Gavia Arctica Research Articles

The status of breeding Red-throated Divers Gavia stellata and Black-throated Divers Gavia arctica in Kintyre, Scotland, 2016–2020

ABSTRACT Capsule An onshore wind farm monitoring programme carried out across Kintyre, Scotland from 2016 to 2020 provided an insight into the status of the area’s breeding Red-throated Diver Gavia stellata and Black-throated Diver Gavia arctica populations and their current threats. Aims This study provides an example of targeted monitoring undertaken for a renewables development which can inform conservation decision-making at a population and species level. The aims were to: (i) determine the population status of the breeding diver populations; (ii) determine whether the Cour Wind Farm, or other wind farms in Kintyre, have had any effects on the populations; and (iii) identify the most likely conservation threats to breeding divers within Kintyre. Methods Annual breeding diver surveys across Kintyre recorded presence, breeding activity and productivity. Within the Cour Wind Farm site carcass searches were conducted to record any incidences of diver collisions with wind turbines. Results Divers were recorded on approximately one third of waterbodies monitored in each year. The current Kintyre breeding populations are estimated to be 18–23 Red-throated Diver pairs, and between two and six Black-throated Diver pairs. The Kintyre Red-throated Diver population appears to have lower productivity rates than the UK average. Predation and interspecific competition may be limiting breeding success. No Black-throated Divers were observed to have successfully bred in Kintyre from 2016 to 2020, which may be partly due to a shortage of waterbodies with preferred conditions for nesting. No diver collisions were recorded during carcass searches and there is no evidence to suggest that the Cour Wind Farm is influencing the numbers or distribution of divers. Conclusion The Kintyre Red-throated Diver population may be, and the Black-throated Diver population is likely to be, in unfavourable condition. Opportunities for conservation should be considered, particularly to manage waterbodies so that they are optimal for breeding.

Data on hunting use of waterfowl resources in Yakutia

Scientific information on waterfowl harvesting in Yakutia is mostly outdated. The lack of reliable bag data prevents the establishment of sustainable use of waterfowl resources under the conditions of massive shooting and a modified legislation base. This research aimed to collect and analyze contemporary information on the hunting take of waterfowl (Anatidae, Coot, loons, and grebes) in Yakutia. We used data from the State Hunting Registry (2017–2022) to estimate the total harvest. Species-specific shares in hunting bags were identified using digital photographs of shot birds collected from the Internet in 2015, 2017, and 2018 (around 1000 photos). The distribution and results of traditional spring hunting of scoters were studied through a survey of hunters conducted in 2015. On average, 18,400 geese and 200,000 ducks were shot during the summer-autumn season, whereas 26,600 geese and 160,500 ducks were shot during the spring season. Overall, 23 waterfowl species were identified, namely three species of geese, 17 species of ducks, Coot, Arctic Loon, and Red-necked Grebe. The autumn bag included 22 species, of which the bean goose, mallard, Eurasian wigeon, and common teal were the most abundant. Spring bags consisted of 14 species with prevailing bean geese, common teals, northern pintails, and mallards. Based on “least concern” international and national conservation status we suggest to exclude the Chinese Spot-billed Duck, Gadwall, Common Scoter and Coot from the Red Data Book of the Republic of Sakha (Yakutia) and resume their hunting use.

Individual variation in song of Black-throated Divers (Gavia arctica)

The intention of the study was to determine whether male Black-throated Divers (Gavia arctica) can be distinguished individually by their vocalization. The songs of 19 male Black-throated Divers (BTDs) were recorded in their territories in the same lake area in 2018–2021 in Finland. The songs were recorded in one year in nine territories and in 2–4 consecutive years in ten territories. The song consists of one introductory phrase and one or more repeat phrases. Seventeen variables were measured from the spectrograms of the introductory phrase and the first repeat phrase. These variables included the frequencies and duration of different parts of the spectrogram. The discriminant analyses were used to examine the recognition of individual BTDs based on the spectral analysis of the male yodels (n = 297) in different territories (n = 19). The discriminant analysis showed that when using 14 of the variables of the yodels, the discriminant analysis classified the yodels to correct territories at a rate of almost 98% based on the cross-validation of all data. This suggests that the same individuals defend their territory from year to year.

