J Ornithol (2009) 150:239–246
DOI 10.1007/s10336-008-0343-5

ORIGINAL ARTICLE

Reduced abundance of raptors in radioactively contaminatedareas near Chernobyl
Anders Pape Møller Æ Timothy A. Mousseau

Received: 3 December 2007 / Revised: 5 September 2008 / Accepted: 15 September 2008 / Published online: 7 October 2008Ó Dt. Ornithologen-Gesellschaft e.V. 2008

Abstract The negative ecological effects of radioactive
contamination around Chernobyl have recently been suggested to be moderate and declining because of anincreasing number of anecdotal observations of several
species of rare animals including predators. However, theseclaims were not based on empirical evidence. Radionuclides show bio-accumulation with trophic level, and theabundance of birds is depressed in radioactively contaminated areas around Chernobyl. Therefore, we predicted thatbirds of prey should be less abundant with increasing levelsof radiation. Here, we use our long-term field data from1991 to 2007 in three different analyses based on observations of raptors using standardized point counts, censuses
during capture of barn swallows Hirundo rustica that
habitually give alarm calls when a raptor is present, andline transects while driving on roads. Analyses suggest thatthe abundance of birds of prey is reduced in contaminatedareas, and that there is evidence of a recent increase inabundance of raptors in less contaminated areas, but not in
the most contaminated ones. Our findings suggest that birdsof prey that are top level consumers in ecosystems sufferfrom reduced abundance in radioactively contaminatedareas.
Communicated by F. Bairlein.
A. P. Møller (&)
Laboratoire de Parasitologie Evolutive, CNRS UMR 7103,
Université Pierre et Marie Curie, Bât. A,
7ème étage, 7 quai St. Bernard, Case 237,
75252 Paris Cedex 05, France
e-mail: amoller@snv.jussieu.fr
T. A. Mousseau
Department of Biological Sciences,
University of South Carolina, Columbia,
SC 29208, USA

Keywords Birds of prey  Predators 
Radiation at Chernobyl  Trophic level

Introduction
The ecological consequences of radiation from the Chernobyl catastrophe remain poorly known, despite 21 years
having passed since the catastrophe (reviews in Zakharov
and Krysanov 1996; Møller and Mousseau 2006). Without
scientific justification, a number of institutions and private
persons have promoted the Chernobyl Exclusion Zone as a
thriving ecosystem because a number of uncommon species
such as eagles, wolves Canis lupus and perhaps even a bear
Ursus arctos have appeared in recent years (Chernobyl
Forum 2005a, b; UN Chernobyl Forum Expert Group‘‘Environment’’ 2005; Mycio 2005; Rosenthal 2005; Stephan 2005). These claims about increasing abundance of
predators and other rare species within the Chernobyl
Exclusion Zone have been promoted by the official United
Nations and International Atomic Energy Agency reports asevidence of a recovery of the ecosystem (Chernobyl Forum2005a, b; UN Chernobyl Forum Expert Group ‘‘Environment’’ 2005). Surprisingly, these agencies did not provide
any empirical basis for their claims by reporting informationfrom control areas, or by reporting temporal trends in population levels, and there are to the best of our knowledge noempirical data supporting the claim. Such casual comments
are surprising given the rigor that these agencies claimed to
be using when investigating the biological, medical, andsocial consequences of the Chernobyl catastrophe(Chernobyl Forum 2005a, b; UN Chernobyl Forum Expert
Group ‘‘Environment’’ 2005).
There are three reasons in addition to the complete
lack of quantitative information why we consider the

