| | Received: 9 January 2018    Revised: 29 May 2018    Accepted: 22 June 2018 DOI: 10.1002/ece3.4366 ORIGINAL RESEARCH Estimating age-­ ependent survival when juveniles resemble d females: Invasive ring-­ ecked parakeets as an example n Juan Carlos Senar1  | Lluïsa Arroyo1 | Alba Ortega-Segalerva1 | José G. Carrillo1 |  Xavier Tomás1 | Tomas Montalvo2,3 | Ana Sanz-Aguilar4 1 Natural History Museum of Barcelona, Barcelona, Spain 2 Agencia de Salut Pública de Barcelona, Barcelona, Spain 3 CIBER de Epidemiología y Salud Pública, Barcelona, Spain 4 Animal Demography and Ecology Group, IMEDEA, CSIC-UIB, Esporles, Spain Correspondence Juan Carlos Senar, Natural History Museum of Barcelona, P. Picasso s/n, E-08003 Barcelona, Spain. Email: jcsenar@bcn.cat Funding information Regional Government of the Balearic Islands and the European Social Fund, Grant/ Award Number: PD/003/2016; Spanish Research Council (Ministry of Economics and Competiveness), Grant/Award Number: CGL-2016-79568-C3-3-P; European Cooperation in Science and Technology, Grant/Award Number: ES1304 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-­ ependent survival using capture–red capture data with uncertainty in age and sex assignment of individuals. We illustrate this modeling approach with capture–recapture data from the ring-­ ecked parakeet n Psittacula krameri. We analyzed capture, recapture, and resighting data (439 recaptures/resightings) of 156 ring-­ ecked parakeets tagged with neck collars in Barcelona n 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. KEYWORDS age-specific survival, capture–recapture, delayed plumage maturation, multievent models, ring-necked parakeet, survival 1 |  I NTRO D U C TI O N the individuals cannot be easily ascertained. The topic is further complicated in species in which juveniles resemble females, such that un- Many life history processes and parameters are age-­ ependent (e.g., d certainty appears not only in relation to the age of a high proportion age at maturity, age-­ pecific survival, or age-­ pecific reproductive s s of the individuals, but also in relation to their sex (Busse, 1984; Jenni investment) (Roff, 1992; Stearns, 1992). Accordingly, the age of an & Winkler, 1994; Pyle, Howell, Yunick, & DeSante, 1987; Svensson, individual is a key ecological parameter in population dynamics stud- 1992). A general approach for studying age-­and sex-­ pecific pops ies (Cam, 2009; Perrins, Lebreton, & Hirons, 1991; Sutherland, 1996; ulation dynamics parameters in these species is to consider only Williams, Nichols, & Conroy, 2002). However, too often, the age of the individuals for which age and sex have been determined with This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. © 2018 The Authors. Ecology and Evolution published by John Wiley & Sons Ltd. Ecology and Evolution. 2019;9:891–898.   |  891 www.ecolevol.org | SENAR et al. 892       reasonable certainty. However, this approach may entail discarding current estimate of about 800 individuals (Senar, Montalvo, Pascual, & substantial data. Even more importantly, this approach can bias data; Arroyo, 2017). Capture and recapture of ring-­ ecked parakeets were n since by definition, we use only individuals that have survived long conducted using a modified Yunick Platform Trap (2 × 1 × 1 m; (Yunick, enough to allow the determination of their sex/age. 1971)) located at the Natural History Museum of Barcelona. The Multievent capture–recapture models (Pradel, 2005) have Museum is located in Ciutadella Park, which hosts one of the largest been successfully used to estimate demographic parameters when ring-­ ecked parakeet colonies in the city (Senar et al., 2017). Between n there is uncertainty in the individuals’ assignment to a particular spring 2003 and spring 2016, we tagged a total of 156 individuals sex (Genovart, Pradel, & Oro, 2012), breeding status (Desprez, with metal rings as well as aluminum neck collars with numbered tags McMahon, Hindell, Harcourt, & Gimenez, 