Assessing the risks of changing ongoing management of endangered species. (30th July 2020)

• Record Type: Journal Article
• Authors: Ferrière, C.; Zuël, N.; Ewen, J. G.; Jones, C. G.; Tatayah, V.; Canessa, S.
• Is Part Of: Animal conservation. Volume 24:Number 2(2021)
• Page Start: 153
• Page End: 160
• Publication Date: 2020-07-30
• Subjects: cost‐effectiveness -- experiment -- Mauritius -- reintroductions -- risk aversion -- supplementary feeding -- stochastic dominance -- uncertainty; Conservation biology -- Periodicals; Wildlife conservation -- Periodicals; Conservation de la biodiversité; Conservation de la faune; Périodique électronique (Descripteur de forme); Ressource Internet (Descripteur de forme); 333.95416
• DOI: 10.1111/acv.12602
• Languages: English
• ISSNs: 1367-9430

Abstract

Abstract: Recovery programmes for endangered species can become increasingly demanding over time, but managers may be reluctant to change ongoing actions that are believed to be assisting recovery. We used a quantitative risk assessment to choose support strategies for a reintroduced population of Mauritius olive white‐eyes Zosterops chloronothos . Facing increasing costs, managers considered changing the ongoing supplementary feeding strategy, but at the same time worried this could jeopardize the observed positive population trend. We used a feeding experiment to compare the current feeding regime and a cheaper alternative (a simple sugar/water mix). Results suggested the cheaper alternative would only marginally reduce population vital rates. We assessed the influence of these results and the associated uncertainty on population recovery and management costs using two decision‐analytic criteria, incremental cost‐effectiveness ratio and stochastic dominance. The new feeding regime was expected to be, on average, more cost‐effective than the status quo . Moreover, even negative outcomes would only likely mean a slower growing population, not a declining one, whereas not changing feeding regime actually entailed greater risk. Because shifting from the current regime to a cheaper sugar/water mixture was both a risk‐averse and a cost‐effective choice, we decided to implement this change. Four years after the experiment, the population continues to grow and costs have been contained, matching predictions almost exactly. In this case, the field experiment provided useful empirical information about prospective actions; the risk analysis then helped us understand the real implications of changing the feeding regime. We encourage managers of recovery plans facing a similar situation to explicitly recognize trade‐offs and risk aversion, and address them by combining targeted research and formal decision analysis. Abstract : On Ile‐aux‐Aigrettes off the Mauritian coast, supplementary feeding has been employed since 2006 to support a reintroduced population of olive white‐eyes Zosterops chloronothos. As the population grew, feeding became more expensive, but managers worried that deviating from the current actions could jeopardize the positive population trend. Combining a field experiment with formal risk assessment methods, we found that changing to a more cost‐effective feeding regime would in fact be a risk‐averse choice, so the change was implemented. Four years later, the population continues to grow but costs have been contained, matching our initial assessment. We encourage managers of recovery plans facing a similar situation to explicitly recognize trade‐offs and risk aversion, and address them by combining targeted research and formal decision analysis.