Birds have made nests in the bathroom vent outlet of our recently purchased house. I took off the external vent cover and found the ductwork (4” uninsulated plastic accordion dryer duct) all torn to pieces to at least 18” into the wall (the ducts are between the first storey ceiling and 2nd storey floor and run horizontally out through the hardiplank siding of the house. Any "tricks of the trade" on how I can get some ducting of some sort from the dryer duct 18” into the house through a 4" round exterior wall hole? I was thinking of using some 3” rigid duct and trying to get it into the 4”plastic vent (hoping air would take the path of least resistance through the 3”duct). I realize this isn’t optimal but I don't want to rip out the ceiling drywall or the exterior siding to do this. I also realize that this verges on the DIY but since it's not on electrical or HVAC systems, I'm hoping that comeone can help me with this one.

Thanks,

keith