resemble females. Under these circumstances,
estimating accurate age‐specific demographic parameters is challenging.
Here, we propose a multievent model parameterization able to estimate
age‐dependent survival using capture–recapture data with uncertainty in
age and sex assignment of individuals. We illustrate this modeling
approach with capture–recaptu
Psittacula krameri.
We analyzed capture, recapture, and resighting data (439
recaptures/resightings) of 156 ring‐necked parakeets tagged with neck
collars in Barcelona city from 2003 to 2016 to estimate the juvenile and
adult survival rate. Our models successfully estimated the survival
probabilities of the different age classes considered. Survival
probability was similar between adults (0.83, 95% CI = 0.77–0.87) and
juveniles during their second (0.79, 95% CI = 0.58–0.87) and third
winter (0.83, 95% CI = 0.65–0.88). The youngest juveniles (1st winter)
showed a slightly lower survival (0.57, 95% CI = 0.37–0.79). Among
adults, females showed a slightly higher survival than males (0.87, 95%
CI = 0.78–0.93; and 0.80, 95% CI = 0.73–0.86, respectively). These high
survival figures predict high population persistence in this species and
urge management policies. The analysis also stresses the usefulness of
multievent models to estimate juvenile survival when age cannot be fully
ascertained.
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