Golden Eagles Aquila Chrysaetos Research Articles

Habitat selection by adult Golden Eagles Aquila chrysaetos during the breeding season and implications for wind farm establishment

ABSTRACTCapsule: Global Positioning System (GPS)-tagged adult Golden Eagles Aquila chrysaetos breeding in forests in northern Sweden selected clear-cuts, coniferous forests with lichens and steep slopes during the breeding season but avoided wetlands and mixed forest.Aims: To investigate the habitat selection patterns of tree-nesting Golden Eagles, and identify how potential conflicts with wind farm development could be minimized.Methods: The study is based on GPS tracking data from 22 adult eagles. We estimated home range sizes using a biased random bridge approach and habitat selection patterns using resource selection functions following a use-availability design.Results: Core home range size among adults was variable during the breeding season (5–30 km2). Individual movement extents were variable, but sexes did not significantly differ in their scale of movement. At the landscape scale, individuals selected for clear-cuts and coniferous forest with ground lichens, whereas wetland, water bodies and mixed forest were avoided. Steeper and south facing slopes were selected for, whereas, north facing slopes were avoided.Conclusions: Potential conflicts between eagles and wind energy establishment can be reduced if wind farms are placed away from steep slopes, minimizing areas that are clear-cut during construction, and locating turbines within dense, young and other less favoured forest habitats.

Итоги проекта «Оценка влияния воздушных линий электропередачи средней мощности на орнитофауну Мангистауской области (Республика Казахстан)»

The article highlights the project results on the assessment of the impact of middle voltage overhead power lines (PL) on avifauna of Mangistau region of the Republic of Kazakhstan. On repeated examination of 440 km of PL there was determined a fact of death of 123 birds belonging to 29 species. In particular, 23 birds died from injuries because of collision with wires, and 100 birds were electrocuted. Among the latter, about 60 % are eagles (Steppe Eagle Aquila nipalensis, Golden Eagle Aquila chrysaetos, Imperial Eagle Aquila heliaca). There is the dependence of a number of electrocuted birds on the engineering design of PL. There was an extrapolation of the bird electrocution survey results on the whole territory of Mangistau region.

The Bald and Golden Eagle Protection Act, Species-Based Legal Protection and the Danger of Misidentification

The Bald and Golden Eagle Protection Act of 1940 bestows legal protection on two North American eagle species in the United States of America. The Act was originally aimed at the legal protection of only one species: the Bald Eagle Haliaeetus leucocephalus, the national symbol of the USA. Later the Act was amended to extend protection also to the Golden Eagle Aquila chrysaetos. The Bald Eagle was an Endangered Species, but the Golden Eagle was not formally listed as Endangered nationwide in the USA. One of the reasons for extending legal protection to the Golden Eagle under the Act was to strengthen the legal protection of the Bald Eagle, because immature Bald Eagles were being misidentified as Golden Eagles and shot. Additional factors relating to Golden Eagle mortality also made legal protection of the Golden Eagle desirable. The danger that a rare and legally protected species can be misidentified and mistaken for a more common and unprotected species can therefore serve as a reason for bestowing legal protection on the more common species as well. Other factors may also indicate that legal protection of the more common species is desirable, making the case more compelling. If this line of reasoning is applied in respect of South African birds of prey, a strong case can be made in favour of extending legal protection under the national biodiversity legislation to more species than the small number of species currently enjoying such protection. Species that are listed as Vulnerable under South African national biodiversity legislation may be misidentified as species that are not subject to such protection. Additional factors are also present that make such an extension of legal protection desirable. 

Limitations and mechanisms influencing the migratory performance of soaring birds

Migration is costly in terms of time, energy and safety. Optimal migration theory suggests that individual migratory birds will choose between these three costs depending on their motivation and available resources. To test hypotheses about use of migratory strategies by large soaring birds, we used GPS telemetry to track 18 adult, 13 sub‐adult and 15 juvenile Golden EaglesAquila chrysaetosin eastern North America. Each age‐class had potentially different motivations during migration. During spring, the migratory performance (defined here as the directness of migratory flight) of adults was higher than that of any other age‐classes. Adults also departed earlier and spent less time migrating. Together, these patterns suggest that adults were primarily time‐limited and the other two age‐classes were energy‐limited. However, adults that migrated the longest distances during spring also appeared to take advantage of energy‐conservation strategies such as decreasing their compensation for wind drift. During autumn, birds of all age‐classes were primarily energy‐minimizers; they increased the length of stopovers, flew less direct routes and migrated at a slower pace than during spring. Nonetheless, birds that departed later in autumn flew more directly, indicating that time limitations may have affected their decision‐making. During both seasons, juveniles had the lowest performance, sub‐adults intermediate performance and adults the highest performance. Our results show age‐ and seasonal variation in time and energy‐minimization strategies that are not necessarily exclusive of one another. Beyond time and energy, a complex suite of factors, including weather, experience and navigation ability, influences migratory performance and decision‐making.

