This year, the British Trust for Ornithology (BTO) will be 90 years old. These nine decades represent an extraordinary period of partnership between citizen scientists and professional staff, which has charted changes in bird populations at a scale that would have been impossible by other means. As a result, more is known about our bird populations than those in almost any other country in the world. The BTO as we’ve come to know it today was founded in 1933 by pioneering environmentalists – including Max Nicholson, who recognised the potential of ‘cooperative birdwatching for conservation’. At its core are several long-term, UK-wide surveys that provide a framework within which volunteer observers can gather systematic data on numbers and distributions of birds in summer and winter, as well as data on survival and breeding success. The value of these surveys rests, to a large extent, on repeatability and thus the ability to compare data between sites and years. However, despite relying on constancy, the BTO has evolved and adapted through its 90 bird-and-people-rich years. The changes reflect advances in field methods and technologies, advances in analytical methods, changes in societal concerns and global challenges. 

Here, three of the BTO’s CEOs – Jeremy Greenwood (CEO from 1988 to 2007), Andy Clements (2007 to 2020) and Juliet Vickery (2020 to present) – reflect on the organisation’s history and give a personal take on their time in office. A period of almost 35 years is covered between the three authors, and it’s hoped that this BB eye will provide an insight into the way that the BTO has grown and changed with the times, while remaining true to its origins and keeping the three core elements of birds, science and people at its heart.

Jeremy Greenwood, 1988–2007
The period 1988–2007 was bracketed by two major pieces of work for BTO members and other volunteers: a second Breeding Bird Atlas (1988–91) and a Breeding and Wintering Atlas (2007–11). Methods used this time around were more systematic than in previous atlases, which allowed relative abundances to be mapped, in addition to simple distributions, and provided more robust comparisons between distributions in successive atlases. Such increasingly systematic methods characterised the whole of the Trust’s work during that period, work that increased substantially in volume, supported by a 60% growth in membership, an approximate doubling of staff numbers and a threefold increase in financial turnover in real terms. Underpinning that growth were the move of the headquarters to its current location at The Nunnery, Thetford, Norfolk, and increasing computerisation throughout the Trust’s activities. 

A good illustration of progress in methods for the BTO’s core schemes was the development in 1994 of the BTO/RSPB/JNCC Wetland Bird Survey (WeBS), designed to better monitor the huge winter numbers of shorebirds and waterbirds in Britain. Prior to this, the BTO and the Wildfowl and Wetlands Trust ran the Birds of Estuaries Enquiry and the National Wildfowl Counts respectively. Merging these as one scheme increased efficiency and allowed the Low Tide Counts Scheme and the Non-Estuarine Waterbird Surveys to be added to fill gaps that had previously existed. In addition, a system of formal Waterbirds Alerts based on WeBS data was developed in 1994, delivering vital information for designation and protection at site- and UK-level.

Similarly, the BTO/JNCC/RSPB Breeding Bird Survey (BBS) replaced the Common Birds Census (CBC), and the Waterways Breeding Bird Survey (WBBS) replaced the Waterways Bird Survey. Both changes reduced the effort required at individual sites, paving the way for better coverage, geographically and across different habitats. A formal habitat classification was introduced in 1990, to replace informal habitat descriptions that were difficult to interpret, and paper forms for data submission were improved and later replaced by digital and eventually online data entry and submission forms.


1. Renovations taking place on the house at The Nunnery, Thetford, Norfolk, ahead of the BTO’s move to its new headquarters there, summer 1990. 

Jim Wolf

Advancements in field methods were paralleled by advancements in analytical techniques, in particular Integrated Population Monitoring (IPM). This sought to bring together data from all of the relevant schemes to assess population levels, breeding success and survival rates and to build population models. These, in turn, enabled the BTO to not just document changes in breeding populations but also to identify the stage of the bird’s life cycle where changes were taking place and thus to help identify the drivers of population change. They were successfully used for farmland birds, such as Northern Lapwings Vanellus vanellus, Song Thrushes Turdus philomelos, Yellowhammers Emberiza citrinella and Reed Buntings E. schoeniclus. In the early to mid 1980s, to aid the calculation of survival rates for target species, ringers were required to list the number of birds ringed every breeding season by age, as well as species, and encouraged to run BTO/JNCC Constant Effort Sites (CES). In 1999, BTO/JNCC Retrapping Adults for Survival (RAS) studies were introduced, quickly attracting over 100 datasets across 40 species. 

