Was it in liquid form or tiny pellets? Diazinon is available in both for grubs
but I'd never use the granular type for exactly the reasons you state. Liquid
with heavy watering after goes way down into the ground. We never noted a
decrease in the bird etc population nor any dead ones from it in our yard.

Ian wrote:

Heather,

Ian here in Brampton, another part of the GTA that has the grub infestation.

A word of advice: I don't know if it was Diazinon I used, but I bought some
grub killer chemical at Home Depot a few years ago, applied it to my lawn as
the directions instructed, and it did indeed kill the grubs. Also killed the
mourning doves, a few starlings, and a robin.

--
John S. DeBoo