Use of multiple modes of flight subsidy by a soaring terrestrial bird, the golden eagle Aquila chrysaetos, when on migration.

Large birds regularly use updrafts to subsidize flight. Although most research on soaring bird flight has focused on use of thermal updrafts, there is evidence suggesting that many species are likely to use multiple modes of subsidy. We tested the degree to which a large soaring species uses multiple modes of subsidy to provide insights into the decision-making that underlies flight behaviour. We statistically classified more than 22 000 global positioning satellite-global system for mobile communications telemetry points collected at 30-s intervals to identify the type of subsidized flight used by 32 migrating golden eagles during spring in eastern North America. Eagles used subsidized flight on 87% of their journey. They spent 41.9% ± 1.5 ([Formula: see text], range: 18-56%) of their subsidized northbound migration using thermal soaring, 45.2% ± 2.1 (12-65%) of time gliding between thermals, and 12.9% ± 2.2 (1-55%) of time using orographic updrafts. Golden eagles responded to the variable local-scale meteorological events they encountered by switching flight behaviour to take advantage of multiple modes of subsidy. Orographic soaring occurred more frequently in morning and evening, earlier in the migration season, and when crosswinds and tail winds were greatest. Switching between flight modes allowed migration for relatively longer periods each day and frequent switching behaviour has implications for a better understanding of avian flight behaviour and of the evolution of use of subsidy in flight.

Nesting Season Diet of Golden Eagles (Aquila chrysaetos) in Western Iran

I studied the diet of the Golden Eagle (Aquila chrysaetos) in western Iran by identifying food items in prey remains, pellets, and video recordings at seven nests during the 2011–2013 breeding seasons. Two methods were used to calculate diet composition: minimum number of individuals of each prey species and estimated biomass for prey items. I identified 316 prey items, which included five species of birds, four species of mammals, and two species of reptiles. Mammals made up the greatest proportion of the diet, 44.0% by frequency and 76.8% by biomass, and birds accounted for 43.7% of the diet by frequency and 17.7% by biomass. Cape hare (Lepus capensis), Chukar (Alectoris chukar), Common Magpie (Pica pica), large-toothed souslik (Spermophilus fulvus) and common fox (Vulpes vulpes) were the most important prey species. The percentage of mammals in the Golden Eagle’s diet in western Iran was lower than in North America, Scotland, the mountains of the Mediterranean, and across Europe and Asia.

Population structure and dispersal patterns in Scottish Golden Eagles Aquila chrysaetos revealed by molecular genetic analysis of territorial birds

Conservation management of species distributed across fragmented habitats requires consideration of population genetic structure and relative levels of genetic diversity throughout the relevant geographical range. The Golden Eagle Aquila chrysaetos is monitored within Scotland to ensure its survival in the face of land‐use pressure, persecution and future climate change. In this study we constructed DNA profiles for 271 individual birds using a collection of over 1600 moulted feathers collected from 148 territories, representing 34% of known Scottish territories in the largest population genetic study of Golden Eagles undertaken to date. The results, based on data from 10 nuclear microsatellite loci, revealed previously unreported genetic structure between the islands of the Outer Hebrides and the rest of Scotland (FST = 0.03), together with evidence of reduced genetic diversity in the Outer Hebridean population compared with mainland Scotland. Analysis of gene flow supports a hypothesis of limited, predominantly male‐mediated, dispersal from the Outer Hebrides to mainland Scotland. The persistence of this pattern is discussed with respect to variation in population density and persecution pressure across Scotland. A finding of non‐random mating within the Outer Hebrides is interpreted as evidence of natal philopatry that was revealed by more intensive sampling in these islands, and is likely to be accentuated by the apparent degree of isolation of the islands from the rest of Scotland.

