The provision
of water can turn an average wildlife habitat into an extraordinary
one. While most species depend daily on water for drinking, some
also require it for other reasons. Many birds need water to bathe
in to keep their feathers in shape. The eggs and young of dragonflies,
frogs, toads, and most salamanders need to be in water to develop.
Of all habitats
that you might consider creating to attract wildlife, a pond can
be the most satisfying. A well-managed pond adds a spot of beauty
and tranquility to your landscape and provides food, cover, and
water for an amazing array of creatures. Rich communities of plants
and animals can exist in and around the smallest garden pond.
The first priority
in creating a pond is to have a clear idea of why you want it. Pond
management can succeed only where there is a sense of purpose, of
knowing not only what you are doing but why you are doing it. Whether
you are targeting frogs, salamanders, birds, dragonflies or fish,
you will need to know the needs of these animals to optimize the
pond design for them.
| Figure
1. Habitat features in and around a pond |
Click to Enlarge |
| The
provision of water can turn an average wildlife habitat
into an extraordinary one. While most species depend daily
on water for drinking, some also require it for other
reasons. Many birds need water to bathe in to keep their
feathers in shape. The eggs and young of dragonflies,
frogs, toads and most salamanders need to be in water
to be developed. |
|
Before constructing even a small backyard pond, first check with
your local planning office for permit requirements. Also, check
with your insurance company, which may have additional safety requirements.
For a one-time
consultation or help with design and construction, look in the Yellow
Pages under “Ponds,” “Landscape Contractors,”
or “Nurseries” that specialize in water gardens. If
a pond exists nearby, ask the owner for information on how it was
constructed, who did the work, what permits were required, and what
problems were encountered. Also, ask pond owners what they would
do differently next time. If you decide to use a contractor, find
one with experience building ponds and request a list of references.
Most likely,
you’ll want to locate your pond where you can enjoy watching
the wildlife that use it. A pond that can be seen from the house
is especially important if small children play in the area. To help
you experiment with different locations, you can lay out a rope
or hose, or pound in short stakes to indicate the pond edge.
As you assess locations for the pond, consider all underground utilities
and other potential obstacles, including tree roots, which can make
excavation difficult. You may also require supplemental water to
keep the pond full, and electricity to run a pump for a filter or
waterfall. Your pump dealer can provide specifications.
A healthy pond
needs daily exposure to at least five hours of sunlight during the
growing season (spring through fall). Some shade is a good thing,
however. It helps to prevent algae growth and keeps a shallow pond
cool. Try not to locate the pond directly under trees which drop
leaves or needles; decaying vegetation in a pond can make the water
acidic and low in oxygen.
An obvious place
to locate a pond is in a low area where water naturally collects.
However, because a high water table will cause a synthetic liner
to “bubble up” or a concrete one to crack, it is better
to locate these types of ponds above the high-water line. Also,
stay away from direct surface runoff from nearby roads, parking
lots, and heavily fertilized areas, all of which negatively affect
water quality. Finally, consider where natural drainage will go,
and how the pond might flood in a heavy rain.
Figure
2. Examples of ways to create the edge of a pond
 |
|
Figure
3. Steps to follow when installing a pond liner
 |
|
A pond can be almost any shape and any depth. Even a one-foot-deep
pond can contain a variety of aquatic life if kept full and in partial
shade in the summer. A more stable pond would have to be at least
24 inches deep, and 36 inches is preferable. No matter how big you
make your pond, after a while you’ll probably wish you had
made it bigger. Generally it’s not much more time-consuming
to take care of a large pond than to take care of a small one.
A natural appearance
can be achieved if the general shape of the pond and its slopes
are varied. Varying the slopes on the edge (Fig. 2) will allow for
a mixture of plants and provide the different water depths sought
by wildlife.
A gradual slope,
or beach-like area, on at least 50 percent of the edge is optimum.
Many songbirds, including robins, chickadees, and warblers, use
the shallow (1/4-inch to one-inch) water at the beach for drinking
and bathing. Mud in this area is also used as nesting material by
cliff and barn swallows; a variety of insects use mud for basking
and nesting. Coarse-textured material, such as sand or pea gravel,
should be used to create traction and a natural-looking surface
on slopes when a synthetic liner is used.
If your new pond doesn’t hold water naturally, you’ll
want to make it watertight by using a liner. The liner may be concrete,
earth (clay), or a flexible, synthetic material manufactured for
ponds. Prefabricated shells are both durable and easy to install.
