Guest blog by Hugo Langezaal, PhD candidate at the Netherlands Institute of Ecology (NIOO-KNAW) and Living Lab B7. Based on his ongoing research into biodiversity in the Dutch Flower Bulb Region, he shares his insights into the ‘bulb birds’ of JUB Holland.
 

ALSO READ OUR PRESS RELEASE: BREEDING SUCCESS AMONG THE BULBS

The Flower Bulb Region is internationally renowned for its vibrant fields of tulips, hyacinths, and daffodils. Yet few realise these same fields are also home to thriving bird populations during the breeding season. Biodiversity is not the first thing that comes to mind when people think of bulb cultivation.

During the JUB Study Days, I had the opportunity to share my findings with visitors, offering a researcher’s perspective on farmland birds in the bulb-growing landscape. By walking through the fields of JUB Holland, participants were able to witness the birds' presence first-hand. Many were surprised, asking questions like: “Can birds really raise chicks successfully here?” and “Don’t nesting birds get disturbed by farming practices?”

Thanks to 20 years of monitoring by the Agrarian nature and landscape association Geestgrond (ANLV Geestgrond), we now have a wealth of data on farmland bird densities in bulb fields. Five species stand out as being particularly well-represented: Northern Lapwing, Grey Partridge, Skylark, Yellow Wagtail and Eurasian Oystercatcher. These are affectionately known as the “Bulb Birds” – or the “High Five of the Flower Bulb Region”, as coined by ANLV Geestgrond.

All five species can be found on the grounds of JUB Holland. As part of my PhD research at NIOO-KNAW, I study how these birds thrive in a landscape of intensive horticulture. Where do they find food? What do they eat? And how successful are their breeding attempts? The Yellow Wagtail serves as a model species in this context. Being a specialist insectivore, it’s a perfect indicator of insect availability around bulb fields. From April onwards, wagtails return from their wintering grounds in Africa, often choosing to nest among the bulb crops at JUB Holland. They remain there until mid-June, when the bulbs are lifted – giving them just enough time to lay eggs and raise their chicks.

Breeding Success at JUB Holland: Numbers and Observations

In 2024, four Yellow Wagtail nests were found on JUB Holland’s 16-hectare site – three among the tulips, one among the daffodils. To avoid disease transmission, no nest surveys were carried out in the hyacinths, though it is likely that at least one additional nest was missed. Based on field observations, an estimated five to seven breeding pairs nested at JUB Holland this year.

While that may not sound like many, it translates to a remarkable 30.9 to 43.2 nests per 100 hectares – significantly higher than the regional average of 21 territories per 100 hectares recorded by ANLV Geestgrond between 2002 and 2022. For comparison: similar farmland regions in the Netherlands such as Flevoland or Groningen often show densities of just 5 to 15 territories per 100 hectares.

Not every territory results in a breeding attempt – some birds fail to find a mate. Had we also included adjacent fields with less favourable crops such as peonies or fallow land, the average density might have dropped closer to the regional mean. Nevertheless, the results at JUB Holland clearly demonstrate that under the right conditions, Yellow Wagtails can achieve very high breeding densities in bulb fields. Similar patterns were observed for Skylarks.

The four wagtail nests found at JUB Holland produced a total of 22 eggs, of which 21 hatched and 20 chicks successfully fledged. Only one chick – the smallest – fell prey to a mammal predator after its siblings had left the nest.

The chicks were fed a variety of insects. To understand the foraging behaviour of adult birds, I followed the their foraging flights. Most often, they flew to ditch edges, but they also foraged in the bulb crops – with hyacinth fields proving surprisingly popular.
 

CURIOUS TO SEE HOW THE YELLOW WAGTAIL RESEARCH WORKS IN THE FIELD? WATCH THE VIDEO

Ditches and their vegetated banks appear to serve as key insect reservoirs, from which insects spread into the surrounding fields. The insect fauna around bulb crops consists mainly of flies and midges, which were frequently fed to the young. Some ditch banks are notably richer in insect life, likely due to more diverse vegetation resulting from varied management regimes. In addition, the wagtail diet included dragonflies, beetles, caterpillars, bees, wasps, and ants.

This highlights the importance of targeted ditch management. A mosaic of low-mown and taller, flower-rich edges is considered beneficial. Within the ditches themselves, phased mowing and careful dredging help preserve insect habitats year-round.

The Yellow Wagtail is not the only species to benefit from the varied bulb landscape with its many watercourses. Crop diversity also plays an important role. Fallow fields – for example, those waiting to be planted with summer bloomers like sunflowers or dahlias – offer early-season breeding and foraging opportunities for Skylarks, Lapwings, and Oystercatchers. Even small, uncultivated corners of just a few square metres can serve as crucial insect hotspots, as these areas are left undisturbed throughout the season.

