Organochlorines and mercury in the eggs of Golden Eagles Aquila chrysaetos from Scotland

This paper documents the organochlorine levels found in unhatched eggs from 234 clutches of Golden Eagles Aquila chrysaetos obtained in Scotland during 1963-86. Organochlorine levels were highest in eggs from western coastal districts, somewhat lower in eggs from western inland districts, and lower still in eggs from eastern districts. These regional trends were associated with corresponding dietary differences.
Levels of HEOD declined in western districts during the period 1963-86, but not in eastern districts where they were low throughout. Levels of DDE declined generally, but significantly only in the east. In contrast, levels of PCBs increased generally, but significantly only in western inland districts.
No differences in organochlorine levels were found between clutches that produced no young and those that produced one young.
Mercury residues were examined in eggs from 66 clutches obtained during 1981-86. Low levels were detected in 10 out of 29 eggs from western coastal districts, in 2 out of 27 eggs from western inland districts, and in none out of 10 eggs from eastern districts.     

ORGANOCHLORINE RESIDUES AND EGGSHELL THINNING IN THE PEREGRINE FALCON FALCO PEREGRINUS MINOR IN ZIMBABWE

Hartley, R.R., Newton, I., & Robertson, M. 1995. Organochlorine residues and eggshell thinning in the Peregrine Falcon Falco peregrinus minor in Zimbabwe. Ostrich 66: 69–73.

Several types of organochlorine residues were found in eggs of Peregrine Falcons Falco peregrinus minor taken in Zimbabwe in 1990. DDE (range = 0.2–22 ppm wet weight; geometric mean 1.8 ppm) was found in all eggs (n = 15) from 13 sites, including two pars in captivity. Eggs from two sites in the mid-Zambezi Valley, the most recently and heavily sprayed areas (5–8 times for tsetse fly Glossina sp. control), had the highest levels, one beyond that regarded as critical for successful reproduction. Mean shell thickness (Ratcliffe index) of the 1990 eggs was 10% (range = 2–29%) lower than the presumed pre-DDT mean. HEOD was detected in two eggs, HCB in one egg, and PCBs in all eggs, but at levels too low to affect breeding performance. Young were fledged from each of 12 sampled sites, yielding 1.86 young per site.     

Residue levels of organochlorine and mercury compounds in unhatched eggs and the relationships to breeding success in white-tailed sea eagles Haliaeetus albicilla in Sweden

Eighty-five unhatched eggs from 68 white-tailed sea eagle clutches were collected during 1965–1978 along the Baltic coast and in Lapland. The eggs were analysed individually for residue levels of DDT and its metabolites, PCB and mercury. Pooled samples were analysed for levels of dieldrin and hexachlorobenzene (HCB). The variations in residue levels within and between clutches were studied before the material was grouped for investigations of relationships between reproduction and contamination.
Levels of DDE, PCB and mercury were significantly higher in the Baltic as compared to the Lapland material. In the Baltic, the reproductive success on a clutch basis and on a nest basis was significantly and negatively correlated to the egg residue levels of DDE and PCB; no correlation was found with mercury. Critical ranges were estimated to 500–600 mg kg¹ of DDE and/or 800–900 mg kg⁻¹ of PCB (lipid basis). The levels of dieldrin and HCB in the pooled samples were not considered important to reproduction. In a comparative study including six sea eagle and six bald eagle populations, productivity showed the strongest correlation with DDE.     

Umweltchemikalien in Eiern von Binnenland- und Wattenmeerbrütern des Austernfischers (Haematopus ostralegus)

Zusammenfassung 1994/95 durchgeführte Vergleichsuntersuchungen zur Belastung von Binnenland- und Wattenmeerbrütern des Austernfischers mit den Bioziden DDT, DDE und HCH sowie den Industriechemikalien PCB, HCB und Hg ergaben in Austernfischer-Eiern vom Unteren Niederrhein signifikant höhere Konzentrationen chlororganischer Verbindungen als in Eiern der Wattenmeerinseln Griend (NL) und Mellum (D). Nur Hg wurde in niederrheinischen Eiern in hoch signifikant geringerer Konzentration gefunden als in Eiern von Brutvögel des Wattenmeeres. Austernfischer-Eier von Griend waren bezüglich der meisten analysierten Parameter geringer belastet als Eier von Mellum (Ausnahmen: pp'DDT, PCB). Von den untersuchten Umweltchemikalien war die PCB-Konzentration in allen drei Untersuchungsgebieten am höchsten. Die hohe PCB-Kontamination am Unteren Niederrhein spiegelt die auch heute noch erhebliche Belastung des Flusses mit Altlasten wider. Weder die Konzentration der untersuchten Industriechemikalien noch die der Biozide dürften von embryotoxischer Wirkung gewesen sein.

