Calcium availability may limit the reproductive output of birds and snail shells are considered to be the main source of calcium in many passerine species. This study of collared ( Ficedula albicollis) and pied ( F. hypoleuca) flycatchers evaluates calcium intake of a natural diet in Central Europe, and sex differences in the utilization of experimentally supplemented sources of calcium during the entire breeding period in aviary birds. The study provides the first evidence that successful reproduction of these species depends on the availability of woodlice (Isopoda) and millipedes (Diplopoda). Each of these two components provided about 3 times more calcium than the snail shells contained in a natural nestling diet. The breeding performance of aviary birds was poor when only snail shells and the fragments of eggshells were provided in food, i.e., irregular laying, smaller clutches, eggshell defects (25 of 53 eggs), and eggs dried-up during incubation. In contrast, no defective eggshell or dried-up eggs were found and the overall breeding performance increased 2-3 times when woodlice were added to the food. Females increased their intake of woodlice during both the pre-laying and laying periods, and both sexes did so during the nestling period. Both sexes took more woodlice in the evening than in the morning, independent of the nesting stage. Intake by females was low until 4 days before laying the first egg, then increased to the highest level, dropping immediately after laying the last egg. Intake of woodlice by both sexes increased steadily from hatching until the nestling age of about 10-12 days decreasing thereafter, which corresponds with the period of rapid skeletal growth. In contrast, the intake of mealworms increased until the nestling age of 13-14 days leveling off thereafter which corresponds with the growth curve of nestling body mass.

Laboratory of Ornithology Palacky University tr Svobody 26 77146 Olomouc Czech Republic

Zobrazit více v PubMed

Anim Behav. 1971 Aug;19(3):490-9 PubMed

Physiol Zool. 1997 Jan-Feb;70(1):74-84 PubMed

Nature. 1989 Jun 8;339(6224):431-2 PubMed

Evolution. 1986 May;40(3):574-583 PubMed

Br Poult Sci. 1974 Jul;15(4):349-59 PubMed

Nature. 2001 May 3;411(6833):45-50 PubMed

Proc Nutr Soc. 1983 Jun;42(2):195-212 PubMed

Experimental evidence for species-specific habitat preferences in two flycatcher species in their hybrid zone