New statistical tools for ecologists
Submitting Institution
University of KentUnit of Assessment
Mathematical SciencesSummary Impact Type
EnvironmentalResearch Subject Area(s)
Mathematical Sciences: Statistics
Environmental Sciences: Environmental Science and Management
Summary of the impact
The impact of statistical ecology research at Kent
is on both the survey design of data collection
on wild animals, and the analysis of the resulting data. As a
result of our research, better quality
data are being collected more efficiently, and a wide range of new methods
of data analysis are
being used. This is essential for the conservation and management of wild
animal populations and
the preservation of biodiversity. New methods developed at Kent are now
standard tools used in
ecology. Examples of impact are improved understanding of the decline of
British farmland birds,
underpinning conservation action plans; and analysis of data from tiger
surveys, supporting the
Indonesian Government's National Tiger Recovery Plan.
Underpinning research
Research in statistical ecology undertaken at Kent over more than 25
years has involved many
PhD students and RAs, as well as permanent members of staff. The specific
underpinning
statistical ecology research cited here was conducted at Kent by Besbeas
(RA 1999-2002, lecturer
2003-2006, RA 2013-present), Freeman (RA 1994-1997), Guillera-Arroita
(PhD student, 2009-2012),
Morgan (1972-present), Ridout (2000-present).
In 2005, the National Centre for Statistical Ecology (NCSE, www.ncse.org.uk)
was established
as a joint research centre between the Universities of Kent, Cambridge
and St
Andrews, supported
by an EPSRC Mathematics Multidisciplinary Critical Mass Award. In
2010, NCSE expanded to
include the Universities of Bath,
Bristol,
Exeter,
Glasgow
and Sheffield,
together with the Centre for
Ecology and Hydrology (CEH), while the University of Cambridge dropped
out, following departure
of staff. This expansion was achieved with the aid of a joint EPSRC/NERC
grant, and total funding
to date exceeds £2,000,000.
To ensure that our research is relevant and responds to the changing
demands of the real world,
as technology advances, since 2010 NCSE has included four non-academic Project
Partners: Biomathematics and Statistics Scotland; the Centre for
Environment, Fisheries and
Aquaculture Science (Cefas); the Game and Wildlife Conservation Trust; and
Marine Scotland.
Estimating the survival of wild animals and integrated population
modelling. The use of
covariates in describing mortality of wild animals originated at
Kent. The ecological insights that
can result from this approach are illustrated by [3.1], which
models the mortality of Soay sheep
(Ovis aries), showing how population regulation depends in a
complex manner on measures of
climate, population density and individual characteristics, differentially
for animals of different ages.
This led on to a highly-cited Science paper [3.2].
Research at Kent has also pioneered methods of integrated population
modelling (IPM) [3.3,
3.4], which are now in widespread use by wildlife conservation
authorities, including the innovative
use of state-space models. This approach integrates different
types of information into a single
analysis, which can greatly reduce the uncertainty of estimates or indeed
make possible the
estimation of features that cannot be estimated from a single data source.
The method can also
deliver increased power for detecting the possibly subtle effects of
covariates, such as climatic
factors. This is important for understanding the effects of climate
change. Kent statisticians have
applied the methodology to several bird species, including northern
lapwings (Vanellus vanellus),
grey herons (Ardea cinerea), snow geese (Chen caerulescens)
and great cormorants
(Phalacrocorax carbo), and have continued to develop the
methodology; for example, by extending
it to multi-site models, where animals can move between sites.
Occupancy modelling and camera trap data. Occupancy surveys, which
aim to estimate the
proportion of study sites at which a species is present, are widely used
by practicing ecologists and
wildlife managers. Direct estimates of the proportion of sites occupied
are misleading, because
species are often not detected when present, and the statistical analysis
must account for this. The
work of Guillera-Arroita [3.5] covers both design and analysis of
occupancy studies, including the
development of hidden Markov models for occupancy data collected
along a transect. The
methods were developed for studying tigers in Sumatra, but are applicable
much more widely. One
method of assessing species presence at a site is the use of camera traps
— cameras linked to
detectors that trigger a photograph when an animal passes; these have
revolutionised the study of
cryptic animal species. The time of the photograph is recorded and [3.6]
provides a method of
using these data to estimate temporal overlap of competing species or
predator and prey species.
