Key points:
- This study brings together the most comprehensive dataset of nest-camera studies across Britain, analysing over 2,000 nests from 24 bird species.
- Mammals, particularly foxes and badgers, were identified as the main nest predators, especially for ground-nesting waders such as curlew and lapwing.
- For songbirds, predation came from a mix of mammals and birds, with Eurasian jays and raptors responsible for most attacks, while magpies, crows and grey squirrels were rarely observed.
- Hedgehogs, adders, sheep and deer, were also recorded destroying eggs and chicks, showing that nest losses can come from a wide range of animals.
- Most camera studies were in woodland and grassland habitats, leaving major gaps in knowledge for farmland, hedgerows and urban areas—highlighting the need for more targeted research to inform effective, evidence-based conservation.
Background
Predation is one of the leading causes of nest failure in birds. When eggs or chicks are taken, whole breeding attempts can be lost. Knowing which predators are responsible is important for conservation because it helps decide whether habitat management or predator control might be effective. However, until now, most of the information on nest predators in the British Isles came from localised studies, often focusing on a few species or habitats.
Increases in the UK populations mammalian and
avian generalist predators have been linked with particularly strong evidence that this is limiting populations of seabirds, waders and game birds. Evidence is crucial for effective predator control as part of conservation efforts for vulnerable bird species to avoid unreliable perceptions guiding emphasis on certain predators. Evidence on which predators are most important in which situations can ensure that effort is appropriately targeted and the management strategy is defensible.
In-field signs of nest predation have largely been used in the past to assess nest predator identity. However, estimating predator identity based on signs such as what remains of the prey, or lack there-of, is left behind is not a totally fool proof method. Nest cameras have recently made it possible to directly record what happens at nests without relying on guesswork. This study brings together existing nest-camera data from across the British Isles to give a much clearer picture of which animals are preying on nests, and whether some predators are more important for particular groups of birds.
What they did
Researchers conducted a systemic literature review and data collection on nest predation of UK birds. They searched multiple databases up to January 2024 and screened nearly 3,900 articles. Strict inclusion criteria included that they must be UK studies, natural nests, camera-based monitoring and adequate reporting. Only 14 published studies were suitable by these standards. To broaden coverage, they also gathered 32 unpublished datasets from researchers, NGOs and other groups, giving a total of 46 studies and 106 nest groups.
The nest studies were conducted mostly using trail cameras with infrared night-imaging ability to identify predators. Type of camera was recorded in case different technologies impacted the quality of information each model provided – for example, to account for differences in night vision abilities or detectability of smaller mammals. Data were standardised at the level of species, nest stage (clutch or brood), site and year. Small datasets were sometimes pooled, and failures, such as broken cameras or unclear life-stage predation, were excluded. At least half of all predation events were successfully attributed.
Birds were grouped into three major categories: waders (e.g., curlew, lapwing), passerines (songbirds such as warblers, tits, finches), and other groups such as pigeons, doves, and raptors. Analyses compared broad predator classes: mammals, birds, and unknown and finer categories (e.g. fox, badger, hedgehog, stoat, other pooled groups). Reptiles were rare and mostly excluded. By performing a meta-analysis of all studies, the authors were able to estimate which predators were most often recorded taking eggs or chicks.
What they found
A total of 2,088 nests from 24 bird species were monitored using nest cameras, with 29.2% predated on camera. In total, 32 predator species were confirmed by footage and two more (little owl and grass snake) reported anecdotally. The frequency and identity of nest predators varied between prey type, nesting stage and habitat.
Wader nests were most often predated by mammals. Badgers were responsible for 41.7% of wader nest predation, followed by foxes at 23%. On some islands, hedgehogs also played a significant role, while sheep and deer were recorded taking eggs, together accounting for 6.3% of events. Corvids (crows, jays and magpies) accounted for only a small proportion (about 4%) of wader nest predation.
