@OwOarchist@pawb.social @Memes@lemmy.dbzer0.com

lol, why specify both here? Tell me more about these non-bird avians and/or these non-avian birds…

At least to me, an ESL (English as a second language) person, both words carry different meanings:

Birds = Passeriformes, such as corvids, mockingbirds, parakeets, etc...
Avians = everyone else from Aves clade, especially the "larger" ones, such as owls, falcons, eagles and swans, but also hawks and chickens.

In Portuguese (I'm Brazilian) we have "pássaros" and "aves", which are definitely going to refer to different winged beings, and owls aren't passerines, therefore they'd be more of an "ave" than a "pássaro".

Both of these categories, however, have species that are equally going to be affected by solar panels, hence my distinction and inclusiveness.

Aren’t they only active at night, though?

That's the beauty of Strigiformes: there are lots of misconceptions about owls in what our common sense believes. There are diurnal and crepuscular owls, such as the northern hawk-owl (Surnia ulula) and the burrowing owl (Athene cunicularia, although she isn't used to fly as higher as her cousins because, and here's another common sense belief to be broken, she doesn't nest on trees and other higher places, she nests underground).

Many owls are crepuscular, active during dawn/dusk when the sun has a lower apparent angle. Depending on the solar panels' position and arrangement (e.g. solar panels facing slightly north/south), this means a sunlight reflected towards the far horizon instead of reflecting upwards. Given how the sunlight during dawn/dusk is fainter, yeah, it's not gonna burn the avians/birds, however it'll definitely blind them if they're flying towards the solar panels, because they'll be looking directly at a focused and magnified sunglare.

And even the so-defined "nocturnal owls" may meet the sunlight, either by being faced by danger/annoyance during sleep/roosting (such as corvids harassing owls or evil hominids attacking owls, among other situations requiring the owl to wake up and flee) or (a guess of mine) by getting active earlier during summer (when sunset happens later than usual), then they'll face the same problem as their crepuscular/diurnal cousins.