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Acrocephalus 33 (154/155): 247−254, 2012
Monitoring of raptors in Norway
Monitoring ptic roparic na Norveškem 
Torgeir Nygård
Norwegian Institute for Nature Research, P.O. Box 5685 Sluppen, NO–7485 Trondheim, Norway, 
e–mail: torgeir.nygard@nina.no
All diurnal raptors and owls have been protected by law in Norway since 
1968–1972. Since then, most species that had been heavily persecuted earlier 
(eagles and hawks), and those especially susceptible to environmental pollution 
(Peregrine Falcon Falco peregrinus and Osprey Pandion haliaetus) have 
increased in numbers. A national monitoring programme for the terrestrial 
environment in Norway, which also includes population monitoring of the 
Golden Eagle Aquila chrysaetos and Gyrfalcon F. rusticolus, was established 
in 1990. Monitoring of environmental pollutants in eggs of diurnal raptors 
and owls on a country-wide basis was started at the same time. A data series 
on pollutant levels in eggs of several species covers a time-span of up to 40 
years for DDE and PCB, including shell thickness measurements. Only the 
Golden Eagle and Gyrfalcon are included in a comprehensive state-financed 
monitoring programme, while other species are locally financed and run by 
special interest groups and NGOs. The Golden Eagle is under pressure from 
farmers’ and reindeer husbandry organizations, while the Goshawk Accipiter 
gentilis suffers from clear-cutting of old forests. High mortality of White-tailed 
Eagles Haliaeetus albicilla due to collisions with wind-turbines is a serious 
problem locally. The Osprey is on its way back to pre-DDT levels. In general, 
pesticide levels have dropped significantly during the last couple of decades, 
resulting in improved shell quality. The major constraints to comprehensive 
monitoring of diurnal raptors and owls in Norway are lack of funding and 
qualified personnel.
Key words: diurnal raptors, owls, monitoring, Norway
Ključne besede: ujede, sove, monitoring, Norveška
1. Introduction
In pre-World War II times, the classical attitude towards 
raptors in Norway was persecution by shooting, nest 
destructions and poisoning, encouraged by bounties. 
During the 1940s and 1950s, some pioneering work 
on raptor breeding numbers and reproductive rates 
in relation to fluctuations in their prey basis was 
performed, and a more realistic picture of their place in 
nature slowly gained foothold (Hagen 1952 & 1969). 
Still, no permanent monitoring schemes existed, while 
pesticides and persecution drove many species to the 
brink of extinction. Turning points came when all 
Norwegian diurnal raptors and owls were protected 
by law in 1968 (eagles) and 1972 (Barth 1971). 
Nevertheless, in 1975, when monitoring of Peregrine 
Falcon Falco peregrinus was initiated, only about eight 
pairs were known to breed in the whole country 
(Lindberg et al. 1988). At the same time, monitoring 
of Golden Eagle Aquila chrysaetos and White-tailed 
Eagle Haliaeetus albicilla was started by NGOs.
Initially, during the early 1990s, monitoring of 
flora and fauna in Norway focused on subalpine and 
alpine ecosystems to investigate impacts of long-range 
air pollution. Later, the objective was broadened 
to include effects of climate change and response 
to anthropogenic changes. Raptors positioned at 
the top of food-chains were included as sentinels of 
environmental pollution.
In recent years, predation on livestock by large 
carnivores and eagles has become a major issue. 
Therefore, there is an increasing pressure from the 
248
T. Nygård: Monitoring of raptors in Norway
farming and reindeer husbandry organizations, 
advocating culling and limiting of predators, 
including eagles. Also, there is an increasing conflict 
between forestry organizations and the conservation 
of forest-dwelling diurnal raptors and owls, especially 
those species depending on mature forest, such 
as the Goshawk Accipiter gentilis. At present, the 
development of wind farms along the coast poses a 
new threat, especially for the White-tailed Eagle, and 
electrocution by power lines has gained new attention 
owing to large declines of the Eagle Owl Bubo bubo.