Behavioural responses of non-breeding waterbirds to marine traffic in the near-shore environment

ABSTRACT Capsule Recording of behavioural responses to ferry traffic for 11 target species showed that Red-throated Diver Gavia stellata, Slavonian Grebe Podiceps auratus, and Black-throated Diver Gavia arctica were most likely to react to passing vessels. Aim To provide information on how responses to marine traffic vary between waterbird species to inform marine spatial planning and environmental impact assessments in the near-shore environment. Methods We recorded behavioural responses to ferry traffic for 11 target species in near-shore waters: Common Eider Somateria mollissima, Goldeneye Bucephala clangula, Long-tailed Duck Clangula hyemalis, Velvet Scoter Melanitta fusca, Red-breasted Merganser Mergus serrator, Black-throated Diver, Great Northern Diver Gavia immer, Red-throated Diver, European Shag Gulosus aristotelis, Slavonian Grebe and Black Guillemot Cepphus grylle. Responses were analysed using generalized linear models and mixed models. Results Red-throated Diver, Black-throated Diver and Slavonian Grebe were the most likely species to exhibit a response to passing vessels. While Red-throated Divers and Slavonian Grebes were highly likely to flush, Black-throated Divers and Great Northern Divers rarely took flight, instead favouring swim or dive responses. In rougher sea conditions birds were more likely to take flight, and the propensity to respond declined across the wintering period. Conclusions This research provides comparative evidence on the behavioural responses of waterbirds to marine traffic. The results support previous studies which highlighted the high sensitivity of diver species to disturbance and provide new evidence that Slavonian Grebe may also be a high sensitivity species.

Use of an INLA Latent Gaussian Modeling Approach to Assess Bird Population Changes Due to the Development of Offshore Wind Farms

The utilization of marine renewable energies such as offshore wind farming leads to globally expanding human activities in marine habitats. While knowledge on the responses to offshore wind farms and associated shipping traffic is accumulating now at a fast pace, it becomes important to assess the population impacts on species affected by those activities. In the North Sea, the protected diver species Red-throated Diver (Gavia stellata) and Black-throated Diver (Gavia arctica) widely avoid offshore wind farms. We used an explicit spatio-temporal Bayesian model to get a robust estimate of the diver population during the spring season between 2001 and 2018, based on a set of aerial surveys from long-term monitoring programs within the German North Sea. Despite the erection of 20 offshore wind farms in the study area and marked responses of divers to wind farms, model results indicated that there was no population decline, and overall numbers fluctuated around 16,600 individuals, with average annual 95% CI ranging between 13,400 and 21,360 individuals. Although, avoidance behavior due to wind farm development led to a more narrowly focused spatial distribution of the birds centered in the persistent high concentration zone in the Eastern German Bight Special Protection Area, the results provide no indication of negative fitness consequences on these long-lived species. However, more research is needed on habitat use and food availability in this regard.

The helminth fauna of brown trout (Salmo trutta) from a sub-alpine lake revisited after 40 years with introduced European minnow (Phoxinus phoxinus)

