Do pipits use experimentally supplemented rich sources of calcium more often in an acidified area?

How birds respond to the recent phenomenon of calcium deficiency in acidifi ed areas is still poorly known. This study, carried out in the Jeseniky Mou ntains (heavily polluted, acidified area in the Czech Republic), in alpine ecosystems of central Norway, and in the limestone part of the Mala Fatra M ountains (Slovak Republic), provides the first experimental evidence that b irds select and bring supplemented calcium-rich items to their nestlings mo re often in an acidified area, Meadow Pipits Anthus pratensis and Water Pip its A. spinoletta selected calcium-rich items (mainly snail shells) from va rious materials placed near their nests and this selectivity did not differ between areas or species. Thinning of egg shells (8% at blunt pole, 5% at egg side) suggests that Meadow Pipits in the Jeseniky, Mountains were negat ively influenced by the low calcium availability in spite of their ability to adjust foraging behaviour.