Haven't seen any willow (most of the trees are maple, some oak, some Hemlock) but have a pond probably a good 1/8 mile or more back into the property. Thing's about 30-40 feet in diameter and was used for watering livestock when this was an operating dairy farm - which it hasn't been for a number of years now. You sort of have to weed-whack your way back into it now because of all the opportunistic brush that has grown up around it. (An old aerial photo from 1976 or so shows that this entire piece of property was bare of trees except for the Hemlocks near the house and a big oak back by the pond - now trees have grown up everywhere and thorn bushes, probably wild rose of some sort grow in the remaining spots..)
The first time we worked our way back to it after we moved in (we saw it on the satellite view) we noticed that there were goldfish in it. Regular generic carp are native and I would have expected them as maybe a possibility since the pond has a small rivlet feeding it, but goldfish - not exactly. (OK, so they are fancy carp - but they're not native!) However, this past summer we had quite a number of sightings of a Blue Heron flying over coming from the direction of the pond. Last fall when the grandkids were visiting we trekked back to the pond to check on the goldfish and we provided the kids with some stale bread to feed them. Didn't see a single goldfish.. The heron probably was stopping at his private restaurant each evening for a fishfest, and all we managed to get from our inspection tour were a bunch of ticks that we spent the rest of the evening picking off.. (I keep saying that 'next year' I'll clean up the path back to the pond - but so far next year hasn't arrived!)