Estimating age‐dependent survival when juveniles resemble females: Invasive ring‐necked parakeets as an example

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–recapture data from the ring‐necked parakeet 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.

Biology and Impacts of Pacific Island Invasive Species. 15. Psittacula krameri, the Rose-Ringed Parakeet (Psittaciformes: Psittacidae)

“…Adult plumage is usually complete at about 2-2.5 years of age (Butler 2003). Senar et al (2019) followed 156 wild RRP for 13 years in Barcelona, Spain, and estimated annual survival probabilities for adults (0.83, 95% confidence interval [CI]: 0.77-0.87) and juveniles during their first (0.57, 95% CI: 0.37-0.79), second (0.79, 95% CI: 0.58-0.87), and third winter (0.83, 95% CI: 0.65-0.88); adult females had slightly higher survival (0.87, 95% CI: 0.78-0.93) than adult males (0.80, 95% CI: 0.73-0.86). Average life-span of these wild RRP was estimated as 4.8 years (95% CI: 3.6-6.4 years), although one bird was 12 years old and one was 14 years old at the end of the study.…”

“…Because invasive species eradications from islands are not always possible or successful, population suppression is often the next best management practice. Because RRP have few effective predators and long lifespans of 14+ years (Pithon 1998, Senar et al 2019, the most effective way to reduce population growth is by removing breeding aged birds from the population (Butler 2003). Whereas RRP are protected by law in Hong Kong, there was a period of RRP lethal control in Japan in the 1980s to protect agricultural crops from RRP damage.…”

Adapting to urban ecosystems: unravelling the foraging ecology of an opportunistic predator living in cities

“…S2 in Online Resource 1). These findings, together with sporadic predation on the invasive rose-ringed parakeet (Psittacula krameri) in Barcelona by the yellow-legged gull (Senar et al 2019), suggests that yellow-legged gulls could be acting as a natural predator of these problematic avian species. In fact, the consumption of pigeons and parrots overlaps with the trophic habits of the urban population of peregrine falcons (Falco peregrinus) breeding in Barcelona (Anton et al 2017), a raptor introduced in Barcelona to increase the city's biodiversity and contribute to the control of the populations of problematic urban bird species (García and Durany 2005).…”

Control of invasive ring-necked parakeet (Psittacula krameri) in an island Biosphere Reserve (La Palma, Canary Islands): combining methods and social engagement

“…Penalties and fines for intentional release are very low, and our actions aimed to mitigate the difficulty this legislative anomaly imposes on identifying and successfully prosecuting offenders (Bomford 2003). Because ring-necked parakeet lifespan is more than 30 years in captivity (Butler 2003) and up to 10 years in the wild (Senar et al 2019), a fourth phase has been developed and established by the island council as an early detection and rapid-response programme (EDRR). The main goal is to efficiently manage any future sightings of this alien bird in the Biosphere Reserve, and to proactively manage captive parakeets island-wide, whether already identified, or not.…”