2013), health state that could be read without having to trap the bird (Senar, Carrillo-­ (Conn & Cooch, 2009), or behavioral characteristics (Sanz-­ guilar, A Ortiz, & Arroyo, 2012). During the study period, we obtained 157 re- Jovani, Melián, Pradel, & Tella, 2015). Here, we propose a mul- captures and collected 282 resightings of the numbered birds from tievent model parameterization able to estimate age-­ ependent d several sources: via transects conducted in Ciutadella Park to locate survival using capture–recapture data with uncertainty in age the birds, via reports from birdwatchers in Barcelona, and via obser- and sex assignment of individuals. We illustrate this modeling ap- vations made during the course of other activities, such as censuring proach with capture–recapture data from the ring-­ ecked paran Monk parakeets (Myiopsitta monachus). The resightings were pooled keet Psittacula krameri. Male ring-­ ecked parakeets over 3 years n with recaptures to obtain a better estimate of parameters. Parakeets old can easily be sexed due to males’ rose-­olored neck-­ings c r were captured, recaptured, or resighted on average 3.9 times (SD: 4.1), and black bibs (Butler & Gosler, 2004). However, although the with great variation between individuals (a range of 0–26 reobserva- shape of the primaries and the amount of yellow in undercovers tions per individual). As the estimation of annual survival rates requires has been suggested to discriminate adults and juveniles (Butler & short sampling periods, only birds recorded between December and Gosler, 2004), the differences are far from clear. Thus, immature April each year were used. This is also the period in which more para- males and both immature and adult females are, in practice, highly keets are trapped. The sample sizes and values provided refer to that monomorphic. The species thus exemplifies a typical case of un- period. certainty in the age and sex of a proportion of the population. We only distinguished two classes of birds in the field: uncer- The ring-­ ecked parakeet is also interesting as it is an invasive, n tain plumaged birds (coded “1”; which could be immature males, im- exotic, pest bird species that has established feral populations in mature females, or adult females) and adult males (coded “2”; over many temperate regions in Europe, North America, and Asia (Jackson 3 years old). However, capture–encounter histories per se contain et al., 2015; Le Gros et al., 2016; Strubbe, Jackson, Groombridge, & additional information that informs the model about individual’s age Matthysen, 2015; Strubbe & Matthysen, 2009). It is considered a pest and sex (i.e., the real biological state). For example, an encounter his- in most of these newly established areas as it is known to cause agricul- tory “10122220000000” belongs to a male marked as 1st winter tural damage and noise pollution and to compete with some native spe- juvenile. On the contrary, an encounter history “00000101100101” cies (Covas, Senar, Roqué, & Quesada, 2017; Hernández-­ rito, Carrete, B belongs to a female captured and marked with uncertain age, but Popa-­ isseanu, Ibáñez, & Tella, 2014; Menchetti & Mori, 2014). Recent L clearly adult after its 2nd resighting. studies have estimated ring-­ ecked parakeet breeding success (Braun, n Survival probabilities were modeled by means of multievent cap- 2004; Butler, Cresswell, Gosler, & Perrins, 2013) and dispersal (Braun, ture–recapture models accounting for uncertainty in young and adult 2009). However, the age-­ ependent survival probabilities of the sped female identification. The multievent framework distinguishes what cies, which are key parameters to estimate the intrinsic rate of increases can be observed in the field (the events coded in the encounter histo- in its populations (Butler et al., 2013), are still unknown. ries) from the underlying true biological states of the individuals, which The aim of this study is twofold: (a) to provide a