However, they are available only in limited sizes and shapes, and
their slopes can be steep and slippery, features that are not child-friendly
or hospitable to some wildlife. Also, some swimming pool liners
and children’s play pools are treated with chemicals to combat
algae, which will leach into the pond and kill plants, fish, and
possibly other wildlife that use the pond.
For a small
pond, a flexible, synthetic liner is recommended (Fig. 3). Available
at landscape supply centers or aquatic plant nurseries, a flexible
liner allows you to easily shape the contours of the pond to your
specifications. Furthermore, a flexible liner is guaranteed, impervious
to freezing, nontoxic to plants and wildlife, and not too difficult
to install.
To calculate
the size (length and width) of a liner required:
- Length
= length of pond + (2 x depth) + 4 feet (2 feet overlap, each
side)
- Width
= width of pond + (2 x depth) + 4 feet (overlap)
If the pond
has been excavated, measure the length and width of the liner you’ll
need by running a measuring tape down one bank, along the bottom,
and up the other side, and add enough for overlap.
Place the liner
over the protective layer (old rug, cardboard) in the pond and allow
it to sag in. Work the liner into the shape, folding it over at
the corners and making sure that there is plenty extending all around
the pond edge. Wrinkles and folds won’t weaken the liner.
Temporarily secure the liner in place by laying large, smooth stones
on the apron around the pond.
If desired,
a dd a two to four-inch layer of sand or washed gravel over the
liner. If the sides of the pond aren’t too steep, the material
won’t settle into the bottom. This provides shelter for small
organisms, creates a natural appearance, increases the surface area
for growth of bacteria that break down fish wastes and other organic
matter, and gives the fish something to root in for food (algae).
Fill the pond
slowly with water. (If you use water that contains chlorine, let
it stand for at least 24 hours before adding any plants or animals
to allow the chlorine to evaporate.) Soil may be added or removed
under the liner’s edge to adjust the level and overflow point.
Lay rocks directly on the liner around the pond edge to help conceal
the liner. For safety, rocks at the edge should be able to stay
in place on their own. Trim the excess liner.
Reaching and maintaining an ecological balance in a small pond with
an artificial liner can be difficult, especially if it contains
fish. A filter will generally be necessary if you want to view fish
in a lined pond. A pond without fish may not require a filter.
Filters work
in two ways: mechanically, by physically screening out particles
in the water; and biologically, by converting toxic ammonia and
nitrites from fish wastes and other material into material that
can be utilized elsewhere.
Waterfalls and
cascades can be practical as well as aesthetically pleasing. They
can give an extra dimension in the liveliness of movement of the
water. If water is circulated by one means or another, it will be
constantly replenished with oxygen, to the greater benefit of pond
life. Not all plants appreciate moving water; water lilies, for
example, prefer still water. But if the cascade is a trickle rather
than a torrent and is carefully sited, there will be quiet backwaters
for the lilies.
A commercial
pump dealer can help you with general design questions for your
filter and waterfall. Let them know that your intent is to provide
wildlife with a safe environment.
Families with young children need to consider the hazards of a pond
and perhaps postpone construction until children are old enough
to understand the danger associated with water. If you construct
a pond, contact your neighbors with small children to educate them
about safety.
Access points
such as a large, sturdy flat rock or platform at the pond’s
edge can make visiting safer for children and the elderly. Any rocks
at or near an access point should be able to easily support the
weight of an adult. A series of steps, or shelves can be dug within
the pond to make it safer. Dig a shelf around the pond in the range
of 10-12 inches and plant marginal plants in this area, with the
final depth in the middle of the pond 18-24 inches. A shelf should
be 12-24 inches wide. In addition, areas can be made inaccessible
by closely planting shrubs or other vegetation at the edge of the
pond.
Stringently
follow safety guidelines and avoid electrocution by having electrical
outlets near your pond installed with a ground fault circuit interrupter
(GFCI), which prevents any shorting out or similar problems associated
with outdoor electricity. (See “Maintaining
Birdbaths” for additional information.)
Plants provide food, oxygen, shelter, hiding places, and platforms
on which wildlife rest, live, lay eggs, and metamorphose. Plants
also stabilize the pond edge, hide the pond liner, and shade the
surface of the water to limit algae growth and keep the water cool
in summer.
A new pond will
need a year or so of plant growth before it will look natural and
begin to appeal to a variety of wildlife. Plants nearby will colonize
on their own, but adding your own will speed the process along and
assure you get what you want. Wetland and aquatic plant nurseries
carry stock to get you started. Never dump aquarium plants into
your pond. Many are aggressive growers and can quickly take over.
Your pond should
have no more than 65 percent of its surface covered with plants
during the summer months. Oxygen enters the pool where water and
air meet, and sunlight needs to reach submerged plants, animals
and their eggs.