In the 1990s, BTO data and science became increasingly important in highlighting, understanding and solving large-scale conservation issues, such as impacts of changes in climate and land use. Throughout the 1980s, astute observers of CBC trends became increasingly concerned about farmland bird populations, concerns reinforced by the publication of Population Trends in British Breeding Birds (1990) and the New Atlas of Breeding Birds (1993), which documented dramatic declines in populations and distributions of many farmland species. A flurry of work on farmland birds followed. By 2002, the BTO was engaged in 25 projects on farmland birds. These used long-term data and novel experimental work to show, for example, how the provision of food in winter resulted in higher populations of some seed-eating birds in nearby areas in the following summers. These two big themes of farmland birds and IPM fell neatly into the two BTO science departments, headed by Rob Fuller and Stephen Baillie. Wise, intelligent, knowledgeable and determined, they took the BTO’s science steadfastly forward in those years and later.

Papers in the late 1990s had showed that many bird species had advanced their timing of breeding (measured by egg-laying dates) and that distribution limits of some ‘southern’ species had shifted northwards, providing the first evidence of climate-related impacts on the UK’s birds. As the climate has continued to change, BTO’s datasets remain one of the best sources of information documenting the impact on the UK’s nature. Growing concerns about human-related impacts – combined with more efficient processing of data – meant that it became useful and possible to produce reports on the status of British birds annually. The government launched Indicators of Sustainability (1998) and Indicators of Climate Change (1999), with much of the data and analysis coming from the BTO. BTO monitoring continues to illuminate the discourse on the fate of our bird populations, notably through the annual publication The State of the UK’s Birds.

Many birdwatchers find much pleasure in watching the birds in their gardens, and monitoring of these is an easy and accessible way to understand more about populations in urban and suburban environments. The Garden Bird Feeding Survey (GBFS) started in 1970, and this early start meant it was the best dataset available on trends in the number of House Sparrows Passer domesticus, as the species was poorly covered by other surveys during the 1970s and 1980s. Now, GBFS has been largely replaced by the Garden BirdWatch (GBW), which received submissions from over 8,800 participants in 2022 and collects information on garden birds throughout the year. It has elucidated the story of the increasing numbers of Blackcaps Sylvia atricapilla overwintering in Britain and provided information on how disease has driven declines of species such as Greenfinches Chloris chloris. From 2007 onwards, the scheme has been used to record the occurrence of non-avian wildlife in gardens.

In 2004, BTO/RSPB/BirdWatch Ireland/SOC BirdTrack was established as a way to collate observations by birdwatchers, allowing comparisons between seasons, years and geographical locations. All observations are accepted but users are encouraged to produce full lists of the species observed, which enables a measure of the frequency of occurrence to be derived. These data are valuable for studies of both phenology and year-round distributions and, because they are gathered online, can also provide near-real-time data on, for example, migration and movement. Almost 20 years later, data can be entered from the field via a mobile app and there are facilities to enter historical records, for local recorders to download the records for their area and, as for GBW, to record some non-avian taxa.

BTO has always been an enthusiastic supporter of collaboration with similar organisations. The European Bird Census Council was set up in 1992, with the BTO Director as its Chair, to improve and integrate knowledge of birds across Europe. The first European Breeding Bird Atlas, co-edited by staff members from BTO and from SOVON (the BTO’s equivalent in the Netherlands), appeared in 1997 (the second in 2020) and the Pan-European Common Bird Monitoring Scheme was established in 2002. 

As the operator of the largest ringing scheme in Europe, it was natural that, in 1963, BTO was a founder member of the European Union for Bird Ringing (EURING). In 2006, BTO took over the running of the EURING databank, which holds the ringing recovery records for all the Continent’s ringing schemes. This remarkable database has been used to study, amongst many other things, the hunting of migratory birds in Europe and the post-breeding roosts of Barn Swallows Hirundo rustica. In 2022, the Migration Mapping Tool was published online, based on the EURING data, providing maps and tables of the movements of 21 waterbird species. An unforeseen use of this dataset is its current used in informing the management of the spread of Highly Pathogenic Avian Influenza (HPAI). 


2. The Duke of Edinburgh formally opens the Max Nicholson Building at The Nunnery, August 2006. 

Simon Lane

Andy Clements, 2007–2020
On my arrival at the BTO in the summer of 2007, the predominant activity was the start of field seasons collecting data for the Bird Atlas. The first summer’s recording period had just ended, and we were moving towards the initial winter of fieldwork, this being the first Atlas to have year-round data. BTO science was in rude health too, with two Science Directors at the peak of their careers. On the one hand, robust analysis of volunteer data was enabled through Stephen Baillie’s statistical and analytical capability, whilst Rob Fuller led a strong programme of land-use change research, particularly the decade-long programme of agri-environment measures to address the decline in farmland birds.

