Blackbirds and GMO Corn

As I mentioned in my last post I was surprised to see Red-winged Blackbirds last Sunday. That was because I have noticed the lack of blackbirds in Late-August and Early-September. Not just Red-winged Blackbirds but also Brown-headed Cowbirds and Common Grackles.

rwbl-1 Blackbirds

Not a bird to usually catch my attention but this was my first Red-winged Blackbird of the fall. Franklin Township Community Park 9/18/16

 

rwbl-indiana

From eBird the seasonal distribution of Red-winged Blackbird in Indiana. Note the big drop off in August.

So where do Blackbirds Go in Late Summer?

As I have previously mentioned I try to pick and choose what I read about birding so I don’t spend my life on the internet. H. David Bohlen reports around the 5th of each month his sightings from Sangamon County Illinois on the Illinois Listserv. One of the things I noticed is his report of “inexplicably low numbers of Blackbirds” and wonders if it is sterile or GMO corn.

From what I can gather from the internet it’s not that blackbirds don’t eat the GMO corn but there are none of the normal “weeds” for them to eat. If I understand correctly the GMO corn has been modified to withstand the use of pesticides. When farmers use pesticides it doesn’t effect the corn. But the “weeds” have not been modified so it will kill them. Leaving nothing for the blackbirds (and birds in general) to eat.

Probably Molting

Having said that the Red-winged Blackbirds are probably just molting during this time. As Arthur Cleveland Bent states in Life Histories of Familiar North American Birds “early in August, all the redwings seem to disappear, during the molting period, and are not much in evidence until the middle of September or later”.

So molting is probably what the blackbirds are doing in August and September and not directly effected in August by GMO corn.

But I can’t think in the long run GMO corn will have an effect on blackbird population as their main food are weed seeds and insects.

It will be interesting to watch the population trends of the Red-winged Blackbird as it is usually the most numerous species on our spring counts. Hopefully over time we won’t see their numbers drop but I’m not hopeful.

This entry was posted in Conservation and tagged . Bookmark the permalink.

Leave a Reply

Your email address will not be published. Required fields are marked *