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Acrocephalus 33 (154/155): 283−284, 2012
A preliminary overview of 
monitoring for raptors in 
Belgium
Predhodni pregled monitoringa populacij 
ptic roparic v Belgiji
Glenn Vermeersch1 & Jean-Yves Paquet2
1 Research Institute for Nature and Forest (INBO), 
Kliniekstraat 25, BE–1070 Brussels, Belgium,  
e–mail: Glenn.vermeersch@inbo.be
2 Aves-Natagora Ornithological Society, Study 
Department; Rue Nanon 98, BE–5000 Namur, 
Belgium, e–mail: jean-yves.paquet@aves.be
Belgium is divided in three highly autonomous 
regions: Flanders in the north, Wallonia in the south 
and Brussels in the centre. Each region has its own 
regional government and, therefore, its own nature 
administration. Because of this situation, large-
scale bird monitoring projects and atlas work have 
been implemented at the regional level resulting in 
different methodology, scale and timing. However, 
scientists responsible for the coordination of these 
projects meet on a regular basis and it is statistically 
possible to merge the data and produce national status 
assessments, trends and indices.
Although small, Belgium hosts 20 breeding raptor 
species, many of which, however, in small numbers 
(Vermeersch et al. 2004 & 2007, Weiserbs & Jacob 
2007, Jacob et al. 2010).
Main players
Large scale bird monitoring projects and atlas work in 
Wallonia and Brussels are coordinated by Aves-Natagora 
(BirdLife partner in Wallonia) in collaboration with 
the regional nature administration “Département 
d’Étude des Milieux Naturels et Agricoles” (DEMNA) 
in Wallonia and Brussels Institute for the Environment 
(BIM) in Brussels. Similar work is conducted in 
Flanders where Research Institute for Nature and 
Forest (INBO), a scientific institute of the Flemish 
government coordinates the projects in collaboration 
with Natuurpunt, a non-governmental organisation, 
and Flemish BirdLife partner that provides the 
essential volunteer-network. Data on these large-scale 
projects are easily accessible and are merged to produce 
national reports (e.g. for cyclic reports under the Birds 
Directive 2009/147/EC).
Apart from these organisations, independent 
working groups are active in all three regions, 
focusing mainly on one or two species per group. 
Harriers, kites, owls and Peregrine Falcons Falco 
peregrinus are monitored on a voluntary basis within 
the framework of these groups. The resulting data are 
less accessible and more patchily distributed. Many of 
the independent working groups monitor breeding 
success of the study species and many young birds are 
ringed at the nest. These ringing data are collected at 
the national level by the Royal Belgian Institute for 
Natural Sciences (KBIN).
Main data users
The three regional nature administrations are the 
main users of the collected ornithological data. 
They are mainly used for the development of several 
indicators and for nature directives reports. Nature 
associations form another group of data users. They 
are able to quickly inform a large number of people 
since they coordinate the volunteers and thanks to 
the rapidly growing number of their members. Data 
can sometimes be used for risk-assessment: impact 
of planned windmills, large infrastructure building 
plans and other potential problems.
Coordination
Although we have no national coordinating scientific 
institute, Aves, INBO and BIM work closely together 
to compile the cyclic Birds Directive reports as well 
as trends and indices for the European Bird Census 
Council (EBCC) and BirdLife International.
Key species and issues
Apart from the large scale monitoring and atlas 
projects, which cover a wide array of species, most 
independent working groups focus on owls, harriers, 
kites and Peregrine Falcons. In Wallonia, Eagle Owl 
Bubo Bubo and Tengmalm’s Owl Aegolius funereus 
breeding numbers are closely monitored. In both 
Wallonia and Flanders, Barn Owl Tyto alba and Little 
Owl Athene noctua receive much attention. Barn Owl 
is probably the best studied bird species in Flanders 
with long-term data on its breeding success and 
survival. Wallonia has a separate programme for Red 
Kites Milvus milvus, but coverage is restricted to the 
core area of its breeding range. Breeding numbers of 
Marsh Circus aeruginosus, Montagu’s C. pygargus and 
Hen Harriers C. cyaneus are monitored on a yearly 
basis in Wallonia.
The relationship between the presence of these 
species and the implementation of agri-environmental 
schemes has received growing attention in both 
Flanders and Wallonia. In Flanders, the nature 
conservancy is interested in presence/absence data of 
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G. Vermeersch & J.-Y. Paquet: A preliminary overview of monitoring for raptors in Belgium
Marsh Harriers in relation to ground water levels in 
reedbeds. INBO has recently started a new research 
project focusing on movements, habitat choice and 
breeding success of Marsh Harriers in fragmented 
landscapes (Anselin et al. 2011). An important 
issue is the illegal trade of Eagle Owl and Peregrine 
Falcon resulting in increasing time investment in site 
protection. Finally, the location of new wind farms has 
received considerable attention recently (Everaert 
2011), especially in relation to the breeding grounds 
of the endangered Red Kite.
