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Total mercury concentration in kidneys of birds of prey tram different part of Poland - same interspecies and geographical differences

Komosa A., Kitowski I., Kowalski R., Komosa Z., Grochowicz J.

Ecological Chemistry and Engineering. S

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2009

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Vol. 16, nr 1

19-28

EN

Mercury concentration levels in kidneys of 46 individuals of 13 species of birds of prey have been determined. The greatest mean concentration of mercury in kidneys was found in White-tailed Eagle Haliaeetus albicilla 1.54 mg/kg d.m. however the maximum concentration of mercury in kidney was determined in a Eurasian Buzzards Buteo buteo: 4.54 mg/kg d.m. The level of mercury concentration in kidneys of young individuals of raptors was lesser than in adults. In the light of research carried out birds of prey feeding and hunting birds accumulated less mercury in their kidneys in comparison with species whose diet was based on small mammals. Birds of prey bound with the agricultural landscape of north-east Poland seem to accumulate more mercury in kidneys as compared with raptors who originate from other parts of Poland.

PL

Zbadano poziomy stężeń rtęci w nerkach 46 osobników z 13 gatunków ptaków drapieżnych. Największe średnie stężenie rtęci, wynoszące 1,54 mg/kg suchej masy, oznaczono w nerkach bielika Haliaeetus albicilla. Natomiast maksymalne stężenie wynoszące 4,54 mg/kg suchej masy stwierdzono u myszołowa Buteo buteo Wykazano również, że osobniki młode mają mniejsze koncentracje rtęci w nerkach w porównaniu z dorosłymi ptakami. Przeprowadzone badania pozwoliły ustalić, że drapieżniki polujące na ptaki kumulują w nerkach mniejsze ilości rtęci niż drapieżniki o diecie składającej się z drobnych ssaków. Drapieżniki związane z obszarami rolniczymi północno-wschodniej Polski kumulowały w nerkach większe ilości rtęci w porównaniu z ptakami z innych części Polski.

2

Hunting habitat preferences of raptors in a mountainous area (Northwestern Spain)

Tapia L., Dominguez J., Rodriguez L.

Polish Journal of Ecology

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2008

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Vol. 56, nr 2

323-333

EN

The hunting habitat preferences of six diurnal raptors (see below) were studied during spring-summer and autumn-winter periods in a mountainous area of northwestern Spain (the Baixa Limia-Serra do Xures Natural Park). For this, 15 counting-points were established (at 800 m a.s.l.) in the study area between February 1997 and January 1998. Each point was sampled 4 hours per month. The dependent variables used were presence-absence and specific relative abundance (number of birds hr[^-1]km[^-2]). Seventeen environmental variables (number of settlements, surface area occupied by settlements, road length, minimum altitude, maximum altitude, max-min altitude, mean altitude, min slope, max slope, max-min slope, mean slope, surface area occupied by scrub-pasture, surface area occupied by forest, scrub-forest edge, number of people hr[^-1] km[^-2], livestock hr[^-1] km[^-2], vehicles hr[^-1] km[^-2]) were used as predictors for characterizing the hunting habitat patterns between March and August (spring-summer period) and between September and February (autumn-winter period). Information regarding each independent variable in the monitoring areas was obtained from 1:50000 digital maps. We analysed the habitat selection patterns of six raptor species, using univariate and multivariate analysis. The PCA generated three factors that accounted for 84% of the variance in spring-summer and 81% of the variance in autumn-winter. The Short-toed Eagle Circaetus gallicus (Gmelin) did not show any pattern in their habitat selection. The Hen Harrier Circus cyaneus (L.) and Montagu's Harrier Circus pygargus (L.) were more often observed in higher, more gently sloping areas. The spring-summer abundance of the Common Buzzard Buteo buteo (L.) was positively correlated with the surface area occupied by human settlements and the surface area occupied by forest, and in the autumn-winter period its abundance was negatively correlated with the mean slope. The Golden Eagle Aquila chrysaetos (L.) showed similar hunting habitat selection patterns in both periods, with a preference for shrub areas and weak presence of human settlements. The Common Kestrel Falco tinnunculus (L.) did not show any pattern of habitat selection in the spring-summer period but its abundance was negatively correlated with the mean slope in the autumn-winter period.

3

Effect of felling on the distribution of rodents and their predators in a transitional mixed forest

Sidorovich V., Solovej I., Sidorovich A., Rotenko I.

Polish Journal of Ecology

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2008

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Vol. 56, nr 2

309-321

EN

The influence of felling on the distribution of rodents and their predators in a transitional coniferous-deciduous forest in northern Belarus was investigated in relation to stand age, forest type, and soil richness. The study was conducted in two areas differing by top-grounds (clay and sand soils) and, in turn, having different habitat carrying capacities. Three forest parts were investigated: 1) 10%, 2) 20-30%, and 3) 40-60% covered by recent clearcuts. Three age classes of the clearcuts, namely 1) less than 2 years old, 2) 2-5 years old and 3) 6-12 years old, were considered. In total, we obtained data on small rodent numbers in 84 clearcuts, and the data on predators - in 67 clearcuts and the woodland parts differed by logging rate. Eventually, we became convinced that felling generally led to an increase in the abundance and species richness of rodents and their predators and that was attributable in the clearcuts aged up to 12 years. First, logging led to higher densities of Apodemus mice, the red fox Vulpes vulpes L., weasel Mustela nivalis L., tawny owl Strix aluco L., common buzzard Buteo buteo L. and adder Vipera berus L. Also, with the increased felling rate Microtus voles and the longeared owl Asio otus L. penetrated in transitional woodlands. Too intensive forest harvesting (more than 40% of recent clearcuts) led to the decline in the populations of several predatory species such as the pine marten Martes martes L., Tengmalm.s owl Aegolius funereus L., Ural owl Strix uralensis Pall., and pygmy owl Glaucidium passerinum L. The decline in rodent predators found in the conditions of too intensive logging rate was different in the woodlands on sand and clay top-grounds. In the conditions of clay soil too intensive felling led to the pronounced decline of a marked part of the rodent predatory guild inhabiting woodlands, and the species densities decreased to the level that was lower than the initial one. Conversely, in initially poor habitats in the woodland on sandy deposits, logging of any rate led to the increase in numbers of rodents and their predators compared to undisturbed forest. But moderate logging was found to be the most favourable for the community there.