Estimation of calcium intake by Meadow Pipit nestlings in an acidified area

Calcium availability might limit reproductive output in birds either by effects on eggshell formation or on skeletal growth of nestlings. Quantitative data on calcium intake by nestlings of free-living passerines are needed to test the second hypothesis. In an acidified area of the Jeseníky Mountains (Czech Republic), estimates were made of calcium requirements and intake in Meadow Pipit Anthus pratensis nestlings during the nestling period. Analyses of nestling diet, determined by neck ligatures, showed that only snail shells were an important source of calcium. During the whole nestling period dry matter intake per nestling was 31.1 g, of which snail shells contributed 0.626 g. The total calcium necessary for successful development of each nestling was estimated as 139.8 mg. Arthropods in the diet provided only 16% of the calcium requirement. However, sufficient calcium was ensured by intake of snails (mainly Arianta arbustorum ), despite their low abundance in the area.