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conclusions by the official reports of the United Nations
and the International Atomic Energy Agency to be unlikely. First, bio-accumulation of radionuclides are common(Voitovich and Afonin 2002; Yakushev et al. 1999), andanimals at higher trophic levels generally have higher
levels of radionuclide concentrations than animals at lower
levels (e.g., Kryshev and Ryabov 1990; Kryshev et al.
1992; Smith et al. 2002). Therefore, we should expect
predators to have higher concentrations of radionuclides
than detritivores, herbivores, or primary level predatorssuch as many song birds. Second, Møller and Mousseau(2007b, c) reported that the most contaminated forest sites
in Chernobyl have severely depressed species richness,abundance, and population density of birds, reduced bymore than 50% compared to nearby sites with normal
background levels of radiation. Given that avian predators
mainly eat passerine birds and small mammals, we should
expect species richness and density of birds of prey to be
depressed in Chernobyl compared to uncontaminatedcontrol areas because the abundance of prey is reduced.
Third, birds of prey are generally more abundant in manmade habitats such as farmland and managed forests thanin undisturbed habitats, simply because the abundance ofpotential prey reaches much higher levels in manmade
habitats (e.g., Newton 1986). The Chernobyl Exclusion
Zone has not been managed by humans for 21 years,
suggesting that the abundance of prey should be reduced
compared to nearby agricultural and forest habitats managed by humans.
Here, we provide the first quantitative assessment of theclaim that the abundance of raptors is high and increasingaround Chernobyl compared to nearby uncontaminatedsites, relying on our own extensive data collected in
10 years during 1991–2007, using three different census
methods. First, we used standardized point counts lasting
5 min each to census breeding birds at 489 points in forests
mainly within the Chernobyl Exclusion Zone during 2006–
2007 (see Møller and Mousseau 2007a, b). Second, we
censused birds of prey during our capture sessions of barnswallows Hirundo rustica around Chernobyl and inuncontaminated control areas in 1991–2007. Barn swallows act as sentinels for the presence of raptors that arereadily detected. The presence of a raptor is revealed byfrequent alarm calls that barn swallows emit at a frequency
of more than 50 per min. Other passerine birds respondquickly to these alarm calls by giving their own alarm calls.
Møller (1987) showed that a little owl Athene noctua
model was detected by barn swallows after a maximum ofa few minutes, but much more rapidly in colonies, where
this raptor was detected after less than a minute. Third, weused line transects on roads by recording all birds of preyduring our regular trips between Kiev and our study sites
for barn swallows in Central and Northern Ukraine and123

J Ornithol (2009) 150:239–246

Belarus during 1991–2007. Relying on data collectedduring more than 100 such trips we were able to assess theabundance of birds of prey for a total distance exceeding
12,000 km.

Materials and methods
Bird census
A.P.M. (wearing a radiation protection suit during censusesin the Red Forest) conducted standard point counts during
29 May–9 June 2006 and 1–11 June 2007, with each countlasting 5 min during which all bird species and individuals
seen or heard were recorded (Møller 1983; Bibby et al.
2005). The census was conducted within the Chernobyl
Exclusion Zone with a permit from the Ukrainian authorities or in areas adjacent on the southern, western, andnorthern borders in Ukraine and Belarus (Fig. 1). A total of489 points were located at a distance of ca. 100-m intervals
within forested areas, excluding successional stages ofsecondary forest due to abandoned farming; these areas arestill almost exclusively open grassland. The following
point counts of birds provide highly reliable estimates of
species richness and abundance (Møller 1983; Bibby et al.
2005). We directly tested the reliability of our counts for asample of 10 points where two persons performed thecounts. The second person performing the counts wasunaware of the purpose of his counts. The Pearson product–moment correlation between species richness in these
two series of counts was high (Møller and Mousseau
2007b).
The second type of census was conducted during capture
sessions of barn swallows during 1991, 1996, and 2000–
2007 in the same areas, as described above for point counts(Fig. 1). The annual duration of these censuses lasted on
average 23.45 h (2.61), range 15.24–41.30 h. When barnswallows encounter a bird of prey, they emit alarm callsthat can be readily heard while mobbing the predator.
Therefore, every time barn swallows emitted alarm calls,
we determined the cause of the alarm and it was in all cases
the presence of a raptor. Capture sessions lasted 0.5–9.5 h,
on average 3.8 h (SD = 0.3), n = 56, and duration of
capture sessions was used as a predictor variable to control
for differences in sampling effort. A.P.M. conducted similar censuses during 142 capture sessions of barn swallows
in open farmland in Northern Denmark during May–June
2008.
The third type of census was conducted while driving
between Kiev and various sites where barn swallows were
captured (most of these transects are shown in Fig. 1)
during 1991, 1996 and 2000–2007. While a driver was
driving a normal speed (ca. 80–90 km/h), A.P.M. recordedJ Ornithol (2009) 150:239–246

