Sustaining Wildlife Biodiversity
Most species considered "wildlife" by pond owners are relatively large, and include waterfowl, mammals, amphibians and reptiles. Most of these larger species, however, view their environment as a "patchwork" of habitats, with some locations especially suitable for grabbing a tasty meal, while other locations are better for resting. The patchwork consists not only of other ponds, but wetlands, streams and even temporary water bodies. Amphibians have both aquatic and terrestrial requirements as they develop through the larval (tadpole) stage to become adults. Although a pond owner can improve the chances of seeing wildlife out the back window through wise pond management, it is thus important to recognize the need for suitable surrounding land to support wildlife.
Buffers of natural vegetation are an excellent way to increase wildlife diversity. The buffer serves as cover where wildlife species can hide from predators, reduces sediment and nutrient inputs to the pond, and may also be a corridor for getting from one location to another. Vegetated buffers also reduce the attractiveness of a pond to Canada Geese. Regularly mowed grass, by contrast, provides very inhospitable habitat that few species are willing to cross. Birds are often the exception, and the single tree on the island in the center of the pond shown above serves as a nesting site for a Great Blue Heron.
Although fish do attract the occasional heron, they can also eliminate a large number of species that would otherwise be present at the pond. Ponds with fish not only have greatly reduced numbers of invertebrates, for example, but also have relatively few of the larger, charismatic species such as dragonflies that make wildlife viewing more enjoyable. Many frogs likewise coexist poorly with fish (Bullfrogs are an important exception, and are common in fish ponds). It is possible, however, to simultaneously manage ponds for both fish and wildlife biodiversity by encouraging the growth of a diverse community of aquatic plants. The plants provide invertebrates with protection from fish predators, and also protect small fish. Ponds with shallow slopes from shoreline into deeper water are typically colonized by an assortment of plants, and the deeper areas still provide open water for navigating a boat or casting a fishing lure. Yes, it's possible to have it both ways.