Ultrasound devices have been demonstrated to be ineffective in repelling rodents and other pests.
http://www.ratbehavior.org/rathearing.htm Don't waste your money.
The most effective mouse trap I've ever used was actually home made. The idea was given to me by a ranger stationed in the Olympic National Park who had a ton of mice to deal with at his cabin. It contains no toxins and, best of all, can catch multiple mice. My aunt once caught 24 mice in her garage just over night using this method.
You'll need a bucket, an empty soda can, a piece of wood like a ruler about 18-24" long, and a wire coat hanger to build the basic trap.
Punch a hole about the size of a pencil in the bottom of the soda can. Straighten the wire coat hanger and run it through the soda can, making sure that the can can rotate freely on the coat hanger. Bend the coat hanger so the can is suspended in the bucket. The can should be 4-6" below the top of the bucket. Lean the wood against the bucket to form a ramp from the floor to the top of the bucket. Pour about 6" of water into the bucket. The water needs to be deep enough so that the mice can't rest on the bottom, but not so deep that they can reach up and grab hold of the soda can. Smear a little peanut butter on the can (it works best if you smear it in three of four stripes along the length of the can.
The trap works by attracting the mice to the smell of the peanut butter. They climb the ramp to get it, but because the can is too low for them to reach, they jump down onto the can, which spins and dumps them into the water where they drown.
I would not recommend having this trap out while your parrots are out of their cages, as it could just as easily catch them as it catches mice. Set it out at night after your birds have been tucked in to their cages. Mice are most active at night anyway, so it is really the best time to trap them.