Does nutrient intake of British predators occupying urban and rural habitats vary according to habitat and/or season? Implications for species’ dietary flexibility and targeted nutrient profiles

Variation provided by the diet of free-ranging predators is thought to confer nutritional benefits, and evidence for nutrient-seeking behaviours in a range of predator species indicates it may be an important mechanism by which free-living carnivores balance their nutrient intake (Hewson-Hughes et al. 2011; Hewson-Hughes et al. 2012; Raubenheimer et al. 2009; Kohl et al. 2015). This is particularly relevant when we consider that the nutritional requirements of many non-domestic predator species are unknown, but likely to align to the nutrient composition of their naturally consumed prey (Kohl et al. 2015; Hewson-Hughes et al. 2011). However, very few data exist to establish prey nutrient composition across seasons or habitat types. Additionally, human land use may influence the availability, selection, or even body composition of prey consumed by free-ranging predators. Pollution or reduced biodiversity may likewise be reflected in diet composition, with subsequent implications for predators and ecosystem health as a whole. In contrast, captive dietary provision for carnivores is often monotonous or severely restricted in prey types (Dierenfeld 1990; Dierenfeld et al. 2002), potentially compromising the health of captive animals. Given the hypothesised use of the wild diet as a proxy for predicting nutrient requirements, the current lack of knowledge of prey composition represents a significant limitation to captive animal management. As such, the following key research questions arise; how does nutrient intake of predators vary spatially and temporally, how does human land-use influence this intake, and how does ex situ dietary provision compare to in situ nutrient intake as a proxy for nutritional requirements?
This project aims to determine the dietary intake of British predators occupying urban and rural habitats across seasons. The first step of the project will consist of documenting and cataloguing the list of prey species included in the natural diet of target predators (mammalian and avian) and identify the gaps in nutritional data for each of the identified prey species. Concurrently, unpublished datasets from our external collaborators will be analysed to determine seasonal and prey-based variation in the nutrient intake of the endangered Black-footed ferret (Mustela nigripes). These datasets include the nutritional composition of prairie dog carcass components (being the staple diet of black-footed ferrets) collected from multiple sites, of differing ages, across four seasons. Evaluation of this existing dataset will serve as a foundation study for comparison to British predators. Moreover, better understanding of their wild diet and associated nutritional intake will benefit current practice in captive breeding and release programmes, potentially increasing the rate of successful outcomes. Due to the critical role that captive populations of Black-footed ferrets play in reintroduction programmes (thus far preventing the extinction of this species in the wild), this study hence offers significant conservation impact.
The next step will consist of UK-based fieldwork focusing on collection and analysis of hairs or feathers and scat from predators to determine prey (and associated carcass component) intake profiles via stable isotope analysis. Wild prey species and their scat (from each habitat type and across seasons, as well as of varying age groups) will be analysed for stable isotope profile, as well as nutrient composition and heavy metal concentrations. Stable isotope analyses have previously been used to monitor predator dietary intake across seasons and geographic regions (Codron et al. 2006; Darimont & Reimchen 2002; Hall-Aspland et al. 2005), but have thus far not been applied to assessing dietary flexibility of predators in terms of habit disturbance or human activities. Likewise, there is a paucity of data pertaining to the nutrient intake (as opposed to the prey species intake) of wild predators and this project will therefore advance this fundamental understanding of predator physiology. This will ultimately lead to the comparison between wild-diet nutritional provision and captive diets in order to assess captive diet suitability and adequacy. Combined analysis of heavy metal levels and habitat degradation scores will permit the evaluation of human impact on predator dietary intake and potential influence across trophic levels within the ecosystem.

Entry Criteria
UK 1st Class/2:1 Bachelor’s degree (or UK equivalent according to NARIC) in zoology, biology, animal science, chemistry, ecology, or equivalent (essential). Masters degree in nutritional science, biochemistry, or equivalent (desirable).