Purger, J. J., Kletečki, E., Trócsányi, B., Mužinić, J., Purger, D., Széles, G. L., Lanszki, J. (2012): The Common Leadwort Plumbago europaea L. as a natural trap for the wintering Goldcrests Regulus regulus: a case study from Adriatic islands. Journal of Biological Research 17: 176-179.
Abstract
Goldcrests Regulus regulus are found wintering in high numbers from October to April in the Adriatic coast and islands, feeding mainly on insects in the undergrowth and on the ground. Common Leadwort Plumbago europaea L. continues to flower on stone walls well into October, exposing its sticky calyx and seed capsules for at least 30 days, meaning a threat to small birds by clinging to their feathers. The entangled feathers restrain the birds in their free movement, which either die or become easy prey for cats, rats or birds of prey. As estimated from plant coverage rate (0.63% of stone walls) and the number of observed birds “captured” by Common Leadwort (5), at least 47 Goldcrests could have been killed by this natural trap in the built-in area of the island of Olib (0.388 km2) during one month. At lower coverage rates (<0.1%) such as in the outer areas of the island of Olib and in the outskirts and central areas of neighboring Silba island, such losses could be much lower, but because of the considerable distribution overlap between of this plant species and the wintering areas of Goldcrests, this mortality factor should not be overlooked.
Keywords
natural trap, mortality, threatening factor, Mediterranean island
Abstract
Goldcrests Regulus regulus are found wintering in high numbers from October to April in the Adriatic coast and islands, feeding mainly on insects in the undergrowth and on the ground. Common Leadwort Plumbago europaea L. continues to flower on stone walls well into October, exposing its sticky calyx and seed capsules for at least 30 days, meaning a threat to small birds by clinging to their feathers. The entangled feathers restrain the birds in their free movement, which either die or become easy prey for cats, rats or birds of prey. As estimated from plant coverage rate (0.63% of stone walls) and the number of observed birds “captured” by Common Leadwort (5), at least 47 Goldcrests could have been killed by this natural trap in the built-in area of the island of Olib (0.388 km2) during one month. At lower coverage rates (<0.1%) such as in the outer areas of the island of Olib and in the outskirts and central areas of neighboring Silba island, such losses could be much lower, but because of the considerable distribution overlap between of this plant species and the wintering areas of Goldcrests, this mortality factor should not be overlooked.
Keywords
natural trap, mortality, threatening factor, Mediterranean island
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