There's a shallow pond in the meadow near my office -- we've called it unofficially the 'leaky' pond, since it's never held water very well, even though we've tried to seal it a couple of times with bentonite treatments.
In spite of the shallow water (and probably because of it), it's been a good pond for frogs, dragonflies, and birds.
heron and azolla in the Meadow pond
Leaving work the other day, I spotted this Great Blue Heron (perhaps a young individual), 'knee deep' in the azolla or mosquito fern (that's colonized the edges of the pond, and is turning red with cold weather). Presumably, it's Azolla caroliniana, a native mosquito fern, rather than one of the invasive ones.
It's interesting to consider how it's colonized the pond.
I'm thinking that it may have come in with some of the semi-aquatic plants that were transplanted on the edges of the pond at the end of a research project. But, that's just a guess.
Click on the photo for a closer look.
Note: this is a duplicate post from my blog, Natural Gardening.