multievent model must be inferred (Pradel, 2005). Our model included six biological approach to overcome the problem, typical to many species, of un- states: 1st winter juvenile parakeet alive (coded J1), 2nd winter juve- certainty in age and sex determination of individuals when estimating nile parakeet alive (coded J2), 3rd winter juvenile parakeet alive (coded age-­ ependent survival probabilities; and (b) to provide estimates of d J3), adult female parakeet alive (coded F), adult male parakeet alive age-­ ependent survival rates (and sex-­ ependent in the case of adults) d d (coded M), and parakeet locally dead (coded D). Encounter histories for the ring-­ ecked parakeet, which can be of use in population dynamn were coded using three different events (see below). Each row of en- ics and viability models, essential to evaluating the risks of invasion of counter histories belonged to a different individual, and each column this species (Pruett-­ ones, Newman, Newman, Avery, & Lindsay, 2007). J referred to year. The three events used were as follows: Event “0” was used to indicate that the individual was not cap- 2 |  M ATE R I A L S A N D M E TH O DS tured/resighted at a particular time point. Event “1” was used to indicate that the individual was captured/resighted at a particular time point and showed a female/young plumage. The study was conducted in the city of Barcelona, Spain. The ring-­ Event “2” was used to indicate that the individual was captured/ necked parakeet became established in Barcelona in the early 1970s resighted at a particular time point and showed an adult male plum- (Batllori & Nos, 1985), and the population has steadily increased to the age (i.e., evident neck collar). |       893 SENAR et al. TA B L E   1   Results of the goodness-­ f-­ it test of the Jolly o f Movement model for multistate data calculated using U-­ ARE2.3.2. C Data showed a good fit to a general CR model TEST χ 3G.SR 2 df p-­value 16.910 18 0.53 3G.SM 9.640 24 0.99 M.ITEC 13.398 11 0.27 M.LTEC 5.873 7 0.56 45.821 60 In a second step and conditional on individual survival, we modeled transition between states ψ probabilities (matrix  As the 2). period between capture/resight occasions lasted 1 year, surviving juveniles of 1st and 2nd winter move to the next age class (matrix 2) 0.91 Total Multievent models use three kinds of parameters: the initial state probabilities, the transition probabilities, and the event probabilities (conditional on the underlying states). The initial state probabilities correspond in our model to the proportions of newly tagged individuals belonging to the different and juveniles of 3rd winter become adults (males or females) with the same probability (i.e., assuming that sex ratio is balanced in the population, ψ = 0.5). This assumption is critical to making the model parameters identifiable. J1 J1 ⎛ ⎜ J2 ⎜ J3 ⎜ ⎜ Transition = F ⎜ ⎜ M ⎜ ⎜ D ⎝ J2 J3 F M D 0 1 0 0 0 0 0 1 0 0 0⎞ ⎟ 0⎟ 0⎟ ⎟ 0⎟ ⎟ 0⎟ ⎟ 1⎠ 0 0 0 𝜓 1−𝜓 0 0 0 1 0 0 0 0 0 1 0 0 0 0 0 Matrix 2 states (i.e., proportions of 1st, 2nd, and 3rd year juveniles, adult females, and adult males at first capture, vector 1). We did not consider temporal variation in initial state probabilities. ( Initial_ State = The event probabilities relate the observations coded in the capture histories (columns) to the underlying biological states (rows). J1 J2 J3 F M 𝜋1j 𝜋2j 𝜋3j 𝜋f 1 − 𝜋1j − 𝜋2j − 𝜋3j − 𝜋f ) Vector 1 Here, we modeled the probability of resighting (p, matrix 3). We did not consider age or sex effects on resighting probabilities because as we used resightings in addition to recaptures, we did not have a The transition probabilities correspond to survival and transition between state processes and were modeled in two steps. The first step accounted for survival Φ and mortality 1 -­Φ probabilities (matrix 1). Here, we tested the effects of time, age and sex (only for adults) on survival using different parameter structures, as follows: We allowed priori reasons