Very sad case here. Thankfully rare. A couple of years ago I was the victim of a bird strike whilst riding in the country a few miles from home. Fortunately it was a small bird, possibly a swift. It swooped across from my right and hit my helmet visor with considerable force. i was wearing a full face helmet. The visor did not crack but the mechanism busted. I consider myself very lucky. It happened so fast and was completely unavoidable. Gave me a shock, but I was able to stop safely without injury. Obviously a new helmet was required, apart from the visor damage, there was copious amounts of bird blood and gore residue.
http://www.telegraph.co.uk/news/2018/02/21/motorcyclist-killed-pheasant-struck-helmet-60mph/
http://www.telegraph.co.uk/news/2018/02/21/motorcyclist-killed-pheasant-struck-helmet-60mph/