Just to put the number of 1,000 to 28,000 birds per year in perspective. If you do the math for birds killed by house-cats (1.3-4 billion birds a year in US) into the square miles of the united states. You end up with house-cats killing 350 to 1078 birds per square mile per year. Of course this is a silly approximation, but large numbers are harder to grasp than small ones without mental tools like this.
Anyway, while killing birds with solar death beams is bad, I don't think it's bad enough to halt the progress. I mean, at least build a solar death array that can outdo mittens.
Better technology should avoid or not have collateral damage. Technologists should strive for something that's better in every way. What if the issue is not addressed, and it turns out these solar farms particularly attract one type of bird, and that population is destroyed, and it has repercussions on other populations?
Won't the birds just eventually go around the solar farm. Just like they eventually learn not to eat the poisonous berries, and not to get caught by house cats?
If you place non-natural objects into the path of creatures that are (just like many humans) unable to appreciate the dangers of those objects then carnage will ensue.
It's almost impossible to do anything on a large scale without affecting flora and fauna in some way, the mental image generated by 'birds bursting into flames' is quite gruesome (which I suppose was the intention). But it's not that much different than radar installations, large scale deforestation and building houses in its eventual result.
Anyway, while killing birds with solar death beams is bad, I don't think it's bad enough to halt the progress. I mean, at least build a solar death array that can outdo mittens.