2. National programmes
The Monitoring Programme for Terrestrial Ecosystems 
(TOV) is a national monitoring programme 
initiated and financed by the Directorate for 
Nature Management in 1990 (Løbersli 1989). The 
Norwegian Institute for Nature Research (NINA) 
coordinates a large part of the scientific investigations 
in the programme, including raptors. TOV generates 
knowledge of long-term changes in biota, and when 
possible relates this to the influence of: (1) acid rain 
(both sulphur and nitrogen), (2) long-range pollutants 
(metals and organic pollutants), (3) climate change, (4) 
land use, and (5) the interaction between several factors 
of influence. The programme focuses on commonly 
occurring habitats and species, mainly in forests and 
mountains, and is based on integrated monitoring of 
different species and other elements of the ecosystem 
in seven selected mountains and birch forest areas, 
plus a nationwide survey of selected parameters and 
vegetation monitoring in eleven spruce forest areas. 
Monitoring areas are distributed throughout the 
country from south to north in a way that reflects 
both climate variations and differences in the burden 
of long-range pollutants. All areas are located in places 
where they are not subjected to rapid changes in land 
use, mainly in protected areas. Raptor monitoring 
has only been performed in the southern part of the 
country up to present, but is currently being expanded 
(Figure 1). Only the Golden Eagle and Gyrfalcon F. 
rusticolus are encompassed within this programme.
The national monitoring programme Rovdata was 
established by the Directorate for Nature Management 
in 2000 to ensure that monitoring and surveillance 
of large predators was performed in the best possible 
way throughout the country, using the standardized 
methods. Data on breeding, predators’ tracks and kills 
are processed, compiled and reported at the national 
level by an independent research body (NINA). 
During the first years, only the four large carnivores, 
the Lynx Lynx l. lynx, Wolverine Gulo gulo, Brown 
Bear Ursus arctos and Wolf Canis lupus, were part of 
the scheme. From 2006 on, the Golden Eagle has 
been included. New modules for other large diurnal 
raptors and owls are presently being added.
The Species Databank (Artsdatabanken) of Norway, 
managed by the Norwegian Biodiversity Information 
Centre (NBIC), has a web-site open for on-line 
registration of bird observations, including diurnal 
raptors and owls, which over the years has accumulated 
a substantial amount of data regarding their occurrence 
and distribution. Some local interest groups (NGOs) 
also run their local monitoring projects.
3. National coverage
Today, only two raptor species are subjected to 
comprehensive, state financed population monitoring 
Figure 1: Existing (horizontal and vertical shading) and 
planned (slanted shading) areas for monitoring of Golden 
Eagle Aquila chrysaetos in Norway. In addition, Gyrfalcon 
Falco rusticolus is monitored in the vertically shaded areas. 
The areas have an approximate diameter of 100 km.
Slika 1: Obstoje~a (horizontalno in vertikalno sen~ena) 
in na~rtovana (po{evno sen~ena) obmo~ja za monitoring 
planinskega orla Aquila chrysaetos na Norve{kem. 
Poleg tega poteka v horizontalno sen~enih obmo~jih tudi 
monitoring arkti~nega sokola Falco rusticolus. Premer vseh 
obmo~ij je približno 100 km.
Ringvassøya
Finnmarksvidda
Dividalen
Fauske
Børgefjell
Aure
Åmotsdalen
Gutulia
 Voss
Møsvatn
Lund
km
km
Solhomfjell
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Acrocephalus 33 (154/155): 247−254, 2012
on a national basis in Norway; the Golden Eagle and 
Gyrfalcon (from 1990, ongoing, in selected areas 
under the TOV umbrella). For other species, such as 
the White-tailed Eagle, Peregrine Falcon, Goshawk 
and Osprey Pandion haliaetus, monitoring has been 
less systematic in time and space, but NGOs such 
as the Norwegian Ornithological Society (NOF) 
and other regional groups are active. The County 
Governors’ offices in various counties finance regional 
monitoring projects for a range of species of diurnal 
raptors and owls, with NOF and local interest groups. 