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Environmental chemicals in eggs of inland and Wadden Sea breeding Oystercatchers (Haematopus ostralegus)

Summary Due to the international importance of the Wadden Sea for waders and waterfowl a long-term programme to monitor contamination of birds breeding in the Wadden Sea has been established in the early 1980s. One of the species selected is the Oystercatcher. Comparatively little is known about contamination of birds breeding inland. Therefore, we collected eight eggs of Oystercatchers breeding at the Lower Rhine (district of Kleve) and analysed their contamination with biocides (DDT, DDE, HCH) and industrial chemicals (PCB, HCB, Hg) in comparison to birds breeding on the Wadden Sea islands of Griend (NL) and Mellum (D), where ten eggs were collected in 1994/95. We found distinctive differences between inland and Wadden Sea breeding Oystercatchers. Eggs from the Lower Rhine had significantly higher residues of all organochlorines, whereas concentration of mercury was significantly lower than in those from birds breeding on the Wadden Sea islands. In general, eggs collected on Griend held lower concentrations than those collected on Mellum island, except pp'-DDT and PCB. The high PCB contamination in Ostercatcher eggs from the Lower Rhine nowadays reflects the extreme pollution in the past. However, concentrations of the parameters studied obviously had no embryotoxic effects in Oystercatchers.

     

Organochlorine exposure and health effects in stranded Steller sea lions (Eumetopias jubatus) and Pacific harbor seals (Phoca vitulina richardii) from Oregon and southern Washington coasts

Organochlorine (OC) pesticides and polychlorinated biphenyls (PCBs) have been detected in a variety of marine mammal species at levels associated with adverse health effects. Little is known about OC levels and impacts on health in pinnipeds with different life histories. We determined the health and levels of 18 OC pesticides and 16 PCB congeners in blubber samples from 20 Steller sea lions and 39 Pacific harbor seals stranded from Oregon and Southern Washington. The most commonly detected OC at the highest concentration was p,p′- dichlorodiphenyldichloroethylene (DDE). PCBs were detected in all samples as well. Hypothesis testing indicated that diseased Steller sea lions (males and females combined) had higher contaminant concentrations than healthy Steller sea lions, and diseased Pacific harbor seals had higher concentrations of total OCs than healthy animals. Differences were also noted between diseased and healthy animals when looking at individual sexes of each species. Diseased Steller sea lions had higher mean contaminant levels than diseased harbor seals and healthy Steller sea lions had higher mean contaminant concentrations than healthy Pacific harbor seals. These results show that species differences exist in both contaminant loads and sensitivity to contaminants, which may be due to differences in life histories and physiology.     

Comparison of two techniques for quantifying environmental contaminants in human serum

Peak area matching and linear regression were used to quantify eight chlorinated pesticides and polychlorinated biphenyls (as Aroclor 1260) in human serum. There are no statistically significant differences in data obtained by these two quantifying techniques which were indicated by the paired t-test. For chlorinated pesticides, p = 0.053-0.62, and for polychlorinated biphenyls (as Aroclor 1260), p = 0.64. Analyte residues for the chlorinated pesticides ranged from 0.5 ppb for hexachlorobenzene (HCB) to 186 ppb for dichlorodiphenyldichloroethylene (DDE). Analyte residues for the polychlorinated biphenyls (as Aroclor 1260) ranged from 5-114 ppb. The absolute mean percent difference between the two quantifying techniques ranged from 0.06% for DDE to 8.06% for dieldrin (HEOD) among the chlorinated pesticides. The absolute mean percent difference between the two quantifying techniques for the polychlorinated biphenyls (as Aroclor 1260) was 3.4%. Peak area matching and linear regression were found to be comparable for quantifying these environmental residues in serum when the following conditions apply: 1) the concentration of the chlorinated pesticides is greater than or equal to 0.5 ppb (e.g., HCB, hexachlorocyclohexane (HCCH), oxychlordane (OC), heptachlor epoxide (HE), transnonachlor (TN), HEOD, and dichlorodiphenyltrichloroethane (DDT); 2) the concentration of the chlorinated pesticide is greater than or equal to 3 ppb (e.g., DDE); and 3) the total concentration of polychlorinated biphenyls (e.g., as Aroclor 1260) is greater than or equal to 5 ppb.     

