Calcium supplementation of breeding birds: directions for future research

  • Published source details Reynolds S.J., Mänd R. & Tilgar V. (2004) Calcium supplementation of breeding birds: directions for future research. Ibis, 146, 601-614.


This study is summarised as evidence for the following.

Action Category

Provide calcium supplements to increase survival or reproductive success

Action Link
Bird Conservation
  1. Provide calcium supplements to increase survival or reproductive success

    A 2004 literature review (Reynolds et al. 2004) looked at 14 studies of calcium supplementation across a total of seven species. Several studies are discussed in this section. Positive effects on at least one egg-related trait were detected in three species: house wrens Troglodytes aedon (clutch size but not egg size), pied flycatchers Ficedula hypoleuca (eggshell thickness and egg volume) and great tits Parus major (fewer females not nesting, fewer abandoning nests, thicker eggshells and higher hatching success; uncertain evidence for increases in clutch size and advanced laying date (4,7,10)). However, such effects were missing in all traits measured in a study of blue tits P. caeruleus in Scotland (egg mass and volume, eggshell thickness, laying date, clutch size, fledging success). Similarly, positive effects on chick traits were detected in four species: cape vultures Gyps coprotheres (reduced incidence of bone deformation (1)), black terns Childonias niger (higher weight gain (3)), pied flycatchers (higher chick growth rates (11)), great tits (chick growth and fledging success (10)). Such impacts were absent in house wrens (fledgling body mass or number of fledglings, (2)) or purple martins Progne subis (growth rate of fledglings, (9)). One study (11) also reported a positive effect on adult female body condition in pied flycatchers but not great tits in Estonia.


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