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A preliminary overview of 
monitoring for raptors in 
Portugal
Predhodni pregled monitoringa populacij 
ptic roparic na Portugalskem
Luís Palma
CIBIO Research Centre in Biodiversity and Genetic 
Resources, Universidade do Porto, Campus de Vairão, 
PT–4485-661 Vairão, Portugal,  
e–mail: luis.palma@cibio.up.pt
Portugal has a diverse assemblage of diurnal raptor 
and owl species, made up of the majority of species 
that occur in the Iberian Peninsula. 22 diurnal raptors 
and six owl species are accounted for as regular 
breeders, with a few others wintering or occurring as 
migrants or vagrants. Some of the breeding species are 
especially noteworthy, such as the Spanish Imperial 
Eagle Aquila adalberti, which is currently building up 
its numbers as a breeding bird after ca. 30 years of 
extinction as a breeder in Portugal, and the Bonelli’s 
Eagle A. fasciata, whose fast growing tree-nesting 
population already sums about 100 pairs in the south 
of the country. Most of the raptors populations are 
currently recovering after a period of general decline 
during the 20th century. Only one species went extinct 
recently as a breeder, the Osprey Pandion haliaetus, 
but is now being reintroduced.
Main players
There are four main types of actors performing raptor 
and owl monitoring:
(1) people working for environmental agencies and 
Natural Parks (involved in the management of 
protected areas and endangered species);
(2) people working for private companies (carrying 
out EIA – environmental impact assessment 
studies, especially of wind farms, power lines and 
dams); 
(3) members of environmental NGOs (involved in 
EIA and conservation projects);
(4) academic researchers. 
As for the latter, monitoring has been part of 
some long-term scientific projects, namely of the 
Bonelli’s Eagle tree-nesting population in the south 
of the country, and of shorter academic studies (BSc, 
MSc and PhD theses) covering several species such 
as the Eagle Owl Bubo bubo, the Bonelli’s Eagle, the 
Egyptian Vulture Neophron percnopterus or the Lesser 
Kestrel Falco naumanni among others. These studies 
have been carried out within universities and research 
centres, e.g. the Universities of the Algarve, Évora, 
Lisbon, Trás-os-Montes e Alto Douro and Porto, 
and the CIBIO (Research Centre in Biodiversity 
and Genetic Resources). Additionally, tree-nesting 
Bonelli’s Eagles were also widely monitored during 
the 4.5 years of a LIFE Nature project (2008–2011), 
coordinated by NGO “Centro de Estudos da Avifauna 
Ibérica”.
Some collaboration has been established with 
Spain, concerning both state entities and NGOs, 
on the monitoring of cliff-nesting species (vultures, 
large eagles and Eagle Owls) in border areas, and of 
some endangered priority species (Spanish Imperial 
Eagle, Bonelli’s Eagle and Black Vulture Aegypius 
monachus). Bonelli’s Eagle research has been the 
subject of substantial scientific collaboration between 
Portugal, Spain and France, covering ecological, 
demographic and genetic issues. In turn, the Noctua-
Portugal Programme, a monitoring scheme of owls 
and nightjars, coordinated by GTAN-SPEA (working 
group on nocturnal birds of the Portuguese Society for 
the Study of Birds), follows the same methodology of 
Noctua-Spain, allowing data to be analysed altogether 
for the Iberian Peninsula. Out of Europe, collaboration 
existed in the recent past with Cape Verde on the 
monitoring of the country’s Osprey population.
Main users of the data obtained from monitoring 
are officials of the Institute for Nature Conservation 
and Biodiversity (including protected areas) and 
other environmental agencies for e.g. protected areas 
management, emergency conservation measures, 
evaluation of infrastructure projects and issue of 
permits (construction, hunting, recreation). Also 
NGOs (e.g. Quercus, LPN – Liga para a Protecção 
da Natureza, CEAI – Centro de Estudos da Avifauna 
Ibérica, ATN – Associação Transumância e Natureza) 
have used monitoring data for intervention in 
conservation emergencies and for the planning and 
development of conservation projects, as well as 
private environmental companies (e.g. STRIX, Bio3, 
Mãe d’Água, Oriolus, Profico Ambiente) for the EIA 
and monitoring of infrastructure and development 
projects.
Big companies, e.g. of the energy and industrial 
paper pulp sectors, which need up-to-date data 
on the distribution and breeding condition of 
species of higher conservation rank to incorporate 
impact preventive and mitigation measures on their 
production and management schemes are also regular 
users of monitoring data.
