RAU Architects and RO&AD Architecten have built an egg-shaped observatory to watch several bird biotope in the Scheelhoek Nature Reserve in Stellendam, Netherlands. 

Thatched reed-covered structure, situated in the middle of Scheelhoek - a nature reserve close to the Haringvliet sluice near Stellendam, lets people experience and explore bird biodiversity, a series of bird observatories realized in the Haringvliet area.

Named Tij Observatory, the 150-square-metre structure was parametrically designed to achieve a good ratio between form, structural integrity, size of the timber, and size of the openings. 

Tij is a Dutch word joke. ‘Tij’ means ‘tide’ which refers to the returning tides in the Haringvliet, but quickly pronounced it also means ‘the egg’). Tij is the biggest and most striking of a series of objects designed to celebrate the opening of the Haringvliet sluices in November 2018.

Image © Merijn Koelink

"The sluices were opened in order to improve water quality and biodiversity, while also stimulating fish migration from the North Sea to the river delta system of Maas and Rhine in the Netherlands," said the architects.  

"This will create a new, salt-resistant and salt-loving natural environment. The biodiversity in the surrounding nature reserves will increase and a more robust, healthier ecosystem will develop in the coming years."

 Image © Merijn Koelink

The reserve consists of large reed beds on the inside of the coastal defences and some flat sand islands outside. These islands are breeding and feeding grounds for several species of birds like the common tern, spoonbill, and the icon of this area, the sandwich tern.

Tij Observatory was designed as part of a large scale landscaping plan where people can experience the Scheelhoek nature reserve in a walk from the car parking area to the Ei. Walking along the path, visitors can view several types of bird biotope favoured by sand martins, several kind of waders and, of course, terns.

 Image © Merijn Koelink

To prevent the birds from being disturbed, the last section of the path is actually a tunnel made of re-used mooring posts and second-hand azobe planks which were once used in the brick industry. The tunnel is covered in sand to provide habitat for terns or waders. The outside of the tunnel provides artificial nesting holes for sand martins. 

The end point of the walking route is the egg-shaped bird hide from where you can view hatching Terns and all the other species that live in and around the water.

"The egg itself is modelled on a sandwich tern egg, and sits on a nest of sand, much like a tern would have done it herself. The nest of the egg consists of vertical ‘feathers’ of chestnut poles, reeds and small sand dunes," added the architects. 

"The egg itself is parametrically designed to achieve a good ratio between form, structural integrity, size of the timber, and size of the openings. The structure has been constructed as a File-to-Factory Zollinger to provide relatively big spans with small timber parts."

The lower part of the egg, which floods a few times a year, is made of accoya. The upper part, which stays dry all year, is made of pine. The upper part is thatched with local reed, harvested from the inside of the sea defences. 

The thatched roof stops just above the highest possible water line. The floor inside the egg is a hybrid wood (Cross-laminated timber) - concrete floor which acts as a structural stabiliser and from where there is a beautiful view of the surrounding islands, the Haringvliet sluices and the water.

Tij was made of thatched with local reed and has a timber structure which has been completely File-to-Factory produced in 402 parts and has been assembled at the site. It can be completely dissembled. 

Through its re-usability, its modularity, its materials and its contribution to the nature environment, it is almost completely circular and sustainable.

"Reflecting the transitory nature of all things, it must also be noted that the Bird-EI is also temporary and will be taken apart at some point in the future," added the team. 

"At that time, it may be reused or recycled without detrimental effects to nature or man. In this way, we have created an (eco)system where man and nature can come closer together and be a part of each other’s world."

Project facts

Architects: RAU Architects, RO&AD Architecten

Location: Scheelhoekweg, 3251 LZ Stellendam, The Netherlands

Design team: Thomas Rau, Ad Kil, Ro Koster, Jochem Alferink, Martin van Overveld, Michel Tombal, Athina Andreadou, Loyse Rebord

Area: 150.0 m2

Year: 2019

All images © Katja Effting unless otherwise stated.

> via RAU Architects / RO&AD Architecten