Strengths and weaknesses
Being one of the most densely populated and 
highly accessible countries in Europe, the large scale 
monitoring schemes in Belgium are characterised by a 
very good coverage (sample size) and a high number of 
skilled volunteers. The development of databases and 
online data-collection has received a lot of attention 
so that data can rapidly be used in various reports and 
risk-assessments.
Obvious weaknesses are the non-existing inte-
gration of independent working groups at a national 
or even a regional level and the integration of the 
ringing data in the monitoring schemes. A growing 
problem is the fact that our young highly skilled and 
most active birdwatchers hardly show any interest 
in actively contributing to the monitoring schemes, 
resulting in an ageing pool of volunteers.
Despite of the different monitoring schemes, we 
have no good data for a few diurnal or nocturnal raptor 
species like Long-eared Owl Asio otus, Honey Buzzard 
Pernis apivorus, Goshawk Accipiter nisus and Hobby 
F. subbuteo. We would highly welcome input from 
workshop-participants to provide a useful standard 
protocol for monitoring raptors at a regional scale.
Belgian priorities
To summarize, Belgium should coordinate the 
different independent working groups at a regional and 
national levels and invest in monitoring of “difficult” 
species based on standard protocols. Moreover, we 
should integrate national ringing data in large-scale 
monitoring schemes and provide standard protocols 
for ringers. Last but not least, appointing a national 
coordinator is of vital importance to achieve these 
priorities.
References & supporting bibliography
Anselin, A., Castelijns, H. & De Bruyn, L. (2011): 
Movements, Habitat Choice And Breeding Success Of 
The Marsh Harrier (Circus aeruginosus) In Fragmented 
Landscapes. Poster presentation. 8th Conference of the 
European Ornithologists’ Union, 27–30 August 2011, 
Riga, Latvia.
De Bruyn, L., Anselin, A., Bauwens, D., Colazzo, S., 
Devos, K., Maes, D., Vermeersch, G. & Kuijken, 
E. (2003): Red lists in Flanders: scale effects and trend 
estimation pp. 111–120 In: Longh, de H.H. (ed.): 
The harmonisation of red lists for threatened species in 
Europe – The Netherlands Commission for International 
Nature Protection, Leiden.
Everaert, J. (2011): Site selection for new wind farms in 
Flanders (Belgium): new dynamic decision-instrument 
for birds and bats. pp. 86 In: May, R. & Bevanger, K. 
(eds.): Proceedings of the Conference on Wind energy 
and Wildlife impacts, 2–6 May 2011, Trondheim, 
Norway. – NINA Report 693. – [http://www.nina.no/
archive/nina/PppBasePdf/rapport/2011/693.pdf ]
Jacob, J.-P., Dehem, C., Burnel, A., Dambiermont, J.L., 
Fasol, M., Kinet, T., Van Der Elst, D. & Paquet, 
J.Y. (eds.) (2010): [Breeding Bird Atlas of Wallonia 
2001–2007.] Série Faune Flore Habitats no. 5. – Aves 
et la Région Wallonne, Gembloux. (In French, English 
summary)
Paquet, J.-Y., Jacob, J.-P., Kinet, T. & Vansteenwegen, C. 
(2010): [Common bird population trends in Wallonia, 
1990–2009.] – Aves 47: 1–19. (In French, English 
summary)
Vermeersch, G. & Anselin, A. (2009): [Breeding bird 
in Flanders in 2006–2007: recent status and trends of 
rare, colonial and exotic bird species and species of the 
Flemish Red List and/or European Birds Directive.] 
– Mededelingen van het Instituut voor Natuur- en 
Bosonderzoek, 2009 (3). Instituut voor Natuur- en 
Bosonderzoek, Brussels. (In Dutch, English summary)
Vermeersch, G., Anselin, A., Devos, K., Herremans, 
M., Stevens, J., Gabriëls, J. & Van Der Krieken, B. 
(2004): [Atlas of Flemish Breeding Birds 2000–2002.] 
Mededelingen van het Instituut voor Natuurbehoud 23. 
– Brussels. (In Dutch, English summary)
Vermeersch, G., Anselin, A., Onkelinx, T. & Bauwens, 
D. (2007): Monitoring common breeding birds in 
Flanders: a new step towards an integrated system. – Bird 
Census News: 20 (1): 30–35.
Vermeersch, G., Anselin, A. & Devos, K. (2007): [Status 
and trends of diurnal raptor species in Flanders.] – 
Natuur.oriolus: 73: 41–44. (In Dutch, English summary)
Weiserbs, A. & Jacob, J.-P. (2007): [Breeding birds 
of Brussels 2000–2004: distribution, numbers, 
development.] – Aves, Liège. (In French)
Arrived / Prispelo: 27. 3. 2013
Accepted / Sprejeto: 1. 7. 2013