The known monitoring activities of diurnal raptors 
and owls are listed in Table 1. 
The Merlin F. columbarius has been monitored 
only for pesticides. A long data series is available in 
Norway for DDE, PCBs, HCB and HCH in eggs of 
bird of some prey (up to 40 years of monitoring), and 
from 1991 eggs have been analyzed for a wider range 
of pollutants, including brominated and fluorinated 
organic compounds (Herzke 2002 & 2005, Nygård 
& Polder 2012).
4. Key species and issues with overview of results
4.1. Key species
Golden Eagle
No long-term trend in the production of chicks 
has been shown in any of the six TOV areas. 10–15 
territories are monitored in each area. The territory 
system of Golden Eagle is sufficiently stable from 
year to year to make the productivity monitoring 
Table 1: Known ongoing monitoring projects of diurnal raptors and owls in Norway
Tabela 1: Znani potekajo~i projekti monitoringa ujed in sov na Norve{kem
Species / Vrsta Geographical area/ Geografsko območje
Responsible/
Odgovorna inštitucija
Red-list status 
in Norway/ 
Norveški Rdeči 
seznam
Honey Buzzard Pernis apivorus locally in the south Local interest groups VU
White-tailed Eagle  
Haliaeetus albicilla
nationwide NOF LC
Smøla Wind Farm area NINA LC
Goshawk Accipiter gentilis some counties Local governments and NGOs NT
Golden Eagle Aquila chrysaetos TOV areas NINA LC
some counties Local governments and NGOs LC
Osprey Pandion haliaetus some counties Local governments and NGOs NT
Kestrel Falco tinnunculus Hedmark County Agder Nature Museum and  
local enthusiasts (nest boxes)
LC
Merlin Falco columbarius nationwide TOV, for pollutants only,  
5-year intervals 
LC
Hobby Falco subbuteo locally in the south Local interest groups VU
Gyrfalcon Falco rusticolus TOV areas NINA NT
Finnmark Local interest groups NT
Peregrine Falcon Falco peregrinus some counties Local governments and NGOs LC
Eagle Owl Bubo bubo nationwide, species  
of special concern
NOF, NGOs and district colleges EN
Snowy Owl Bubo scandiaca Finnmark County NINA, Agder Nature Museum  
and NOF, research and monitoring
EN
Pygmy Owl Glaucidium passerinum Troms County NOF (nest boxes) LC
Tawny Owl Strix aluco Sør-Trøndelag County Local interest groups (nest boxes) LC
Ural Owl Strix uralensis Hedmark County Local interest groups (nest boxes) VU
Tengmalm’s Owl Aegolius funereus Troms County NOF (nest boxes) LC
250
T. Nygård: Monitoring of raptors in Norway
scheme suitable. Territory occupancy and chick 
production per territory in each area are recorded. It 
has been shown that the productivity of Golden Eagle 
is higher a year after the peak year of small rodents, 
when numbers of ptarmigans and other small game 
are high (Gjershaug 1996). Moulted feathers and 
addled eggs are collected for analysis of metals and 
organochlorine contaminants. In the future, feather 
DNA will be used to monitor adult turnover. There 
has probably been a population increase since the 
species was fully protected in 1968, but there are not 
enough historical data available to substantiate this 
assumption. The current population estimate is at 
1,200–1,400 pairs. See Gjershaug et al. (2008) for 
details. Three monitoring areas in the north are to 
be added in the near future, two of them new, while 
the third (Finnmarksvidda) has been used since 2002 
during a special research project (see Figure 1).
Gyrfalcon
Gyrfalcon populations are being monitored in three 
TOV areas in the southern half of Norway. One 
new monitoring area in Finnmark will probably be 
added in the near future (Figure 1). Breeding success 
and the number of large chicks are recorded. Line 
transects of Willow Ptarmigan Lagopus lagopus (the 
main prey of Gyrfalcon) provide data from same 
areas as explanatory variables for Gyrfalcon breeding 
performance. The annual proportion of territories with 
confirmed nesting attempts is related to population 
variation of its main prey species, the Rock Ptarmigan 
L. muta and the Willow Ptarmigan. The best predictor 
of Gyrfalcon reproductive success has been shown to 
be the production of Willow Ptarmigan chicks in year 
t–1 (Falkdalen et al. 2012). An estimate of 200–
500 territorial pairs in Norway has been suggested 
(Myklebust 1996), but no comprehensive national 
census has been performed.