Songbird (passerine) nests were predated by a broader range of species. Badgers and foxes were again significant, accounting for 26% of all predation, but avian predators, particularly Eurasian jays (~23%) and raptors (21%), were also major contributors. By contrast, magpies, crows and grey squirrels were rarely observed taking nests. Reptiles, particularly adders, were occasionally recorded preying on chicks of ground-nesting species such as wood warbler and woodlark. It should be noted that the study did not consider the level of predator control at each site, even though some sites with intensive management were included, and this could explain the apparent importance of badger relative to fox predation and the low incidence of corvid predation.
Nest location strongly influenced which predators were most important. In high-canopy nests, almost all predation came from birds (around 81% of egg clutches and 90% of broods), while ground and low-canopy nests suffered higher rates of mammalian predation. Cats were the only mammals recorded at canopy nests, but sample sizes were small.
For other bird groups, including seabirds, gamebirds and raptors, mammals again dominated, accounting for about three-quarters of predation events. Specific examples included foxes taking raptor chicks (hen harriers), hedgehogs preying on seabird eggs, pine martens on gamebirds, with otters, stoats and rats seeming to target waterfowl.
Most of the camera studies were conducted in woodlands (73% of songbird data) and grasslands (81% of wader data), with very few in farmland, hedgerows, uplands or urban settings. This leaves gaps in understanding of how predator pressures may differ across the wider countryside, particularly for farmland and gamebird species.
What this means
This study provides the clearest picture yet of which animals are responsible for nest predation in Britain. The evidence shows that mammals, especially foxes and badgers, are the main threat to ground-nesting birds like waders, while a mix of mammals, corvids (such as jays and crows) and raptors take songbird eggs and chicks. Some surprising predators also featured, including adders and even sheep and deer, which sometimes eat eggs. By contrast, grey squirrels, often thought of as a danger to nests, were found to have very little impact, however this study’s focus likely represents habitats in which they are less prevalent.
The findings highlight the complexity of understanding and addressing predation. This study indicates that not all corvids are equally important in every habitat. Jays, for example, were recorded as nest predators far more often than crows or magpies, but this was probably because most of the songbird nests monitored were in woodland . Predator numbers and behaviour are shifting due to changes in land use, climate, and reintroductions of species like red kites, pine martins and while-tailed eagles. These changes could ripple through ecosystems in unpredictable ways.
For conservation, this means that management actions need to be carefully tailored to species and habitat concerned.. This study suggests that controlling corvids (such as crows and magpies) might help some woodland songbirds, where these predators are a key cause of nest failure. This paper highlights the significance of mammalian predation on wader species. However, other research and in-field experience show that corvid predation can still be significant for ground-nesting birds in many landscapes. For example, lapwings on open farmland or upland sites, where crows and ravens can heavily predate eggs and chicks. This highlights the need for local evidence and adaptive management. Combining insights from broad-scale studies like this one, with on-the-ground knowledge from keepers and farmers to build a fuller picture of how different predators affect different species across habitats.
Fencing, or in some cases lethal control, may help protect vulnerable ground-nesting birds, but management needs to be targeted, evidence-based and mindful of knock-on effects. Improving habitats and food resources for breeding birds will remain essential.
The study also shows the limits of current knowledge. Most nest camera studies have focused on woodlands and grasslands, leaving farmland, moorland, urban areas, and species like gamebirds far less studied. GWCT research on farmland and moorland shows that nest predation can be a significant factor limiting wild gamebird population success but more research is needed to join up the full picture. Ultimately, more nest camera studies in under-represented places, like farmland, hedgerows, towns and tree canopies, are needed to build a fuller picture and guide conservation decisions.
Paper title: Meta- analysis of predator identity in nest-camera studies in the British Islands
Authors: Madeleine G. Barton, Greg J. Conway, Ian G. Henderson, Jack Baddams, Chris S. Balchin, Kane Brides, Nigel Butcher, Tom C. Cameron, Tony Davis, John Eyre, Robert Foster, Daniel Gornall, Nilesh Karipal Kallamballi, Patrick Laurie, Adam Nixon, Paul Noyes, David M. B. Parish, Louise Samson, Jennifer Smart, Nigel Wilde, Max A. Wright, and Paul M. Dolman.