Most of the white-tailed eagle (Haliaeetus albicilla) populations in Europe experienced dramatic declines during the twentieth century. However, owing to intense conservation actions and the ban of DDT and other persistent pollutants, populations are currently recovering. We show that despite passing through demographic bottlenecks, white-tailed eagle populations have retained significant levels of genetic diversity. Both genetic and ringing data indicate that migration between populations has not been a major factor for the maintenance of genetic variability. We argue that the long generation time of eagles has acted as an intrinsic buffer against loss of genetic diversity, leading to a shorter effective time of the experienced bottleneck. Notably, conservation actions taken in several small sub-populations have ensured the preservation of a larger proportion of the total genetic diversity than if conservation had focused on the population stronghold in Norway. For conservation programmes targeting other endangered, long-lived species, our results highlight the possibility for local retention of high genetic diversity in isolated remnant populations.
The grey seal (Halichoerus grypus) population in the Baltic Sea is recovering after a century of bounty hunting and 3 decades of low fertility rates caused by environmental pollution. A conservative estimate of the population size in 2003 was 19,400 animals, and available data suggest an annual rate of increase of 7.5% since 1990. The growing population has led to increased interactions with the fishery, and demands are being raised for the re-introduction of the hunt. We provide a demographic analysis and a risk assessment of the population, and make recommendations on how to decrease the risk of overexploitation. Although hunting increases the risk of quasi-extinction, the risk can be significantly reduced by the choice of a cautious hunting regime. The least hazardous regimes allow no hunting below a 'security level' in population size. Obviously, to implement such a hunting regime detailed knowledge of the population size and growth rate is required. It is not possible to estimate "true" risks for quasi-extinction, but we used an approach where the relative difference for different scenarios can be compared. With a security level at 5,000 females, the population quasi-extinction risk increases 50 fold at an annual hunt of 500 females compared with a scenario with no hunting. The risk of quasi-extinction is very sensitive to declines in the mean growth rate and to increased variance in growth rate. The variance in the population estimates over the last 14 years imply that it would take 9 years to detect a decline from 1.075 to 1.027 in the rate of population increase. We also show how the age composition of killed animals influences the impact of the hunt. The overall recommendation is that hunting should be kept to a minimum, carefully documented and accompanied by close population monitoring.Harding, K.C., Härkönen, T., Helander, B. and Karlsson, O. 2007. Status of Baltic grey seals: Population assessment and extinction risk. NAMMCO
Lead poisoning of animals due to ingestion of fragments from lead-based ammunition in carcasses and offal of shot wildlife is acknowledged globally and raises great concerns about potential behavioral effects leading to increased mortality risks. Lead levels in blood were correlated with progress of the moose hunting season. Based on analyses of tracking data, we found that even sublethal lead concentrations in blood (25 ppb, wet weight), can likely negatively affect movement behavior (flight height and movement rate) of free-ranging scavenging Golden Eagles (Aquila chrysaetos). Lead levels in liver of recovered post-mortem analyzed eagles suggested that sublethal exposure increases the risk of mortality in eagles. Such adverse effects on animals are probably common worldwide and across species, where game hunting with lead-based ammunition is widespread. Our study highlights lead exposure as a considerably more serious threat to wildlife conservation than previously realized and suggests implementation of bans of lead ammunition for hunting.