Peregrine Falcon
The species was on the brink of extinction in 
Fennoscandia in the mid-1970s (Lindberg et al. 
1988), due to DDE effects on shell thinning (Nygård 
1983). Local NGOs in the south and central parts 
of Norway have been monitoring its recovery and 
pollutant levels since that time.
White-tailed Eagle
Its population has been monitored in Norway 
since 1974 by the NOF as part of an international 
monitoring programme initiated by the WWF. 
Nesting success and production of chicks has been 
monitored nationwide since 1974 and is ongoing, 
and an extensive ringing scheme has been in place 
(Folkestad 2003). Since the White-tailed Eagle was 
fully protected in 1968, its population has increased 
from about 700–800 territorial pairs to a minimum 
of about 1,900–2,200 territorial pairs in population 
(Folkestad 2003), which probably amounted to 
about one third of the European population, and 
numbers have probably increased since. The increasing 
populations of Golden Eagle and White-tailed Eagle 
in Norway are most probably a result of protection, 
but lowered pollutant loads have also probably played 
a role. However, the quest for “green” energy has led 
to the allocation of large amounts of public subsidies 
into the development of wind-power in Norway, which 
may pose a long-term threat to White-tailed Eagle 
populations. At the 68-turbine wind-power plant at 
Smøla alone, 53 White-tailed Eagles have been found 
killed since 2005 (Bevanger et al. 2011 & unpubl.).
Eagle Owl
The Eagle Owl has decreased dramatically in 
Norway during the last few decades, mainly because 
of electrocution (Bevanger & Overskaug 1998). 
Therefore, it was red-listed as a species of special 
concern, and is presently subjected to nation-wide 
surveys, monitoring and research. A national census 
in 2008 revealed that less than 300 sites still had 
territory-holding Eagle Owls (Øien et al. 2009), 
and it has almost disappeared from large tracts of its 
former range, especially in the interior of the country. 
The national government is now financing mitigation 
measures to remedy the situation through a national 
action plan (Direktoratet for naturforvaltning 
2009). A research and monitoring project, focusing 
on electrocution and mitigation measures, is ongoing. 
Mitigation by mounting perching devices on power-
poles to prevent electrocution seems to be effective 
(Bevanger et al. 2013).
Other species
The Goshawk, once very numerous in the forested 
areas in Norway, has been severely reduced in 
numbers since the advent of large-scale forestry in 
Norway. From an estimated number of 10,000 pairs, 
its present population level is now probably less than 
2,000 pairs (Grønlien 2004). Regarding Merlin and 
Osprey, banning and restrictions in use of poisonous 
organochlorines and mercury have been of vital 
significance to the recovery of their populations. The 
Merlin was heavily burdened by pollutants, but no 
good historic population data are available. However, 
the migration counts at the bird station Falsterbo on 
the southern tip of Sweden indicate a historic trend 
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Acrocephalus 33 (154/155): 247−254, 2012
similar to that of the Peregrine Falcon (Nygård 
1999). The Osprey was long absent from large areas 
of its former range, but has now recovered greatly, 
and the present estimate is now ca. 500 pairs (own 
estimate based on enquiries).
4.2. Monitoring of persistent pollutants
The monitoring of pollutants in eggs of raptors is part 
of TOV, and samples of addled eggs and moulted 
feathers are collected for analysis when possible. 
For Merlin, we have been able to collect fresh eggs 
under special permission during sampling campaign 
every fifth year. Addled eggs and moulted feathers 
from other raptor species are collected ad hoc during 
ringing efforts and local monitoring activities. By 
incorporating available published and unpublished 
data, we are able to produce time trends for pollutants 
and shell thickness over 4–5 decades. Recently, data 
on organobromines and fluorocarbons have also 
become available (Herzke et al. 2005, Nygård & 
Polder 2012).