241

Fig. 1 Location of linetransects and clusters of farms(dots) where barn swallows
Hirundo rustica were captured,with information on levels ofradiation from Chernobyl inparts of Ukraine, Belarus andRussiaall birds of prey. The distances traveled ranged from 5 to
250 km, mean (SE) = 118 km (5), n = 105, taking on
average 0.06–3.13 h of driving. The annual distance of
these censuses was on average 1,373 km (137.5), range
840–2,025 km. A.P.M. conducted 92 similar censuses of
raptors in open farmland in Northern Denmark during
May–June 2008.
Confounding variables
Bird abundance estimates can be affected by numerous
potentially confounding variables (Møller 1983; Bibby
et al. 2005). Thus, it is crucial to control for such variables
statistically. We quantified habitat as follows: agricultural
habitats with grassland or shrub, either currently or previously cultivated, deciduous forest, or coniferous forest
estimated to the nearest 10% of ground coverage within adistance of 50 m from the observation point. Agricultural
habitat thus also controlled statistically for any effects ofedge habitat. Maximum height of trees was estimated to thenearest 5 m, and soil type was recorded as loam/clay orsand. The presence of open water within a distance of 50 m

was also recorded. Weather conditions can affect animal
activity and hence census results (Møller 1983; Bibby et al.
2005), and we recorded cloud cover at the start of eachpoint count (to the nearest eighth, range 0–1 during thecensuses), temperature (°C, range 12–30°C), and windforce (Beaufort, range 0–4 during the censuses). For eachpoint count, we recorded time of day when the count wasstarted (to the nearest min). Because bird activity may
show a curvilinear relationship with time of day, with highlevels of activity in the morning and to a lesser extent in theevening (Møller 1983; Bibby et al. 2005), we also included
time squared as an additional variable.
Confounding variables during capture sessions weredate, duration of the session, time of day, and time of day
squared as defined above. We did not include habitat as aconfounding variable because all capture sessions took
place at farms.
Confounding variables during car censuses were date,distance travelled, time of day, and time of day squared as
defined above. Car censuses by definition covered a rangeof different habitats, and we had no possibility for quantifying habitats during the censuses. Hence, the conclusions

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from these censuses should be considered with this caveat
in mind.
Measuring background radiation levels
We obtained radiation estimates from our measurements
and cross-validated these with measurements by the Ministry of Emergencies. We measured a, b, and c radiation at
ground level directly at each point where we censused birds
using a hand-held dosimeter (Inspector; SE International,
Summertown, TN, USA). All measurements were deliberately made after the census to avoid any unintentionalbias, ensuring that censuses were made blindly with respect
to radiation level. We measured levels 2–3 times at eachsite and averaged the measurements. Our data were validated with correlation against data from the governmental
measurements published by Shestopalov (1996), estimatedas the mid-point of the ranges published. This analysis
revealed a strong positive relationship (Møller and Mousseau 2007b), suggesting that our estimates of radiation
provided the same ranking of levels of radiation as did
published estimates. The measurements by the Ministry of
Emergencies were obtained by repeated standardized
measurement of radiation at the ground level in a large
number of different localities in Ukraine. Radiation levels
vary considerably at very short geographical distances dueto heterogeneity in the deposition of radiation after the
Chernobyl accident (Shestopalov 1996). Our measurements
at the census points ranged from 0.04 to 135.89 mR/h,while levels of radiation at the barn swallow breeding sites
ranged from 0.02 to 2.90 mR/h, and the levels along theroad transects ranged from 0.02 to 1.00 mR/h.
Statistical methods
Radiation level was log10-transformed, while coveragewith farmland, deciduous forest, and coniferous forest was
square-root arcsine-transformed. We also included radiation level squared to account for non-linear relationships
between species richness and abundance, respectively, andradiation. We developed best-fit general linear models toassess the relationship between abundance (dependent
variable) and radiation, assuming a Poisson distribution,
after inclusion of potentially confounding variables, as
implemented in the statistical software JMP (SAS Institute2000). We started with the full models including radiation,
radiation squared, and all potentially confounding variables
as predictors. We then eliminated terms using F test or
likelihood ratio test (LRT) for model selection. The statistical significance of each variable was tested using a
backward stepwise procedure. The final model was reachedwhen all variables had a significant effect at P \ 0.10. The
final models from this approach are listed in Tables 2, 3, 4.

