Chronology and spatial distribution of cockatoo damage to two sunflower hybrids in south-eastern Australia, and the influence of plant morphology on damage

• Published in: Agriculture, ecosystems & environment Vol. 91; no. 1; pp. 127 - 137
• Main Authors: Fleming, Peter J.S, Gilmour, Arthur, Thompson, Jim A
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.09.2002; Elsevier Science
• Subjects: Australia; Biological and medical sciences; Bird damage; Cockatoo; Crops; Fundamental and applied biological sciences. Psychology; New South Wales; Phytopathology. Animal pests. Plant and forest protection; Sunflower hybrid; Vertebrates; Australia; Oceania; New South Wales; Sunflower hybrid; Cockatoo; Australia; Bird damage; Crops; Hybrid variety; Cultural control; Compositae; Spatial variation; Growth habit; Time variation; Vertebrata; Pest; Helianthus annuus; Dicotyledones; Morphology; Angiospermae; Spermatophyta; Intraspecific comparison; Aves; Damage; Oil plant (vegetal); Plant height
• ISSN: 0167-8809; 1873-2305
• DOI: 10.1016/S0167-8809(01)00241-9

Cockatoos ( Cacatua spp.) and other birds cause significant damage to sunflower ( Helianthus annuus L.) crops in NSW, Australia. Growing sunflower hybrids with pendulous heads has been suggested as a means of reducing damage. Also, the chronology of damage caused by cockatoos to sunflower heads and whole crops has not been well documented. The patterns and amount of damage caused by cockatoos to two sunflower hybrids, one representing the growth habit of commonly grown hybrids and the other being more pendulous, were studied in one growing season. The crop attracted a flock of galahs and sulphur-crested cockatoos that fed on the crop until after the normal harvest date. Two techniques for estimating damage to sunflower heads were highly correlated. No differences in the susceptibility of the two hybrids to cockatoo damage were observed. However, within the crop, heads that were taller or larger were more susceptible to damage while down-facing heads were less susceptible to damage. Early damage occurred near the margins but later the whole crop was damaged. This work supports previous suggestions that early harvesting, reducing the edge to area ratio of the crop, and planting of hybrids of uniform height and with down-facing heads might help reduce the damage to sunflowers caused by cockatoos.