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Godwit Chick Survival

About the project

The black-tailed godwit – our national bird – has been under pressure for years. Despite numerous conservation measures, the number of breeding pairs continues to decline. Researchers now know where the problem lies: too few chicks survive their first few weeks of life. The Black-tailed Godwit Chick Survival Project (2026–2030) therefore focuses on one crucial question: why do so many black-tailed godwit chicks not make it, and what can we do about it?

Why chicks in particular? — Black-tailed godwits are so-called precocial birds: their chicks leave the nest shortly after hatching and immediately set out to find food themselves, under the guidance of their parents. During those first 20 to 40 days, they are extremely vulnerable. They need to grow quickly to become strong enough to fly and later migrate to Africa. But they face three major challenges:
1) Food scarcity – fewer insects in the grassland
2) Predation – birds of prey and mammals that eat chicks
3) Land use – mowing, fertilisation and water management affect habitat and food
Exactly how these factors are interrelated is not yet fully understood. And it is precisely this insight that is needed to formulate effective policy. Zuidwest-Friesland as a living laboratory

Zuidwest-Friesland as a Living Lab — The research is taking place in an 11,500-hectare study area in Zuidwest-Friesland. Since 2004, precise records have been kept here of how many black-tailed godwits breed, how many nests are successful and how many chicks survive. Thanks to long-term collaboration with farmers, land managers and volunteers, this area has become one of the best-studied meadow bird areas in the world. These long-term data series make it possible to analyse trends reliably.

A unique experimental approach — What makes this project special is that it not only observes but also experiments. Some of the reared chicks are temporarily placed in small, fenced-off sections of plots with different management practices. During the day, they forage for food there under the supervision of the researchers. In the evening, they are brought safely indoors. This allows us to measure precisely how different land uses influence their growth when predation is not a factor. In a second experiment, some chicks are given a rich diet, comparable to the food supply in the 1980s, so they are expected to grow faster than chicks given a diet comparable to that of chicks growing up in the wild today.

In addition, wild and reared chicks will be fitted with ultra-light transmitters. These will allow researchers to track exactly where chicks forage, how they move through the landscape, when they depart for southern Europe or West Africa, which routes and habitats they use, whether and where they return to breed after 1–3 years.

All data – from insect numbers to migratory movements – is integrated into an advanced population model. This model simulates how the population develops under various scenarios.

Objectives

The project is investigating three possible ways to improve chick survival:

1) More food for chicks: by measuring the abundance of insects in different types of grassland, the scientists are investigating which management practices – such as later mowing or higher water levels – are beneficial.
2) Reduced predation: using small camera traps, DNA analysis and transmitters, the project is identifying which predators are responsible for chick mortality, and how this relates to mouse population density and the landscape.
3) ‘Headstarting’ – an extra helping hand. This involves collecting eggs from areas without meadow bird management, hatching them artificially, and rearing the chicks safely until they are fledged. They are then released into the wild. This method is already used for highly endangered bird species, but its effectiveness for black-tailed godwits in the Netherlands is still unknown.

BirdEyes role

BirdEyes was the lead applicant of the Godwit Chick Survival consortium and coordinates much of the field work, with the assistance of volunteers from BFVW to collect eggs from nests with low survival probability, and with help of project partner Avifauna who breed the eggs and rear the chicks for warm and cold release experiments. BirdEyes is also responsible for deploying new chick-tracking technology and measuring food availability for godwit chicks across different study sites, while Altenburg & Wymenga are responsible for mapping vegetation structure in chick-tracking sites, and BFVW operates novel drone-based nest and chick detection software to facilitate capture of godwit chicks in the wild.

The BirdEyes team includes two project coordinators, multiple field technicians, two PhD students and at least one postdoctoral researcher. The BirdEyes PhDs and postdoc will, respectively, study (i) the role of diet in chick growth and development, (ii) the mobility and causes of mortality of wild and experimentally reared chicks, (iii) habitat and space use of chicks before and after fledging and during recruitment in the Netherlands.