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Predation on Artificial Nests Imitating the Broods of Two Rallid Species: The Influence of Habitat Features

Chibowski P., Brzeziński M., Jedlikowski J.

Polish Journal of Ecology

2015

Vol. 63, nr 4

573--584

We tested the influence of nest concealment (vegetation type, density and height), water depth and nest distance from the bank on predation rates upon simulated nests of the water rail (Rallus aquaticus) and the little crake (Porzana parva). Broods of both rallids were simulated by real and wax-filled quail (Coturnix coturnix) eggs coloured typically for each species. Three grades of nest concealment were used: uncovered nests located on wooden floating boards, nests hidden in littoral vegetation and nests hidden under a plastic mesh covered with plants, which made them invisible from the air. Concealment proved to have a stronger impact on the fate of artificial nests than water depth; 95% of the nests on boards were depredated after one week of exposure. Nests attached to a peg at water level and hidden in vegetation had survival rates of 18 and 22%, after three weeks of exposure in two experiment repetitions. In 2012, we found significant differences between survival rates of nests located in different types of vegetation after the first week of the experiment: nests in bulrush (Typha spp.) had a higher survival rate than nests in sedge (Carex spp.) and common reed (Phragmites australis), and nests in sedge had a better survival rate than nests in reed. Those differences disappeared after the end of the experiment. In 2013, nests located in sedge (Carex spp.) had a better survival rate than nests located in bulrush (Typha spp.) or the common reed (Phragmites australis). Covering nests with plastic mesh and plants increased nest survival up to 38% after a three-week-long exposure period. Potential nest predators were monitored: mammals (mustelids and rodents) using live traps and birds by observation of their hunting activity. Filling quail eggshells with wax allowed us to identify the marsh harrier (Circus aeruginosus) as the main nest predator — in 67% of depredated nests, wax eggs carried marks of a raptor beak. American mink (Neovison vison) and the water vole (Arvicola amhibius), though abundant in the study area, were not important nest predators, as only a few bite marks of these mammals were recorded.

Research on radioisotope and heavy metal accumulation levels in bones and eggshells of selected wetland birds from Lublin region (South-Eastern Poland)

Komosa A., Kitowski I., Ślepecka K.

Chemia i Inżynieria Ekologiczna

2007

Vol. 14, nr 8

805-818

The radionuclides and heavy metal concentration levels were studied in eggshells and bones of grey herons, mute swan, marsh harriers and montagu's harriers, nesting in SE Poland. Relatively high concentrations of Zn and Cr are found in eggshells of all investigated species. A considerably high Pb concentration is observed in eggshells of mute swan which is most likely connected with the presence of load bullets shot by hunters on foraging areas of waterfowls. Study confirmed importance of zinc and manganese for development of bones in young birds. There is no simple correlation between metal concentration in eggshells and bones of young grey heron. It was found low activities of 137Cs and natural 40K isotope in bones and eggshells, as well as a lack of correlation of these two isotope concentrations. Concentration of 137Cs was lower than observed in plants of nesting areas of studied birds.

Badano poziomy kumulacji radionuklidów i metali ciężkich w skorupkach jaj oraz kościach u czapli siwej, łabędzia niemego, błotniaka stawowego i błotniaka łąkowego gniazdujących w południowo-wschodniej Polsce. Relatywnie duże koncentracje Zn i Cr zostały znalezione w skorupkach jaj badanych ptaków. Zauważalne koncentracje ołowiu, wykryte w skorupkach jaj łabędzi na niektórych stanowiskach pozostają w ścisłej relacji do obecności kul ołowianych wystrzelonych podczas polowań przez myśliwych na żerowiskach ptaków kaczkowatych. Badania potwierdziły rolę Mn i Zn w procesie rozwoju kości młodych ptaków. Wykazano brak korelacji pomiędzy koncentracjami metali w skorupkach a koncentracjami w kościach młodych czapli siwych. Stwierdzono niewielkie aktywności 137Cs i naturalnego izotopu 40K (ok. 1 Bq/kg) w kościach i skorupkach jaj badanych ptaków, jak również brak korelacji pomiędzy stężeniami tych dwu izotopów. Stężenia 137Cs były do 50 razy mniejsze niż stężenia tego izotopu w roślinach na terenach gniazdowania badanych ptaków.