to expect age or sex effects of resighting probabilities. Additionally, we had insufficient data to estimate a more complex model, which is apparent from the fact that trying these models produced a CI in parameter estimators that were too large, reducing confidence in these models. for differences between 1st winter birds and older birds together, so 0 that we assumed that once the birds have reached their second year, they enjoy a survival rate similar to adult birds (J1, J2 = J3 = AD); we considered the same survival for 1st and 2nd winter birds (i.e., young juveniles) but different from the others together with 3rd year birds and adults being equal (J1 = J2, J3 = AD); we allowed for differences between 1st winter, 2nd and 3rd winter (being equal), and adults (J1, J2 = J3, AD); we considered differences between juveniles (all ages together) and adults (J1 = J2 = J3, AD); and we considered a constant model with no differences between juveniles and adults in survival rate, so that survival is independent of age (.). Finally, we additionally tested the effect of sex on adult survival using two possible age structures for juveniles: (J1, J2 = J3, F, M) and (J1 = J2 = J3, F, M). Note that survival and mortality probabilities estimated in this way must be considered local/apparent (i.e., they do not allow for distinguishing between mortality and permanent emigration). J1 ⎛ ⎜ J2 ⎜ J3 ⎜ ⎜ Resighting = F ⎜ ⎜ M ⎜ ⎜ D ⎝ 1 2 0⎞ ⎟ 0⎟ 0⎟ ⎟ 0⎟ ⎟ p⎟ ⎟ 0⎠ 1−p p 1−p p 1−p p 1−p p 1−p 0 1 0 Matrix 3 The overall goodness-­ f-­it test of the Jolly Movement model o f for multistate data was calculated using U-­ ARE2.3.2 (Choquet, C Lebreton, Gimenez, Reboulet, & Pradel, 2009; Choquet, Rouan, & Pradel, 2009) and was not statistically significant (Table  1). Overdispersion was not apparent (χ2 = 45.82, 60 df, p = 0.91), and thus, there was no indication of violation of the assumption that fates of the individuals were independent of each other (Anderson, Burnham, & White, 1994). Parameters were estimated simultaneously by maximum likeli- J1 J1 ⎛ ⎜ J2 ⎜ J3 ⎜ ⎜ Survival = F ⎜ ⎜ M ⎜ ⎜ D ⎝ J2 J3 F M 𝜙1j 0 0 0 0 0 𝜙2j 0 0 0 0 0 𝜙3j 0 0 0 0 0 𝜙ad 0 0 0 0 0 𝜙ad 0 0 0 0 0 D 1 − 𝜙1j ⎞ ⎟ 1 − 𝜙2j ⎟ 1 − 𝜙3j ⎟ ⎟ 1 − 𝜙ad ⎟ ⎟ 1 − 𝜙ad ⎟ ⎟ 1 ⎠ Matrix 1 hood using the program E-­ URGE 1.6.3 (Choquet, Rouan & Pradel, S 2009). Model selection was based on Akaike’s information criterion adjusted for the effective sample size (AICc) (Anderson et al., 1994; Burnham & Anderson, 2002). Models with AICc values differing by less than 2 were considered equivalent. We only tested additive temporal effects on survival to avoid overparameterized models. Estimates were obtained by model averaging using Akaike weights (Burnham & Anderson, 2002). | SENAR et al. 894       TA B L E   2   Model selection for age and time effects on survival probability and time effects of recapture probability (p) of ring-­ ecked n parakeets in Barcelona (2003–2016) Model Survival p 1 J1, J2 = J3 = AD . 2 J1, J2 = J3 = AD Time 3 J1 =  J2, J3 = AD . 4 J1 =  J2, J3 = AD np Time Deviance AICc 7 1,046.19 1,060.53 0 19 1,020.37 1,060.78 0.25 7 1,047.13 1,061.47 0.94 19 1,021.25 1,061.65 1.13 ΔAICc 5 . . 6 1,049.46 1,061.72 1.19 6 J1, J2 = J3, AD . 8 1,045.52 1,061.96 1.43 7 J1 = J2 = J3, AD . 8 . Time 9 J1 = J2 = J3, AD 10 J1, J2 = J3, AD 11 J1, J2 = J3 = AD + Time 12 J1, J2 = J3, AD + Time 7 1,047.87 1,062.21 1.68 18 1,024.17 1,062.33 1.80 Time 19 1,022.08 1,062.49 1.96 Time 20 1,019.92 1,062.59 2.06 . 19 1,023.28 1,063.69 3.16 Time 20 1,021.26 1,063.92 3.40 13 J1, J2 = J3 = AD + Time Time 31 997.92 1,066.44 5.91 14 J1 = J2, J3 = AD + Time Time 31 998.83 1,067.36 6.83 15 J1, J2 = J3, AD + Time Time 32 997.87 1,068.84 8.31 16 J1 = J2, J3 = AD + Time . 19 1,030.54 1,070.94 10.41 17 J1 = J2 = J3, AD + Time . 19 1,031.11 1,071.52 10.99 18 Time . 