I don't know if it will work on corn, but it does work for birds on grapes.

We stake bright colored canvas balls with different colored canvas strips coming off the bottom. Suspend them off the stake with string, and they move in the slightest breeze. I think they sell these in garden centers if you don't want to play making your own.
Since we started using these we haven't had anywhere near the problems we once had with birds.
These could be used after row covers come off (good idea on the row cover usage). If the crows are that interested in your corn, they might take plantings that are a bit bigger than can stay in the row covers.

Throw some feed corn out for them. They are lazy and will eat that first. You might get lucky and catch them eating "their" feed and you might get a shot or two off. I like to use a .22
They'll flutter a while and draw more in.

I hunt down and shoot a crow and then hang it by the wing on a post in the field. Yes it stinks but they get the message.
Jay

i've heard of putting some rubber snakes out in the rows. move them every chance you get. worth a try?

I take hard plastic dinner plates boughten at thrift stores (any color but usually bright. I than drill holes in them where I want the eyes to be. I use caps of soda, water and powder aid bottles or any other caps from bottles etc. for the eyes. Drill holes into the caps and than use a screw and nut to attach. Instant scare crow face. Screw the plate onto posts (my husband makes them out of 2x4x6)with pointed bottem and a short piece for arms(like a cross) so that he can pound them in. It is reccommed that they be moved at least once a week but we dont move them. We grow u-pick blueberries and the year before last the crows ate everything. Last year they didnt touch them. Oh we also took a black garbage bag and stapled it around the scarecrow so it would move in the wind. Be creative we make them in the winter. We made about 10 faces the other night in about 1 hour. Its a fun craft for us to do as a family.

I have an idea for this year. I ( and everyone I know) get the cd for a very popular internet provider in the mail almost monthly. I will be hanging mine on fishing line above the corn rows. Of course since their so popular the crows might take up the internet and leave the corn alone.
Tom

Plant onion seedlings before the corn germinates. The crows think the onions are the corn and grab the onions. they hate onions so the learn that your corn field ir really a onion patch and they leave it alone until the corn plants are too big for them to steal.

You can cover the corn with a row cover that is light weight. The farmer I talked to went back and uncovered the rows when the plants were tall enough to not be of interest to the crows. Within a few days the plants had greened up nicely and were standing straight.

The row cover would allow one to plant non treated/organic corn a week or two earlier as well

If you use the cover I would use medium weight like agripro 30 as that will keep in a lot more heat and moisture than the 17 or 19 weights.

Okay the number does not refer to weight but how much light is blocked. I find the covers that block 30% work the best for almost all applications.

lucy

CDs do work, and keep birds away, they get scared of the flashes. We had crows going down our rows and found out a .22 and M1 garand worked nicely.

I have been using cd's and fishing line for critter deterant in my gardens the last two years. We have so MANY deer, crows, and rabbits out here. So far, so good. I keep wondering when they will "get it" and i will move on to the next deterrant idea from some other grower ;-)
Toni

The hardest part is shooting the crow! My neighbor Joe has a crow hanging on a pole this year and by his observation it is working very well. Joe says you know it works when you watch the crows fly over and not stop.

Paul

It's actually illegal to have a loaded gun in the car someplaces, but you can go out in the country somewhere and do a 'drive-by' in a field. They don't seem to be so scared of people in cars. They are darn smart to hunt, that's for sure. Listen to Joe. It works. Hang 'em high!

I'm not a market gardener, so this method won't work in a large field. I place posts 15-20' apart in the patch. place them IN the rows, too. Bamboo 6' tall is fine. Then get discarded cassette tapes, break the tape and start wrapping around the tips of your stakes. Run it around the edges and criss-cross it. Heat, wind, rain will stretch it, so you'll need to take extra turns around your poles from time to time. It twirls and gleams in the slightest breath of air. Maybe they think it's a trap. When your seedlings are well up and growing strong you can remove the poles and tapes. Then worry about deer and racoons. Good luck! Bob