The helminth fauna of brown trout (Salmo trutta) in the Norwegian subalpine lake, Øvre Heimdalsvatn was studied by examination of gills, eyes, body cavity, kidney, stomach, pyloric region and intestine in a total of 112 brown trout randomly sampled in June, July, and September 2011. Ten helminth species, Discocotyle sagittata, Phyllodistomum umblae, Crepidostomum farionis, C. metoecus, Diplostomum sp., Proteocephalus sp., Cyathocephalus truncatus, Dibothriocephalus ditremus, D. dendriticus, and Capillaria sp. were identified. These data were compared to data from the period 1969 to 1972, just after the first record of the European minnow (Phoxinus phoxinus) in 1969. All ten helminth species, except D. dendriticus, were also present in 1969–72. However, a few major changes in infection intensities have occurred. The cestode D. ditremus and the trematode Diplostomum sp., both with piscivorous birds as final hosts, had markedly higher relative densities (abundance) in brown trout in 2011 compared to 1969–72, while the two Crepidostomum species showed a substantial decline in relative densities. We suggest that these changes may be indirectly related to the establishment and subsequent population increase of European minnow in the lake. The abundance of minnows may have increased the food basis for the piscivorous birds, primarily mergansers and the black-throated diver that now regularly forage in the lake. In addition, there have been changes in the littoral invertebrate community, including species serving as intermediate hosts of some of the brown trout parasites.

Behaviour of Black-throated Diver Gavia arctica and Red-throated Diver Gavia stellata during autumn migration stopover

The stopover behaviour of Black-throated Divers Gavia arctica and Red-throated Divers Gavia stellata during autumn migration was observed in two sites in Poland. Differences in time-activity budget and diving pattern were recorded from mid-October to mid-January of 2004 and 2005. A total of 1,516 minutes of observation was achieved. Birds spent their time diving (60.7%), followed by preening (14.8%), surface swimming (12.5%), and other activities (12%). The feeding pattern of Red-throated Divers and Black-throated Divers was similar. Immature birds had significantly longer dives than adults and they made longer dive-pause intervals. This is suggested to be caused by the differences between age classes in detecting and capturing prey. Moreover, our results show that, in autumn, first-year divers spent less time foraging than adult birds, instead spending more time resting and surface swimming.

A Ship Traffic Disturbance Vulnerability Index for Northwest European Seabirds as a Tool for Marine Spatial Planning

Ship traffic in Northwestern European seas is intense and continuing to increase, posing a threat to vulnerable seabird species as a result of disturbance. However, information on species-specific effects of ship traffic on seabirds at sea is limited, and tools are needed to prioritize species and areas to support the integration of conservation needs in Marine Spatial Planning. In this study, we investigated the responses of 26 characteristic seabird species in the German North and Baltic Seas to experimental ship disturbance using large datasets collected as part of the Seabirds at Sea counts. We developed a Disturbance Vulnerability Index (DVI) for ship traffic combining indicators for species’ shyness, escape costs, and compensatory potential, and analyzed the relationships among shyness, escape costs, and vulnerability. The DVI was calculated using the following eight indicators: escape distance, proportion of escaping birds, proportion of birds swimming prior to disturbance, wing loading, habitat use flexibility, biogeographic population size, adult survival rate, European threat and conservation status. Species-specific disturbance responses differed considerably, with common scoters (Melanitta nigra) and red-throated loons (Gavia stellata) showing the longest escape distances and highest proportions of escaping individuals. Red-throated loon,black guillemot (Cepphus grylle), Arctic loon (Gavia arctica), velvet scoter (Melanitta fusca), and red-breasted merganser (Mergus serrator) had the highest DVI values, and gulls and terns had the lowest. Contrary to theoretical considerations, shyness correlated positively with escape costs, with the shyest species also being the most vulnerable among the species studied. The strong reactions of several species to disturbance by ships suggest the need for areas with little or no disturbance in some marine protected areas, to act as a refuge for vulnerable species. This DVI can be used in combination with distribution data to identify the areas most vulnerable to disturbance.

Methylmercury and total mercury content in soft tissues of two bird species wintering in the Baltic Sea near Gdansk, Poland

