Generally we care about a bird species as a whole rather than about individual birds of that species.
If something is killing birds, even a lot of birds, but in a place where those birds are abundant and whatever is killing them will just lower lower their equilibrium population a bit rather than set it on a decline or lower it so far that they might die out in the area then there generally isn't a lot of concern over it.
Hence activities in places with species of birds that have low population or are threatened or endangered tend to draw more concern than activities in places where that isn't the case even if the latter kills way more total birds.
If something is killing birds, even a lot of birds, but in a place where those birds are abundant and whatever is killing them will just lower lower their equilibrium population a bit rather than set it on a decline or lower it so far that they might die out in the area then there generally isn't a lot of concern over it.
Hence activities in places with species of birds that have low population or are threatened or endangered tend to draw more concern than activities in places where that isn't the case even if the latter kills way more total birds.