The frequency distribution of lead concentration in feathers, blood, bone, kidney and liver of golden eagles Aquila chrysaetos: insights into the modes of uptake

Several cases of acute lead poisoning of golden eagles Aquila chrysaetos have been documented in the Alps. The question, however, remains how often golden eagles take up lead (once, chronically or episodically) and whether this uptake is in fatal or sublethal amounts. We approached this question by examining the level and frequency distribution of lead concentration in different tissues and in three segments of flight feathers in 41 golden eagles found dead, injured or moribund in the Swiss Alps. The frequency distribution of lead concentration in the blood, liver, kidney, wing coverts and shaft of flight feathers were all right-skewed. The highest values in blood, kidney and liver reached levels typical for acute fatal poisoning. In contrast, the frequency distribution of lead in bones was more symmetrical, but 71 % had bone lead concentrations >10 µg/g, which are considered elevated, and 29 % >20 µg/g, values often observed in cases of lethal poisoning. In 22 % of individuals, only one segment of a flight feather had a high lead concentration, while the other two segments had a low concentration. These findings indicate an episodic intake of lead of various amounts that may be immediately fatal (generating high blood levels) or sublethal. The patterns of lead in flight feathers and in bone suggest a repeated sublethal lead intake by the same individual. Such an episodic lead uptake seems only possible through ingestion of lead particles from carcasses or offal left behind by hunters. This also constitutes a risk to other scavengers, notably to the bearded vulture Gypaetus barbatus for which several high bone lead values have been found.

The role of predation and food limitation on claims for compensation, reindeer demography and population dynamics.

Summary A major challenge in biodiversity conservation is to facilitate viable populations of large apex predators in ecosystems where they were recently driven to ecological extinction due to resource conflict with humans.Monetary compensation for losses of livestock due to predation is currently a key instrument to encourage human–carnivore coexistence. However, a lack of quantitative estimates of livestock losses due to predation leads to disagreement over the practice of compensation payments. This disagreement sustains the human–carnivore conflict.The level of depredation on year‐round, free‐ranging, semi‐domestic reindeer by large carnivores in Fennoscandia has been widely debated over several decades. In Norway, the reindeer herders claim that lynx and wolverine cause losses of tens of thousands of animals annually and cause negative population growth in herds. Conversely, previous research has suggested that monetary predator compensation can result in positive population growth in the husbandry, with cascading negative effects of high grazer densities on the biodiversity in tundra ecosystems.We utilized a long‐term, large‐scale data set to estimate the relative importance of lynx and wolverine predation and density‐dependent and climatic food limitation on claims for losses, recruitment and population growth rates in Norwegian reindeer husbandry.Claims of losses increased with increasing predator densities, but with no detectable effect on population growth rates. Density‐dependent and climatic effects on claims of losses, recruitment and population growth rates were much stronger than the effects of variation in lynx and wolverine densities. Synthesis and applications. Our analysis provides a quantitative basis for predator compensation and estimation of the costs of reintroducing lynx and wolverine in areas with free‐ranging semi‐domestic reindeer. We outline a potential path for conflict management which involves adaptive monitoring programmes, open access to data, herder involvement and development of management strategy evaluation (MSE) models to disentangle complex responses including multiple stakeholders and individual harvester decisions.

Availability of optimal‐sized prey affects global distribution patterns of the golden eagle Aquila chrysaetos

Climate and landscape change are expected to significantly affect trophic interactions, which will especially harm top predators such as the golden eagle Aquila chrysaetos. Availability of optimal prey is recognized to influence reproductive success of raptors on a regional scale. For the golden eagle, medium‐sized prey species between 0.5 and 5 kg are widely considered to be optimal prey during the breeding season, whereas smaller and larger species are deemed as energetically sub‐optimal. However, knowledge about the effects of optimal prey availability is still scarce on larger scales. To decrease this apparent knowledge gap, we combined biogeographical information on range margins with information about the foraging behaviour and reproductive success of golden eagles from 67 studies spanning the Northern Hemisphere. We hypothesized that availability of optimal prey will affect foraging behaviour and breeding success and, thus, distribution patterns of the golden eagle not only on a local but also on a continental scale. We correlated the diet breadth quantifying foraging generalism, breeding success and proportions of small (< 0.5 kg), medium (0.5–5 kg) and large‐sized (> 5 kg) prey species within the diet with the minimum distance of the examined eagles to the actual species distribution boundary. Closer to the range edge, we observed decreased proportions of medium‐sized prey species and decreasing breeding success of golden eagles. Diet breadth as well as proportions of small and large‐sized prey species increased, however, towards the range edge. Thus, availability of optimal‐sized prey species seems to be a crucial driver of foraging behaviour, breeding success and distribution of golden eagles on a continental scale. However, underlying effects of landscape characteristics and human influence on optimal prey availability has to be investigated in further large‐scale studies to fully understand the major threats facing the golden eagle and possibly other large terrestrial birds of prey.

