I know you are worried that I am getting a little far afield from the pond. Glug, while PonDocing I saw that the pond extended far outside its shore. Many ponds were overwhelmed with voles and gophers. Deer ate everything around the pond.
The absolute best top predator is a raptor. The common barn owl is excellent; although there are others. I hear, “Oh, we have an owl.” I say, “Do you have a resident owl?” Owls often range over many miles moving to caves in the mountains in the winter. If you build a house, they will come and stay; you will have an air force.
Materials and general dimensions can vary somewhat depending upon materials available. A long box 40” X 12” (wide) X 16” (tall) is easily constructed. A 6-inch square hole at one end cut 6 inches above the floor of the box provides access. Ideally, the entranceway is positioned high inside the barn wall such as 20-25 feet above the ground or under a protected eve. This provides a permanent home for the queen of the sky.
The female barn owl is the owner of the box. She attracts a mate in the spring; lays eggs; and hunts with him until the chicks are a few weeks old and then she kicks her husband out. When the chicks mature, she hunts with them; and then her sons are kicked out. The mother and daughters will spend the winter in the box. The next spring, either the mother or the dominant daughter will become owner of the box. Therefore, once inhabited, the box will remain occupied generation after generation.
You will not notice their presence. They remain in the box throughout most of the day to hunt in the evening twilight. They will hunt about one mile from the box covering 10 square miles. She is small but lethal being about the size of a PonDoc fist. She is a ghost killer where her ruffed feathers make her silent. She is skilled at breaking the necks of her victims without being detected. The only thing you will see is a small pile of skulls and bones in little packets she regurgitates after digesting a meal.
Glug, I know you are nervous when she is around. But that is the point, everybody is. She will rake deer, dogs, cats, anyone in her domain. A balance is achieved in the populations of animals and birds around a pond. Nothing dominates and the “middle way” is achieved…
PonDoc from the pond