Effects of PCBs, DDT, and mercury compounds in chickens and Japanese quail.

In well-controlled experiments using white leghorn chickens and Japanese quail, dietary polychlorinated biphenyls (PCBs), DDT and related compounds produced no detrimental effects on eggshell quality. A drastic reduction in hatchability of chicks occurred with 10-20 ppm PCBs, but no detrimental effects on eggshell quality, egg production or hatchability were found with 0.5 and 1.0 ppm PCBs, or DDT up to 100 ppm. Dietary PCBs potentiated a vitamin E-selenium deficiency in the chick, increased exudative diathesis, and decreased plasma glutathione peroxidase levels. Dietary PCBs induced hepatic microsomal benzopyrine hydroxylase. Dietary levles of 100 or 200 ppm inorganic mercury as HgSO4 or HgCl2 had little effect on egg production, hatchability, shell quality, morbidity and mortality. Methylmercury chloride, however, at levels providing 10 or 20 mg Hg/kg of diet, severely affected all of these parameters. Even though the present experiments demonstrate that neither DDT nor PCBs has any effect on eggshell quality in chickens and Japanese quail, they may cause thinning of eggshells in other species. Controlled experiments are lacking. Eagles, ospreys and pelicans all consume fish which in many areas of the world are known to contain methyl mercury. The thinning of eggshells in the species in the wild may have been due, at least in part, to environmental contamination with methylmercury rather than DDT, DDE or PCBs, as has been claimed.     

Mercury levels in feathers of eagle-owls Bubo bubo in a captive, a reintroduced and a native wild population in SW Sweden

Mercury levels in feathers are presented for both captive and wild eagle-owls from the period 1963-1976. Levels are compared between wild birds occupying old territories and released birds in newly occupied territories. The wild population in SW Sweden shows decreasing levels in the inland territories, and at present these levels are similar to the natural background level. The coastal owls have significantly higher levels which show no decrease. Low levels prevail in captive eagle-owls, fed on low-contaminated food. Birds in newly occupied territories (mainly released birds) have similar mercury levels as native birds. After being released captive birds therefore seem to accumulate mercury rather quickly.     

Dynamics of storage of organochlorine pollutants in herring gulls

Several organochlorine pollutants were studied over the period of one annual cycle in caged juvenile and wild-collected adult herring gulls (Lagus argentatus) from Lake Michigan. Fish, mostly alewives (Alosa pseudoharengus), comprised the major year-round food items in the wild; alewives were also fed to the caged juveniles. Fish residues averaged around 3 mg/kg of p,p′-DDE, 2 mg/kg p,p′DDT + p,p′-TDE, and 2 mg/kg apparent PCBs. Juvenile body-burdens of DDE and PCBs showed a continual buildup after fledging, then a temporary dynamic equilibrium, related only in part to annual lipid deposition. Maximum body-burdens were reached in both juveniles and adults when winter fat deposits were declining prior to the breeding season—followed by a return to dynamic equilibrium. Residues of DDT and TDE followed closely the annual pattern of lipid deposition in both juveniles and adults. Total body-burdens in both age classes were similar after the buildups to equilibrium in juveniles in their eighth month after fledging. Seasonal variations of residues of DDE and PCBs were characterised by two phases in adults and three in juveniles, which gradually assumed the adult cyclic pattern. The maximum body-burdens attained by caged juveniles fed a diet of Lake Michigan alewives were 290mg/kg DDE, 19 mg/kg DDT + TDE, and 200 mg/kg apparent PCBs. Residues in wild adults at the same time were 300, 4, and 200 mg/kg of the same residues. Apparent PCBs and DDE were highly accumulative, although DDE levels resulted from dietary DDE, as well as conversion from DDT.     

