Science

Why do so many chicks end up dead?

The mystery of the spoonbills

Are the spoonbills in the Netherlands really doing as well as people think? UKrant helped UG researcher Petra de Groeij to ring spoonbill chicks on the island of Schiermonnikoog and discovered that appearances can be deceiving.
By Christien Boomsma, video by Rianne Aalbers
22 June om 11:29 uur.
Laatst gewijzigd op 9 July 2021
om 14:43 uur.
June 22 at 11:29 AM.
Last modified on July 9, 2021
at 14:43 PM.

I suddenly understand why bird researchers always walk through the marsh in single file, why the person at the front carefully checks the ground and everyone puts their feet exactly where the person in front of them puts theirs.

On the ground, right next to my feet, is a seagull chick. It’s grey-ish with black specks, and approximately the size of my fist. It turns away from me, hiding its head under a lump of dirt.

One step to the left and I would have crushed it. Bye bye, seagull chick.

Head researcher Petra de Goeij nods. ‘It’s easy to make a mistake’, she says. ‘Especially when you’re with a group. You say something to the person next to you, don’t mind your feet, and there you go.’

Fortunately, it’s never happened to her, although she did step on an egg once, which is bad enough, especially if it’s fertilised. ‘Trust me, that’ll keep you up at night!’

A gull chick is hiding on the salt marsh

Long-term study

It’s six o’clock in the morning, and we’ve been walking for an hour. We saw the sun come up over the Oosterkwelder at Schiermonnikoog. In the distance, a group of eider ducks is flying towards the sea, and screeching seagulls are circling over our heads. The chick near my feet wasn’t the only one. On the way to our end goal, a group of approximately twenty nesting spoonbills on a small sand dune, we’re crossing a giant gull colony. 

For De Goeij’s long-term study, we’ll be catching, measuring, weighing, and ringing the spoonbill chicks, who are approximately a month old. She’s been doing this every year since 2011, in nearly all large spoonbill colonies around the Wadden Sea, where 53 percent of the more than three thousand pairs in the Netherlands are currently nesting. 

Some breeding pairs use old herons’ nests

‘People think spoonbills are doing just fine’, says De Goeij. ‘In a way, they are. In 1969, there were only 147 breeding pairs in the Netherlands, but now they’re everywhere. Some of them even nest in trees, in old herons’ nests.’

But appearances can be deceiving. Even here in the marshes, a stone’s throw away from the Wadden Sea and at least ninety minutes from civilisation, spoonbill pairs only manage to raise one in three chicks to adulthood. Why is that? De Goeij wants to use hard data and measurements to figure it out. Right now, all she has is a hunch.

Good year

Nico Jonker, ecologist at Spot Noord Holland and volunteer on today’s ringing mission, points ahead of him. ‘Look!’ he says, ‘Over there! Can you see them?’

In the distance, I can spot slender, white birds in between the high grass. As we approach, they take to the skies, their distinctive bills visible against the morning air.

De Goeij divides the group into pairs. They roll out the sheep’s nets they brought with them, forming a circle. With the bird parents watching to see what is happening to their babies from a distance, thirty-two spoonbill chicks nervously huddle together as the researchers close in.

Thirty-two! ‘This is a really good year!’ De Goeij says happily. Another four chicks are hiding in one of the sloppily built nests made of sticks; they hadn’t hatched yet when De Goeij was here last month, giving the new-borns temporary rings. Normally, she finds quite a few rings from chicks that didn’t make it. A late spring storm and the resulting high waters in April washed away all the nests, but fortunately, the birds simply started again, and with good results. We find a single dead chick, next to the nest of little ones.

Petra de Goeij opens the tent cloth for another spoonbill chick

Chick tents

One volunteer throws a vest over the chicks; the dark will calm them down and the cover will protect them. No researcher could forgive themselves if one of the seagulls snatches a chick now that the parents are away. A little ways away, people are setting up two chick tents, where the birds are protected and free from stimuli as they wait to be ringed.

Streamer: Everything’s working out for the birds this year

Theunis Piersma, the Groningen expert on migratory birds, as well as De Goeij’s life partner, steps up to the tent and starts handing birds to volunteers. He hands me two, as well. The bare skin on the underside of their wings is surprisingly warm. I can feel the feathers barely poking through the skin, pricking me. Piersma, who has years of experience in the field, holds them by their armpits, near the base of the wings, but I’m too afraid to do that. What if I hurt them? I keep them close to my chest. The birds don’t struggle when I carefully lower them into their tent, head first.

‘Everything’s working out for the birds this year’, says De Goeij, once the ringing, measuring, weighing, and taking of blood samples has started. The cold, wet spring has turned out great for the birds. The eggs hatched during calm, warm weather. The chicks didn’t suffer from the cold, and there are plenty of flatfish in the Wadden Sea. 

Stagnation

It indicates once more the damage that climate change and drought, as well as agriculture and fishing, do to the bird population in the Netherlands. De Goeij, who quit studying godwits because finding hundreds of chicks dead from agriculture activities left her literally depressed, found solace in spoonbills. At least they’re a stable species. 

She’s still frustrated at the population’s stagnating growth, however. The Wadden Sea has much less fish than it used to. The spoonbills need fish to feed their young. She suspects a connection between the two.  

‘We’ve been studying these birds since 1994’, she explains. They started out by ringing them, allowing them to pinpoint where the birds were. Later, they put trackers on adult birds. The trackers record their location every ten minutes, allowing researchers to track where they forage, sleep, nest, and winter. Today, we’re collecting data about the birds’ sex and growth. Their vomit will tell us what they eat. Four volunteers, holding plastic bags, are checking the ground.

However, there are no funds to analyse the data or to publish any articles. ‘And in science, unpublished data doesn’t exist’, says De Goeij, bitterly.

Lack of knowledge

For ten years, she’s been hopping from contract to contract, from one subsidy to another. Every time, she has just enough money to continue her research. 

While the agricultural industry gives research money to Wageningen University & Research and the technology sector funds research into new materials or solar cells, conservation agencies don’t get any funds. The government does nothing to help them out, either. De Goeij doesn’t understand. ‘Spoonbills are the top predator near the Wadden Sea’, she says. ‘Everyone loves spoonbills, they want to know all about them. But there is such a lack of proper knowledge. I don’t understand why.’

In science, unpublished data doesn’t exist

Why isn’t there money to hire one PhD candidate, one post- doctoral researcher, to tackle all that data? To confirm that it’s the lack of fish in the Wadden Sea that’s endangering the spoonbill population?

De Goeij fears that people, or rather, governments, just don’t want to know. ‘Because then they’d have to do something about it.’ Other parties’ interests are great: sand extraction, fishing, gas drilling, laying cables in areas with vulnerable wildlife.  People would rather look away and ignore the data.

But she keeps going. She has no choice. If she stops collecting data, she’ll never have a chance to make up for it.

Theunis Piersma rings a spoonbill chick

Disoriented

We’re working on the last bird. Piersma rings the bird, and volunteer Jesse takes a slide rule and measures its wingspan and tarsus – the length of its feet. We tie a sack around the bird and weigh it for the last time: 1,325 grams. A nice, average weight. The time has come to open the tents and release the birds.

The thirty-two chicks look around, disoriented. They wander around for a bit, but our work doesn’t seem to have affected them very much.

As the researchers retreat in the same single file, the bird parents return to their nests.

All the children are still accounted for.

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