The reproduction of white-tailed sea eagles was monitored in 1964-1999 in 3 differently contaminated sub-populations: Baltic Sea coast (Bp), inland central Sweden (Ip) and Lapland (Lp). 249 dead eggs from 205 clutches were obtained for analyses of DDE and PCBs and for eggshell measurements. A desiccation index (Di) value was calculated for each egg as a measure of water loss through the shell. In the highly contaminated Bp, p,p'-DDE concentrations in the eggs decreased continuously and 5-fold during the study period and PCB concentrations decreased 3-fold from the mid 1980s. The PCB pattern changed slightly over time towards more high-chlorinated congeners but the relative toxicity of the PCB mixture, expressed as 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents (TEQ), remained constant and TEQ can be assumed to have decreased in a similar way as PCB over time. Productivity (P), shell thickness (St), shell index (Si) and Di increased over time in the Bp but no change in Di or productivity occurred in the Lp, where residue concentrations were 5-8 times lower. P of the Bp was not correlated to St or Si but was negatively correlated to Di, DDE and PCB. An S-shaped dose-response relationship was indicated between P and DDE. After 1988, when the PCB/DDE ratio was considerably higher than previously, PCB but not DDE concentrations were significantly higher in eggs with dead embryos as compared to undeveloped eggs, implying lethal concentrations of PCB, and a LOEL of 320 pg g-1 TEQ is suggested for embryo mortality. In a subset of 21 eggs, representing productive and unproductive females, analyzed for a selection of coplanar PCB congeners, tris(4-chlorophenyl) methanol and bis(4-chlorophenyl) sulphone, there was no evidence for a correlation between P and any of these compounds. A reduction in residue concentrations in old females did not lead to increased P or improved Di-values, indicating a remaining effect from a previous, higher exposure to contaminants. The inability to reproduce included a high rate of undeveloped eggs, indicating effects at a prezygotic stage. P showed the strongest correlation with Di, and Di was most strongly correlated to DDE. Thus, the remaining effect of previous exposure resulted in a stronger correlation to the symptom (Di) rather than to the suggested causative agent (DDE). LOEL values for depressed P were estimated at 120 micrograms g-1 DDE and 500 micrograms g-1 PCB (lipid basis). It is concluded that the major reason for depressed P during the study period was DDE, but that effects also from PCB were largely concealed by the effects from DDE.
Biomonitoring using birds of prey as sentinel species has been mooted as a way to evaluate the success of European Union directives that are designed to protect people and the environment across Europe from industrial contaminants and pesticides. No such pan-European evaluation currently exists. Coordination of such large scale monitoring would require harmonisation across multiple countries of the types of samples collected and analysed-matrices vary in the ease with which they can be collected and the information they provide. We report the first ever pan-European assessment of which raptor samples are collected across Europe and review their suitability for biomonitoring. Currently, some 182 monitoring programmes across 33 European countries collect a variety of raptor samples, and we discuss the relative merits of each for monitoring current priority and emerging compounds. Of the matrices collected, blood and liver are used most extensively for quantifying trends in recent and longer-term contaminant exposure, respectively. These matrices are potentially the most effective for pan-European biomonitoring but are not so widely and frequently collected as others. We found that failed eggs and feathers are the most widely collected samples. Because of this ubiquity, they may provide the best opportunities for widescale biomonitoring, although neither is suitable for all compounds. We advocate piloting pan-European monitoring of selected priority compounds using these matrices and developing read-across approaches to accommodate any effects that trophic pathway and species differences in accumulation may have on our ability to track environmental trends in contaminants.Electronic supplementary materialThe online version of this article (doi:10.1007/s10646-016-1636-8) contains supplementary material, which is available to authorized users.
Aim Late Pleistocene glacial changes had a major impact on many boreal and temperate taxa, and this impact can still be detected in the present-day phylogeographic structure of these taxa. However, only minor effects are expected in species with generalist habitat requirements and high dispersal capabihty. One such species is the white-tailed eagle, Haliaeetus albicilla, and we therefore tested for the expected weak population structure at a continental level in this species. This also allowed us to describe phylogeographic patterns, and to deduce Ice Age refugia and patterns of postglacial recolonization of Eurasia.Location Breeding populations from the easternmost Nearctic (Greenland) and across the Palaearctic (Iceland, continental Europe, central and eastern Asia, and Japan).Methods Sequencing of a 500 base-pair fragment of the mitochondrial DNA control region in 237 samples from throughout the distribution range.Results Our analysis revealed pronounced phylogeographic structure. Overall, low genetic variability was observed across the entire range. Haplotypes clustered in two distinct haplogroups with a predominantly eastern or western distribution, and extensive overlap in Europe. These two major lineages diverged during the late Pleistocene. The eastern haplogroup showed a pattern of rapid population expansion and colonization of Eurasia around the end of the Pleistocene. The western haplogroup had lower diversity and was absent from the populations in eastern Asia. These results suggest survival during the last glaciation in two refugia, probably located in central and western Eurasia, followed by postglacial population expansion and admixture. Relatively high genetic diversity was observed in northern regions that were ice-covered during the last glacial maximum. This, and phylogenetic relationships between haplotypes encountered in the north, indicates substantial population expansion at high latitudes. Areas of glacial meltwater runoff and proglacial lakes could have provided suitable habitats for such population growth.Main conclusions This study shows that glacial climate fluctuations had a substantial impact on white-tailed eagles, both in terms of distribution and demography. These results suggest that even species with large dispersal capabilities and relatively broad habitat requirements were strongly affected by the Pleistocene climatic shifts.
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