My focus from the start was to strengthen the programmes that supported our volunteers and the science enabled by their observations. BTO was still a ‘best kept secret’, so developing communications, fundraising and membership became a priority. BTO’s first real strategy took shape after a year or so, usefully helping us to focus on healthy funding in response to the financial crash of 2008. There were two aspects of BTO’s external profile where we needed to change. I was fortunate to be able to bring a strong government and partner network from my experience in the environment public sector, and we set about making it an important support network. Strangely, for a bird-oriented organisation, we were far from the beating heart of the birding community!

Making the BTO more appealing to a wider audience underpinned the effort in our communications, fundraising and membership programmes. We modernised the BTO’s look, changing the logo and including a strapline that said more about what we were there for, rather than what we did: ‘looking out for birds’. BirdTrack came more into the limelight with new developments and strong leadership from our own birders known throughout that community. Atlas fieldwork finished in 2011 and the data and writing was finished in 2013; this led to something of a turning point. Our then Chair, Ian Newton, suggested we should be confident in our marketing and design capabilities and publish the book ourselves. The resulting launch event at the Royal Society in London brought together a very broad church including volunteers, a Government Minister, our NGO partners and the business community.

During the second half of the 2010s, the BTO evolved its strategy to build on the organisation’s wider appeal, making our vision – ‘inspired by birds, informed by science’ – an explicit balance between science and engagement. Given the improved nature of our external network, we invited inputs to our future direction, both by holding a summit in Cambridge, where 40 or so leaders from society gave us their wisdom, and by issuing a Green Paper of intended themes for wider comment. This led to three clear programmes: actively encouraging participation through volunteering, delivering great science, and inspiring people to know and understand more about birds.

Recognising that the best organisations have strong and diverse governance, we worked with the Centre for Charity Effectiveness at City University, London, to modernise our Board, and to strengthen the role of BTO’s Trustees. In line with governance reforms and recognising that internal culture can be the key enabling the best contributions from our staff, we also modernised our people and organisational development programmes. Being open to this sort of change enabled the BTO to respond to significant developments in society. Awareness of equality, diversity and inclusion became more explicit as a result of societal issues such as Black Lives Matter and the #MeToo movement. The diversity of our organisation, with a 50:50 gender balance on our Board of Trustees, was an important marker, as was the strong BTO Youth programme, which was born at this time.

I was aiming to step down in 2020, a departure slightly delayed by the need for consistent and steady leadership through the challenging times that the Covid-19 pandemic brought. That the BTO not only survived but continued to flourish during the massive changes that Covid-19 wrought was testament to our volunteers, our dedicated and committed staff, and support from our friends and partners. 

There is so much that I’ve not mentioned from my 13 years at the helm: the cover-to-cover, must-read quality of BTO News; our partnership with business to use science to help minimise the impact of offshore windfarms on birds; satellite tracking Common Cuckoos Cuculus canorus to understand their migrations and convey the wonder of these birds and their movements to people; and data collection using automated audio recordings, allowing partnerships on taxa other than birds. Having an opportunity to steward an organisation for only a small window in its 90-year history is a privilege I will never forget.

Juliet Vickery, 2020–present
And so to the present day, where many themes of previous years remain as constants at the BTO – but in a changed, and changing, world. We have, we all hope, navigated the worst of the pandemic and are now learning to live with Covid-19. At BTO headquarters, this means finding ways to balance the risks and benefits of hybrid working. The virtual world has enabled our work to become more accessible to more people, epitomised by the huge increase in attendance at our now-online annual conference and the exponential growth of online training courses in bird identification. Staff in offices in Scotland, Wales and Northern Ireland can more easily join meetings and events in our headquarters in England and all of us can attend events that might have been too costly in time and money ‘in real life’. But there is also widespread recognition of the challenges in keeping connected, building communities and thinking creatively over Zoom. Our fears that volunteer coverage would suffer long-term damage post-Covid proved unfounded; we should have had more faith in our incredible supporters. Observers, quite simply, got right back out there and the BBS achieved record coverage in Scotland and Northern Ireland in 2022. The survey is now undertaken in almost 4,000 1-km squares across all four countries in the UK. 

