It is not uncommon at this time of year to hear of blackbird damage. Birds will often feed on developing ears in corn fields following pollination and early in the grain filling period.
What Does Bird Damage Look Like? Typical symptoms include missing or damaged kernels on the cobs. In the first photo, shredded husks is the key symptom in identifying birds as the culprit. Secondary damage can result from ear rots as kernels eaten by the birds will often turn brown or black once the ear rots begin infecting the damaged tissue.
R.L. Nielsen in his article ‘Corn Ear Damage Caused by Bird Feeding‘, indicates birds, especially large flocks, can cause quite a bit of damage. The most damage occurs along field edges or by wooded areas such as bush, but damage can extend throughout an entire field.
Preference for one hybrid over another? It is not unusual for birds to prefer one hybrid over another, although the reasons are unclear. Perhaps it can be attributed to birds being able to detect slight differences in kernel maturity or other kernel characteristics between hybrids. Bollinger and Caslick (1985) indicated that kernel maturity (as measured by date of silking) was the most important factor in determining the level of blackbird damage to corn. Within a field, the degree to which the husk leaves extended beyond the tip of the ears (husk coverage) was also strongly correlated with the severity of damage.
Hybrid specific feeding has been observed in past corn committee trials, and not only with birds but with other animals such as raccoons. Amazingly, the animal can pick out a hybrid within each replicate of the trial without damaging other hybrids.
Control? As seen in other crops such as sunflowers, damage from blackbirds can be an on-going, variable, and uncontrollable natural phenomena with no practical means of management or mitigation. Current scare techniques such as cannons offer little relief as the birds quickly become accustomed to the sounds.
Nielsen, R.L. (Bob). 2008. Corn Ear Damage Caused by Bird Feeding. https://www.agry.purdue.edu/ext/corn/news/timeless/birddamagedears.html
Bollinger, Eric and James Caslick. 1985. Factors Influencing Blackbird Damage to Field Corn. J. Wildlife Mgmt 49(4):1109-1115.
Originally Posted on Crop Chatter in October 2014
Last Revised August 2017