In a wooded area of the Parkland I heard this unusual what can be best described as a medium/high pitched 'Trilling' sound like a mobile phone (Cell phone) call. It lasted about 2 seconds each time and continued to be repeated as I approached it. Then I observed a Jay fly off through the branches. It was closely followed by a second Jay. I have never heard this sound before and would never have believed it was a sound of a Jay, but I followed and the second Jay pitched again and continued making this noise. I took a few shots of it amongst the branches and then it flew off.
I can only assume that due to the fact that its the breeding season coming along now that its some kind of mating call.