How garden feeding affects the health and foraging behaviour of foxes, badgers and hedgehogs
Student Spotlight - Jono Fletcher
PhD Research at Nottingham Trent University
Email: jonathan.fletcher2021@my.ntu.ac.uk Twitter: @jwjfletcher
Project overview
Urban environments can be challenging places to live for animals due to dangers such as traffic, misadventure, toxic substances, conflict with humans and disease. However, for those species that can adapt to cope with these problems, they have access to a plentiful and predictable supply of food. These can originate from either unintentional sources like refuse, allotment crops and compost, or from food intentionally provided by households. Previous survey data suggests food supplied by households includes a large proportion of leftover food intended for human consumption, which presents potential problems for urban mammals that eat it.
The UK diet typically consists of highly manufactured foods formed mainly from food derivatives and additives. Over half the average UK adult’s calorie intake consists of this processed food which can contribute to adult obesity. Examples include industrial packaged bread, reconstituted meat, and biscuits designed to be tasty, convenient and cheap. The intake of highly processed food can result in an increase in fat, carbohydrates and free sugar levels in the diet, whilst protein and fibre levels decrease. Research on urban-living coyotes (Canis latrans) in Canada showed an increase in anthropogenic food intake compared to rural coyotes, but those associated with conflict with humans had a lower protein intake. If the presence of highly processed food is typical of the general UK diet, what is its potential impact on the wildlife that eats it?
I am a PhD student at Nottingham Trent University, coming towards the end of my first year. My project aims to explore the impact of intentional feeding by households in three mammal species known to visit our gardens: the red fox (Vulpes vulpes), the European badger (Meles meles) and the European hedgehog (Erinaceus europaeus). My aims are:
- To establish the use of human food across the seasons by each species and how this might affect their body condition.
- To find out macronutrient (protein, carbohydrate, lipid) composition of the food intentionally offered to each species by householders in the UK.
- To understand the macronutrient targets of each species across the seasons.
- To examine if each species has a foraging preference for human food over their naturally associated dietary items and if diet selection addressed a nutrient gap through compensation.
Assessing the extent of human food use by each species
To understand the potential impact human food use has on the fox, badger and hedgehog, I am aiming to find out the proportion of this food in their diet across the seasons. Studies have previously highlighted that each species uses supplementary food. This project plans to examine human food use in different seasons across urban and rural areas in the UK. Currently, we are collecting whiskers from animal carcasses collected for other purposes and using a process called stable isotope analysis to determine food source use. Essentially, food items will have a particular signature and since that signature is passed from the food item to the body tissues of an animal, we can use this to work out the composition of their diet. We will also measure body condition to explore the impact of human food use on animal health.
Examining the nutritional content of food offered by households
Research suggests animals, including humans, regulate their food intake towards a particular balance of carbohydrate, fat and protein. But when their environment contains food which does not allow them to meet these nutritional targets, they will try to compromise. Each species may compromise differently, but for humans for example, we will aim to reach our protein target at the cost of overeating or undereating carbohydrates and fats.
By examining the nutritional content of the human food offered to each species, we can determine their nutritional environment and see if it may lead them to compromise in their foraging. I aim to do this by analysing survey data that asked households their wildlife feeding habits. Using nutritional content studies and national nutritional databases, I will be able to form a nutritional profile of the food offered by households. On a first look, the food offered appears to be low in protein, whilst high in carbohydrates and fats.
Determining the nutritional targets of the fox, badger and hedgehog
Leading on from understanding the nutrition of the human food offered by households, I am aiming to work out the macronutritional requirements of each species. These targets change and can vary throughout the seasons and at different points in life. Recent research worked out the macronutritional targets of the badger by examining previous diet studies from across Europe and found that, like humans, badgers primarily seem to protect their protein target at the cost of their carbohydrate and fat intake.
Unifying the aims and food preference studies
The hope is that by finding out the extent of human food use in the diet, understanding their macronutritional environment from human food offered by households and observing how it differs from their nutritional requirements, this can inform hypotheses about their behaviour towards using human food. Would the fox, badger and hedgehog make use of supplementary food due to its accessibility and predictability, but at the cost of their nutritional requirements? However, if their environment offers only nutritionally poor food, we expect them to compromise and get as close to their nutritional targets as possible.
This aspect of the project is still in the planning stage, but I am designing food preference experiments with households that have regular animal visitors, collecting faecal samples to determine their current macronutritional intake and offering food varying in macronutritional composition to measure their foraging preferences. If you have any suggestions or have a regular fox, badger or hedgehog visitor and would like to help, please feel free to contact me.
Acknowledgements
I would like to thank my supervisors: Professor Dawn Scott (Nottingham Trent University), Dr Bryony Tolhurst (University of Brighton), Dr Ruth Cox (The Animal and Plant Health Agency) and Dr Nawroz Kareem (University of Keele). I would also like to thank Dr Malcolm Bennett, Dr Graham Smith and Dr Illa Krishnaveni for their help with data collection. I would also like to thank Dr Andy Robertson for his advice on stable isotope analysis. All research methods have been approved by an Ethical Review panel.