References to the research
All references except [3.5] are papers in international journals.
The research reported in [3.5] is the
subject of six refereed papers in international journals.
[3.1] Catchpole, E.A., Morgan, B.J.T., Coulson, T.N., Freeman,
S.N. and Albon, S.D. (2000)
Factors influencing Soay sheep survival. Journal of the Royal
Statistical Society Series C-Applied
Statistics, 49, 453-472. doi: 10.1111/1467-9876.00205
[3.2] Coulson, T., Catchpole, E.A., Albon, S.D., Morgan,
B.J.T., Pemberton, J.M., Clutton-Brock,
T.H., Crawley, M.J. and Grenfell, B.T. (2001) Age, sex, density, winter
weather, and
population crashes in Soay sheep. Science, 292, 1528-1531.
doi: 10.1126/science.292.5521.1528
[3.3] Catchpole, E.A., Freeman, S.N., Morgan, B.J.T.
and Harris, M.P. (1998) Integrated
recovery/recapture data analysis. Biometrics, 54, 33-46.
doi: 10.2307/2533993
[3.4] Besbeas, P., Freeman, S.N., Morgan, B.J.T.
and Catchpole, E.A. (2002) Integrating mark-recapture-recovery
and census data to estimate animal abundance and demographic
parameters. Biometrics, 58, 540-547. doi:
10.1111/j.0006-341X.2002.00540.x
[3.5] Guillera-Arroita, G. (2012) Occupancy modelling: study
design and models for data collected
along transects. PhD thesis, University of Kent. (Supervisors B.J.T.
Morgan and M.S.
Ridout).
[3.6] Ridout, M.S. and Linkie, M. (2009) Estimating overlap of
daily activity patterns from camera
trap data. Journal of Agricultural, Biological and Environmental
Statistics, 14, 322-337.
doi: 10.1198/jabes.2009.08038
(References marked with a star best indicate the quality of the
underpinning research.)
Details of the impact
The impact of Statistical Ecology research at Kent has been to improve
substantially the
effectiveness of wildlife conservation policy and practice by providing
better methods of data
collection and analysis. The beneficiaries of the research are
individuals, charities and
environmental agencies that collect and analyse ecological data and the
organisations that plan
and implement management and conservation strategies that utilise these
data.
A variety of approaches are used to encourage the incorporation of our new
methodologies into
ecological practice. These include workshops and multidisciplinary
conferences, studentships with
collaborating bodies, joint research with external agencies and provision
of computer software.
Before detailing impact in (a) and (b) below, we expand on the context.
Multidisciplinary conferences: EURING meetings have been held
regularly since 1986 to
promote collaboration between ornithologists, statisticians and population
biologists. Kent
statisticians have contributed to all of them, editing or co-editing
proceedings of 6 of the 9
meetings. NCSE initiated the highly successful and influential series of
International Statistical
Ecology Conferences (St
Andrews 2008, Kent 2010, Oslo
2012, Montpellier
2014, British
Columbia
2016). Both conference series incorporate training workshops and attract
strong participation from
outside of academia; for example, approximately 1/3 of the 146
participants at the 2010 ISEC at
Kent were from outside academia (e.g. Alaska Dept of Fish & Game;
British Trust for Ornithology;
Microsoft; Proteus Consulting, New
Zealand; Snow Leopard Trust, India;
US Geological Survey;
Wildlife Conservation Society, Malaysia).
Studentships with collaborating bodies, some funded by CASE
awards, have addressed the
spread of an invasive species (CEH), the effect of dredging on benthic
organisms (Cefas) and the
phenology of overwintering wild birds (the Wildfowl and Wetlands Trust).
These close
collaborations ensure that research is directly relevant to ecologists.
Two research students have
produced introductory videos, targeted at an ecological audience, to
facilitate uptake of new
methods published in Methods in Ecology and Evolution, a journal
of the British Ecological Society
[5.1], and two students won a poster prize at the International
Congress in Conservation Biology,
Auckland, New Zealand,
2011.