Of the various forms of Hg occurring in nature, (mono) methylmercury (MeHg) is an especially toxic form and practically all forms of Hg can be converted into MeHg as a result of natural processes. Total mercury (THg) and MeHg were determined in tissues of two piscivorous birds: razorbill Alca torda and black-throated loon Gavia arctica to provide baseline data on current mercury concentrations for liver, kidneys and pectoral muscle mercury concentrations of birds which winter on the south Baltic Sea coast. Intra and inter-specific comparisons were carried out. The study is conducted between winter and autumn and the distributions of mercury in tissues were compared with data in other studies. The following paper contains discussion of the results based on the statistical analysis and ecology aspect. The highest average Hg content was in the liver (loon ≈ 3.86 mg kg−1 dw; razorbill ≈ 1.57 mg kg−1 dw), then in the kidneys (loon ≈ 3.14 mg kg−1 dw; razorbill ≈ 1.53 mg kg−1 dw) and the lowest concentrations were in pectoral muscles (loon ≈ 1.97 mg kg−1 dw; razorbill ≈ 0.67 mg kg−1 dw).

Mitochondrial genome of the black-throated loon, Gavia arctica (Gaviiformes: Gaviidae): phylogeny and evolutionary history

We sequenced the complete mitochondrial (mt) genome of Gavia arctica. The circular mt genome is 17,065 bp long, consisting of 37 genes (13 proteins, 22 transfer RNAs, and two ribosomal RNAs) and a control region. Phylogenetic analysis based on the full mt genome sequences confirmed that the genus Gavia is a monophyletic group, containing the G. stellata, G. arctica, and G. pacifica. These data can provide insights into the phylogenetic relationships for inferring the pattern and degree of mt genome evolution among the loon species.

Post-breeding densities, population sizes and lake size partitioning of loon species in western Chukotka, Russia

Loons (family Gaviidae) breed in small ponds and lakes across Arctic landscapes and are high level predators in the lake ecosystems. As such, they may serve as sentinel species, warning humans of alterations in habitat and ecosystem integrity in a region that is undergoing vast change due to climate warming. Here, we characterized the abundance and habitat use of four arctic breeding species of loons in the plains and surrounding mountains of western Chukotka, Russia. Loon surveys were conducted on foot and by boat from 2009–2015. Loon species differed in their use of the four lacustrine habitat types within the study area. In yedoma habitat, the yellow-billed loon (Gavia. adamsii) was the most abundant (0.593 birds/km2); on fluvial plain habitat, Pacific loons (G. pacifica) outnumbered other loons (0.701 birds/km2); mountain valleys were inhabited similarly by pacifica (0.354 birds/km2) and red-throated loons (G.stellata; 0.307); and maritime tundra was used only by pacifica (1.13) and Arctic loons (G. arctica; 0.553). G. adamsii was not observed in mountain valleys or maritime tundra. Mountainous portions of rivers were predominantly occupied by stellata and pacifica, and lowland rivers by stellata, pacifica and arctica. There was a significant difference in the size of lakes occupied by the four congeners. The largest loon, adamsii, occupied the largest lakes (0.69 km2), 80% larger than lakes utilized by pacifica (0.39 km2) and arctica (0.38 km2), and 35 times larger than stellata (0.02 km2). Most lakes were occupied by a single loon species (125/162, 77.2%).

Individual identification of Black-throated Divers (Gavia arctica)

The potential to identify individual Black-throated Divers (Gavia arctica) on the basis of breeding plumage features was explored using 278 photos, including two paired birds followed during the years 2007–2015 at a specific breeding location. Observations were focused on: 1) white lines on the sides of neck, 2)mantle having rows of sharply contrasting white squares, and 3) small white spots on lesser andmedian coverts. In photos, the number ofwhite lines on the sides of neck varied from four to seven (mean = 5.0, n = 278), and the second line from the head was the highest in 92.1% of the photos. The number of “white square” rows on the mantle varied from 11 to 14 and the small white spots on coverts from 27 to 67. Identification of individual Black-throated Divers was potentially easiest if the plumage had some special patterns (19.4% of birds, n = 278). Plumage remained the same in the followed pair between years, as was also shown by the discriminant analysis, since the followed pair was correctly classified by sex but not by sides showing that sides are similar. To estimate whether it is possible to separate these two birds from other birds, a second discriminant analysis was accomplished. Thus, 125 other birds were added to analysis as a third group together with the followed pair (female andmale, nine years and n = 18 per sex). The linear discriminant analysis yielded a classification rate of 70.8% in original analysis and 69.6% based on the leave-one-out analysis (n = 161). These analyses were based on the relative height of the neck lines, their average relative height and standard deviation.When the number ofwhite spotswere added to this discriminant analysis, a correct classification rate of 77.4% in original analysis and 75.7% in the leave-one-out analysis was obtained (n = 115). These analyses suggest that the plumage can be used in identification, especially when following nesting pairs during their breeding seasons in different years. Presumed female andmaleBlack-throatedDiver could be distinguished based on the shape of the forehead.

