Rescue data as an alternative for assessing trends and phenological changes in two invasive parakeet species

Eleonora Ciprari,Leonardo Ancillotto,Valentina Studer,Chiara Chessa,Emiliano Mori

doi:10.1007/s11252-022-01224-9

Abstract

Monitoring population trends of alien species is pivotal to design effective management plans to preserve native biodiversity, particularly urban areas, where most populations of alien birds are established. Urban wildlife rescue centers, with personnel trained to record species, age and sex of each individual brought by the public, may represent a reliable citizen-science based method to estimate both local changes in alien species phenology and population trends. In this work, we analysed records of monk and ring-necked parakeets by comparing rescue records in the urban area of Rome from the last 15 years. We also tested whether breeding phenology of alien parakeets showed any changes since the start of the invasion processes.We recorded a strong correlation between the number of rescued parakeets and their population trends, thus confirming the importance of wildlife rescue centers in monitoring populations of alien species in urban areas. We also observed a shift in the breeding phenology of these parakeet species. The hatching peak for ring-necked parakeet occurred in early spring, in line with previous studies on the reproduction of this species, but with a slight increase in the number of months with evidence of breeding in the last years. As to the monk parakeet, our findings support the expansion of its reproductive season between 2006 and 2020 in Rome, with chicks currently being observed for seven months a year. Therefore, data collected through wildlife rescue centers may help improving models of population growth of alien species established in urban areas.

Highlights

Amongst conservation scientists, global consensus highlights that alien species represent one of the main causes of the worldwide current biodiversity crisis (Blackburn et al 2019; Liu et al 2020; Pyšek et al 2020)
Our findings confirmed the importance of WRCs in monitoring the population increase of alien species in urban and suburban ecosystems
A strong correlation occurred between the number of rescued parakeets belonging to two species and their population increase in an European metropolitan area

Summary

Introduction

Global consensus highlights that alien species represent one of the main causes of the worldwide current biodiversity crisis (Blackburn et al 2019; Liu et al 2020; Pyšek et al 2020). All alien species may exert impacts on native ecosystems (Kumschick and Nentwig 2010; Blackburn et al 2014; Evans et al 2018), and these effects should be limited through addressed management actions (Hulme 2006; Mazzamuto et al 2020; Saavedra and Medina 2020), often involving high economic costs (Bacher et al 2018; Diagne et al 2020). Monitoring large populations is challenging and may require a high number of field operators, in the case of invasive species with high mobility such as birds, with increasing difficulties when surveillance is required in urban areas, where most populations of introduced birds thrive (Rodríguez-Pastor et al 2012; Sol et al 2017). Monitoring urban animal populations is hindered by the difficulties in applying several methods for census counts (including direct captures for marking), e.g. due to restricted access to private properties, or conflict with the general public opinion and animal-rights groups (cf. La Morgia et al 2017; Archibald et al 2020)

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Results

Conclusion