Bird damage to sunflower harvest

Abstract

Sunflower has recently attracted attention as a suitable oil-producing crop for biofuel, and the area of cultivation in Japan is expected to increase. However, damage to the crop by birds is considered to be a major problem in its cultivation. We confirmed that Oriental Turtle Dove Streptopelia orientalis, Oriental Greenfinch Carduelis sinica and Eurasian Tree Sparrow Passer montanus all fed on sunflower seeds in four fields of sunflowers (100a in total) at the National Agricultural Research Center in Tsukuba city. Seventy doves, 5,277 greenfinches, and 318 sparrows in total were observed in the fields during 27 surveys, and the appearance ratio (the number of days the birds appeared divided by the total number of survey days) were 44.4%, 100%, and 37.0%, respectively. Both the total number and the appearance ratio were highest for the greenfinch, and the largest feeding flock consisted of 300 individuals. Damage to sunflowers occurred from the time when the flower petals were still attached, until harvest time. Damage was quantified in two of the four fields; the ratio of damaged flower heads was 72.1% in the field in which seeds were sown earlier, and 30.8 in the later sown field. The results indicate that without appropriate countermeasures being taken, birds could substantially impact sunflower harvests.