Abstract

BackgroundThe population of Bonelli’s eagle (Aquila fasciata) has declined drastically throughout its European range due to habitat degradation and unnatural elevated mortality. There are less than 1500 breeding pairs accounted for in Europe, and the species is currently catalogued as Critically Endangered in Italy, where the 22 territories of Sicily, represent nearly 95% of the entire Italian population. However, despite national and European conservation concerns, the species currently lacks a specific conservation plan, and no previous attempts to estimate the risk of extinction have been made.Methodology/Principal FindingsWe incorporated the most updated demographic information available to assess the extinction risk of endangered Bonelli’s eagle in Italy through a Population Viability Analysis. Using perturbation analyses (sensitivity and elasticity), and a combination of demographic data obtained from an assortment of independent methods, we evaluated which demographic parameters have more influence on the population’s fate. We also simulated different scenarios to explore the effects of possible management actions. Our results showed that under the current conditions, Bonelli’s eagle is expected to become extinct in Italy in less than 50 years. Stand-alone juvenile mortality was the most critical demographic parameter with the strongest influence on population persistence with respect to other demographic parameters. Measures aimed at either decreasing juvenile mortality, adult mortality or decreasing both juvenile and adult mortality resulted in equivalent net positive effects on population persistence (population growth rate λ>1). In contrast, changes aimed at increasing breeding success had limited positive effects on demographic trends.Conclusions/SignificanceOur PVA provides essential information to direct the decision-making process and exposes gaps in our previous knowledge. To ensure the long-term persistence of the species in Italy, measures are urgently needed to decrease both adult mortality due to poaching and juvenile mortality due to nest plundering, the top ranking mortality causes.

Highlights

  • Estimating the risk of extinction of threatened species is a crucial aspect of population ecology and conservation biology [1]

  • Population Viability Analysis (PVA) were initially designed to estimate the likelihood of a population’s extinction [2], due to their flexibility, PVAs have been used in risk-assessment studies aimed at determining which demographic parameters are the most influential in population persistence [7,9,10]

  • Recent research has revealed the extensive cascading effects caused by the disappearance of large top predators in terrestrial, marine and freshwater ecosystems worldwide, with far-reaching effects on ecological processes [50]

Read more

Summary

Introduction

Estimating the risk of extinction of threatened species is a crucial aspect of population ecology and conservation biology [1]. Higher extinction risks are associated with species occupying high trophic levels, exhibiting a long-lifespan, delayed maturity, and breeding at a low population density in a small geographical range [3]. Such is the case with Bonelli’s eagle, Aquila fasciata, a threatened species for which population models have played an important role in informing management decisions aimed at eagle conservation [17,18,19]. Despite national and European conservation concerns, the species currently lacks a specific conservation plan, and no previous attempts to estimate the risk of extinction have been made

Objectives
Methods
Results
Conclusion
Full Text
Published version (Free)

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call