It's been a long time since you asked, but I just watched this movie for the first time today. Which is kinda crazy since I watch all sorts of low budget horror but anyways..
I laughed a bit at the ending I guess we're to believe that the bird was infected at the glacial site and then migrated and eventually died where the dog began eating it, or perhaps a whole bunch of birds have it and that was just one example of how the "bugs" were beginning to invade the whole world.
The global warming stuff got a little heavy-handed towards the end, but otherwise I enjoyed the film. Bugs freak me the heck out.. I REALLY hate 'em. I realize these were vertebrates n not true bugs, but that doesn't matter lol, I hate isopods too and those are not true insects.. ughh. These feelings of hatred & fear certainly make me a lil biased on how creeped out I was by this film.