Eggshell thinning
Eggshells in most species have gradually increased in 
thickness since the ban on DDT became effective in 
1972, but have in most species still not obtained values 
comparable with the pre-DDT era (before 1947) 
(Figure 2). Severe shell thinning has been observed 
in the Peregrine Falcon, Merlin, and Osprey, which 
coincides in time with very depressed populations of 
these species.
Contaminant levels
The results show in general that the levels of the 
“classic” pollutants such as DDTs and PCBs are 
decreasing in Norwegian diurnal raptors such as the 
White-tailed Eagle (Figure 3). Similar trends are 
documented for other species, as well as for pesticides 
such as dieldrin, HCH, and HCB. The trends of the 
“new pollutants” such as brominated flame retardants, 
i.e. polybrominated diphenyl ethers (PBDE), 
polybrominated biphenyls (PBB), and hexabromo-
cyclo-dodecane (HCB) and perfluorinated 
compounds (PFCs) are still somewhat uncertain, 
because of the limited number of analyses, and the 
time series is short. We still know very little about the 
possible biological effects of these compounds, which 
are extensively used in fire-fighting foams, surface 
treatment of textiles, etc.
In general, the Golden Eagle is exposed to low levels 
of pollutants, due to its position at the apex of a short 
terrestrial food-chain. However, in a study of long-
term reproductive performance in a coastal population, 
there was evidence of reduced productivity, which 
correlated with elevated pollutant levels in eggs. This 
was attributed to an influx of pollutants from coastal 
birds as prey, representing the longer marine food-
chains with much higher pollutant levels than the 
terrestrial ones (Nygård & Gjershaug 2001). As for 
the Golden Eagle, the contaminant levels in Gyrfalcon 
eggs were in general low. The levels of pollutants in 
White-tailed Eagle eggs are now below the levels 
known to be detrimental to the species (Helander 
et al. 2002). The DDT-transformation product p,p’-
DDE is still a prevalent pesticide in all predatory bird 
eggs, 40 years after the ban in western countries, and 
is the dominating pollutant in the migratory and bird-
eating species such as Merlin and Sparrowhawk A. 
nisus. In other species, such as the White-tailed Eagle, 
PCBs today accounts for the major organochlorine 
burden, which is typical of marine environments.
5. Strengths and weaknesses
The strength of a monitoring programme is connected 
with the predictability and level of financing, and 
Figure 2: The change in eggshell thickness (white dots) 
and shell indices (black dots)  in four raptor species (A – 
White-tailed Eagle Haliaeetus albicilla, B – Golden Eagle 
Aquila chrysaetos, C – Peregrine Falcon Falco peregrinus, 
D – Merlin F. columbarius) in Norway; average values per 
decade. Values before 1947 are considered base levels.
Slika 2: Sprememba v debelini jaj~ne lupine (bele pike) in 
indeksih lupin (~rne pike)  {tirih ptic roparic (A – belorepec 
Haliaeetus albicilla, B – planinski orel Aquila chrysaetos, C – 
sokol selec Falco peregrinus, D – mali sokol F. columbarius) 
na Norve{kem; povpre~ne vrednosti na desetletje. Vrednosti 
pred letom 1947 so obravnavane kot izhodi{~ne.
95
%
 C
l
Decade / Desetletje
20
10
0
–10
–20
–30
p
-re 1
947
194
7–1
959
196
0–1
969
197
0–1
979
198
0–1
989
199
0–1
999
200
0–2
010
20
10
0
–10
–20
–30
20
10
0
–10
–20
–30
20
10
0
–10
–20
–30
A
B
C
D
252
T. Nygård: Monitoring of raptors in Norway
also with the quality and strength of the responsible 
institution. Only the national projects financed by 
the Directorate for Nature Management are of such 
a type (TOV-projects, Golden Eagle, Gyrfalcon, 
pollutant monitoring and the Rovdata system). Some 
monitoring projects financed by the regional County 
governors have also been long-lasting and suitably 
financed. Weaknesses are often seen connected with 
projects run by NGOs and other interest groups, 
often being poorly financed over time and based on 
idealism. Such time-series can suffer greatly from poor 
descriptions and consistency of methods, poor and 
inconsistent data-storage, and change of personnel. 