Mortality causes in British Barn Owls Tyto alba, with a discussion of aldrin-dieldrin poisoning

During 1963-89, 627 Barn Owl Tyto alba carcasses were received for autopsy and chemical analysis. Much larger numbers were received per month outside the breeding season than within it, with peaks in autumn (mainly juveniles) and late winter (adults and juveniles).
The main causes of recorded deaths were collisions (mostly with road traffic) and starvation. No great seasonal variation occurred in the main causes of recorded deaths and starved juveniles were reported even in summer. Most starved males weighed less than 240 g, and most starved females less than 250 g.
Another important cause of mortality in eastern arable counties, at least to 1977, was poisoning by organochlorine pesticides, especially aldrin/dieldrin. Levels of HEOD (the metabolized product of aldrin/dieldrin) in the livers of birds that had apparently died of aldrin/ dieldrin poisoning were in the range 6–44 ppm (geometric mean 14 ppm). Pesticide victims formed up to 40% of all dead Barn Owls obtained from some eastern counties during 1963-77. By 1987-89, HEOD levels in Barn Owls in eastern counties had fallen to less than 1.6 ppm, and no deaths from organochlorine poisoning were recorded.
Organochlorine pesticides almost certainly contributed to population decline in eastern England evident in the 1950s and 1960s, and reductions in the use of these chemicals may have allowed a subsequent increase, apparent over the last 10–15 years.     

Monitoring of level of mean concentration and toxicity equivalence (TEQ) of polychlorinated biphenyls (PCBs) in selected vegetables,beans and grains in khanewal and multan,Pakistan

Contamination of food chain by Polychlorinated biphenyls through use of pesticides, electric and industrial waste poses human health risk. In previous studies, PCB species were stated as endocrine disrupting pollutants and showed toxic health effects like cancerous and noncancerous in animals. The aim of this study was to investigate the levels of PCBs and its toxicity equivalence in food item from plant source to evaluate the health risk in Khanewal and Multan, Pakistan. Samples were collected and processed for further analysis of PCB species through GC/MS after extraction and clean up. The mean concentrations of PCBs ranged as 2.71–151.67 ng/g in beans and grains and 2.30–97.00 ng/g dry weight in vegetables and were lower than 200–3000 ng/g PCBs recommended by FDA tolerance level for all foods. The mean concentrations of two NDL-PCB species detected in all vegetables, beans and grains except S.indicum and T.aestivum were lower than maximum allowable concentration of non-dioxin like PCBs i.e. 40ngg^?1 reported by European Commission. Mean TEQ of sum of 14 PCB species ranged as 1.52–5.91 ng-WHO-TEQg^?1 in vegetables and 1.46–10.04 ng-WHO-TEQg^?1 in beans and grains. The present study concluded that the mean concentrations and mean TEQs of PCB species in most of the vegetables, beans and grains were found safe but due to higher consumption rate of some vegetables and grains, posed the moderate level of risk for human health. This study emphasizes on an implement of the strict rules regarding the use of restricted chemicals to diminish the effluence in food chains. Current research will be useful in up gradation of effective measures to reduce the poisonous contribution of PCB sources and the sustainability of terrestrial ecosystem in the country.     

Distribution and ecological risks of polychlorinated biphenyls (PCBs) in surface sediment of the Forcados River,Niger Delta,Nigeria

Concentrations of Σ15 PCBs in sediments of the Forcados River, Nigeria, were determined in 2012 to provide information on the profile, sources and ecotoxicological risks of PCBs in the sediment. The screening concentrations of PCBs were quantified using a gas chromatograph equipped with a Ni-63 electron capture detector. The concentrations of the Σ15 PCBs ranged from 2.7 to 202.3 µg kg???1 with a mean concentration of 46.5 µg kg???1. The composition of PCB congeners was clearly dominated by octa-PCBs, hepta-PCBs and hexa-PCBs, constituting 68.1% to 93.7%, respectively, of the total amounts of PCBs. All sites had Σ15 PCB levels below the prescribed probable effect concentrations, and therefore no adverse effects are expected for the majority of sediment-dwelling organisms of the Forcados River system.     