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None of the conclusions from these models differed fromthose derived from the full models.
The frequency distribution of counts of birds was
skewed, with a disproportionate number of zeros. Therefore, we repeated the analyses using Kendall rank-ordercorrelation and partial rank-order correlation (controlling
for the confounding variables listed above), and the statistical conclusions remained unchanged.

Results
We censused birds using standardized point counts at a
total of 489 points during 2006–2007 (Møller and Mousseau 2007b, c) and recorded a total of 12 raptors belonging
to five species (Table 1). Species composition differedamong methods, but this reflected habitat differences (point
counts were mainly made in forests; censuses during catches of barn swallows at farms; and car censuses in open
farmland). The mean (SE) abundance of raptors observed
per 5-min census was 0.031 (0.011), n = 489 point censuses. In comparison, the abundance of raptors per point
census in Northern Denmark was ca. 0.200 (Grell 1998),
which was significantly more than recorded in Ukraine andBelarus (Mann–Whitney U test: U = 55,000, P \ 0.0001).
The abundance of raptors decreased significantly withincreasing level of background radiation [F = 5.06,
df = 1, 487, P = 0.025, slope, (SE) = -0.010 (0.005)].
There was a higher level of coverage with coniferous trees
at points with radiation levels above compared to below themedian level of radiation (0.45 mR/h) [above median:
Table 1 Number of birds of prey recorded during three different
types of censuses in Ukraine and Belarus, 1991–2007
Species

No. birds of No. birds of
No. birds ofprey recorded prey recorded
prey recorded
duringduring censuses during car
standardized during barnline transects
point counts swallow captures

Accipiter gentilis

1

1

1

Accipiter nisus

0

16

1

Aquila pomarina

1

0

0

Buteo buteo

10

14

103

Circaetus gallicus

1

1

1

Circus aeruginosus
Circus pygargus

0
0

2
2

54
30

Falco subbuteo

0

0

1

Falco tinnunculus

1

2

12

Falco vespertinus

0

0

1

Haliaeetus albicilla

0

0

16

Pernis apivorus

0

1

1

Total

14

39

221

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243

Table 2 Best-fit model of the relationship between abundance ofbirds of prey recorded during standardized point counts and environmental variables, including background radiation (mR/h)
Variable

Sum ofsquaresdf

FP

Slope (SE)

Year

0.068

1

5.73

0.017

-0.015 (0.006)

Date

0.065

1

5.48

0.020

-0.007 (0.003)

Time

0.042

1

3.54

0.061

-0.004 (0.002)

Cloud cover

0.200

1

16.88

\0.0001-0.008 (0.002)

Farmland

0.039

1

3.32

0.069

0.0007 (0.0004)

Radiation

0.084

1

7.08

0.008

-0.014 (0.005)

Error

5.697

482

The overall model had the statistics F = 5.12, df = 6, 482, r2 = 0.06,
P \ 0.0001

