Key points
- Curlew populations are under threat, and there are concerns that increasing woodland cover could make the landscape less suitable for these iconic birds.
- Researchers studied where curlews chose to nest in the New Forest for three years between 2020 and 2022.
- From the 76 nests studied, curlew showed a strong preference for wetter habitats like mire and wet heath.
- Despite dry heath being more abundant, curlew had a weaker preference for dry heath. Grassland and woodland were avoided.
- Nests in mire also had higher nest survival, while dry heath appeared to worsen the nest survival. Woodland had no effect.
- These findings emphasise the need to maintain and improve wetland habitat availability in the New Forest to support curlew breeding.
Background
Curlews are a large wading bird, once a familiar sight across marshes, meadows, moorland and arable fields. With long, curved bills and mottled cream/brown feathers, they are quite distinctive. Yet, across the UK the species is under threat. Their populations are estimated to have declined by 48% since 1995.
Curlews can live longer than 30 years. The experience these birds gather during their lifetime helps them breed more successfully. This makes older birds incredibly valuable to the overall population. Curlews are usually site faithful, returning to the same location to nest each year. Despite this life experience, their breeding success is very poor, making it hard for populations to recover.
One concern is that increasing woodland cover could make the landscape less suitable for curlews. As ground-nesting birds, their nests are already vulnerable to predators. Red foxes and corvids are the main predators of curlew eggs across the UK. Previous studies have shown that predators are likely to be more common in fragmented woodland landscapes than in open landscapes, with some research showing that curlews are less successful in areas with more trees.
Tree-planting initiatives across the countryside aim to combat climate change and restore habitats. However, some trees are being planted in naturally open habitats. Where open habitat is limited, curlew struggle to adapt to this rapidly changing environment and may be forced to nest in lower quality habitat where the nest is less camouflaged or where predator activity is higher.
The New Forest is an important breeding area for curlews. It has large areas of open heathland and wetlands, maintained by livestock grazing. These habitats may provide better conditions for curlew nests than more wooded landscapes.
What they did
Researchers studied where curlews chose to nest in the New Forest for three years between 2020 and 2022. They surveyed all known breeding areas and recorded the exact location of 76 nests. They compared these locations to 10,000 randomly placed nests in the surrounding landscape to understand what features influenced nest placement and chick survival.
To get a better picture of curlew movements, some birds were fitted with GPS trackers. This allowed researchers to see how far they travelled from their nests and how they used different habitats.
The scientists investigated:
- The types of habitat around nests (mire, wet heath, dry heath, grassland, woodland, and ponds).
- The influence of roads, campsites and car parks on nest distribution.
- How nest survival varied depending on habitat type.
- Whether curlews moved their nests after losing eggs to predators.
What they found
Of the curlew nests surveyed in the New Forest, 39.5% nested in wet heath, 31.6% in dry heath and 8.3% in mire. Despite dry heath being more abundant, curlew showed a strong preference for wetter habitats like mire and wet heath, and a weaker preference for dry heath. Grassland and woodland were avoided.
Nest survival rates were low at just 13% overall, which is similar to findings from other UK studies. Importantly, nest survival was highest in mire habitats at 21%, and this remained stable throughout the breeding season. Wet heath also had a survival rate of around 13%. By contrast, only 5% of nests survived in dry heath, making it the worst habitat for curlew success. These dry heath areas possibly had poorer camouflage; higher levels of predator activity and human disturbance. Curlews strongly avoided woodland when choosing where to nest, likely due to perceived predation risk but more research is need to investigate this.
GPS tracking allowed the researchers to assess how curlews used the surrounding habitat while they were nesting, and the composition of their ‘home ranges’. Using this information they discovered that the 500m area surrounding nests is critical for habitat selection.
For nesting curlews, a home range refers to the wider area around their nest which covers the majority of their daily activity, such as foraging for food The results showed that birds nesting near to ponds had smaller home ranges, which may allow for better feeding.. Birds with larger home ranges did not have these habitat features nearby, so possibly had to travel further to find resources.
Some curlews appear to adjust their nesting strategy after failure, relocating from wetter to drier habitats or vice versa. Unfortunately, in some cases, this shift increased their risk because the drier areas had lower nest survival rates.
What does this mean?
These findings emphasise the need to maintain and improve wetland habitat availability in the New Forest to support curlew breeding. While tree planting is often promoted for conservation, planting without careful planning and a solid understanding the area’s wider ecology could harm curlew populations by excluding them from optimal nesting habitat .
Despite more of the New Forest being covered in dry heathland, curlews preferred wet mire for nesting, and had higher rates of nest survival there. This may be because predators like foxes and badgers, find wetter areas harder to access. Additionally, improved camouflage could make curlews feel safer, encouraging them to stay on the nest rather than flee when threatened. This, in turn, may reduce the scent they leave around the nest. In contrast, drier areas tend to have dense networks of paths, making them more accessible to both predators and humans, while also offering poorer camouflage for the adult bird and their eggs.
The study confirms that curlews are highly selective about where they nest, and that habitat directly affects their breeding success. These insights can help guide conservation efforts to better protect one of the UK’s most threatened birds.
Conservation efforts for curlews should focus on protecting and restoring existing wet habitats. Tree planting should follow the ‘right tree, right place’ guidelines outlined by organisations such as the Game & Wildlife Conservation Trust and the Forestry Commission. Reducing predation pressure through providing suitable nesting habitat and effective predator management could also improve nesting success.
Read the original paper
Rivers, E.M., Short, M.J., Page, A., Potts, P.M., Hodder, K., Hoodless, A., Robinson, R. and Stillman, R. (2025), Factors influencing nest site selection in a rapidly declining shorebird, the Eurasian curlew. J Avian Biol, 2025.