Current projects with external agencies/users include developing
models for the spread of ring-
necked parakeets (Psittacula krameri) with the British Trust for
Ornithology (BTO); devising new
models and methods for evaluating the effect of global warming on the
phenology, abundance and
distribution of British butterfly species, with Butterfly Conservation;
and investigating the causes of
the decline of sea birds in the North Sea, with CEH. These close links
promote the wider use of our
methodology within these non-academic institutions.
-
Estimating the survival of wild animals and integrated population
modelling [3.1-3.4]
Discussion of the sheep model [3.1, 3.2] now appears in several
textbooks on ecological modelling
[5.2]. The estimate of the annual survival of shags developed in
[3.3] was incorporated in the
update of The Birds of the Western Palearctic [5.3]. Our
models demonstrated the probable reason
for the decline of the Northern Lapwing, a species that is now on the UK
red list of globally
threatened species [5.4]. Organisations such as the BTO use
information about population decline
"to inform the public, opinion-formers and decision-makers... and to
make a significant contribution
to environmental policy." [5.5]
Our methodology for integrated population modelling (IPM) [3.4],
which allows the combined
analysis of data from different sources, is now widely used by
ecologists. For example, the
methodology has been used extensively by the BTO to "understand the
demographic mechanisms
that drive population changes and hence to better identify the
ecological causes of change and the
management actions needed to alter population trajectories." [5.5].
This testimonial also highlights
the important contribution of other areas of statistical ecology
research at Kent, including "analyses
of survival involving individual covariates" [3.1, 3.2] and
"occupancy modelling" [3.5] and
concludes that our work "makes a particularly important contribution to
ecological science within
the UK and
to the policy-relevant work that flows from this". Another testimonial
indicating the
impact of IPM on ecological practice, from the Head of the Ecology
Department at the Swiss
Ornithological Institute [5.6], states that the paper [3.4]
"changed the view of population ecologists
about the quantitative treatment of their data" and leads to "more
efficient conservation actions,
because management decisions can be reached earlier or with more
certainty".
- Design and analysis of occupancy studies [3.5-3.6]
In 2009, Guillera-Arroita visited Sumatra and provided training
on occupancy modelling to 30
people from the Indonesian Ministry of Forestry and 8 NGOs [5.7].
A training manual was
developed and translated into Indonesian [5.7]. Many of the
participants were co-authors of a
landmark 42-author article reporting the first island-wide assessment of
tigers in Sumatran
rainforests, based on occupancy surveys conducted in priority tiger
landscapes across Sumatra.
Guillera-Arroita led the analysis, with advice from Morgan
and Ridout. There is great public
interest in this flagship conservation species and this open-access
article, which is readily
accessible to the public via the Wikipedia page on Sumatran Tiger, plays
an important role in
informing the public, as well as those more actively involved in its
conservation, of the current
status of the species. From November 2011 to July 2013, this article has
been viewed 3583
times.
The survey informed the Indonesian Ministry of Forestry's National
Tiger Recovery
Programme which is using "science-based adaptive management" by
providing the baseline
against which future progress in conservation will be gauged. The survey
is highlighted in the
Global Tiger Recovery Program Implementation Report (Box 6, p.18) [5.8].
Priorities identified in
the report (p.19) include development of a $10million Global Environment
Facility grant for
transforming the effectiveness of biodiversity conservation in priority
Sumatran tiger landscapes,
and "the occupancy approach of Guillera-Arroita will be the main
monitoring technique" [5.7].
New methodology for camera trap data [3.6] was also motivated by
Sumatran tiger data, but has
since been applied in many other conservation and wildlife management
projects, including
human-tiger conflict in Nepal;
carnivores in South
Africa and Madagascar;
sympatric cat species in
Thailand; feral cats and dingoes in Australia;
and various cat species in Thailand,
Borneo and
Brazil. Rapid uptake
of the methodology was facilitated by (i) publication of a follow-up
paper in J.
Zoology, targeted at ecologists, with an accompanying podcast
discussing the work in non-
technical terms and (ii) provision of an R package (overlap) developed
with a scientist at Wildlife
Conservation Society, Malaysia, and available through the Central R
Archive Network (CRAN).
