Sudden increase in dead birds

I was just curious as to whether there is a reason behind the sudden increase in dead birds in my area. I live in Braintree, Essex and I walk my dogs for about 3hrs every day, I cover a large amount of the local area and over the last two years I had not seen one dead bird that I can remember now in the last 2 weeks I have seen 6, none of which seem to show any sign of attack from cats or such. Is this normal at this time of the year?