Organochlorine and mercury residues in fish from Lake Simcoe,Ontario 1970–76

Synopsis Lake Simcoe located in the central Ontario plain has four major streams draining the watershed. Persistent organochlorine insecticides were used in the basin for mosquito control and agricultural production until restricted. Methyl mercury compounds have been phased out and a voluntary restriction occurred for PCB.Ten species of fish were collected between 1970 and 1976 for organochlorine and mercury analysis. DDT residues significantly declined between 1970 and 1975–76 in all species except small Stizostedion vitreum vitreum and large Salvelinus namaycush. Eggs taken 1975–76 from small S. namaycush had DDT residues below the critical level reported for the production of viable offspring, but this was not so for large members.HEOD residues between 1970 and 1975–76 significantly declined in five species, showed no change in two, whereas in two species the Larger members of one had Lower residues and the smaller members of the other showed no change.PCB residues declined.in all species except the larger Perca flavescens. Chlordane and heptachlor-epoxide were identified in S. namaycush for the first time in 1975–76. Mercury residues showed no change between 1970 and 1975–76 in five species, it declined in two species and increased in small S. v. vitreum.Correlations existed between Levels of organic contaminant and Lipid content of fish especially in the immediate post period of their use. Where the increasing Lipid content was associated with an increasing trophic level a preypredator relationship existed for contaminant accumulations. However, where Lipid contents were Low, no correlation appeared to exist in the prey-predator.     

Mercury and chlorinated hydrocarbons in the food chain of Lake Päijänne, Finland

The sediments and various organisms in Lake Päijänne were examined for contaminants. The average mercury content of water plants was 9, of plankton 14, of sediment 114, of zoobenthic predators 83, of fish 332–1510 and of birds 240–13685 μg kg⁻¹ (wet weight). The average PCB content of plants was 3, of plankton 21, of the zoobenthos 44, of fish 36-117 and of birds 219–13490 μg kg⁻¹. The average ΔDDT content of plants was 0.5, of plankton 6, of the zoobenthos 14, of fish 7–42 and of birds 144-8262 μg kg⁻¹. Regional differences in mercury content were most pronounced in sediment and fish. PCB concentration was highest near a town. ΔDDT was quite evenly distributed. Water plant species did not differ from each other, nor did the plankton fractions. The zoobenthic predators contained more chlorinated hydrocarbons than did the herbivores. There were clear differences between most species of fish and the chlorinated hydrocarbon content was highest in vendace. In adult birds levels of all residues were significantly higher than in juveniles.
In most cases PCB content was positively correlated with ΔDDT and in birds PCB, ΔDDT and mercury levels were correlated. DDT residues occurred mostly as DDE, but in vendace the proportion of DDT was high. At most trophic levels, ΔDDT/PCB was 0.15-0.40 but in birds it reached 1–2.     

Residues of DDE and PCB in Eggs from Herring Gull (Larus Argentatus) and Common Gull (Larus Canus) in Norway

In 1969 294 eggs from herring gull were collected from eight different localities in Norway. The eggshell thicknesses were measured, and 10 eggs from each locality were analysed by gas liquid chromatography for organochlorine insecticides and polychlorinated biphenyls (PGB). Residues of DDE were demonstrated in all eggs, the concentrations varying from 0.2 to 5.4 p.p.m. in herring gull, and from 0.2 to 3.5 p.p.m. in common gull. DDT occurred only in four eggs from herring gull and then only in concentrations of from 0.1 to 0.3 p.p.m. Other organochlorine insecticides were not detected. Residues of PGB were found in all eggs from herring gull in concentrations of from 0.2 to 3.8 p.p.m. PGB 10, and in six out of nine eggs from common gull, from trace to 0.8 p.p.m. PGB 10. The analysed material showed a positive correlation between amounts present of DDE and of PGB. There was a significant difference between localities concerning the contents of DDE and PGB in eggs from herring gull. This variance may be taken into consideration by using the herring gull as an indicator organism, since this bird, especially in the northern part of Norway, is migratory. The residue concentrations of DDE and PGB were markedly higher in eggs from herring gull than in eggs from common gull. It is suggested that this may be related to the difference between these species in their feeding habits. The residues of organochlorines demonstrated in this investigation do not seem to have had any effect on eggshell thickness in herring gull.     