40.7% (SE = 2.3), below median: 21.8% (SE = 2.1)], andthere was less habitat with deciduous trees [above median:
51.8% (SE = 2.4), below median: 77.0% (SE = 2.1)] andfarmland [above median: 9.3% (SE = 1.2), below median:
1.4% (SE = 0.4)] in areas with high levels of radiation.
However, the effect of radiation remained after adjustment
for effects of year, date, time, cloud cover, and habitat
including farmland habitat (Table 2). We found a significant difference in abundance of birds of prey among years,
a decrease in abundance with time during the season, and areduction in abundance with increasing cloud cover as
expected (Table 2). In addition, we found weak effects oftime of day (lower abundance recorded later in the day) andfarmland habitat (increasing abundance with increasinglevel of farmland habitat, as expected because farmland has
higher abundance of potential prey) on abundance of birdsof prey (Table 2).
While catching barn swallows we spent a total of 211 h
in the field during 56 field trips. This amount of time
produced 39 observations of raptors belonging to 8 species(Table 1) that were associated with alarm calls by barnswallows. The mean abundance (SE) of raptors observed
per h was 0.16 (0.03), n = 56. This was significantly lessthan the mean number of raptors recorded during ringing ofbarn swallows in Denmark in 2008 [Mann–Whitney U test:
U = -795, P \ 0.001; mean (SE) = 0.96 (0.03),
n = 142]. There was highly significant variation in abundance of raptors among sites (F = 5.78, df = 24, 55,
P \ 0.0001), showing that the same sites tended to have
similar abundances of raptors, with an additional effect of
duration of observations [F = 17.58, df = 1, 55,
P = 0.0002, slope (SE) = 0.146 (0.035)]. The among-site
variation was accounted for by level of radiation [Fig. 2;
Table 3; F = 6.86, df = 1, 55, P = 0.012, slope (SE) = 0.37 (0.14)]. There was no significant temporal trend in
raptor abundance (effect of year: F = 0.57, df = 1, 52,
P = 0.45).

Fig. 2 Abundance of birds of prey during point counts in relation tolevel of radiation [mR/h, mean (SE)]. Among the 489 point counts,
446 had no raptors

Table 3 Best-fit model of the relationship between abundance ofraptors recorded during barn swallow captures and background radiation (mR/h), year and observation effort (number of hours ofobservation)
Variable

Sum ofsquaresdf

FP

Slope (SE)Radiation

3.13

Observation effort

5.07

1

6.91

0.011

-0.37 (0.14)

1

11.17

0.00150.15 (0.05)

Error

24.05

53

Year was not retained in the model. The model had the statistics
F = 10.48, df = 2, 53, r2 = 0.28, P \ 0.0001

Fig. 3 Abundance of birds of prey during captures of barn swallows
in relation to level of radiation (mR/h), after adjustment of abundanceof raptors for sampling effort (number of h of observation). Meanabundance at the lowest level of radiation (0.02 mR/h) was
standardized to 1 to facilitate comparison with Fig. 4

The third data set consisted of observations of birds ofprey from a car while driving between sites where we
captured barn swallows. This data set consisted of 106 tripsof a total of 12,540 km, revealing a total of 221 birds of

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J Ornithol (2009) 150:239–246

prey belonging to 11 species (Table 1). Mean (SE) numberof raptors per 100 km driven was 1.74 (0.26), n = 105transects, which was significantly less than was recorded
by A.P.M. in Northern Denmark in 2008 [Mann–Whitney
U test: U = 2,570.5, P \ 0.001, mean (SE) = 6.22 (0.12),
n = 92 transects]. There was highly significant variation inabundance of raptors among sites (F = 6.03, df = 38, 66,
P \ 0.0001), showing that the same sites tended to have
similar abundances of raptors, with an additional effect of
distance travelled [F = 64.16, df = 1, 103, P \ 0.0001,
slope (SE) = 0.031 (0.004)]. Mean abundance was 1.52
raptors per 100 km in Chernobyl (SE = 0.16), n = 13,
while it was 3.23 raptors per 100 km in other areas(SE = 1.77), n = 92. The among-site variation was
accounted for by level of radiation (Fig. 3, Table 4). There
was a weakly increasing temporal trend in raptor abundance during 1991–2007 (Table 4). Finally, there was asignificant interaction between year and radiation, with anincreasing trend in population size in uncontaminatedareas, but no significant trend in contaminated areas[Table 4; slope for uncontaminated areas: 0.011 (0.005);
slope for contaminated areas: 0.038 (0.038)].

