Bird Poo Smell

A little more than a week ago I noticed a bad smell in my apartment, but I couldn't figure out where it was coming from. It was a vaguely familiar smell, but wasn't any of the typical things you'd easily recognize (like rotting food or mold).

Then one day I noticed a duct vent outside my apartment and realized what it was:

Some birds had been building a nest inside the duct and were pooping up a storm inside, so much that it spilled out, down my window. The duct connected to my clothes dryer as well as the oven fan vent.

Unfortunately this vent outlet is between the second and third floors, so it's impossible to reach without an extra-tall ladder. I called the maintenance crew and they were able to pull the bird nest out (there were no baby birds or eggs, luckily), and put a grate over it.

I think the birds must have pooped a whole lot inside of the duct (which didn't get cleaned up), because there's still a small lingering smell wafting through the apartment a week later. I'm hoping that the smell will eventually go away by itself, but in the meantime I have one of those plug-in air fresheners, which masks it so that you don't notice.