18 1,033.41 1,071.57 11.04 19 J1 = J2 = J3, AD + Time Time 31 1,007.31 1,075.83 15.31 20 Time Time 28 1,016.16 1,077.45 16.92 Note. Models are ranked according to ΔAICc values. Notation: Time: parameters are allowed to change between capture occasions; (.): Parameters independent of time; J1, J2, and J3 refer to juveniles in their 1st, 2nd, or 3rd year, and AD refers to adult birds, from their 3rd year on. TA B L E   3   Model selection for sex effects on survival probability of adult ring-­ ecked parakeets in Barcelona (2003–2016) n Model Survival p 21 J1 = J2 = J3, F, M . 22 J1 = J2 = J3, F, M Time 23 J1, J2 = J3, F, M 6 J1, J2 = J3, AD np Deviance AICc ΔAICc 8 1,043.92 1,060.36 0.00 20 1,018.09 1,060.76 0.39 . 9 1,042.73 1,061.29 0.92 . 8 1,045.52 1,061.96 1.60 21 1,017.05 1,062.00 1.63 7 1,047.87 1,062.21 1.85 24 J1, J2 = J3, F, M Time 7 J1 = J2 = J3, AD . 9 J1 = J2 = J3, AD Time 19 1,022.08 1,062.49 2.13 10 J1, J2 = J3, AD Time 20 1,019.92 1,062.59 2.23 Note. Models are ranked according to ΔAICc values. Notation: Time: parameters are allowed to change between capture occasions; (.): Parameters independent of time; J1, J2, and J3 refer to juveniles in their 1st, 2nd, or 3rd year; AD refers to adult birds of both sexes, from their 3rd year on; F refers to adult females, and M refers to adult males. Mean life span was estimated from survival rate according and 3). The model with the lowest AICc assumed a constant re- to Mean life span  (1/(-­N(Survival rate))) (Brownie, Anderson, =  L sight probability (0.44, 95% CI = 0.38–0.50, Model 21, Table 3). Burnham, & Robson, 1985). Survival probability was modeled according to different age structures, differing in how we pooled ages (Table 2) and with and 3 |   R E S U LT S without sex effects for adult birds (Table 3). Models with temporal variation of survival were not retained (Table 2). In general, models with different age structures were close in terms of AICc Models with time-­ ependent variation in resight probability were d (Table 2) indicating no significant differences in survival probabili- not better than models with constant resight probability (Tables 2 ties among the different age classes (Table 2, Figure 1). Regarding |       895 SENAR et al. their state (age) on an annual basis with all the males acquiring their adult plumage at the same age. Our results suggest that ring-­ ecked n parakeets may suffer higher mortality probability during their first year than older birds. This is a common phenomenon in most bird species (Newton, 1998), including parakeets (e.g., Monk parakeet: 1st year 0.61, adults 0.81 (Bucher, Martin, Martella, & Navarro, 1991); Puerto Rican parrot: 1st year 0.68, adults 0.85 (Snyder, Wiley, & Kepler, 1987)). Alternatively, juveniles during their first year may permanently disperse from the study area in higher proportions than other juveniles and adult birds; unfortunately, very little is known about dispersal patterns in this species. F I G U R E   1   Model-­ veraged estimates of juvenile (aged 1 to 3; a Models 1–10, Table 2), adult (both sexes; Models 1–10, Table 2), adult females, and adult males (Table 3) survival probabilities of ring-­ ecked parakeets at Barcelona (2003–2016) n The fact that models with different age structures were close in terms of AICc may indicate that in our population there are no substantial differences in survival probabilities between age classes. This could be due to the fact that we used birds captured in winter (December–April). If the higher mortality filter occurs soon after age-­ d ependent survival, model-­ averaged survival estimates fledging and thus before our first captures, our data would be unable (Models 1 to 10, Table 2; Figure 1) were as follows: 0.57 (95% to clearly detect this mortality (Payo-­ ayo, Genovart, Bertolero, P CI = 0.37–0.79) for first year juveniles, 0.79 (95% CI = 0.58–0.87) Pradel, & Oro, 2016). Alternatively, in the city, early mortality could for second year juveniles, 0.83 (95% CI = 0.77–0.88) for third year be less marked than in the wild (Rebolo-­ frán et al., 2015), but again, I juveniles and 0.83 (95% CI = 0.77–0.87) for adults (Models 