Discussion
The main findings of this study were that (1) the abundanceof birds of prey decreased with increasing level of radiation, according to three different census methods; (2) theseeffects were independent of a number of potentially confounding variables; and (3) the abundance of birds of preyincreased weakly in recent years, but mainly in areas withlittle or no radioactive contamination.
We assessed the abundance of birds of prey during
standardized point counts, censuses during field work while
catching breeding barn swallows, and line transects by car,and analyses of all three data sets revealed a negative
relationship between abundance of raptors and level ofradiation independently of whether we controlled forTable 4 Best-fit model of the relationship between abundance ofraptors recorded during car transects and background radiation (mR/h), distance (km) and year
Variable

Sum ofsquaresdf

FP

Slope (SE)Radiation (R)

0.74

1

17.45

\0.0001

Year (Y)

1.17

8

3.46

0.00170.10 (0.05)

R9Y

2.17

8

6.39

\0.0001

0.40 (0.14)

Distance

2.44

1

57.69

\0.0001

0.031 (0.004)

Error

3.64

86

-0.43 (0.10)

The model had the statistics F = 9.61, df = 18, 86, r2 = 0.67,
P \ 0.0001

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Fig. 4 Abundance of birds of prey during car line transect censusesin relation to level of radiation (mR/h). Mean abundance at the lowest
level of radiation (0.02 mR/h) was standardized to 1 to facilitatecomparison with Fig. 3

potentially confounding variables. Radiation accounted for
25% of the variance explained by point counts, 12% of thevariance for the censuses during capture of swallows, and
23% for car transects. The three census methods are notdirectly comparable because they targeted birds of prey indifferent habitats. The point counts were only used tocensus birds in forests, while the censuses during capture ofbarn swallows accounted for birds of prey near farms, andthe line transects mainly birds of prey in open habitats near
main roads. The values of R2 of the three models differedconsiderably from 6% for point counts over 28% for censuses during barn swallow captures to 67% during car
censuses. These differences among methods are related to
the large number of zeros in point counts (91%) comparedto swallow censuses (57%) and car censuses (34%), causing the many different factors associated with an absenceof raptors to play a disproportionately large role for thistype of census. The slope of the relationship between
abundance of raptors and radiation was less steep for point
counts (-0.014) than for swallow censuses (-0.37) and car
censuses (-0.43). Again, point counts in areas covered
with forest provided less opportunities for locating raptors
than the two other kinds of censuses, and the frequency ofpoints with low levels of radiation was very low. Indeed, if
mean abundance of raptors at the lowest level of radiation(0.02 mR/h) was standardized to one, the slope of abundance in relation to level of radiation was -0.12 for point
counts, -0.32 for swallow censuses and -0.36 for car
censuses.
The official reports by the United Nations and theInternational Atomic Energy Agency have indicated that
there is a temporally increasing trend in abundance of birdsof prey in the Chernobyl Exclusion Zone (Chernobyl
Forum 2005a, b; UN Chernobyl Forum Expert Group‘‘Environment’’ 2005), although no empirical evidence forthis claim has ever been provided. Using extensive census

