Evaluating the Effectiveness of a Conservation Project on Two Threatened Birds: Applying Expert-Based Threat Analysis and Threat Reduction Assessment in a Mediterranean Wetland

Pietro Giovacchini,Corrado Battisti,Letizia Marsili

doi:10.3390/d14020094

Abstract

We applied two recent approaches largely used in biological conservation: Threat Analysis (TAN) and Threat Reduction Assessments (TRAs), assessing the effectiveness of a project focused on two water-related bird species (common tern, Sterna hirundo and little tern, Sternula albifrons), commonly breeding in some wetlands of Italy. We used the IUCN standardized lexicon for the classification of threats, utilizing a panel of experts to assess a set of regime attributes (extent, severity and magnitude) of each human-induced disturbance. Our aims were: (i) through the TAN approach, to carry out an arrangement and quantification of the main threats acting on our focal species and select the priority ones; (ii) through the TRA approach, to test the effectiveness of an operational project focused on mitigating the threats and improving the breeding success of species (i.e., building rafts and floating islands to encourage their nesting). Using the TAN approach, experts identified the following human-induced threats (IUCN code): 6.1—Generic disturbance; 7.2—Water stress; 7.3—Salinization; 8.8—Vagrant dogs; 8.8—Mediterranean gulls; 8.8—Wild boars, all significantly different in their magnitude. Among them, wild boars and Mediterranean gulls appeared the priority threats with the greatest extent, intensity and magnitude. Using the TRA approach, after the project, we assessed an overall decrease in the threat magnitude of 23.08% (21.42% when considering only the threats directly affected by our project). These data suggest that further efforts should be devoted to achieving greater effectiveness of conservation actions focused on our target species. With limited time and resources to quantify threats, expert-based approaches could be useful for rapidly assessing the effectiveness of small conservation projects by providing a range of scores obtained following an analytical procedure. In this regard, Threat Analysis and Threat Reduction Assessment could be considered useful tools to support adaptive management in project management cycles.

Highlights

When launching conservation projects focused on target species in demographic decline, it is necessary to monitor the effectiveness of the actions aimed at reducing the causes of anthropogenic threats
The values of the threat regime attributes showed as wild boars and Mediterranean gulls appeared to be the threats with the largest extent, intensity and magnitude (Table 1; Figure 1), with a significant difference in magnitude among threats (H = 17.37, p = 0.003; Kruskall-Wallis test for equal medians)
Similar to many other Mediterranean wetlands, these ecosystems are embedded in anthropized landscapes where, since historical times, a series of human-induced driving forces acted, modifying the environmental matrix: in the last two centuries, land reclamation has transformed these wetlands into agricultural areas, and, in recent decades, urbanization and infrastructures have given rise to several threats and related impacts on biodiversity, as observed in many other Mediterranean wetlands (e.g., [9,42])

Summary

Introduction

When launching conservation projects focused on target species in demographic decline, it is necessary to monitor the effectiveness of the actions aimed at reducing the causes of anthropogenic threats. It has recently emerged that monitoring through biological indicators (see [2]) based on the quantification of the status of the biodiversity targets shows some weaknesses: for example, the biological components often show long response times and are observable on different spatial scales due to their ecological, phenological, and behavioral characteristics This can make it difficult to evaluate the effectiveness of projects using biological indicators [3]. To overcome this problem, alternative approaches have recently been developed that focus on assessing the threat events impacting our targets, recording the changes in their regime and considering specific attributes (e.g., extent, intensity, magnitude; [4]). Having limited time and resources, an assessment of this type can be carried out quickly by a project team using expert-based approaches [6]

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Conclusion