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L. Palma: A preliminary overview of monitoring for raptors in Portugal
Research institutes (e.g. CCMAR – Centre of 
Marine Sciences, CIBIO) Universities (e.g. Algarve, 
Évora, Trás-os Montes e Alto Douro) and scientific 
societies (SPEA) also use monitoring in academic, 
research and conservation projects. For example, under 
the scope of long-term multidisciplinary research 
on tree-nesting Bonelli’s Eagles, monitoring of the 
population was comprehensively and continuously 
carried out from 1991 to 2010. Only from 2011 
onwards has it been patchily carried out. Also, 
both within the scope of research and conservation 
initiatives, Lesser Kestrel is another species that has 
been the object of regular monitoring since 1994.
National coverage
Traditionally, monitoring has been mostly restricted to 
areas with the richest cliff-nesting raptor communities 
or with top endangered species (e.g. Black Vulture, 
Egyptian Vulture, Spanish Imperial Eagle, Bonelli’s 
Eagle, Lesser Kestrel). This has occurred mainly in 
areas of the north-east and central east along the 
Spanish border, and in the south-west uplands as well 
as in the open lowlands of the south-east. However, 
there is no formal national coordination or national 
network for raptor monitoring in Portugal.
Common raptor and owl species have been 
monitored in a few academic and research studies, 
and in some EIA studies. In this kind of studies, the 
Eagle Owl has been one of the most often surveyed 
species. Additionally, the Common Bird Census carried 
out by SPEA since 2004, although not specifically 
aimed at raptors and owls despite being a countrywide 
survey, has obtained some information on common 
raptor species like Black-winged Kite Elanus caeruleus, 
Black Kite Milvus migrans, Buzzard Buteo buteo, 
Booted Eagle A. pennata, Kestrel F. tinnunculus and 
Little Owl Athene noctua.
Currently, the only countrywide survey is the 
above mentioned owl monitoring scheme of GTAN-
SPEA, which started in 2010. Another SPEA working 
group (especially dealing with the monitoring and 
conservation of Bonelli’s Eagle in highly urbanised 
habitats) has recently expanded fieldwork to include 
common forest diurnal raptor species counts in 
suburban areas. SPEA has also regularly monitored 
Buzzards in the Azores and Madeira archipelagos, as 
well as Barn Owl Tyto alba in Madeira in partnership 
with Madeira National Park. 
In recent years, monitoring has been carried out 
by some private environmental companies within the 
impact assessment of wind farms, infrastructures and 
development projects throughout mountainous areas 
of the western part of the country. A long-term study 
of autumn raptor migration in Sagres area (south-
western corner of the country) has been undertaken 
almost annually since 1990, at first organized by 
the local Natural Park staff, then by SPEA (1996–
2001) and from 2005 onwards by STRIX, a private 
environmental company, linked with impact 
monitoring of local wind farms. 
In summary, despite diurnal raptor and owl 
monitoring has been often though patchily carried 
out, Portugal lacks a long-term comprehensive and 
countrywide monitoring programme encompassing 
all of the country’s raptor and owl species.
Key species and key issues
The key species addressed by monitoring for raptors 
in Portugal are primarily endangered species (Black 
Vulture, Egyptian Vulture, Spanish Imperial Eagle, 
Bonelli’s Eagle, Lesser Kestrel), and secondly the rarer 
cliff-nesting species (besides Egyptian Vulture and 
Bonelli’s Eagle, these include Griffon Vulture Gyps 
fulvus, Golden Eagle A. chrysaetos, Peregrine Falcon 
Falco peregrinus and Eagle Owl). Additionally, owls in 
general have been the aim of an increasing monitoring 
effort in Portugal during the last five years.
Threats addressed by monitoring are the potential 
impact of man-made structures (wind farms, power 
lines, dams, roads) in mortality, habitat loss and 
breeding impairment. Commonly, this monitoring 
has been carried out by technicians working for 
small private companies dedicated to EIA. In turn, 
the impacts of agriculture, forestry and hunting on 
nesting habitat degradation and breeding disturbance 
have been key issues addressed by monitoring within 
scientific studies or conservation projects (e.g. LIFE 
Nature projects) that target a few species, namely the 
Bonelli’s Eagle.
