Scat‐Tered Evidence. Understanding the Diet of Forest‐Associated Mammalian Mesopredators in a UK Peatland Ecosystem

TL;DR

This study uses DNA from animal droppings to understand what forest-associated predators eat in a Scottish peatland, revealing unexpected dietary patterns.

Contribution

The study provides direct evidence of predator diets using DNA metabarcoding, challenging assumptions about prey interactions in peatland ecosystems.

Findings

Foxes and pine martens primarily consumed small mammals, non-wader birds, and frogs.

Wading birds were not found in the predator diets, contradicting prior assumptions.

Red deer carrion and pine marten scat were significant food sources for foxes.

Abstract

Peatland ecosystems and the unique biodiversity they support are under risk from multiple stressors, including changes in species interactions. Land use changes that lead to increases in the density and activity of mammalian mesopredators such as red fox (
Vulpes vulpes
) and pine marten (
Martes martes
) could be particularly detrimental to vulnerable peatland species such as wading birds (Chardiiformes). However, our understanding of predator–prey interactions in the context of land use change remains limited, because most published evidence is correlative. In contrast, DNA metabarcoding of scats can reliably identify both the host and the prey consumed, thereby clarifying the role of consumption in species interactions. In this study, we collected scats from areas of open peatland and non‐native forestry on peatland across the Forsinard Flows Nature Reserve, part of The Flow Country UNESCO World Heritage Site in Scotland. We focused our collections during the wader breeding season of 2023. Following DNA extraction and metabarcoding, we found that diets of foxes and pine marten were made up of small mammals (e.g., Rodentia and Soricidae), non‐wader bird species, and frogs. By frequency of occurrence, birds formed a substantial part of the pine marten diet (50%), while red deer carrion and pine marten (or their scat) were key food resources for foxes (46% and 50% respectively). Surprisingly, wading birds were absent from our samples, challenging the assumption that forest‐associated mammalian predators actually prey on waders in adjacent peatland. DNA metabarcoding may be crucial to understanding the trophic and non‐trophic interactions that govern recruitment and habitat use of vulnerable native species in remote and complex landscapes.

DNA metabarcoding of predator scat can provide direct evidence of trophic interactions in a landscape that may refute prior indirect evidence based on correlative data.

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