One excellent example is a so-called “stepping stone” at JUB Holland – a small-scale habitat feature designed in partnership with ANLV Geestgrond to support Grey Partridge. These stepping stones include hedgerows, flower-rich field margins, and rough corners planted with native species such as redcurrant, wild rose, and hawthorn. They offer shelter and food and help connect fragmented habitats in the agricultural landscape. In 2024, a pair of partridges was spotted in the fields at JUB. It would be fascinating to explore how this species uses bulb fields across the seasons.

Dolph Uittenbogaard, Director of JUB Holland, explains that biodiversity has long been a core part of the company’s operations:

“As a bulb grower, you work in the landscape every day – and with that comes the responsibility to care for it. At JUB, we’ve combined flower bulb cultivation with nature-inclusive measures for years – from wildlife-friendly ditch management and installing duck nesting baskets to planting beech hedges and creating flower-rich buffer strips. We're now looking to go a step further by transforming the strip alongside our barn into a biodiversity zone with bee banks, brushwood piles, hedgerows and bird thickets. We also design those uncultivated corners and stepping stones as intentional habitats for partridges. Because true biodiversity only flourishes when we’re willing to make room for it.”

Food and Shelter: Why Birds Thrive in Bulb Fields

The consistent presence of breeding birds over many years suggests a stable population. We also found evidence that food supplies are sufficient for successful chick rearing. Much of this can be attributed to the bulb crops themselves: they emerge early in the season, creating a vegetation structure that is both low and open – ideal for nesting, but with enough cover for protection. In short: bulbs offer a safe and functional nesting habitat, while the surrounding landscape provides ample food sources.

Bulb Fields as a Refuge for Declining Species

It is remarkable how well certain farmland birds are doing in bulb fields, especially compared to their steep declines elsewhere in the Netherlands. For species like the Skylark and Grey Partridge, the Flower Bulb Region seems to offer a stronghold. In fact, one of the highest densities of Skylarks in Dutch arable farmland are found here.

Each bulb bird species has its own crop preferences. Yellow Wagtails, for example, prefer tulips – the broad leaves help conceal their nests. Daffodils and hyacinths are also used, especially cultivars that offer dense but not overly tall cover (ideally between 40–60 cm).

Nature-Inclusive Measures: Challenges and Opportunities

Despite growing interest in nature-inclusive farming, implementing measures for bulb birds can still be a challenge in the Flower Bulb Region. Complications include the complexity of agri-environment schemes, limited availability of appropriate funding, and the pressure of high land values. Measures for biodiversity may sometimes appear at odds with cultivation practices. However, from my experience, growers like JUB are genuinely committed to making a difference – and there is real potential here.

Simple interventions can already yield benefits: phased ditch mowing, retaining uncultivated corners, and combining mandatory buffer zones with wildflower margins. More ambitious – but feasible – actions include creating nature-friendly banks with gentle slopes and planting hedgerows at field edges, without compromising the open character of the landscape. Ongoing reductions in chemical crop protection use also work in favour of biodiversity. Many of these best practices are summarised in a poster available online at www.livinglabb7.nl.

20 Years of Monitoring: Stable Populations, New Insights

Since 2002, ANLV Geestgrond has conducted standardised surveys of bulb birds. Their data show relatively stable populations across two decades, with the region consistently supporting high densities. The only exception is the Grey Partridge, which has shown a slow decline. Recently, concerns have arisen about the early-season use of plastic crop covers, especially in crops like sunflowers – making large areas unsuitable for wildlife.

A Personal Note: Science, Soil, and Stewardship

In addition to the Yellow Wagtail and Skylark, I’m always uplifted by a sighting of Grey Partridge at JUB. Despite relatively high numbers in this region compared to national trends, the population remains small and fragmented, with a real risk of local extinction. Fortunately, local initiatives – including new hedgerows and habitat stepping stones – are already helping to reverse this trend.

As both a researcher and a native of the Flower Bulb Region, I feel a strong connection to this landscape. Contributing – however modestly – to its future is what drives me. I love studying birds, but I equally enjoy collaborating with growers and local stakeholders to raise awareness about biodiversity and bulb birds. Working constructively with a sector under pressure to improve biodiversity gives me great energy and hope.


Hugo Langezaal MSc
PhD Candidate | Netherlands Institute of Ecology (NIOO-KNAW)
Focusing on biodiversity restoration and sustainable agriculture in the Flower Bulb Region. Combining local roots with scientific expertise in aquatic ecology and ecological restoration, he develops practical measures and indicators as part of Living Lab B7 – promoting nature-inclusive intensification with space for nature. https://nioo.knaw.nl