Some (many in fact) years ago I lined up for take off in a Viscount on a long runway. We were light weight due it being a positioning flight. We spotted large flocks of birds several hundred yards ahead on the runway. We delayed take off and requested the fire engine crew to scare them off using the water cannon. This was successful and ten minutes we began the take off roll.
Just before VR we ran head on into a whole bunch of birds initially unseen that had been feeding on the grass flight strip on each side of the runway and which got airborne as we neared them. There were several impacts but no indications of power loss from the four engines.
We rejected the take off at above VR while still on the ground of course and without using brakes deliberately used the full remaining length of 6000 ft to pull up using the propeller ground-fine position which was very effective at high speed. We initially thought prop ground fine had failed to operate as there was a noticeable absence of the ground fine engine noise normally heard in a landing roll. Deceleration was excellent however and the prop ground fine noise came in within a few seconds. We later realised the reason for the perceived delay in hearing ground fine come in was that at that relatively high speed, it takes a finite time for the propellers to turn in their hubs from the take off angle through into the ground fine angle.
Runway inspection revealed 24 dead birds - while the aircraft inspection revealed a few blood smears but no damage. We departed after the inspection and there were no problems on the flight.
The reason we aborted was that everything happened in a flash and with a mile of runway ahead and hearing the multiple strikes it seemed a good idea to stop. Staying off the brakes was the option we took in view of excess stopping distance available. In fact the brakes were quite cold after we returned to the tarmac.
The Viscount incident happened some time after the fatal Lockheed Electra accident in USA where the aircraft hit a large flock of birds during initial climb after take off and lost nearly all power - subsequently crashing into Chesapeake Bay (I think that was the name). The instant decision to abort the Viscount take off roll may have been a subconscious recollection of the Electra accident - but who knows!