An irruption interrupted: eradication of wild turkeys Meleagris gallopavo from Santa Cruz Island, California

AbstractEradication of introduced species is often necessary to conserve native biota on islands. Seven wild turkeys Meleagris gallopavo were introduced to Santa Cruz Island, California, in 1975 and the population began to irrupt in the early 2000s. Turkeys posed a variety of threats to native species, including that they could replace the previously eradicated population of feral pigs Sus scrofa as a prey subsidy for golden eagles Aquila chrysaetos, which through incidental predation had driven three subspecies of island fox Urocyon littoralis to near extinction. We implemented a four-phase programme to eradicate the turkey population, based on general principles for eradication efforts. For example, we focused on preventing individual turkeys from becoming aware of our methods, which increased the likelihood we would be able to detect and dispatch all of the birds. Leveraging the tendency of turkeys to aggregate during winter, we used baited drop nets, precision shooting, and monitoring of surgically sterilized, radio-telemetered ‘Judas turkeys’ to eliminate the population. We estimate the population comprised 310 individuals when the project began in 2006 and that the last bird died in December 2012. Methods used in this project could be applied to other alien bird eradication programmes, of which there are few examples in the scientific literature.

Comparison between DNA and Analyses Morphometrics as Tool for Identification of Sex of the Golden Eagles (Aquila chrysaetos Canadensis)

The Golden eagle (Aquila chrysaetos canadensis) is an endangered species in Mexico, and the captive breeding is relevant to its conservation. Monomorphic raptor species, such as Golden eagle, are difficult for sex determination based only on morphometric measures and plumage characteristics, and a reliable method to determine the sex of birds is important for conservation strategies. With the purpose of forming new captive breeding couples, the sex of 10 adult Golden eagles was identified using DNA analysis such as CHD gene amplification (P8, P2 primers), and by CHD amplification by ARMS technique. In addition bioinformatic, and PCA statistical analysis of morphometric characteristics were conducted. We confirmed that the P2-P8 pair of primers inside the CHD gene was not a good option for Golden eagles because fragments derived from sex specific alleles CHD-W and CHD-Z differed just in 6 bp, which are not enough to be distinguished in agarose gel electrophoresis. In contrast, sex identification in Golden eagles with ARMS technique was fast, reliable and useful, obtaining a difference of more than 60 bp between CHD-W and CHD-Z that allows discriminating directly the alleles in a simple agarose gel. The PCA analysis of morphometric characteristics indicated three significant morphological patterns that differentiated males from females.

Habitat use and ranging behaviour of juvenile Golden Eagles Aquila chrysaetos within natal home ranges in boreal Sweden

Capsule Fledgling Golden Eagles in northern Sweden preferred clearcuts and other open forest habitats, as well as steep slopes.Aims To study the post-fledging habitat use and ranging behaviour of juvenile Golden Eagles on their natal territories.Methods Fourteen juvenile Golden Eagles in northern Sweden were marked with GPS transmitters and tracked until they left their natal territory.Results Eagles fledged at the end of July–beginning of August and remained on their natal territories until October–early November. Fledged eagles' home range size before flying south was on average 41 km2. Juvenile eagles showed a preference for clearcuts, coniferous forest on lichen-covered bedrock and edges between clearcuts and forest, whilst all other habitat types were used less than expected. The eagles showed a preference for steep slopes, in particular south-facing ones, whilst north-facing slopes were used less than expected.Conclusion Golden Eagles' preference for clearcuts and steep slopes can be used in the planning and management of ‘eagle friendly’ wind farms.

