Non-invasive genetics outperforms morphological methods in faecal dietary analysis, revealing wild boar as a considerable conservation concern for ground-nesting birds.

Ragne Oja,Egle Soe,Urmas Saarma,Marco Apollonio,Harri Valdmann

doi:10.1371/journal.pone.0179463

Abstract

Capercaillie (Tetrao urogallus) and other grouse species represent conservation concerns across Europe due to their negative abundance trends. In addition to habitat deterioration, predation is considered a major factor contributing to population declines. While the role of generalist predators on grouse predation is relatively well known, the impact of the omnivorous wild boar has remained elusive. We hypothesize that wild boar is an important predator of ground-nesting birds, but has been neglected as a bird predator because traditional morphological methods underestimate the proportion of birds in wild boar diet. To distinguish between different mammalian predator species, as well as different grouse prey species, we developed a molecular method based on the analysis of mitochondrial DNA that allows accurate species identification. We collected 109 wild boar faeces at protected capercaillie leks and surrounding areas and analysed bird consumption using genetic methods and classical morphological examination. Genetic analysis revealed that the proportion of birds in wild boar faeces was significantly higher (17.3%; 4.5×) than indicated by morphological examination (3.8%). Moreover, the genetic method allowed considerably more precise taxonomic identification of consumed birds compared to morphological analysis. Our results demonstrate: (i) the value of using genetic approaches in faecal dietary analysis due to their higher sensitivity, and (ii) that wild boar is an important predator of ground-nesting birds, deserving serious consideration in conservation planning for capercaillie and other grouse.

Highlights

Grouse (Galliformes: Tetraoninae) have long been a conservation concern [1]
Of 109 wild boar faeces analysed with the molecular method, 49 were identified as wild boar and of these in 6 we identified bird DNA
The genetic analysis could not identify the predator for three faecal samples, either because the sample had degraded or included inhibitors that prevented DNA amplification, they clearly belonged to wild boar

Summary

Introduction

Grouse (Galliformes: Tetraoninae) have long been a conservation concern [1]. Many populations are declining and have become threatened, in regions with dense human populations [2]. The capercaillie (Tetrao urogallus) is one of the most threatened and best studied species among this group of ground-nesting birds [1]. Non-invasive genetics outperforms morphological methods in dietary analysis

Objectives

Methods

Results

Conclusion