J Ornithol (2009) 150:239–246

data based on three different methods, we found a weakly
increasing abundance of birds of prey in our long-term data
based on car transects. This effect was not the same acrosssites, only applying to study sites uncontaminated byradioactivity (radiation by year interaction in Table 4).
Therefore, there was no evidence that the abundance ofbirds of prey increased in the most contaminated areas inrecent years as claimed by the United Nations and theInternational Atomic Energy Agency. We could also showthat the overall abundance of raptors was very small
compared to similar data collected by the same observer inDenmark (A.P.M.).
The abundance of birds of prey is high in farmland
because farmland habitats often have high population
densities of potential prey (e.g., Newton 1986). Accordingly, we found a weakly increasing abundance of birds ofprey in areas with a larger fraction of farmland, although
this effect did not reach statistical significance (Table 2).
Previous studies of a number of organisms in Chernobyl
and other contaminated areas suggested that bio-accumulation of radionuclides is common (Voitovich and Afonin
2002; Yakushev et al. 1999), and that levels of contamination increases with trophic level (e.g., Kryshev andRyabov 1990; Kryshev et al. 1992; Smith et al. 2002).
Thus, we suggest that effects of bio-accumulation withincreasing trophic level may account for the findings
reported here.
Radioactive contamination from Chernobyl apparently
has strong negative effects on many species of birds asreflected by their reduced species richness and abundance(Møller and Mousseau 2007b, c). These effects may at least
partly be caused by a preference for nest sites in uncontaminated areas (Møller and Mousseau 2007a).
Furthermore, passerine birds breeding in contaminatedareas have reduced levels of antioxidants, reduced hatching
success and fecundity, and reduced survival prospects(Møller et al. 2005a, b). Therefore, populations breeding inradioactive sites can only be maintained by immigrationfrom elsewhere, rendering Chernobyl an ecological trap forsuch immigrants (Møller et al. 2006). The findings that wehave reported here suggest that a similar situation may
apply to birds of prey.
In conclusion, populations of birds of prey are reduced
in radioactively contaminated areas, as revealed by threedifferent census methods. Although population sizes ofbirds of prey increased weakly in recent years according to
one type of census, this effect was significantly more
pronounced in areas with low levels of radiation than in themost contaminated areas. Therefore, we suggest thatbreeding populations of birds of prey around Chernobyl
may be reduced due to the effects of radiation on predatorsthemselves, or due to indirect effects of radiation on theabundance of prey.

245

Zusammenfassung
Verringerte Abundanz von Greifvögeln in radioaktiv
verseuchten Gebieten in der Nähe von TschernobylKürzlich wurde vorgeschlagen, dass die negativen ökologischen Effekte der radioaktiven Kontamination um
Tschernobyl moderat seien und zudem abnehmen, da zunehmend anekdotenhafte Sichtungen seltener Tierarten,
einschließlich Prädatoren, berichtet wurden. Diese Behauptungen basierten jedoch nicht auf empirischen
Befunden. Radionuklide zeigen eine biologische Akkumulation mit höherer Stufe in der Nahrungskette, und die
Abundanz von Vögeln ist in radioaktiv verseuchten Gebieten um Tschernobyl abgesunken. Daher sagten wir
vorher, dass Greifvögel mit ansteigendem Strahlungslevelseltener werden sollten. Hier nutzen wir unsere LangzeitFelddaten von 1991–2007 in drei unterschiedlichen, auf
Beobachtungen von Greifvögeln basierenden Analysen, die
von Standard-Punktzählungen, Erhebungen während desFangens von Rauchschwalben Hirundo rustica, die regelmäßig Alarmrufe ausstoßen, wenn ein Greifvogel
anwesend ist, und Linientaxierung während Autofahrten
Gebrauch machen. Die Analysen lassen darauf schließen,
dass die Abundanz von Greifvögeln in verseuchten Gebieten reduziert ist und dass es Belege für einen kürzlichen
Anstieg in der Abundanz von Greifvögeln in weniger
kontaminierten Regionen gibt, jedoch nicht in den amstärksten kontaminierten. Unsere Befunde deuten darauf
hin, dass Greifvögel, die als Spitzenkonsumenten in Ökosystemen fungieren, unter verringerter Abundanz inradioaktiv verseuchten Gebieten leiden.
Acknowledgments We are grateful for logistic help during ourvisits to Ukraine and Belarus from O. Bondarenko, M. Bondarkov, I.
Chizhevsky, S. Gaschak, E. Konoplya, A. Litvinchuk, G. Milinevski,
A. M. Peklo, E. Pysanets, and N. Saino. We received funding fromThe Natural Science Faculty, Uppsala University, the Swedish Natural Science Research Council, the CNRS (France), the University ofSouth Carolina School of the Environment, Bill Murray, and theSamuel Freeman Charitable Trust, the National Science Foundation,
and National Geographic Society to conduct our research.

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