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Wildlife
Wildlife as Actors
Animals are critical players in our environment, shaping and being shaped by the habitat in which
they live. From insects to mammals to birds, animals perform vital services in an ecosystem. Various
insects help pollinate plants. Mollusks help filter water. Birds help disperse seeds. Animals can also
disrupt the balance in an ecosystem. For example, some non-native animals succeed so well in their
new habitat that they displace native ones.
Wildlife as Symbols
Wildlife are also important for the symbolic role they play in our society (see the poem on the following
page). We often rally around the cause of majestic and charismatic species, or get up in arms over the
invasion of those animals we view as pests. In the Gwynns Falls, symbolic wildlife species may be
important for generating public support and sentiment for environmental protection.
Wildlife as Indicators
The presence or absence of certain animal species can serve as important indicators of the health of
the urban ecosystem. Just as benthic macroinvertebrates and fish can indicate the health of streams in
the Gwynns Falls, the presence of various mammals, birds, or amphibians can be used to indicate the
overall health of our terrestrial environment.
In general, a wide diversity of native species is often an indicator of a healthy environment. In contrast,
the dominance by a few species, especially exotic (non-native) species or invasive (those that invade
and displace others) species, is an indicator of a disturbed or unhealthy environment.
Fish in the Gwynns Falls
The presence and types of fish in a stream can be an indication of the environmental health of that
stream and the watershed. Based on a fish sample conducted in 1987, it is estimated that some 30
species of fish live in the Gwynns Falls, including some that are at least moderately sensitive to pollu-tion.
Generally, the upper tributaries contain more species than the lower tributaries of similar size.
For example, only one species, the mummichog, was found in the Maiden’s Choice Run, while 17
species were found in the Red Run, including brown trout, cutlips minnow, margined madtom, and
native brook trout. Several game fish including smallmouth bass, brown trout, and rainbow trout
are also present in the Gwynns Falls.
Birds in the Gwynns Falls
Another set of animals that may be good indicators of – and symbols for – habitat health in the
Gwynns Falls Watershed are breeding birds. Their presence or absence can indicate the type
and health of surrounding habitat. Another reason that these birds are useful indicators is that,
unlike with many other species, information on them is periodically collected by volunteers through
the Maryland Breeding Bird Atlas Project.
A Final Note
Although we have presented certain species as indicators, it is important to remember that a healthy
ecosystem sustains a diversity of plants and animals. Our focus on one set of species as indicators or
symbols is inappropriate if it causes us to lose sight of this fact, or to favor one species at the expense
of another.
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