1–10, this hypothesis should be further tested. On the other hand, al- Table 2). Regarding sex effects on adult survival, models with sex though our modeling approach allows the estimation of juvenile sur- effects were preferred but they were very close in terms of AICc vival, our estimates are based on uncertain data and consequently to models without sex effects (Table 3). Model-­ veraged survival a are expected to be more uncertain than estimates obtained using estimates (Table  were as follows: 0.87 (95% CI  0.78–0.93) 3) =  encounter data of known-­ ge individuals. a for adult females and 0.80 (95% CI = 0.73–0.86) for adult males. In general, males enjoy a higher survival rate than females, ei- Overall survival rate for the species was estimated at 0.81 (95% ther because of being subordinate to males or because of a higher CI = 0.77–0.85) (Model 5, Table 2), and mean life span was esti- parental effort than males (András & Tamás, 2007; Donald, 2007; mated at 4.8  years (95% CI  3.6–6.4  =  years). Longevity records Promislow, Montgomerie, & Martin, 1992). However, this was not were for one individual that reached 14 years of life and another the case in ring-­ ecked parakeets, in which we found that females n one that reached 12 years. enjoy a slightly higher survival rate than males. This could be the result of intense competition between males (András & Tamás, 2007; 4 | D I S CU S S I O N Promislow et al., 1992) or even, given the apparent stable pair bond of the pair, from protection of females on the part of males (Senar & Domenech, 2011). Multievent models were developed to specifically account for un- Estimating survival probabilities can be critical in alien inva- certainty in state assessment in capture–recapture studies (Pradel, sive species to model their expansion rate (Conroy & Senar, 2009; 2005). The method has been used since then to estimate demo- Neubert & Caswell, 2000). Using the multievent model approach, graphic parameters with uncertainty in assignment of many differ- the overall adult survival probability of ring-­ ecked parakeets in the n ent states such as sex, breeding status, or health status (see Pradel city of Barcelona was estimated at 0.81. This value is very similar (2009) for a review). In this study, we show, for the first time, that to the survival probability of about 0.80 previously found for the the method can be extended to estimate age-­ pecific survival rates s monk parakeet in the same area (Conroy & Senar, 2009). It could be when age cannot be fully ascertained. This is typically the case of argued that survival of birds in cities is higher than in natural hab- species only showing sexual dimorphism at the age of maturity, itats because of the lower predation rate in these urban habitats where juveniles typically resemble females, displaying what has been (Chamberlain et al., 2009; Fischer, Cleeton, Lyons, & Miller, 2012; defined as “delayed plumage maturation” (Butcher & Rohwer, 1989; Møller, 2009; Rebolo-­ Ifrán et  2015; Walter, Fischer, Baruch-­ al., Senar, 2006). Our approach allows the use of all available data to Mordo, & VerCauteren, 2011). In Barcelona city, some instances of estimate age-­ pecific survival probabilities. However, our approach s predation by peregrine falcons Falco peregrinus and yellow-­egged l relies on a critical assumption: The sex ratio must be fixed in the gulls Larus cachinnans on both parakeets have been recorded model to make parameters identifiable. Moreover, parameters in our (J.Quesada pers.comm., E.Durany pers.comm., and pers.obs.) but multievent model are identifiable because: 1) Age in males can be these are considered mostly anecdotal compared with the predation assessed with certitude when they are marked as juveniles and later rates the birds can suffer in the wild. Accordingly, the survival rate recaptured or resighted as adults, and 2) individuals must change of some other similar-­ ized psittacids in the wild show lower survival s | SENAR et