This July, the release of 21 juvenile Montagu’s harriers took place in Castro Verde (Alentejo, southern Portugal) under the Emergency Plan for the Recovery of the Montagu’s harrier (Circus pygargus). This is a migratory species that nests in Portugal, and the Alentejo region is one of the most important for its reproduction. Here, the Special Protection Area (SPA) for Birds of Castro Verde still shelters a few dozen of pairs of the Montagu’s harrier.

At the beginning of spring, monitoring work began to identify the fields chosen by the nesting pairs of the Montagu’s harrier. Then, in Castro Verde, through the collaboration between LPN – Liga para a Protecção da Natureza (League for the Protection of Nature) and local farmers, a first identification of the areas planned for hay cutting and for seed (mowing) took place. After monitoring to locate the nests, eggs were collected or nests with hatchlings were protected before agricultural work began, to avoid their destruction or predation. In the first collection, the eggs were sent to a breeding centre where they were incubated in specialised facilities for this purpose.

In this phase, the eggs were constantly monitored, so that incubation took place at an adequate temperature and humidity level, and hatching success was maximised. After hatching in the same centre, the chicks were fed in cycles of four to five meals a day, in an acclimatised environment, until they could be transferred to the acclimatisation facilities to the natural habitat. These facilities were specifically built for this purpose in a natural environment, at Herdade do Vale Gonçalinho, an LPN property at the heart of Castro Verde Biosphere Reserve. The first chicks were transferred to this site in June, at approximately 30 days old, so that they could be prepared for their return to the wild.

A young Montagu's Harrier peers out from between some golden dried grasses.

A fluffy Montagu’s harrier chick takes shelter in some golden grasses. Photo courtesy of LPN

In 2011, in the Castro Verde Special Protection Area, the presence of 214 breeding pairs was estimated (MADRAP 2010, Monitoring the Steppe Bird Community in the Castro Verde ITI). In 2021, in the same area, the presence of only 50 pairs was recorded (according to ICNF/CIBIO 2021). These figures indicate a decrease in the number of pairs in Portugal of approximately 75%. In the last 10 years, and of 85% in Alentejo. In this period, we have witnessed a change in crops and agricultural and livestock practices, together with a greater frequency of droughts, which are causing a very sharp decline of the species, leading to its disappearance in Portugal.

Rita Alcazar, coordinator of LPN’s delegation in Castro Verde, says that “the Montagu’s harrier was one of the most common birds in the Alentejo plains. The decrease they are having is so accentuated that it is difficult to observe them these days”. She adds that “these emergency actions [incubation of eggs and ex-situ conservation] are only being carried out because the situation of the species is so dramatic, that only with a rescue and salvage intervention will it be possible to ensure the survival of juveniles and prevent the extinction of the species in Portugal”.

A Montagu's Harrier wearing a green band around one leg looks curiously up at the camera.

A Montagu’s harrier with a banded leg looks curiously up at the camera. Photo courtesy of LPN

The Emergency Plan, coordinated by the Institute for Nature Conservation and Forests (ICNF), began last April and is implemented at national level by 3 environmental NGOs – LPN, Palombar, and the Portuguese Society for the Study of Birds (SPEA) – and the Research Centre on Biodiversity and Genetic Resources (CIBIO).

The actions implemented by LPN for the protection and rescue of the Montagu’s harrier are part of the project to promote the conservation of steppe birds in Castro Verde (Aves das Estepes), funded by the Association VIRIDIA – Conservation in Action and the LIFE Agrosteppes project.

All the work carried out throughout this breeding season would not have been possible without the collaboration and contribution of various entities, companies, farmers and citizens who, in some way, gave essential contributions to achieve this first result of releasing 21 juveniles, which will have to be repeated in the coming years to save this species from extinction in Portugal.

A Montagu's Harrier flies over a golden field of grasses

A Montagu’s harrier flying through a field. Photo by Rui Cunha.

Liga para a Protecção da Natureza (LPN) was founded in 1948, thus being the oldest environmental NGO of the Iberian Peninsula. LPN aims to contribute to Nature’s conservation and environmental protection by having the sustainable development definition as a guideline and the desire to assure a quality of life to the present and future human generations.