ASSESSING MERCURY POLLUTION USING BLACK STORK EGGSHELLS

Female birds whose bodies contain environmental contaminants produce eggs with shells that are likewise contaminated, making bird eggshells appropriate indicators for monitoring environmental toxins. Common contaminants include organic mercury compounds, especially methylmercury, which are known to bioaccumulate and biomagnify in the food chain. Black storks (Ciconia nigra) predominantly consume fish and are thus at risk for high mercury intake. In this study, we used eggshells of black storks as a proxy to reconstruct the concentration levels and distribution of mercury, a well-known toxic element, in various parts of Latvia. Preliminary analyses have shown that deposition levels of mercury vary in different parts of the eggshell. Specifically, the shell and shell membrane differ in their level of mercury contamination by an average factor of nine; therefore, we measured the mercury content in these components separately whenever possible. We analysed 34 eggshell samples from nesting sites in Latvia using an atomic absorption spectrometer with Zeeman correction Lumex RA-915M and its attachment for pyrolytic combustion. We found that mercury concentrations varied from 5 to 22 ng/g in eggshells and from 42 to 293 ng/g in shell membranes. We discuss possible contamination sources and reasons behind this disparity.

The Limit to the Density of Species (A Reflection on Human Intervention in Conservation and Its Effects)

Human actions on the natural environment cannot always be considered as impacts resulting from their behavior to survive. Many of these activities have caused irreversible damage and changes in the landscape, flora, and fauna. By contrast, several actions, carried out “a priori” with the best intention, to help in the conservation of species considered in danger, have caused a dangerous decompensation. Aid for the recovery of some species of birds has led to their overpopulation. The artificial contributions of food, always in the same places, have caused an excessive increase in the number of griffon vultures (Gyps fulvus), which has produced the reduction of other endangered species, such as the black stork (Ciconia nigra) and the Bonelli’s eagle (Aquila fasciata), which have been displaced from the rocks in which they nested due to the harassment of a greater number of vultures. Besides, vultures are attacking domestic livestock at the most defenseless times, such as during calving. Greater flamingo (Phoenicopterus roseus) has become out of control in numbers in Europe. The two classic breeding areas, La Camargue (France) and La Laguna de Fuente de Piedra (Spain) have produced an enormous annual number of individuals that are distributed among the few lagoons of Mediterranean Europe. The wetlands are devastated by the flamingo, which removes the mud and prevents sunlight from reaching the underwater vegetation, turning these lagoons into dead water, having to be abandoned (temporarily) by most aquatic species, including the flamingo. The shortage of food resources of natural origin, for such a disproportionate number, has caused the flamingo to invade the rice fields, accepting its grain as a substitute for the invertebrates that it habitually consumed, and which are now scarce. The same is the case with the white stork (Ciconia ciconia) in southern Europe. The increase in their population has reduced the number of reptiles and amphibians, bringing several of their species to the brink of extinction. Storks have varied their prey spectrum, consuming carrion, and preying on Montagu’s harrier (Circus pygargus) brood. In these cases, and many others, the theory of “the more the better” is not valid. If we want to make the protection of some species compatible with the conservation of others, it seems necessary to redirect some situations …

Presence of one ecto- and two endoparasite species of the black stork (Ciconia nigra) in Portugal

Background The black stork (Ciconia nigra Linnaeus, 1758) is a recognized endangered species in Europe and most of the specimens from the Western Palearctic region breed in the Iberian Peninsula. Available works regarding parasites in black storks are scarce. This work reports the presence one ecto- and two endoparasite species from a black stork in Portugal. Case presentation A black stork was found in southern Portugal after colliding against electric cables. The specimen did not survive its sustained injuries and a post-mortem exam was performed. During the procedure, several ecto- and endoparasite specimens were found. The collected parasites were lice (Neophilopterus tricolor), nematodes (Desportesius sagittatus) and trematodes (Cathaemasia hians). Conclusions Three different species of parasites are reported from a black stork in Portugal. Ecto- and endoparasites of C. nigra have not frequently been described in the literature, and this case report is a contribution to the field. Additional studies will be important to better understand the impact that parasites can have on C. nigra health and survival.

Distribution Pattern, Nest-Tree Features and Breeding Performance of Population of the Black Stork, Ciconia nigra (Ciconiiformes, Ciconiidae), in Northwestern Serbia

Distribution pattern, nest-tree characteristics and reproductive features of Black Stork’s population were evaluated in the floodplains of Gornje Podunavlje in Northwestern Serbia over five consecutive years. In total, 44 different nests were discovered and monitored. Nests were mostly placed on wide-diameter European Oaks and White Poplars between 5.5 and 18 m above ground level. Annually, the number of occupied nests varied between 26 and 16 with the declining trend over study years. The mean nesting density was 9.8 ± 2 occupied nests per 100 km2. Through study area, occupied nests were uniformly distributed and very isolated concerning the conspecific pairs. Predominantly, Black Stork preferred to nest on the lateral branches of the autochthonous mature trees with straight trunks and extensive crowns. These results suggest that the existence of old native forest stands represent crucial microhabitat criteria in the choice of the particular nesting site. In almost half of successful nesting cases, the most frequent number of fledglings was three. Overall productivity was relatively low with some variations between years implying poor nesting success.