Geographic variation of PCB congeners in polar bears (Ursus maritimus) from Svalbard east to the Chukchi Sea

We present data on geographic variation in polychlorinated biphenyl (PCB) congeners in adult female polar bears (Ursus maritimus) from Svalbard eastward to the Chukchi Sea. Blood samples from 90 free-living polar bears were collected in 1987-1995. Six PCB congeners, penta to octa chlorinated (PCB-99, -118, -153, -156, -180, -194), were selected for this study. Differences between areas were found in PCB levels and congener patterns. Bears from Franz Josef Land (11,194 ng/g lipid weight) and the Kara Sea (9,412 ng/g lw) had similar DPCB levels and were higher than all other populations (Svalbard 5,043 ng/g lw, East Siberian Sea 3,564 ng/g lw, Chukchi Sea 2,465 ng/g lw). Svalbard PCB levels were higher than those from the Chukchi Sea. Our results, combined with earlier findings, indicate that polar bears from Franz Josef Land and the Kara Sea have the highest PCB levels in the Arctic. Decreasing trends were seen eastwards and westwards from this region. Of the congeners investigated in the present study, the lower chlorinated PCBs are increasing and the high chlorinated PCBs are decreasing from Svalbard eastward to the Chukchi Sea. Different pollution sources, compound transport patterns and regional prey differences could explain the variation in PCB congener levels and patterns between regions.     

Maternal steroids and contaminants in common tern eggs: a mechanism of endocrine disruption?

We looked for evidence for the hypothesis that exposure of female birds to polychlorinated biphenyls (PCBs) results in alteration of blood steroid hormone concentrations and alters subsequent hormone transfer of steroids to eggs. Eggs of three-egg clutches were collected from a PCB-exposed common tern (Sterna hirundo) colony (Ram Island, Buzzards Bay, MA, USA) and from a relatively clean colony (Bodkin Island, Chesapeake Bay, MD, USA), and were analyzed for concentrations of organochlorine contaminants and steroid hormones (17beta-estradiol, 5alpha-dihydrotestosterone, testosterone and androstenedione). There was no relationship between total PCBs and steroid concentrations considering all eggs together, considering eggs of different laying order or considering differences between sequentially laid eggs in a clutch. Similarly, concentrations of di- and tri-chlorinated biphenyls and steroids in eggs were not related. The concentrations of PCBs, mercury and selenium were below estimated thresholds for toxicity to embryos. Maternal steroids, except estradiol, were present in yolk of all eggs, with increasing concentrations in the second and third eggs laid. Our data provided no evidence for a maternal toxicological event that might alter the amount of maternal steroid hormone transferred to eggs.     

Effects of Age,Adipose Percent,and Reproduction on PCB Concentrations and Profiles in an Extreme Fasting North Pacific Marine Mammal

Persistent organic pollutants, including polychlorinated biphenyls (PCBs), are widely distributed and detectable far from anthropogenic sources. Northern elephant seals (Mirounga angustirostris) biannually travel thousands of kilometers to forage in coastal and open-ocean regions of the northeast Pacific Ocean and then return to land where they fast while breeding and molting. Our study examined potential effects of age, adipose percent, and the difference between the breeding and molting fasts on PCB concentrations and congener profiles in blubber and serum of northern elephant seal females. Between 2005 and 2007, we sampled blubber and blood from 58 seals before and after a foraging trip, which were then analyzed for PCBs. Age did not significantly affect total PCB concentrations; however, the proportion of PCB congeners with different numbers of chlorine atoms was significantly affected by age, especially in the outer blubber. Younger adult females had a significantly greater proportion of low-chlorinated PCBs (tri-, tetra-, and penta-CBs) than older females, with the opposite trend observed for hepta-CBs, indicating that an age-associated process such as parity (birth) may significantly affect congener profiles. The percent of adipose tissue had a significant relationship with inner blubber PCB concentrations, with the highest mean concentrations observed at the end of the molting fast. These results highlight the importance of sampling across the entire blubber layer when assessing contaminant levels in phocid seals and taking into account the adipose stores and reproductive status of an animal when conducting contaminant research.     

