It is necessery throughout the year for birds,especially in females during the breeding season.

Nutrients of the cuttlefish bone
Insoluble acids 1.4%
Moisture content 2.3%
Organic content 8.9%
Calcium 85% calcium carbonate
Magnesium carbonate 0.42%
Potassium 63 mg / kg
Total nitrogen 8,300 mg / kg
Total phosphorus 20 mg / kg
Heavy metals (mg / kg = parts per million)
Zinc 167
Iron 101
Cobalt 19
Copper 11
Manganese 8