The first analysis of heavy metals in the Grey Heron Ardea cinerea feathers from the Croatian colonies

Abstract

This study represents the first analysis of heavy metals: lead and cadmium, as well as two metalloids: arsenic and selenium, in the feathers of Grey Herons breeding in Croatia. The Grey Heron was chosen as a model apex predator of the wetland ecosystem due to high trophic level, feeding habits, long lifespan and abundance. Sampling was conducted during the 2019 breeding season in April and May from six Grey Herons colonies in Croatia (Mrsunjski lug, Kopački rit, Piljenice, Kravarsko, Čepin, Slovinci), whose environment is heavily influenced by rivers Danube, Drava and Sava tributaries. The primary and secondary flight feathers were collected under the colonies as shed feathers or from dead birds. The feathers are a suitable non-invasive method for metal and metalloid analysis, and can reflect internal concentrations, depending on the metal. In the Slovinci colony, we measured the highest lead D. Bjedov, A. Mikuška, M. Velki, Z. Lončarić, T. Mikuška: The first analysis of heavy metals in the Grey Heron... (Pb) and cadmium (Cd) concentrations (2194.53 ± 416.20 µg kg -1 dw and 79.30 ± 9.37 µg kg -1 dw, respectively). The highest arsenic (As) and selenium (Se) concentrations were found in the Čepin colony (359.70 ± 301.46 µg kg -1 dw and 3375.61 ± 2502.80 µg kg -1 dw, respectively). All the measured levels of heavy metals and metalloids are below concentrations that can cause adverse health effects in birds.

Application of Non-Destructive Methods: Biomarker Assays in Blood of White Stork (Ciconia ciconia) Nestlings

“…Although some studies still use destructive sampling, such as capturing birds in traps and decapitation [19][20][21][22], blood sampling, if done correctly, is a simple, non-destructive method for laboratory analysis [23] and should be utilized over destructive methods. Non-invasive (e.g., collecting shed feathers [24] and collection of addled eggs [25]) and non-destructive (e.g., blood sampling [26,27]) methods should be employed for the purpose of animal welfare, to minimize the environmental impact on birds, thus helping conserve avian biodiversity, especially when working with near threatened and critically endangered species. For optimal assessment, biomarkers in blood often need to be measured in parallel; therefore, it is recommended to draw a maximum amount of blood at once [28].…”