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White stork Ciconia ciconia nests as an attractant to birds and bats
AbstractWhite storks (Ciconia ciconia), an emblematic bird of high conservation interest, build massive nests which are also important breeding sites for other birds. However, their role as a potential source of food for foraging birds and bats is unexplored. In this study, we counted insectivorous aerially foraging birds (swallows, martins, and swifts), sparrows, and bats foraging around 51 pairs of white storks’ nest and control sites in Poland. The number of birds was significantly higher near active white stork nests than control sites, but this effect was invisible for bats. White storks provide important benefits to the conservation of co-occurring species.
Investigating Sexual Characteristics in Two Frog Species Under Exposure to River Water Polluted with Endocrine Disruptors
Endocrine-disrupting compounds (EDCs) are emerging environmental pollutants that are known to the disrsupt hormonal system of many vertebrates. Amphibians, with their aquatic larval stages and high sensitivity to waterborne contaminants, are especially vulnerable to EDC exposure. Despite increasing concerns over EDC pollution, systematic monitoring of these compounds in surface waters remains limited in many regions, including the European Union. This study investigates the effects of water from the Warta River, one of the largest rivers in Central Europe, an urban waterway subjected to significant anthropogenic pressure and known to contain EDCs on body condition, digit ratio, and gonadal development in two brown frog species: the common frog Rana temporaria and the moor frog Rana arvalis. We propose DR as a potential biomarker of endocrine disruption, as it is linked to hormonal impact in the early development of vertebrates. In this study, tadpoles were reared in the semi-open experimental setup with tanks containing river or potable tap water as a control. Contrary to expectations, no significant differences were observed in body condition, digit ratio, or gonadal structure, suggesting that EDC concentrations in the river water may not have been high enough to induce detectable effects. However, a consistent relation between DR and sex was observed in both species, underscoring its potential as a biologically meaningful trait. Notably, the potable tap water used as a control exhibited contamination levels comparable to the river water, raising concerns about the efficacy of current water treatment methods and highlighting the challenges of establishing true reference conditions in environmental studies.