International networking could be beneficial to the 
countrywide long-term monitoring of priority species, 
especially of those tree-nesting species with wide and 
sparse distributions (e.g. Spanish Imperial Eagle, 
tree-nesting Bonelli’s Eagle), that despite being very 
important for conservation purposes is logistically 
difficult and expensive. Carrying out regular and 
coordinated Iberian censuses of these and other 
endangered species such as Egyptian and Black Vultures 
would also be an important measure. International 
collaboration would be most relevant in exchanging 
information and expertise with Spain, concerning all 
species. Additionally, international networking might 
help raising funds and get manpower support.
Strengths and weaknesses
The main strength of monitoring in Portugal is the 
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young biologists working for private companies or 
NGOs, who are fairly well trained (although in small 
numbers) for raptor monitoring. However, those 
working in private companies are mostly constrained 
to environmental assessment work and have few 
opportunities to participate in research or conser-
vation monitoring. However, the number of available 
skilled observers could rise with some training effort. 
The main weakness is the lack of funding for wide 
range and especially long-term monitoring, and the 
lack of strategic planning and coordination. The 
lack of well-established monitoring methodologies is 
also noteworthy. Strong and coherent coordination 
and leadership could be relevant in establishing a 
comprehensive raptor monitoring scheme in Portugal.
Some major gaps in monitoring can be identified, 
among them the follow-up of the recovery of Spanish 
Imperial Eagle that although carried out since 2003 
still does not cover the whole potential habitat and is 
ill-coordinated despite its conservation relevance and 
urgency. The population monitoring of the common 
raptor and owl species, as well as of less common 
and less known forest species (e.g. Short-toed Eagle 
Circaetus gallicus, Honey Buzzard Pernis apivorus, 
Booted Eagle, Long-eared Owl Asio otus, Scops Owl 
Otus scops) is another major gap throughout the 
country. However, even the better monitored species 
can suffer the consequences of the current economic 
crisis in the country.
Almost the entire western half of northern and 
central Portugal, a highly populated area, is almost 
unknown regarding the raptor community. Yet, some 
on-going regional studies have recently revealed fairly 
high densities of some species, including of previously 
under-detected ones such as Goshawk Accipiter 
gentilis.
The most ill-studied wide range threats are those 
linked with the increasing large scale forest degra-
dation throughout the country; in the north and 
the centre, the extensive tree cover deterioration caused 
by frequent and recurrent wildfires; in the south, 
the high mortality rates observed throughout the 
extensive areas of oak parkland and forest (especially 
of Cork Oak Quercus suber) putatively driven by 
climatic change coupled with unsound understorey 
management, and the increasing mortality caused by 
an introduced Pinewood Nematode Bursaphelenchus 
xylophilus on Maritime Pine Pinus pinaster stands. 
Other threats presumably such as electrocution, 
collision with power lines, loss of habitat by wind 
farms, persecution, and poisoning seem of moderate 
global impact at present but are, nevertheless, worth 
of reference. Furthermore, a general drawback is 
upstream of the threats, the great lack of scientific 
background knowledge of the population dynamics, 
ecological requirements and resource availability for 
most raptors and owls in the country.
Among the weaknesses and challenges for which 
Portugal might benefit from international sharing of 
best practice we can point out raptor conservation 
measures within forestry and game management.
Priorities, capacity-building
Fund raising, uniform methodology, strategic 
planning and national coordination are priority issues 
to strengthen monitoring for raptors in the country. 
Enhanced initiative, expertise and fund-raising ability 
could also help improving monitoring capacity in 
Portugal.
The main capacity building needs identified in 
raptor monitoring in Portugal are the training of 
technicians and nature wardens of environmental 
agencies and protected areas and field assistants on 
monitoring methods and techniques, as well as a well-
established model for coordination of monitoring 
efforts, i.e. governmental vs. academic vs. non-
governmental.
Acknowledgements: I am indebted to Alexandre 
Leitão, Alice Gama, Andreia Dias, Bárbara Fráguas, 
Carlos Pacheco, Jorge Vicente, Nuno Onofre, Pedro 
Rocha, Rita Ferreira and Rui Lourenço for their most 
useful contribution. Acknowledgements are also due 
to Rui Lourenço, Luka Božič (editor) and an 
anonymous referee for their critical revision of the 
manuscript.
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Arrived / Prispelo: 27. 3. 2013
Accepted / Sprejeto: 1. 7. 2013