Сезонная динамика гидрофильного орнитокомплекса бухты Круглая (Севастополь, Чёрное море)

Актуальность изучения гидрофильных птиц в городских зонах черноморского побережья обусловлена их важной ролью в структуре прибрежных биоценозов и необходимостью сохранения биоразнообразия в условиях антропогенной трансформации береговой зоны Крыма. Исследована динамика видового состава и численности птиц бухты Круглая (Севастополь). Материал собран в 1995 и 2005–2016 гг. В бухте Круглая установлено пребывание 51 вида водных и околоводных птиц из 8 отрядов. Зимний орнитокомплекс наиболее разнообразен и многочислен (32 вида: 14 Anseriformes, 7 Charadriiformes, 5 Podicipediformes, 3 Gruiformes, 2 Pelecaniformes, 1 Gaviiformes). Регулярно зимуют и количественно доминируют 8 видов – Cygnus olor, Anas platyrhynchos, Aythya ferina, Aythya fuligula, Fulica atra, Larus ridibundus, Larus cachinnans и Larus canus. Определены численность всех видов птиц, возрастной состав Cygnus olor и половой состав Anas platyrhynchos, Aythya ferina и Aythya fuligula. Основу орнитокомплекса составляли бентофаги (не менее 13 видов), ихтиофаги (5) и эврифаги (4). Отмечено 30 пролётных и кочующих видов, преимущественно Charadriiformes (11), Anseriformes (7) и Ciconiiformes (5). Гнездовой орнитокомплекс отсутствовал, только в 2016 г. зарегистрировано гнездование Ixobrychus minutus. Весенний пролёт проходил с конца февраля до мая, осенний –– с августа до первой декады ноября. Для сохранения данной бухты как ценного природного и эколого-воспитательного объекта целесообразно придание ей статуса природного парка.

Reduced survival of Black-throated Diver Gavia arctica chicks - an effect of changes in the abundance of fish, light conditions or exposure to mercury in the breeding lakes?

The breeding success of Black-throated Diver Gavia arctica in Sweden has been monitored in the period 1994– 2014. The production of young was in balance with the annual mortality, without any temporal trend. However, the percentage of broods with 2–3 chicks decreased significantly, indicating reduced survival of the unfledged chicks. Three plausible causes were investigated: abundance of fish, impaired water visibility, and exposure to methylmercury. There is no indication of any changes in abundance of the main prey fish, such as Perch Perca fluviatilis. Impaired light conditions have been recorded in lakes in South Sweden, but not in the central and northern parts, so increased difficulties in localising prey fish might have been a contributing factor but cannot fully explain any reduction in chick survival. Exposure to methylmercury, however, deserves further study. For Perch, which is the main prey in most breeding lakes, the average mercury levels in muscle tissue exceeds levels for proposed screening benchmarks, with reference to risk of behavioural aberrations or impaired reproduction in Common Loon Gavia immer in North America.

