Thrush anvils are calcium source hotspots for many bird species

Calcium is one of the most important elements determining reproductive success in birds, and snail shells are a well-known source of calcium for egg-laying females. In Europe, song thrushes, Turdus philomelos, break snails open at locations called anvils, eat the soft parts and leave the broken shells. Based on observational studies in 2011–2017 in western Poland, we showed that thrush anvils were visited by 54 other bird species (mainly smaller...