Compensatory response of maturing corn kernels following simulated damage by birds.
Abstract
A study was made to measure compensatory growth responses and to estimate losses associated with bird damage to maturing maize. Maize grains contained 20-40% of their final biomass at the time they were usually consumed by blackbirds (Agelaius phoeniceus). Very slight compensation of grain wt. occurred following simulated bird damage to tip grains. Heavy bird damage early in grain development increased the levels of fungal, sprouting and insect damage before harvest. Estimates of bird damage, subsequent secondary damage and compensation were affected by the amount of damage, maturity of the grains at the time of damage and environmental factors before, during and after damage. Visual estimates of wt. change were closely correlated with actual loss of the total grain wt. Studies of food habits and bioenergetics that have used feeding rates and numbers of birds to estimate the impact of blackbirds on maize crops may have underestimated the reductions in grain yields.