Loss of sunflower seeds to columbids in South Africa: economic implications and control measures

A survey across the sunflower production region of South Africa during November 2003 to July 2005 estimated the loss of sunflower seeds to columbids (doves and pigeons, Aves: Columbidae). Farmers estimated that 12.7% of the national yield was lost to columbids. In a follow-up survey, 37 sunflower fields were visited and accurate measurements applied to assess seed loss, suggesting a national loss of 8.4% (loss in revenue of R197 million). In rows with east–west orientation the mean seed loss was 8.2% and in the north–south orientation the mean seed loss was 5%. There was a non-significant positive correlation (r = 0.270, p > 0.05) between the distance between plants in a row and percentage seed loss. No correlation was found between field size and percentage seed loss (r = –0.35, p > 0.05). Most damage occurred in the centre of the sunflower fields with a mean loss of 10.09% (range 0.08–32.24, SD = 8.88, n = 22) as against 4.76% (range 0.5–11.82, SD = 3.46, n = 22) on the edge. Seed losses did not vary significantly among provinces (analysis of variance, F_2,34 = 2.11, p = 0.136). Proposed control measures are discussed.