Flight crew departing CYXE rejects takeoff at or above V1 due to birds.

Narrative

I was the flying pilot as we were taking off out of Saskatoon. The visibility was around 5000 RVR. The taxi out was normal and on time. I'm not sure the runway because in the course of the morning it changed several times. We started our takeoff and all normal calls made. Right as we were approaching V1 I saw a flock of approximately fifteen seagulls out the Captain's window. Because of the fact that I have hit birds before I thought there was no way that we would not hit them and ingest them in the engine. They were very close. I called 'Birds' 'abort.' At that time we both start to pull the thrust levers back and the Captain then put them in reverse. The Captain's head was down so he was not real sure why at this pint I called for the abort. He had been looking at the airspeed and never saw the birds. The plane came to a stop and we made the turn off at the end. I made a passenger announcement concerning the event. I called the Flight Attendants to tell them what happened. Captain told me he heard some kind of loud bang right before we aborted the takeoff. At this point I was pretty sure we had hit a bird. We called operations to tell hem we were coming back as we taxied to the gate. I did a walk around and found nothing that looked like a bird strike; but to be on the safe side we call maintenance and dispatch to let everyone in on what had happened. The flight was delayed; but after maintenance came put and a though walk around we left for ZZZ with no other problems.