Host specificity and seasonality of helminth component communities in central European grebes (Podicipediformes) and loons (Gaviiformes)

Structure and pattern of helminth component communities parasitizing grebes and loons are poorly understood. Here we analyze the prevalence, intensity and diversity of helminths in 505 Czech grebes (Podiceps cristatus, Podiceps nigricollis, Tachybaptus ruficollis) and loons (Gavia arctica, Gavia stellata) collected between 1962 and 2014. The species richness of helminth component communities ranged from 31±8 (P. cristatus) to 50±4 (G. stellata) species, with helminth load similar in all five host species, but with strong differences in prevalence and intensity of infection at a helminth species-specific level. The dominance was low, ranging from 0.11 (P. cristatus and G. stellata) to 0.21 (P. nigricollis). Dominant species (>25% prevalence) in P. cristatus were Confluaria sp., Tylodelphys clavata, Echinochasmus coaxatus, Petasiger neocomense and Ligula colymbi; in P. nigricollis and T. ruficollis: Confluaria sp. and Tatria sp.; in G. arctica and G. stellata: Tetrabothrius microcephalus, Stephanoprora denticulata, Cryptocotyle concava, Diplostomum gavium and Ichthyocotylurus erraticus; in G. stellata only: Echinochasmus (Monilifer) spinulosus. Four (12%) of the grebe digenean species were not locally acquired (with non-sympatric intermediate hosts) despite the fact that they represented 25% of digenean individuals found. In loons, five (28%) of digenean species and striking 38% of individuals found used the non-sympatric intermediate host species. Component communities of grebes were similar to each other (Sørensen similarity index 0.47–0.65) but differed strongly from those hosted by loons (0.00–0.20). We present the first systematically collected evidence of intra-annual changes of helminth component communities in grebes, and provide 20 new host records.

Diversity and abundance of water birds in a subarctic lake during three decades

The numbers of divers, ducks, gulls, terns and waders in the 15 km2 oligotrophic lake Takvatn, North Norway were estimated six times during 1983-2012. Systematic mapping surveys were done by boat within the first week after ice-break in June. Twenty-one species were observed over the years and 12 were regarded as breeding on the lake. Red-breasted merganser Mergus serrator was the dominant diving bird, with estimated minimum number of pairs varying from 15 to 39 among years. Black-throated diver Gavia arctica (1-3 pairs), tufted duck Aythya fuligula (2-15 pairs) and common scoter Melanitta nigra (1-5 pairs) bred regularly, while velvet scoter Melanitta fusca (1-2) and goldeneye Bucephala clangula (2-4) were found in some years and mallard Anas platyrhynchos (1 pair) and wigeon Anas penelope (1 pair) in one year. Common gull Larus canus (6-30 pairs) and arctic tern Sterna paradisaea (2-35 pairs) bred in all years. Common sandpiper Tringa hypoleucos (3-9 pairs) and redshank Tringa totanus (1-4 pairs) were regular waders. Density variations of mergansers, gulls and terns are possibly related to density variations of three-spined sticklebacks Gasterosteus aculeatus, their dominant fish prey. The water birds are important links in the food web of the lake.

Ways of developing acoustic signals in birds

An analysis of Russian and foreign literature data on the ways of developing acoustic signals in birds is presented. The physical analysis of acoustic signals is given for six species of birds: long-tailed skua (Stercorarius longicaudus Uicill), herring gull (Larus argentatus Pontopp.), sabine’s gull (Xema sabini sab.), curlew sandpiper (Calidris ferruginea Pantopp.), red-throated diver (Gavia stellata Pontopp.), and black-throated diver (Gavia aterica L.). Signals of embryos, baby birds, and adult birds are considered. The denervation of the syrinx in baby and adult birds was investigated to obtain a pattern of generation of acoustic signals in the absence of syrinx innervation. The temporal-frequency signal characteristics are compared to those of decapitated birds. The examples of acoustic signals of these birds confirm the significant role of the physical characteristics of morphological structures participating in the generation of acoustic signals in birds.

