The Idaho fish and game folk said that West Nile had decimated magpies and ravens all over Idaho. However, these birds were around all winter, then disappeared in early spring before the snow was off the ground. I haven't seen or heard a single mosquito here in at least two years, although years ago, when we had plenty of water, marsh land and the river was running full all year, we had hoards of mosquitoes, as well as countless birds. This present situation just doesn't seem like a "West Nile" scenario to me. It doesn't make sense that so many birds are going to become infected without a single obvious vector around.
A few of the magpies of the group that inhabited my ranch, which is about 500 acres, encompassing two homes a mile apart, each with individual magpie colonies that stuck close to the houses where they were fed in winter along with the other birds, were individually recognizable by various traits, and were here year after year. (Partially missing tail, deformed beak, missing foot or leg, or simply a unique personality or habit, etc.) Many of them barked like dogs, a trick they learned to tease one of my dogs away from her food.
I haven't seen a single raven, either, although these were never prevalent in my particular area. One usually sees them across the plains to the south, but even there, they have become rare. Another bird that has obviously declined, although there were still just few of them that showed up this spring, is the starling. Not that this is necessarily a bad thing, since they were an introduced specie.
I just suspect that something is going on beside West Nile. I have never, ever, sprayed any of my property with pesticides or herbicides, but don't know what neighboring farmers and cattle ranchers may be still doing on their own, or what may be drifting in on the wind from elsewhere. Aerial crop spraying ceased here many years ago, and a bunch of us complained about careless fogging of 24D along the water canals by the water district, and this ceased 5 years ago.
I can't imagine an explanation, except West Nile virus doesn't quite fit, at least in this area.