Skip to content
Skip to navigation menu


Dr Robert Thomas 

1. Climate change biology

What are the biological impacts of climate change? My research group is investigating the effects of climate on individuals, populations and ecological processes - particularly how such effects may be mediated by the behaviour of individual animals. Our current work in this field focuses on major study systems that use migratory birds as sensitive bio-indicators of climate-driven changes in trophic relationships.

(i) Effects of climate changes on trophic relationships in marine ecosystems

Photo of a Cetti's warbler.

The body mass regulation behaviour of the smallest Atlantic seabird (the European storm petrel) changes between years in response to climate-driven changes in sea temperatures. Together with Renata Medeiros and collaborators, we coordinate a long-term monitoring project investigating how these changes are mediated by changes in the marine food webs on which storm petrels rely. Read the project blog [ ] for all the latest news from the project.

The speciation of the band-rumped storm petrel “super-species” is the first documented example of sympatric speciation in a bird (and indeed in any tetrapod). Renata Medeiros and collaborators are investigating how diet and foraging ecology varies between sibling-species breeding in different seasons and locations and years, with the aim of understanding how foraging traits are linked to speciation events.

Three species of Pterodroma petrels (Trindade, Kermadec and Herald petrels) breed on Round Island, Mauritius, and hybridise with each other. Together with collaborators from Reading University, the Mauritian Wildlife Foundation and the Mauritius National Parks & Conservation Service, Renata Medeiros is beginning to investigate the diet and foraging ecology of this “hybrid swarm”, with the goal of understanding how the birds are affected by –and cope with- short and long-term changes in food availability and climatic conditions.

(ii) Effects of climate changes on migrant songbirds

Close-up of an eye of a Little Bittern bird.

Migration is one of the major challenges to survival faced by many animals, and the availability of food and other resources along the migration route is of critical importance to successfully completing the journey. Furthermore, climate may impact individuals in different ways in different parts of the annual cycle (breeding grounds, migration stopover sites and wintering areas). Together with Adam Seward, James Vafidis, Rich Facey and collaborators, we combine observational studies in the field, lab and field mesocosm experiments, experimental manipulations of food availability and analyses of long-term climate and bird ringing databases, to examine the effects of climate changes on breeding behaviour, reproductive success, migration decisions, wintering ecology and annual survival of migrant songbirds. The species studied to date are primarily northern wheatears and various species of reedbed warblers, with a new project on barn swallows now underway. This work is carried out at breeding locations (Wales for warblers and swallows, Shetland and Greenland for wheatears), migration stopovers (Portugal and Shetland) and wintering areas (Senegal).

2. Sensory constraints on behaviour

How do animals decide when to be active? My research collaboration with Alex Pollard, Rhian Newman and others focuses on the role of eye design and visual constraints in an animal’s behavioural decisions, particularly under varying light levels at twilight and at night. Specific projects have examined eye size and the timing of singing (in songbirds) and foraging (in shorebirds), as well as aviary and field studies of the impacts of light pollution, using night-singing in European robins as a case-study.

3. Dietary wariness and foraging ecology

Photo of a reed warbler.

When a forager encounters an unfamiliar object, it must decide whether to eat it and risk being poisoned (if it is toxic) or avoid it and risk missing out on a valuable food source (if it is palatable). Foragers generally show brief aversions to novel objects (neophobia) but some individuals also show a much more persistent aversion to eating novel foods (dietary conservatism), which can last for weeks or even years. In collaboration with Nicola Marples, Jo Cable, Loys Richards and others, we are currently investigating the function, control and evolutionary consequences of these aspects of dietary wariness, in a range of taxonomic groups –primarily birds and fish. Related to this, I am also interested in the foraging decisions underlying the strategic regulation of energy reserves in foraging birds, over minutes, days, seasons and years.

4. Impacts of human activities on wild animals 

Photo of a storm petrel bird.

Large numbers of wild animals are captured, handled, often marked for individual identification, and released in the course of scientific research and conservation monitoring programmes. Surprisingly, little is known about the effects of capture and handling on the animals themselves. Together with Leila Duarte and others, I am investigating the impact of capture and handling on the body mass regulation and foraging behaviour of animals throughout the annual cycle, and on breeding behaviour and fitness parameters. This work has implications for the design and implementation of ethical field studies on wild animals. Other studies of human impacts include evaluating and minimising the impacts of eco-tourism, and monitoring habitat use and foraging ecology of birds and other animals, in areas earmarked for –or currently undergoing- development.

Research Group

A beautiful blue butterfly resting on a blade of grass


Dr Renata Medeiros: Molecular scatology, climate change and avian ecology, statistics teaching

PhD Students

Leila Duarte (FCT Portugal, lead supervisor, co-supervised by Ian Vaughan, Nicola Marples and Jaime Ramos): Impacts of capture and handling of wild birds.

James Vafidis (KESS, lead supervisor, co-supervised by Ian Vaughan, Hefin Jones and Rob Parry): Impacts of climate change on reedbed ecosystems.

Nurzafarina (Farina) Othman(multiple funders, co-supervised with Benoit Goosens et al.): behaviour, ecology and conservation of Bornean forest elephants.

Rhian Newman (nee Wilson) (KESS, co-supervised with Sian Griffiths, Steve Ormerod, Alex Pollard and Bill Riley): Impacts of light pollution on salmonid fish.

Silke Waap (FCT Portugal, co-supervised with Bill Symondson and Paulo Catry): Molecular investigation of Atlantic seabird diets.

Jennifer (Jen) Stockdale (NERC, co-supervised with Bill Symondson and Gavin Siriwardena): Molecular tracking of foraging ecology of songbirds in agricultural landscapes.

MPhil student

Richard (Rich) Facey (self-funded, lead supervisor, co-supervised by Ian Vaughan): Breeding productivity of barn swallows Hirundo rustica in relation to local climate conditions. Rich is a part-time MPhil student, who also works for Natural Resources Wales.

MRes student

Rhidian Thomas (KESS, co-supervised with Jo Cable, Sian Griffiths, Alex Pollard & Bill Riley): Environmental change in freshwater ecosystems.

Postgraduate research assistant

Jeremy (Jez) Smith (International Wildlife Consultants): Behaviour and ecology of long-distance migratory peregrine falcons breeding in the high Arctic. Collaboration with Andrew Dixon and Eco-explore.


Charlotte Evans(ASAB Education Officer): Development and distribution of ASAB Educational Resources, promotion of teaching of animal behaviour in schools, colleges and universities.

Dr Alex Pollard: Managing director of Eco-explore and ecological consultant at Wildwood Ecology. Alex is simultaneously secretary of the Cardiff Bat Group and the Valleys Bat Group.

Jeremy (Jez) Smith: Eco-explore expeditions coordinator.

Professional Training Year students (hosted by Eco-explore)

Sophie-Lee Williams –habitat selection and foraging ecology of birds of prey

Amie-Beth Sabin –ecology and conservation of bats

Edward (Ed) Suitters –foraging ecology of rats and songbirds in a farming and shooting landscape

Hayley Roberts –impacts of climate change on reedbed warblers

PhD Alumni

Dr Adam Seward: Now working at Red Squirrel Conservation

Dr Jenny Clapham: Now working as a paramedic around the world!

Dr Loys Richards: Now working at University Hospital of Wales

Dr Joe Woodgate: Now working at Deakin University, Australia

Dr Alex Pollard: Now working at Wildwood Ecology and Eco-explore