Factors affecting daily seed intake of the greenfinch, Carduelis chloris

Abstract

Minimum and maximum intakes of rapeseed (Brassica napus) for greenfinches were established under controlled conditions. In terms of time and energy gained rapeseed proved superior to canary seed (Phalaria sp.) and the seeds of chickweed (Stellaria sp.) plus dandelion (Taraxacum sp.), but in a choice situation the weed seeds were preferred. Seed intake was controlled by the rate of breakdown in the bird's gizzard, which was independent of both time and quantity eaten. A decrease in air temperature caused a significant increase in consumption, especially by juveniles. Moulting birds increased their seed intake and deposited subcutaneous fat to compensate for reduced insulation and overnight weight loss. A method of estimating the damage caused by greenfinches to ripening rapeseed crops is outlined.

Keywords:

• Carduelis chloris
• feeding trial
• energy requirement
• seed intake
• Brassica napus
• nutrient composition
• bird damage estimation
• Phalaria sp.
• Stellaria sp.
• Taraxacum sp.