Two key developments in the last few years are the expansion of species now included in our core, long-term surveys, and the exponential growth of the BTO’s Youth programme. The BTO has been able to take on a leadership role for the partnerships supporting the monitoring of the UK’s seabirds and wetland birds through the BTO/JNCC Seabird Monitoring Programme (SMP) and BTO/JNCC/Nature Scot Goose and Swan Monitoring Programme (GSMP), respectively. The former will pave the way to improve knowledge about our internationally important populations of breeding seabirds, vital in the face of increasing challenges from climate change, as well as the development of offshore renewables and, now, HPAI. The opportunity to integrate the monitoring of geese and swans with WeBS will enable better streamlining and consistency in reporting of wetland birds, particularly wintering waterfowl.

The BTO Youth programme that was launched under Andy’s leadership has, in just three years, taken on a life of its own; and rightly so, as the intention was always to have a youth programme ‘for young people by young people’. BTO’s youth strategy, delivered by a ten-person-strong youth advisory panel of 16–24-year-olds, identified many barriers that young people face when attempting to engage with nature, including aspects such as transport to green spaces, money, time and equipment. The programme is now working to overcome some of these issues through recruiting youth regional representatives to deliver local events, an equipment donation scheme for guidebooks and optics, and online training and workshops. In October 2022, BTO Youth designed and delivered the first UK Youth in Nature Summit, bringing together over 100 young people to be, in their words, ‘inspired, empowered and united’ for nature.


3. The BTO Youth team at the UK Youth in Nature Summit, Greater Manchester, October 2022.

Alicia Hayden

As the BTO heads towards 100 years old, what does the next phase of the society’s history need to look like? Birds, science and people will remain at the core of the BTO. This holds fast to the vision of the BTO founders, reinforced by the Cambridge Summit’s three recommendations for focus: ‘encouraging participation, delivering great science, inspiration through birds’. But times have changed, and the climate and biodiversity crisis we face demand that our science has greater positive impact for birds; and that we strive to include everyone in our work.

Ahead of the climate change talks in Glasgow (COP26) in November 2021, BTO drew together a wealth of data and information on the impact of climate change on the UK’s birds. It showed dramatic climate-related changes in numbers and distributions of many bird species. It also made some deeply worrying predictions about the fate of our most important and iconic bird communities in a warming world – particularly breeding seabirds and upland species. At the same time, the 5th Birds of Conservation Concern was published, based to a large extent on BTO data. This report revealed that a total of 70 breeding bird species are now considered as Red-listed in the UK – a doubling of the number of species in this category of highest conservation concern in just 25 years. A desperately sad state of affairs, beautifully captured in words and art in the books Red Sixty Seven and Into the Red, both produced by BTO and partners to highlight the vulnerability of an increasing number of bird species in Britain.  

The drivers of these declines are many, complex and inter-related, and they require urgent action to stem and reverse them. This will require new and novel approaches and a greater diversity of hearts and minds around the table. Nature needs all of us, not just sections of society, and we all need nature. We know that access and connection with nature has wonderful benefits for our own mental and physical health and wellbeing. Those benefits should be equally accessible to everyone regardless of their background. In 2021, we estimated that volunteers contributed a staggering 2,029,493 hours to BTO work. That is equivalent to almost 1,500 staff years! As BTO moves into its tenth decade, our ambition is to engage a greater diversity of people in our work and to empower them to play an active role in securing the future of birds and the natural world. Our route to 100 will be one through which we will seek to apply the enormous treasure trove of data, knowledge and expertise to help find solutions to, not just to stem but also reverse the declines of so many of our brilliant birds. 

Jeremy Greenwood, Andy Clements and Juliet Vickery, c/o BTO, The Nunnery, Thetford, Norfolk IP24 2PU; e-mail [email protected]

Jeremy Greenwood was a lecturer in Biological Sciences at the University of Dundee for 20 years before becoming Director of the BTO, retiring to an honorary position at St Andrews in 2007. He currently works on aspects of ornithological history and biological statistics. Andy Clements is a naturalist and ornithologist with a background in science. Before becoming CEO of the BTO, he held various senior positions at Natural England. He is most at home birding on the North Norfolk coast or rowing on the River Cam. Andy is currently Chair of the Government’s Species Reintroductions Task Force. Juliet Vickery has worked as a scientist in academic and NGO-based positions. She holds an Honorary Research Fellowship at the University of Cambridge and an Honorary Professorship at the University of East Anglia. Juliet is currently President of the British Ornithologists’ Union. She is a keen triathlete and happiest out on her bike or up a mountain. 

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