Bird Numbers 2019 offers a fieldtrip to Tagus Estuary

EVOA – Tagus Estuary Birdwatching and Conservation Area, Portugal – sees everyday guided tours carried out, as well as regular passerine and ducks ringing sessions. Since opening, more than 2500 birds have been ringed here, some with GPS. Every week bird counts are performed at the three lagoons within the area. Physical, chemical, and biological water parameters are also monitored to work towards increasing wetland knowhow.

Located in the heart of the most important wetland of Portugal, the Tagus Estuary Natural Reserve allows visitors to get to know and enjoy the unique heritage that exists between the floodplain and the Tagus Estuary.

Fig. 1 – Credits: Pedro Colaço
EVOA is managed by Companhia das Lezírias (, and opened to the public in 2013, already having received more than 38.000 visitors, including 22.000 students integrated in environmental education activities.

Fig. 2 – Credits: EVOA
Three freshwater wetlands are integrated in EVOA, equalling a total of 70 ha. These lagoons are very important for the birdlife, being used as refuge or nesting areas.

Fig. 3 – Credits: Pedro Colaço
To guarantee tranquillity for the birds, and to maximize the visitor experience and comfort during the visitation, there are six observatories amongst the lagoons, several inconspicuous viewpoints, and a Visitor Centre.

Fig. 4 – Credits: Pedro Colaço
EVOA sees everyday guided tours carried out. Since 2018, some are performed by electric car, which can drive around up to fourteen visitors. We also have workshops and other events every month. You can follow these activities at or on Facebook @EVOAves.

Figs. 5a, 5b – Credits: EVOA
There are regular passerine and ducks ringing sessions, in collaboration with the Coordinator of European duck nasal marking ( and ICNF (The National Institute for Nature Conservation). Since 2017, we have already ringed 664 ducks, including teals, pintails, shovelers, and mallards. The first European shoveler with GPS was ringed at EVOA on October 22nd, 2017.

Fig. 6 – Credits: Jacques van Wijlick
At EVOA, the mixed colony of collared pratincole, little tern, Kentish plover, and black-winged stilt is being monitored, but counting nestlings and flying chicks is a challenging task. There is still a lot to do in this field, and this is one of the projects that has been developed by ICNF with the EVOA team’s support. Research into potential egg or nest predators (mammals) is still needed.

Fig. 7 – Credits: Pedro Colaço
Physical, chemical, and biological water parameters are also monitored to help increase wetland knowhow and to prevent waterfowl diseases, like botulism. Last year, we became part of a Erasmus project, led by The Norwegian Dokka Upper Secondary School, with three other project partners including: WWT Martin Mere and the WLI initiative (UK), the Randsfjordsmuseum (Norway), and the Urdaibai Bird Centre (Basque Country, Spain). The project, named BioWet – Biological Diversity in Wetlands, aims to develop a monitoring tool that allows students visiting wetland centres to collect and upload data, showing the impacts of climate change on local wetlands. The partners will work with their local school students to carry out survey work and develop guidelines for collecting data, as well as feeding into the design of a user-friendly web-based database that will display their information.