Skip to content

Use of a common pesticide that impairs bird migration

Ever since Rachel Carson published the Silent Spring in 1962, we have known that songbirds are in great danger from pollution and human activities. Recent research has made the causes and the consequences of pesticide pollution even more evident.

A journal article published this month in Science clearly shows that the use of a common pesticide, called a ‘neonicotinoid’, is likely causing bird population declines because it is hindering bird migration. Neonicotinoids are the most widely used type of agricultural pesticide worldwide. In this study, the authors combined an experimental approach of feeding sparrows a neonicotinoid with a telemetry approach – a method of tracking individual movements in natural habitats – to follow the birds’ migratory movements. The research used the white-crowned sparrow, Zonotrichia leucophrys, which is a typical seed-eating songbird of northern latitudes. The exposure conditions that were used in the experiments were well within the dosage that a bird could realistically consume by eating even a few seeds that had been treated with a neonicotinoid.

The authors discovered that even a single exposure to low doses of a neonicotinoid caused negative effects on bird feeding and migration. Birds that were exposed to the neonicotinoid had significantly longer stop-overs, meaning that migration takes longer. The proximate mechanisms by which this effect occurred is that the birds stopped eating; they quickly lost weight from their fat reserves and this weight loss lasted for an extended period of time.  Fat reserves and fuel from feeding are critical for successful bird migration because it is very energetically challenging. The authors suggest that the longer stopover is caused by the fact that the exposed birds eat less and therefore have less fuel to continue. As every 1960s French movie star knows, nicotine suppresses appetite. Neonicotinoids are chemical sisters to nicotine and may well have the same effect on birds. Birds only continue their migration when they have enough reserves to meet the next bout of flight.

The press response to this paper has been high, especially in North America. The message and coverage has been consistent and, as far as I have seen, quite accurate and reflecting the dire state of bird health and its evidenced link to these pesticides. It seems to me that the media response is more on the side of reporting the science and biodiversity conservation now than even a few years ago, when for example in the UK media also presented the chemical industry perspective that neonicotinoids are necessary and not harmful. By now few disagree that birds are being lost at a staggering rate in the northern hemisphere; a different study in Science, on the heels of the pesticide one, found that 3 billion birds have been lost from North America in the last 50 years. Numbers in Europe are believed to be comparably drastic. Birds are indicator species for ecosystem health and evidence from this study shows that a major cause of that decline is likely a chemical that humans choose to apply.

What individual birds experience during migration has population-level consequences because it directly affects mortality and birth rates. In this case the birds were slower to continue migration, which means that they will have poorer quality breeding sites when they arrive at their destination. This is known to result in later breeding, and fewer and lower fitness offspring, with long-term effects on population viability. These consequences are evident in the results from another high profile journal article published this month, birds that are dependent on farmlands have declined in abundance by a staggering 74% over the past ca. 50 years. It is precisely these farmland birds, exemplified by the sparrows, that are most exposed to neonicotinoids and other pesticides. In fact, the authors note that some individuals may experience repeated exposure at successive feeding stopover sites, which would amplify these negative fitness consequences that were detected in their study.

The media coverage has been wide, perhaps because we are currently in a time of increasing awareness about the impact of human activities on the natural environment. The evidence that neonicotinoids inflict huge harm to bees and other pollinators has been growing. The effects are not only direct – as evidenced experimentally in this study on sparrows – but also indirect on ecosystems, for example when pesticides reduce natural insect numbers and therefore remove a valuable food source for bats, birds and other animals. Consequently, the EU, including the UK, banned neonicotinoids in 2018 (except for use in plants that live their entire life in greenhouses). The UK government says they will maintain the ban post-Brexit. However exemptions requested under ‘emergency situations’ may be a route by which neonicotinoids are still used. The fact that neonicotinoids are already banned in the EU and UK – i.e. it is now clearly accepted that they cause harm – might be the reason that the media coverage of this article has been somewhat less on this side of the Atlantic than in North America.

In North America, the timing of this study is particularly important and therefore the media attention is valuable for raising awareness on human and environmental health. Neonicotinoids are on almost all corn and canola seeds, and many soybean seeds, in Canada and are used very widely in the USA. The government agency Health Canada has proposed a phased in ban on agricultural use of neonicotinoids starting in 2019. There are few or no restrictions on their use in the USA. Trump reversed a limited Obama era ban on neonicotinoids in wildlife refuges. Hopefully the evidence that is accumulating from science will help motivate future bans across the globe.

Now it is clear that neonicotinoids are harmful to insects and vertebrates. To date, the burden of proof has clearly been laid on scientists and concerned citizens and public funds through university research to demonstrate these consequences. But other pesticides are dangerous to wildlife as well. For the sake of ecosystem health and biodiversity, let’s hope that the lessons that took so long to learn on neonicotinoids are applied more rapidly to other human actions that significantly harm nature.


Main paper discussed is:

Eng ML, Stutchbury BJM, Morrissey CA (2019) A neonicotinoid insecticide reduces fueling and delays migration in songbirds. Science, 365, 1177–1180.

Available at

Brain blog showcase 2019: Alcohol: A Leading Health Risk or Protective Factor against Dementia?

All this week we’ve been showcasing the work of students who have been “researching the headlines” as part of their undergraduate studies. Their task was to describe an original research report exploring how lifestyle affects brain health in a manner accessible to non-experts, as well as evaluating the media coverage of the research. If you’re interested in using this approach in your own teaching, you can contact Alan Gow for more information and materials.