Occupancy surveys are widely used for amphibians and reptiles, for
example by fieldworkers
involved with National Amphibian and Reptile Recording Scheme (http://www.narrs.org.uk/)
and it
is widely recognised that there is scope to improve survey technique.
For example, the government
is required by EU regulations to undertake surveillance to assess the
status of the great crested
newt (Triturus cristatus), and a recent report commissioned by
Natural England
(NECR080, 2011)
noted that "attempts at assessing population status have been hampered
by problems with survey
data". To address this need, Guillera-Arroita, Morgan, Ridout
and NERC fellow McCrea have
collaborated with scientists from Kent's Durrell
Institute of Conservation Ecology (DICE) to improve
the design and analysis of amphibian and reptile surveys, for example to
detect trends in
occupancy over time. Morgan was part of a NERC Knowledge
Transfer grant ("Development of
standardised protocols for assessing reptile and amphibian populations")
led by Griffiths (DICE),
aimed at improving current practice.
As a final example of impact, our work on occupancy, and the accompanying
software SODA from
[3.5], has been used by staff of the Albany Pine Bush Preserve
Commission and the Wildlife
Diversity Unit of New York State Department of Environmental Conservation
to design occupancy
surveys to support a state recovery plan and monitoring program for the
Frosted Elfin butterfly
(Callophrys irus), a species that is threatened under New York
conservation law [5.9].
Summary: The beneficiaries of the research are individuals,
charities and environmental agencies
that collect and analyse ecological data and the organisations that plan
and implement
management and conservation strategies that utilise these data. The cited
examples illustrate how
novel statistical methodology developed at Kent has changed the practice
of wildlife managers and
conservation ecologists in collecting and analysing their data. As we have
described, considerable
effort is expended to encourage uptake. The impact has worldwide reach
because the methods
are generic and used by ecologists working on many different species, even
when the initial
methodological development was motivated by a particular application.
Impact is also significant,
because the species involved are often critically endangered and efficient
data collection and
analysis is essential to provide reliable inputs to management and
conservation programmes.
Sources to corroborate the impact
[5.1] Videos of PhD student research, including some of the
research from [3.5], help practicing
ecologists to rapidly familiarise themselves with novel methodology and
see how it should be
applied: http://www.methodsinecologyandevolution.org/view/0/VideoPodcastArchive.html.
[5.2] An example of textbook discussion of the Soay sheep models
[3.1, 3.2] is Chapter 1 of J.
Clark's Models for Ecological Data, Princeton University Press
(2007). ISBN:
9780691122625.
[5.3] The estimate of the survival of shags from [3.3]
for Birds of the Western Palearctic is in
Wanless, S. & Harris, M.P.1997. Phalacrocorax aristotelis
Shag. BWP Update 1: 3-13.
[5.4]
Probable causes of the decline in lapwings are discussed at
http://www.bto.org/birdtrends2010/wcrlapwi.shtml
[5.5] Letter from the Director of Science at the British Trust for
Ornithology confirming that BTO is
routinely using IPM and highlighting the impact of Kent's work on
"ecological science within
the UK and the policy-relevant work that flows from this." (See Contact
1.)
[5.6] Email from the Head of the Ecology Department at the Swiss
Ornithological Institute
explaining how research at Kent on IPM has changed the practice of
population ecologists.
(See Contact 3.)
[5.7] Email from the Technical Manager, Fauna & Flora
International, Program Aceh, Indonesia,
highlighting the importance of [3.5] to conservation work on the
Sumatran tiger and
confirming the impact of the training course run in Indonesia. (See
Contact 2.)
[5.8] The Global Tiger Recovery Program Implementation Report,
highlighting the impact of
occupancy modelling is at: http://www.globaltigerinitiative2013.org/site/wp-
content/uploads/2012/07/GTRP_Implementation_Report_2012.pdf
[5.9] Use of SODA software from [3.5] to plan occupancy
surveys for the Frosted Elfin butterfly is
reported in Bried et al (2012) Northeastern Naturalist, 19,
673-684.
If any of the links above is no longer working, pdf copies are
available on request.