I admire those films where the title is something hidden in the movie that you have to find out later. In this case, this film has the title hidden well into the middle of the film, and at first sight there is no clue on why the movie is called "Thursday". By the way, it would be really cool to have a restaurant that is far up the atmosphere!
I think the film presents many issues with technology that are widely known, such as how we have become so dependable on it that when we loose power at work, everything comes to a halt (it is true, not only that, if I loose the internet connection, I just cannot move forward), or how we get so absorbed by technology that our entertainment, our communications, and our activities revolve around technological gadgets such as cell phones (smart phones?), tablets, and so on. This film does not have any dialogue either, but I don't believe the film could have gone without it, I think this a conscious decision from the filmmaker and not the nature of the film (like in Inbox). The original idea in the film is how we get so involved in the life in a big city that we forget that nature is still trying to thrive in those environments, the birds story line is real and true in many cities. What is not true is the fact that the city is presented as a barren, devoid-of-life, place. In fact, there is a whole movement right now on making big cities more green by placing more green areas around.
I am not sure what the question about gains and losses means. I will try my best. I see many gains in the sens that technology has made our life so much easier in many aspects. The fact that I can sen this post to be viewed by potentially many other humans is remarkable, and a positive gain. The loss is that I cannot have all of them in front of me to tell them all this I am typing here, which is depicted in the film with the couple having to communicate by text messages because they are so busy with their lives. Another loss in the film is the fact that nature is so hidden in the city that is hard to see or notice until a bird smashes on your window, just like in the film. The enormous gain is the awareness that comes out one we realize that life is actually thriving around us, despite our best efforts to transform the environment to our needs.
I think the agent in this film is the bird because it is taking the role of nature in the film. The fact that this bird has thrive in the urban environment and has transformed its environment (by building a nest inside an antenna's plate, using wires to build the nest for lack of tree twigs) makes it the main role in the movie. I watched the whole thing waiting for the next sequence where the bird would show up. I think another message in the movie is the fact that life moves on despite our best efforts to manipulate it into complying to our wishes.