For our final “brain blog”, we have…

Read more…

Brain blog showcase 2019: Use it or lose it: Can intellectual engagement offset cognitive decline in older age?

All this week we’re showcasing the work of students who have been “researching the headlines” as part of their undergraduate studies. Their task was to describe an original research report exploring how lifestyle affects brain health in a manner accessible to non-experts, as well as evaluating the media coverage of the research. If you’re interested in using this approach in your own teaching, you can contact Alan Gow for more information and materials.

Next up in the “brain blog” showcase, we have…

Read more…

Brain blog showcase 2019: Students “research the headlines”

At Research the Headlines we explore how research is discussed in the media. We try to add additional details to existing coverage, or help our readers get a clearer understanding of how new research might make its way from “lab to headline”. Through different activities, we also help others develop the skills needed to become more critical consumers of both research and media reporting; for example, via our How to “Research the Headlines” series and our “Rewrite the Headlines”workshops and competition for primary school children.

Many of our contributors also use the ideas behind Research the Headlines in their teaching. In one of his undergraduate courses, Alan Gow (Heriot-Watt University) has his students find a recent media article related to lifestyle factors and brain health. Their task is to describe the original research that report is based on in a manner accessible to non-experts, as well as evaluating the media coverage. A key aim of these “brain blogs” is to explain the important concepts and take home messages, and to highlight issues in interpretation either in the media report or the underlying research.

Over the course of this week we’re showcasing the work of three students, all recent graduates in Psychology at Heriot-Watt. The blogs are presented as submitted by the students; they’ve not been edited. We hope you enjoy reading their work, and learning a bit more about the topics too! If you’re interested in using this approach in your own teaching, you can contact Alan Gow for more information and materials.

Starting the “brain blog” showcase, we have…

Read more…

Biodiversity at risk or eco-propaganda?

The first Intergovernmental Panel for Biodiversity and Ecosystem Services (IPBES) Global Assessment summary for policy makers was released on the day prince Archie was born and the Met Gala took place. While nothing can quite compete for press attention with the birth of a royal baby and celebrities in fancy dress, the IPBES global assessment received plenty of press attention. Since late April, IPBES has featured in over 23 thousand articles. I have not read them all! Examples of press media coverage can be found here and here.

Read more…

Science communication and policy making

The Young Academy of Scotland (YAS) is today launching an exciting new project that will bring politicians and academics together. Five YAS members will shadow their respective MSPs at Holyrood and in their constituency. The politicians will then visit the academics at their institutions. Through this approach each member of the pair will gain an understanding on how the other part works and what challenges they face. You can follow all the action on social media with this hashtag #YASMSPPairing. The scheme is inspired by the well-established and highly successful annual pairing initiative organised at Westminster by The Royal Society, in which I was lucky to participate during 2017. (See picture with paired MP, Stephen Gethins.)

Read more…

Talking Headlines with Debbie Kennett

Debbie is an Honorary Research Associate in the Department of Genetics, Evolution and Environment at University College London. She writes about DNA testing for Who Do You Think You Are? Magazine and Family Tree Magazine, and has written two books for the History Press: DNA and Social Networking and The Surnames Handbook. She promotes the responsible use of DNA testing as a tool for genealogical research. To this end she has helped to create educational resources for the genetic genealogy community, notably by co-founding the ISOGG Wiki. Her blog Cruwys News features articles on DNA, family history and surname research. She has been interviewed about genetic ancestry testing for BBC Radio 4, appearing on You and Yours and The Business of Genetic Ancestry. She is often asked to comment on DNA stories for the UK and US press and has been cited in numerous publications including The Times, The Observer, The Atlantic, Bloomberg News and The Washington Post. Debbie can be found on Twitter commenting and tweeting about anything to do with DNA.

Read more…

Looking back at Research the Headlines in 2018

2018 was another trying year for evidence-based journalism. Research the Headlines was set up in 2013 to examine how research is portrayed in the media, and to give the public helpful advice and tools when trying to get to the heart of a news story.

Read more…

Talking Headlines: Simon Fisher

Simon is director of the Max Planck Institute for Psycholinguistics, and Professor of Language and Genetics at the Donders Institute for Brain, Cognition and Behaviour, both in Nijmegen, the Netherlands. He is interested in tracing the functional links between genes, brains and human traits like speech, language and reading. Simon’s research aims for a multi-disciplinary viewpoint, trying to integrate data from genomics, psychology, neuroscience, developmental biology and evolutionary anthropology. He is keen on communicating science in an accessible but accurate way, on Twitter (@ProfSimonFisher) and beyond. He has given talks at international conferences across a diverse range of fields, and spoken to school, student and public audiences, including at the Rome Science Festival and New Scientist Live. Simon is an elected fellow of the Royal Society of Biology, awards include the Francis Crick Lecture and Medal, and the Eric Kandel Young Neuroscientists Prize.

Read more…

Research the Fringe 2018

Dear readers, as it’s August again we would like to welcome you to another roundup of research related shows on at the various festivals hosted in Edinburgh in the next few weeks. These include the Edinburgh Festival Fringe, its more prestigious elder, the Edinburgh International Festival, the Edinburgh International Book Festival, and the Edinburgh International TV Festival. As we have done in previous years we would like to provide suggestions for research-related shows and events for any Research the Headlines readers who may be visiting Edinburgh this month.

Read more…