Catching swans in Iceland

Catching swans in Iceland

Whooper swan release

Whooper swan release

Gannet

Gannet

Professor Stuart Bearhop
Professor of Animal Ecology

Research

Research interests

My research focuses on spatial and trophic ecology of animals, with a particular interest in the causes and consequences of intra-population variation in foraging and dispersal behaviours. I also work on the cascading effects of nutrient fluxes, and applications of stable isotope techniques. My research group works at field sites all over the world: Sub-Antarctic New Zealand, South Atlantic, Portugal, Germany, Iceland, Great Britain (including Shetland, St Kilda), Northern Ireland & ROI, the Bahamas, USA, Canadian Arctic and the central Pacific.

Research projects

1. Drivers of fitness in long distance migrants

Long distance migration in birds is among the most dramatic and exciting phenomena in nature, enthusing both scientists and members of the public alike. However despite many years of study, the first theories were proposed by Aristotle over 2000 years ago, there are still huge gaps in our understanding of how migration shapes individual ecology and influences population processes. For example, we know little of how migratory animals manage trade offs within and among seasons and how these in turn drive variation in productivity, survival or breeding phenology. Elucidating the causes and consequences of this intraspecific variation, lies at the heart of ecological and evolutionary enquiry as it is material upon which natural selection can operate and understanding of the manner in which events across the annual cycle influence demography has implications for conservation and management.

I am interested in a range of questions linked to this theme such as:

How do interactions among the seasons influence fitness?
Known as carry over effects these phenomena are likely to play a hugely important role in shaping individual life histories, for example settling on a poor quality wintering territory will likely reduce resource intake, which may in turn influence when animals migrate and how much resources they can devote to reproduction. I have a range of projects investigating the role that carry over effects might play.

How do physiological mechanisms such as oxidative stress influence migratory decisions?
Fuelling migration presents a physiological challenge not just in terms of sustained high metabolic performance, but also in how the animals manage to deal with the large amount of oxidative stress (OS) associated with this level of activity. Resources allocated to protection from OS during migration cannot be subsequently allocated to other important systems such as reproduction or immunity. My group is trying to understand how such trade offs are managed.

In order to address these questions we have set up a long-term study on a marked population of light-bellied Brent geese in collaboration with the Irish Brent Goose Research Group and the Wildfowl and Wetlands Trust. These birds spend the winter in Ireland, stage in Iceland and breed in the High Canadian Arctic making one of the longest migrations of any goose species. Over the last 10 years we have marked over 3000 animals and now have a database comprising over 100000 resightings, with data on morphometrics, associations, fat stores and number of offspring. We are also using long-term Whooper swan data bases (held by the WWT).

Collaborators: Dr Richard Inger, Dr Kendrew Colhoun, Prof Tom Tregenza, Dr David Hodgson, Dr Gudmundur Gudmundson, Dr Tony Fox, Dr Geoff Hilton.

2. Social structure among group living animals

Social behaviour is an integral component in the lives of numerous animal species. As such there is a huge body of both theory and empirical work covering the selection pressures and trade-offs that underpin group living. However it is becoming increasingly clear that the associations that individuals form within groups are often non-random. It is also important that we can recognise the form of such associations as they may not necessarily be simply social, and cryptic kin structure appears to be a widespread phenomenon in vertebrate populations. Understanding the causes and consequences of these non-random associations, and the form that they take, has important ecological, evolutionary, disease and conservation implications. Social network theory provides us with the tools necessary to begin to investigate these phenomena.

Here I am interested in questions such as:

What are the benefits of forming stable associations (or having friends) in unrelated animals?
Among group foragers there are well-understood trade offs between foraging, aggression and vigilance. One way of freeing up time for more foraging could be to associate with familiar individuals, thereby reducing the time allocated to aggression.

What evidence is there for cryptic kin structure among such stable associations?
Although, alliances may not necessarily occur between related individuals an obvious way in which they might form is via associations with kin. Such relationships could bring inclusive fitness benefits as well as those outlined above.

We are investigation the causes and consequences of these stable associations in migratory wildfowl and badgers.

Collaborators: Dr Darren Croft, Prof Tom Tregenza, Prof Robbie McDonald, Dr Sasha Dall, Dr Andrew Jackson, Dr Joah Madden.

3. The causes and consequences of individual foraging specialisations

Treating all individuals within a population as ecologically equivalent is an oversimplification and ignoring variation among individuals, particularly with respect to resource use, is likely to impede our ability to grasp a suite of ecological and evolutionary processes. Individuals often vary consistently in the extent to which they exploit different food resourcesand this variation can sometimes comprise the majority of a population’s trophic niche width. Individual specialization in diet and foraging behaviour has important implications for ecology, evolution (including speciation) and conservation but remains largely unevaluated and poorly understood for most free-living consumers.

The kinds of question we are trying to answer here are:

What processes drive patterns of individual specialisation?
Are there environmental variables such as the distribution of resources or the number of intraspecific competitors that can explain why some individuals might choose to specialise on a subset of the population’s dietary niche.

What are the consequences of individual specialisations?
Is specialism better than generalsism? Does this apply in all circumstances? Are all specialists equal? We are trying to link these patterns of foraging to proxies of fitness, such as foraging effort, body condition and reproductive success.
We are using Northern Gannets studied at multiple colonies around the British Isles and multiple badger social groups to investigate these questions.

