Pinowska B. & Krasnicki K. (1985) Changes in the content of magnesium, copper, calcium, nitrogen and phosphorus in female House Sparrows during the breeding cycle. ARDEA 73 (2): 175-182

The concentrations and contents of magnesium, copper, calcium, nitrogen and phosphorus were analysed in female House Sparrows over the breeding cycle. The concentration of Mg and Cu increased till the day preceding ovulation. The concentrations and contents of Mg decreased through successive days of ovulation, and they were maintained at a constant level during incubation and feeding nestlings. The lowest concentration of this element was recorded for nonbreeding females. The concentrations and contents of Cu started to drop several days after the last ovulation. In breeding birds, in the period of advanced incubation and feeding nestlings, they were lower than in non-breeding females. No significant changes were observed in the contents and concentrations of Ca, P, and N. Clutch size depends on the content of Mg retained at the onset of laying.