Lack of harmonization of methods and cooperation 
between local groups may be a problem when trying 
to compile data over a larger geographical scale.
Norway is a large and thinly populated country, and 
there is a lack of competent personnel to carry out the 
necessary monitoring. Volunteers can be hard to find, 
so proper financing is needed. The Government only 
finances monitoring of species that have political and 
economic issues. More comprehensive monitoring of 
the Golden Eagle is required due to problems with 
illegal persecution and compensation issues. Better 
monitoring of the Goshawk is needed due to the threats 
posed by large-scale forestry, especially connected to 
the mature spruce forests of the lowlands. A sufficient 
overview of the status of the Eagle Owl is still needed, 
and so is proper implementation of mitigation 
measures. An assessment of cumulative future effects 
of wind farm developments on raptors is also lacking.
We have much to learn from our neighbouring 
countries, Sweden and Finland, regarding monitoring 
and management of Golden Eagle. They have a system 
of monetary compensation to the communities and 
reindeer husbandry units, which hold breeding 
Golden Eagles on their land. Compensation is given 
per occupied or breeding eagle territory. This requires 
comprehensive monitoring. In Norway, however, 
compensation is given per killed animal, mostly 
reindeer and sheep. The documentation process is 
problematic, and in practice the owners are given 
compensation as a certain percentage of their losses. 
The claims are therefore often grossly exaggerated 
(Gjershaug & Nygård 2003), thus giving the Golden 
Eagle a bad reputation.
6. Priorities, capacity-building
Other future threats come from habitat and climate 
change, urban spread, developments on the coast 
(wind-power developments, industry, tourism), in 
the mountains (tourism, roads, power lines, wind-
power developments). The main goal must be to 
secure funding through long-lasting monitoring state-
run projects, preferably with a research platform. 
Furthermore, one needs to educate state wildlife 
officers of proper species recognition and ecology. 
Also, there is a need to develop and strengthen 
co-operation between NGOs and state agencies. 
Education and information to the public and 
management authorities about the value of raptors 
as environmental sentinels is important, and so is the 
dissemination of results by publishing and making 
them available on the web.
The use of addled raptor eggs has proven a 
nondestructive and efficient way to perform 
environmental monitoring on a broad scale. It is 
important that the national monitoring scheme for 
pollutants in raptors is continued, especially in light of 
the high levels of new contaminants, where the trends, 
sources and pathways are not yet well understood. A 
national repository for biological samples, aimed at 
long-term monitoring of pollutants in the Norwegian 
environment, is under implementation under The 
Environmental Specimen Bank (ESB Norway), and 
will archive eggs and tissue samples for future analyses 
(http://www.miljoprovebanken.no).
Figure 3: Box-and-whiskers chart (medians and quartiles) 
showing time trends of DDE (grey columns) and PCBs 
(fresh weight, white columns) in eggs of White-tailed Eagle 
Haliaeetus albicilla in Norway during 1970–2010
Figure 3: Grafikon z medianami in kvartili, ki prikazujejo 
~asovne trende DDE (sivi stolpci) in PCB-jev (sveža teža, beli 
stolpci) v jajcih belorepca Haliaeetus albicilla na Norve{kem v 
obdobju 1970–2010
100,000
10,000
1,000
100
197
0–
7419
197
5–
7919
198
0–
0420
198
5–
0920
199
0–
9419
199
5–
9919
200
0–
0420
200
5–
1020
Pentade / Petletje
pp
b
253
Acrocephalus 33 (154/155): 247−254, 2012
7. Povzetek
Na Norveškem so vse ujede in sove zavarovane z 
zakonom, sprejetim v letih 1968 in 1972. Od takrat 
se je število večine vrst, ki so bile predtem neusmiljeno 
preganjane (ujede), in vrst, ki so bile še posebno 
občutljive za okoljsko onesnaževanje (sokol selec Falco 
peregrinus in ribji orel Pandion haliaetus), povečalo. 