Long-term investigation of the degree of exposure of German peregrine falcons ( Falco peregrinus) to damaging chemicals from the environment

The contamination of German peregrine falcons (Falco peregrinus) with organochlorine (CHC) biocides and mercury (Hg) was investigated over the years 1955–2002. A total of 960 unhatched eggs from eastern Germany, Baden-Württemberg (BW) and North Rhine-Westphalia/Rhineland Palatinate (NRW/RP) were analysed for the biocides DDE, HCB, PCB, etc., and for shell index and shell thickness. Hg analyses from 367 samples (unhatched eggs, moulted and nestling feathers, tissue samples) complete the investigation. The results confirm that the collapse of the German peregrine populations is correlated with the application of the insecticide DDT. The mean DDE values in BW over the years 1970–1976 were above the relevant threshold values of 70–100 g/g (all concentrations refer to the dry sample mass), with single analyses showing values above 100 g/g until as late as 1987. The mean contamination levels in the 1960s can be retrospectively assumed to have lain above 200 g/g. With the help of thorough conservation measures it was possible after a fall in numbers of about 80% to stabilise the remnant population in BW . Following the West German DDT ban in 1972 and the resulting decline in environmental CHC contamination, this core population was able to recover from about 1980 onwards and has since increased tenfold. The shell index improved steadily from 1.48 (1970–1971) to a normal value of 1.80–1.88 (2000–2002). Hg contamination in western Germany stayed under toxic threshold values over the period 1969–1991. The significantly more intense application of DDT in eastern Germany, continuing until 1989, led to the extinction of the peregrine falcon, of both the cliff- and tree-nesting populations. This phenomenon is described with respect to DDE analysis data and shell thickness/index studies, complemented by observations of breeding biology. In addition, the employment in the GDR of methyl/phenyl Hg as seed treatments had dramatic local toxic effects on embryo survival and shell thickness. Hg burdens reached very high levels in feathers (147 µg/g) and eggs (65 g/g). The combination of DDT and Hg was responsible for the species extinction in this region. The current peregrine falcon population of eastern Germany even now shows biocide contaminant burdens up to 3 times higher than in samples from western German falcons. Shell index and shell thickness had, however, normalised to a large extent by 2002. The tree-nesting habit of the peregrines formerly breeding in the forested lowlands of Central and Eastern Europe, a tradition which had been passed on by imprinting, has been completely eradicated as a result of the effects of the environmental contamination. In NRW/RP unhatched eggs over the period 1989–2002 show uncritical DDE contamination levels in the region of 4–20 g/g with normal shell index values. PCB analyses from all three regions confirm the highest levels of contamination from industrial centres with no clear trend so far. HCB burdens peaked at a maximum of 80 g/g and have been stable at <1 g/g since 1983. Population parameters did not improve in BW until 1976, after DDE and HCB contamination levels had started to decrease as a result of the bans on use. In East Germany and NRW/RP, the documented recolonisation and increases in breeding success parameters were only possible after the DDE levels (and in East Germany additionally the Hg levels) had fallen to below toxic threshold levels.Communicated by F. Bairlein     

Indexing winter gull numbers in Great Britain using data from the 1953 to 2004 Winter Gull Roost Surveys

Capsule Winter Gull Roost Survey data spanning 50 years were used to generate population indices.

Aims To evaluate how wintering numbers of five gull species have changed in Great Britain over the last five decades.

Methods Generalized linear models were used to relate gull numbers to habitat, site and year factors, and so derive species‐specific indices for nine regions of Great Britain. Regional models considered data from different timescales depending on coverage.

Results Patterns of change varied by species and region. All species showed increases in number over the period 1953 to 2004. In most regions, Black‐headed Gull Chroicocephalus ridibundus numbers have declined since peaks between 1973 and 1993; Common Gulls Larus canus have also declined recently in some regions. Lesser Black‐backed Gull L. fuscus numbers have increased dramatically since 1953, whereas numbers of Herring Gull L. argentatus showed large declines between 1963 and 1983. Great Black‐backed Gull L. marinus numbers have increased in the west and the Midlands, but recently declined in eastern regions.

Conclusions Numbers of wintering gulls in Great Britain have shown rapid changes over the last five decades, reflecting changes in the sizes of breeding populations. These changes are likely to be associated with changes in human activities and resource availability.