al. 896       rates than ring-­ ecked and monk parakeets (Amazona finschi 0.73, n Forpus passerinus 0.57; reviewed in Senar et al. (2012)). However, data from other similar wild species are also within the range found in the urban populations (Amazona vittata 0.89, Cacatua pastinator 0.93–0.94, Cacatua leadbeateri 0.81–0.93; reviewed in Senar et al. (2012)), including data on wild monk parakeets (0.81, Bucher et al. (1991)). This suggests that the high survival probabilities estimated AU T H O R C O N T R I B U T I O N S The study was conceived by JCS, LA, TM, and ASA. The data were collected by JCS, LA, AOS, JGC, XT, and TM. The statistical analyses were conducted by JCS and ASA. The manuscript was written by JCS, LA, and ASA, with input from all other coauthors. JCS and TM contributed to funding and materials. here for ring-­ ecked parakeets may be an inherent characterisn tic of the species rather than a simple consequence of urban life. Unfortunately, data from wild populations are lacking and we cannot distinguish between the two hypotheses. DATA AC C E S S I B I L I T Y All data used in this study are available in Dryad. In summary, our multievent model approach has been shown to be successful to estimate age-­ pecific survival probabilities for s species in which juveniles resemble females, such that uncertainty appears not only in relation to the age of a high proportion of the ORCID Juan Carlos Senar  http://orcid.org/0000-0001-9955-3892 individuals, but also in relation to their sex. The method allows us to incorporate what could otherwise be defined as “imperfect data” (Desprez et al., 2013) into demographic analyses. In our example, we have been able to provide the first age-­ ependent survival estimates d for the ring-­ ecked parakeet, allowing us to predict a high increase n in invasive populations of this species (Butler et al., 2013). We therefore strongly advocate for the use of this multievent approach in the estimation of survival rate in species with delayed plumage maturation. Moreover, the method could be adapted to other situations allowing the incorporation of additional information (e.g., data on birds through molecular sexing, intermediate plumages, reproductive behaviors, or the presence of brood patches) even if an exact age or sex determination cannot be made (Genovart et al., 2012). This type of additional information could reduce the uncertainty in the state assignment, and the precision of the estimates can be improved. AC K N OW L E D G M E N T S The present study was funded by CGL-­016-­9568-­3-­-­ re2 7 C 3P search project to JCS from the Spanish Research Council (Ministry of Economics and Competitiveness). ASA was supported by a postdoctoral contract cofunded by the Regional Government of the Balearic Islands and the European Social Fund (ref. PD/003/2016). We thank Jonas Knape for useful comments on a previous version of the paper, David Boné for his help in the field, and Sarah Young for improving the English of the manuscript. Birds were handled and ringed with the permission of Institut Català d’Ornitologia and the Environment Department of the Generalitat de Catalunya. Rings were provided by the Catalan Ringing Office (ICO). We also wish to acknowledge the support provided by COST European Cooperation in Science and Technology Actions ES1304 “ParrotNet” for the development of this manuscript. The contents of this manuscript are the authors’ responsibility and neither COST nor any person acting on its behalf is responsible for the use that may be made of the information contained herein. C O N FL I C T O F I N T E R E S T None declared. REFERENCES Anderson, D. R., Burnham, K. P., & White, G. C. (1994). AIC model selection in overdispersed capture-­ ecapture data. Ecology, 75, 1780– r 1793. https://doi.org/10.2307/1939637 András, L., & Tamás, S. (2007). Mortality costs of sexual selection and parental care in natural populations of birds. 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