Collaborators: Dr Stephen Votier, Dr Keith Hamer, Dr Tom Bodey, Dr Ewan Wakefield, Prof Robbie McDonald

4. Stable isotopes as markers of diet

In much of my work I have used stable isotopes as forensic markers of diet, habitat selection and movement. These are really exciting tools and can provide remarkable insights where conventional methods fail (particularly when multiple approached are combined). I have an interest in how we can better use these tools as measures of resource breadth at both the individual and community level. As such I have also been closely involved in the development of new Bayesian tools that enhance our ability to use stable isotope ratios as markers of diet and resource use.
Collaborators: Dr Richard Inger, Dr Andrew Jackson, Dr Andrew Parnell, Dr Don Phillips, Dr Eric Ward, Dr Jon Moore, Dr Bryce Semmens.

Cannon netting brent geese

Over the last 10 years we have marked over 3000 animals and now have a database comprising over 100000 resightings

Research grants

  • 2012 ERC Consolidators Grant
    Fitness drivers in long-distance migrants: the interacting roles of physiology, social biology, ecological and physical environments
  • 2011 FERA
    Postgraduate programme (PhD and MRes) with Prof R McDonald
  • 2011 WWT
    Population ecology of Greenland White-fronted Geese with Dr D Hodgson, Dr T Fox and Dr G Hilton
  • 2011 TSB
    Impact of tidal power generation devices with Dr R Inger
  • 2010 FERA
    Postgraduate programme (PhD and MRes) with Prof R McDonald
  • 2010 NERC
    Facility grant to carry out stable isotope analyses at SUERC
  • 2010 NERC Std Grant
    Individual specialization in a wide ranging predator. With Dr K Hamer (Leeds) and Dr Steve Votier (Plymouth)
  • 2009 European Union Atlantic Area INTERREG II Initiative
    Top predators in marine systems with Dr Brendan Godley and Dr Annette Broderick.
  • 2009 FCT (Portugal)
    Studentship: individual specialisation in albatrosses, with Dr Paulo Catry (Lisbon)
  • 2009 European Science Foundation
    Internal allocation
  • 2009 FERA
    Migration and dispersal of serotine bats: with Dr David Hosken
  • 2009 FERA
    Stable isotopes as measures of community function with Dr Frank Van Veen
  • 2009 NERC
    NERC Std Grant with Drs Ali Dunn (Leeds) and Jaimie Dick (Belfast)
  • 2008 South West Regional Development Agency
    Wavehub (potential impact on large vertebrates) PI: Brendan Godley
  • 2008 FERA
    Studentship, Social networks in Badgers Co-supervised with Dr Sasha Dall
  • 2008 Leverhulme Trust
    Migrations of bats CoI Iwth Prof J Altringham (Leeds)
  • 2008 NERC CASE Studentship (open competition)
    Rats on islands CASE Studentship (open competition) with Prof J Memmott (Bristol)
  • 2008 NERC
    SMG Facilty Grant: Genetic structure in goose populations
  • 2008 NERC
    Std Grant: Causes and consequences of variation in dispersal with Dr David Hodgson
  • 2008 Royal Society Travel Grant
    Conference grant
  • 2007 NERC
    Facility Grant for funding to carry out isotope analyses at SUERC.
  • 2007 NERC
    CASE Studentship (departmental competition) Dispersal in geese. With Drs Tom Tregenza and David Hodgson
  • 2007 NERC
    CASE Studentship (open competition) Impact of bird feeders. With Dr J Blount
  • 2007 NERC
    CASE Studentship (open competition) Impacts of rats on islands
  • 2007 Leverhulme Trust
    Pump priming for Bat migration study. PI: J. Altringham (Leeds)
  • 2006 NERC
    Facility Grant for funding to carry out isotope analyses at SUERC.
  • 2005 NERC
    NERC Facility Grant for funding to carry out isotope analyses at SUERC
  • 2005 EHS
    Lamprey fisheries in Lough Neagh.
  • 2005 Better Belfast
    Birds, bees and biodiversity.
  • 2005 Quercus
    Alien predators on islands.
  • 2005 DARD
    Studentship: Impact of piscivorous predators
  • 2005 DARD
    Studentship: Rodenticide use in NI
  • 2005 NERC
    Facility Grant for funding to carry out isotope analyses at
  • 2004 NERC
    Standard Grant: The fuelling of terrestrial foodwebs by biogenic methane
  • 2004 NERC
    Facility Grant for funding to carry out isotope analyses at SUERC.
  • 2004 Royal Society
    Conference Grant.
  • 2004 DARD
    Studentship: Bats & agriculture.
  • 2004 DEL
    Impact of bird feeders.
  • 2003 NERC
    CASE Studentship: Foraging decisions in brent geese.
  • 2002 IBLS
    Research support grant (open competition).
  • 2002 Royal Society of Edinburgh
    Travel Grant April.
  • 2002 US Fish & Wildlife Natural Heritage
    Grant.
  • 2001 NERC
    To carry out isotope analyses at SUERC.
  • 2001 NERC
    Postdoctoral Fellowship awarded in February

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