I'm hoping that this isn't the beginning of a trend, but over the past week I have discovered an alarming number of dead hummingbirds on my property. For reference, I live in a suburban area on the western coast of California, and the birds that I've been finding have green feathers, some of which also have beautiful, shimmering red feathers around their necks.
This started about 5-6 days ago, when I found the first bird laying dead on its back on a lawn chair that was up against the couch. I didn't think much of it at the time, but then a couple days later, I found another two dead hummingbirds within about 15-20 feet of where I found the first one, this time on the ground. I'm no expert on birds, but a cursory inspection of their bodies revealed no obvious cause of death: no lacerations or anything that I've come to expect when the neighbors' cats make a catch. They were simply lifeless. There are windows around my house (including where I found them), so maybe they ran into them at some point when I wasn't around... But that's never happened before, or at least it's never killed a bird who's done it. (On rare occasion over the years, I've witnessed larger birds attempting to fly through them, bumping off and flying away without apparent injury.)
For each of the birds, I brought them inside and tried to provide them with sugar-water in an attempt to resuscitate them, just in case I was missing out on some subtle signs of life (I'd found a hummingbird in poor shape in my garage once a number of years ago, and this technique seemed to help it get back on its feet before I released it), but at no point did any of them revive.
At this point, I've already disposed of the birds by placing them in the wild brush out behind my house, to let nature do its own thing with them. But now that I mull it out more in my mind I'm wondering if the deaths could be linked. In all the years I've lived here (a matter of decades), I've never come across the corpse of a hummingbird, so discovering three in such short succession is quite a surprise. I wonder if it could be caused by some recent change in the local environment, but wouldn't have a clue as to what that'd be. Is there something that I should be doing with these birds should I find more, or someone who I should communicate this knowledge to?