Leta 1990 je bil na Norveškem osnovan nacionalni 
program monitoringa kopenskega okolja, v katerega 
je vključen tudi monitoring populacij planinskega 
orla Aquila chrysaetos in arktičnega sokola F. rusticolus. 
Hkrati pa je po vsej državi začel potekati tudi 
monitoring onesnažil v jajcih ujed in sov. Niz podatkov 
o ravni onesnažil v jajcih več vrst ptic roparic zadeva 
obdobje 40 let za DDE (dikloro-difenil-dikloroetilen) 
in PCB-je (poliklorirani bifenili) kot tudi meritve 
debeline jajčnih lupin. Sicer pa sta v celostni program 
monitoringa, ki ga financira država, vključena samo 
planinski orel in arktični sokol, medtem ko druge 
vrste lokalno financirajo in preučujejo posebne 
zainteresirane skupine in nevladne organizacije. 
Planinski orel je pod močnim pritiskom kmetov in 
organizacij, ki se ukvarjajo z rejo severnih jelenov, 
medtem ko na kragulja Accipiter gentilis negativno 
vpliva golosečnja starih gozdov. Velik lokalni problem 
je visoka smrtnost belorepca Haliaeetus albicilla zaradi 
trkov z vetrnimi turbinami. Populacija ribjega orla 
se vrača na raven iz obdobja pred uporabo DDT-ja 
(dikloro-difenil-trikloretan). V zadnjih dveh ali treh 
letih se je raven pesticidov na splošno močno znižala, 
kar se navsezadnje kaže v boljši kakovosti jajčnih 
lupin. Največja ovira za celosten monitoring ujed in 
sov na Norveškem je pomanjkanje finančnih sredstev 
in ustreznega osebja.
8. References
Barth, E.K. (1971): [Birds of prey and Eagle Owl finally 
protected.] – Sterna 10: 153–158. (in Norwegian)
Bevanger, K. & Overskaug, K. (1998): Utility structures 
as a mortality factor for raptors and owls in Norway. pp. 
381–392 In: Chancellor, R.D., Meyburg, B.-U. & 
Ferrero, J.J. (eds.): Holarctic birds of prey. – ADENEX, 
Merida & World Working Group on Birds of Prey, 
Berlin.
Bevanger, K., Berntsen, F., Clausen, S., Dahl, E.L., 
Flagstad, Ø., Follestad, A., Halley, D., Hanssen, 
F., Johnsen, L., Kvaløy, P., Hoel, P.L., May, R., 
Nygård, T., Pedersen, H.C., Reitan, O., Røskaft, E., 
Steinheim, Y., Stokke, B. & Vang, R. (2011): Pre- and 
post-construction studies of conflicts between birds and 
wind turbines in coastal Norway (BirdWind). Report on 
findings 2007–2010. NINA Report 620. – Norwegian 
Institute for Nature Research, Trondheim.
Bevanger, K., Bartzke, G., Brøseth, H., Dahl, E.L., 
Gjershaug, J.O., Hanssen, F., Jacobsen, K.-O., 
Kleven, O., Kvaløy, P., May, R., Meås, R., Nygård, 
T., Refsnæs, S., Stokke, S. & Thomassen, J. (2013): 
Optimal design and routing of power lines; ecological, 
technical and economic perspectives (OPTIPOL). 
NINA Report 904. – Norwegian Institute for Nature 
Research, Trondheim.
Direktoratet for naturforvaltning (2009): 
[Management plan for Eagle Owl.] DN Rapport 2009. 
– Direktoratet for naturforvaltning, Trondheim. (in 
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Arrived / Prispelo: 27. 3. 2013
Accepted / Sprejeto: 1. 7. 2013