Vattenkemi och fiskbeståndens sammansättning i storlommens Gavia arctica häckningssjöar, samt en jämförelse med smålommens Gavia stellata fiskesjöar

Breeding performance of Black-throated Diver Gavia arctica was compared to water chemistry, light penetration and density of fish in 122 breeding lakes in Sweden with a total of 184 pairs (1.5 pairs per lake, about 3% of the national population). The breeding lakes were on average nutrient-poor, and 12% of them had a low buffering capacity (alkalinity <0.10 meq/l). Perch Perca fluviatilis, roach Rutilus rutilus and pike Esox lucius, three species characteristic for nutrient-poor lakes, were found in more than 90% of the lakes. Salmonid fish occurred in half of the lakes, compared to >90% of the fishing lakes used by Red-throated Diver. Reproduction was related to high abundance of Perch, and the survival of chicks to light penetration. Poor nutrient status in combination with low pH or alkalinity in approximatively 10% of the breeding lakes of Black-throated Diver and probably more than 30% of the fishing lakes of Red-throated Diver, indicate susceptibility of exposure to methylmercury. This finding should be considered in relation to recent reports of increased contents of mercury in freshwater fish.

Taxonomic recommendations for British birds: Fifth report

Taxonomic recommendations for British birds: Fifth report

한국에 도래하는 아비류의 카드뮴과 납 축적 레벨

부산 연안에서 월동 중 사망한 아비류 3종 25개체의 체내 조직 중 카드윰과 납 축적 레벨을 밝히고 오염 수준을 파악하였다. 카드뮴과 납 농도는 아비, 회색머리아비, 큰회색머리아비 3종간에 종간차가 인정되지 않았다(p>0.05). 조직 중 카드뮴 농도는 0.02<TEX>$\sim$</TEX>18.3<TEX>${\mu}g/g$</TEX>의 범위로 신장에서 가장 높고 뼈에서 가장 낮은 정상적인 조직분포를 보였다. 간 조직 중 카드뮴 농도 (3.45<TEX>$\sim$</TEX>6.34<TEX>${\mu}g/g$</TEX>)는 다른 나라에서 보고된 아비류 농도(ND<TEX>$\sim$</TEX>7.11<TEX>${\mu}g/g$</TEX>)와 비슷하였다. 큰회색머리아비 1개체를 제외한 모든 개체의 신장 조직 중 카드뮴 농도는 비오염수준(<30 <TEX>${\mu}g/g$</TEX>)에 해당하였다. 조직 중 납 농도는 0.03<TEX>$\sim$</TEX>1.49<TEX>${\mu}g/g$</TEX>의 범위로 뼈에서 가장 높고 근육에서 가장 낮은 정상적인 조직분포를 보였다. 간 조직 중 납 농도(0.19<TEX>$\sim$</TEX>1.22<TEX>${\mu}g/g$</TEX>)는 보고된 정상적인 아비류 농도와 비슷하였다. 대부분의 간 조직 중 납 농도는 비오염수준(0.15<TEX>$\sim$</TEX>3.0 <TEX>${\mu}g/g$</TEX>)에 해당되었다. We investigated Cd and Pb accumulation levels in tissues of 25 individuals of three species of loons wintering in coastal areas of Busan, Korea. Their liver, muscle, kidney and bone tissues were analyzed for Cd and Pb concentrations. Significant difference of Cd and Pb concentrations was not found among the three species (p>0.05). Individual Cd values ranged from 0.02 to <TEX>$18.3{\mu}g/g$</TEX>. Cd concentrations were highest in kidney and lowest in bone. Levels (3.45<TEX>$\sim$</TEX>6.34 <TEX>${\mu}g/g$</TEX>) of all the analyzed liver Cd were similar in comparison with those (ND<TEX>$\sim$</TEX>7.11<TEX>${\mu}g/g$</TEX>) reported for the loons in different areas. All but one (Gavia arctica) of kidney Cd levels were lower than the exposed level (>30 <TEX>${\mu}g/g$</TEX>). Individual Pb values ranged from 0.03 to 1.49 <TEX>${\mu}g/g$</TEX>. Pb concentrations were highest in bone and lowest in muscle. Liver Pb levels in this study were similar to those of normal loons reported from different countries. Based on hepatic Pb levels, almost all of the samples were classified as background level (0.15<TEX>$\sim$</TEX>3.0 <TEX>${\mu}g/g$</TEX>).