First Documented Predation of Sika Deer (Cervus nippon) by Golden Eagle (Aquila chrysaetos) in Russian Far East

First Documented Predation of Sika Deer (Cervus nippon) by Golden Eagle (Aquila chrysaetos) in Russian Far East

Size and density of a feral goat Capra hircus population in a protected area in the Pyrenees

To estimate the number and density of feral goats Capra hircus in Guara Nature Park (Pyrenees, Spain), 30 observation points were established throughout a 440-km2 portion of the park occupied by goats. In April and May, 2009, goats were counted daily during 3-h observation periods that began at dusk. The counts documented 282 goats in 39 groups. Their locations were mapped and, to calculate the area occupied by the groups, the data were analysed using ArcInfo, which indicated that the total visual area was 8,075 ha. Based on Distance Sampling, the estimated density was 2.1 goats km2 (CV 32%), which implied a population of about 940 individuals. That sub-population is part of a larger population in the southern Pyrenees that s distributed over an area of at least 2,100 km2 and, probably, is one of the largest populations in continental Europe. In the Pyrenees feral goats might be an important food resource for the endangered Golden Eagle Aquila chrysaetos. The conservation, control, or eradication of those goats should be based on a comprehensive analysis of its role in the ecology of the Pyrenees.

Distribution of Bonelli's EagleAquila fasciatain Southern Spain: Scale May Matter

Abstract Understanding factors that determine the distribution of the endangered Bonelli's Eagle requires different approaches and analytical tools. These factors may differ depending on the spatial scale at which they act. Bonelli's Eagle distribution in Spain has been studied previously using local and large (nation-wide) study area sizes, and human activities seemed not to affect negatively the occupancy of breeding territories. To study the factors affecting the species at an intermediate spatial scale we modelled Bonelli's Eagle distribution in Malaga province (S Spain), where the breeding density is the highest known in Europe. We applied a favourability function based on generalized linear models using the presence/absence of breeding territories of the species, and the values of a set of variables related to climate, topography, interspecific competition with Golden Eagle Aquila chrysaetos and human activity. We obtained a parsimonious model that included cliff availability and distance to highway...

Golden eagle Aquila chrysaetos in Xinjiang: Nest-site selection in different reproductive areas

The reports about the geographical distribution, reproductive ecology and population dynamics of the golden eagle Aquila chrysaetos were mostly descriptive in China, and lack quantified studies for the nest-site selection of this species. We carried out our investigations by direct observations in the northern Xinjiang during 2004–2011, attempting to reveal the main factors that affected on the nest-site selection and the differences of ecological variables of reproductive areas in the species (Mts. Tian Shan spurs and Mt. Kalamaili). We measured 38 nests totally belonging to the 16 home ranges. The average number of nests in each home range was 2.38±0.41, and with no significant difference (P>0.05) between different reproductive areas. In all cases golden eagles nested on cliffs (n=38) in our study area. The average external diameter of nests was (198.4±8.2) cm × (159.3±14.2) cm (Mean±SE, n=9), and inner diameter was (91.1±4.4) cm. The nest-site selection was extremely significant difference (P<0.01) for the different reproductive areas, i.e. elevation, hill height, nest-site height, cliff height, gradient, the distance to water resource, and the distance to residential area. The distance from the cliff bottom and from the cliff top were significant difference (P<0.05). However, the slope position, nest position, distance to unpaved and paved road were not significant difference (P>0.05). In Mts. Tian Shan spurs, the elevation was obviously selective (χ2=13.99, df=4, P<0.01), and mainly nested in altitude of 1 932–2 197m, where the main aspects were SW (36.4%, n=22) or SE (31.8%), and the slope gradient was above 85°. In Mt. Kalamaili, also it was found the significant differences for elevations (χ2=11.44, df=3, P<0.01), the eagle mainly nested in altitude of 1 112–1 423m, with aspects of NW (68.8%, n=16), and the gradient was relatively flat. In reproductive areas, eagles nested in the mid-slope parts and higher slope position (92.1%, n=38). Eagles nested far from the seriously disturbed places by human, especially roads, residential area, mineral mines, etc. The principal component method of the factor analysis indicated that there were four main factors affecting on the nest-site selection by golden eagle in Mts. Tian Shan spurs: human disturbance factor (eigenvalue is 4.800, Ratio of contribution is 34.28%), nest position factor (3.002%, 21.44%), prey factor (2.601%, 18.58%), and terrain factor (1.305%, 9.32%). In Mt. Kalamaili, there are five main factors as following: terrain factor (eigenvalue is 5.110, Ratio of contribution is 34.07%), nest position factor (3.747%, 24.98%), human disturbance factor (2.123%, 14.16%), prey factor (1.584%, 10.56%), and gradient factor (1.111%, 7.41%). To conclude, human disturbance and landscape are the two main factors affecting on the nest-site selection of the eagle. The nest-site selection is a result of trade-off among the human disturbance, landscape and prey amount. Eagles take corresponding strategy of nest-site selection for adaptation to the various environments, having different conditions for the eagle reproductive. So, we recommended the improvement of the habitat fitness for the increasing of the reproductive success of the golden eagle.

Exploring juvenile golden eagles' dispersal movements at two different temporal scales

The spatial distribution of populations is the result of individuals' movements. In territorial species, the spatial dynamics of populations is to a large degree shaped by individuals' ranging behaviour during their juvenile dispersal. Here we use information on juvenile golden eagles (Aquila chrysaetos) tracked by satellite telemetry, to explore the effects of daily behavioural decisions on their dispersal strategy during their first year of life. When analysed on a biweekly basis, the large-scale movements of golden eagles did not differ from a correlated random walk (CRW) model of dispersal. Although in the long term such a strategy maximises the acquisition of information on good hunting areas, finding a mate and a vacant territory in a landscape, it is expensive in terms of energy requirements. At the finer scale of daily foraging movements, movement patterns were non-random, probably reflecting animals' oriented movements towards sites with high chances of successful hunting. We suggest that the key issue to take into account when exploring the factors determining individuals' dispersal strategies is how strongly the daily movements are influenced by an active search for food. This is to a large degree determined by food availability and individuals' ability to accumulate reserves. In our case, the individuals with the lowest proportion of foraging habitats within their dispersal areas showed large-scale movements more restricted than expected from a CRW. Also, distances covered by individuals in their biweekly movements were both larger and more variable in winter, when food availability diminishes.

Overview of raptor monitoring activities in Europe

Abstract Despite the key role of raptors (including birds of prey Falconiformes and owls Strigiformes) in ecosystems and their sensitivity to environmental change, a well coordinated, Europe-wide monitoring of raptors is lacking. EURAPMON, a Research Networking Programme of the European Science Foundation, was launched with the aim of establishing a sustainable Europewide network for monitoring of raptors. An overview of current monitoring schemes for raptor populations in 28 European countries, as reported by EURAPMON National Coordinators at the workshop in Murcia (Spain) in 2012, showed existing monitoring schemes to be limited to a restricted number of species (mostly diurnal and rare raptor species). The most widely monitored species are the Golden Eagle Aquila chrysaetos amongst diurnal raptors and the Eagle Owl Bubo bubo amongst owls. Broad coverage of a species range across Europe is reached only for restricted-range species. The key driver for monitoring, which is mostly coordinated by NGOs, is conservation, and the main end users are governmental institutions. International collaboration in the field of monitoring of raptors is mainly regional and not yet pan-European in scale. The involvement of volunteers in raptor monitoring was perceived as the main strength of many schemes, but insufficient manpower and a focus on rare species were recognised as the main weaknesses across Europe as a whole. Among priorities identified for the future development of monitoring schemes are: improvements to national coordination; support to increase the number of volunteers; and assurances of stable funding. Further analysis of EURAPMON questionnaires will identify knowledge gaps, which will steer good practice guidance on survey methodologies; the need for the latter was identified as the main benefit that National Coordinators expect to gain from international networking

An overview of monitoring for raptors in Finland

Abstract In Finland, population monitoring for both diurnal and nocturnal raptors has been almost entirely based on fieldwork carried out by voluntary raptor ringers. Responsible organisations include the Finnish Museum of Natural History, with economic support for administration from the Ministry of Environment, “Metsahallitus” (former National Board of Forestry) and WWF Finland. Since the early 1970s, numbers and productivity of four endangered species, the White-tailed Eagle Haliaeetus albicilla, Golden Eagle Aquila chrysaetos, Osprey Pandion haliaetus and Peregrine Falcon Falco peregrinus have been monitored by country-wide Comprehensive Surveys, with the aim of checking all known nest sites of these species every year. The Gyrfalcon F. rusticolus was included in this group in the late 1990s. Data for monitoring the populations of the other raptor species have been gathered by the Raptor Grid and Raptor Questionnaire projects. The Raptor Grid project produces annual population indices, which are calculated from the data collected from 10 × 10 km study plots (n = ca. 130/year) and quite well reflect the annual population fluctuations and longterm trends of seven common species of diurnal and six species of nocturnal raptors breeding in the southern part of Finland. For the rest of the species, which are either rare all over Finland or breed mostly in the north, outside the good coverage of the distribution of Raptor Grid study plots, conclusions on population changes are based on the total numbers of occupied territories and active nests reported annually by the Raptor Questionnaires