Pond vegetation includes these main groups:
Submerged
plants are rooted or free-floating plants that grow completely
underwater and include: coontail (Ceratophyllum demersum)
and elodae (Elodea canadensis).
Floating
leaf plants float either on or are raised slightly above the
pond surface. Floating plants, including water fern and duckweed,
can spread very quickly. Others include: watershield (Brasenia
schreberi), white water lily (Nymphaea odorata), yellow
pond lily (Nuphar lutea ssp. polysepala), pondweed
(Potamogeton natans), and bladderwort (Utricularia vulgaris).
Marginal
plants create the immediate habitat surrounding your pond and
thrive in 6 to 12 inches of water. Floating plants include: great
water-plantain (Alisma plantago-aquatica), inflated sedge
(Carex vesicaria), wapato (Sagittaria latifolia),
hardstem bulrush (Scirpus acutus), wool grass (Scirpus cyperinus),
and small-fruited bulrush (Scirpus microcarpus).
In a pond lined with a flexible liner, plants can be grown in plastic
containers or directly into gravel within in the pond. Containers
facilitate removing plants from the pond for thinning, replanting,
and protection in cold weather. Containers also help keep aggressive
growers in check. Containers that extend above the water surface
serve as small islands in your pond and are places for frogs to
rest and hunt. A nice size for a container is 12 inches wide and
eight inches deep. The containers can rest on the shelves you construct
around the inner edge of the pond (Fig. 2).
To plant containers,
fill them with a mix of one-quarter sand, one-half garden loam,
and one-quarter compost. Be careful not to use materials that float,
such as vermiculite and perlite. Also, be sure there is nothing
sharp on the bottom of the container that could wear a hole in the
liner. An extra piece of liner or carpet remnant placed under the
container will provide added protection from wear and tear.
You can “mulch”
the plants in containers or pockets with an inch of pea gravel and
coarse sand to prevent the soil from clouding the pond. If you use
only soil or fine sand, fish - especially koi - will root around
in it and cloud the water.
Plants in containers
can appear unnatural. Planting directly into the gravel within the
pond can be more visually appealing and works to maintain the water
quality more efficiently than plants in containers.
Animals living in a small pond are very vulnerable. A small pond
can quickly warm up or freeze over, lose water or fill up. This
places considerable stress on aquatic life forms, which cannot instantly
move to a safer, more stable environment. Thus the life that colonizes
a pond must be tolerant of a fluctuating environment or be able
to adapt by mobility.
Even so, a surprising
number of flying aquatic insects will colonize a new pond if there
is another body of water within a half-mile. Water-boatmen, beetles,
and dragonflies investigate new waters quickly and will stay if
conditions suit them. As your new pond begins to mature, other wildlife
will visit and inhabit the area. Tiny aquatic mollusks and crustaceans
will find their way from a nearby wetland on the feathers and feet
of a visiting bird. Fish also may be introduced from eggs brought
in by waterfowl. Larger ponds located in suitable habitat may attract
frogs, newts, salamanders, toads, turtles, and snakes. Many of these
will travel up to about a half-mile from their home pond or wetland,
as long as there is adequate cover along the way.
Seek expert advice from your state Fish and Wildlife office when
stocking fish or any other wildlife in your pond. Non-native species
of reptiles, amphibians (especially bullfrogs), and fish create
many serious difficulties for native populations if they leave your
pond. They take over habitats and food supplies, and they may introduce
diseases to wild populations. In particular, wildlife purchased
from pet stores are sometimes raised under poor conditions and frequently
pass on disease.
Introducing
fish will profoundly alter the pond’s ecosystem. Fish eat
amphibian eggs, tadpoles, and dragonfly larvae. Excess fish create
stress, deplete oxygen, and can add an unhealthy amount of ammonia
to the pond from wastes.
Although small
fish can provide a valuable service by eating mosquito larvae, predatory
aquatic insects such as dragonfly larvae and water striders also
eat mosquito larvae. Bats, birds, toads, and frogs eat the adults.
Also, moving water (with a fountain or cascade) discourages mosquitoes
from laying eggs. Fish are therefore unnecessary for mosquito control.
You can easily observe small aquatic life in your pond using a few
simple tools from your kitchen. With a measuring cup or meat baster,
collect some water near a pond-side plant. Put your sample in a
white pan or deep white plate. A hand lens or magnifying glass will
help you to see very small organisms. Sampling different places
along the edge will net different creatures. Enjoy bug watching,
but ensure a steady diet for fish and other vertebrate life by putting
your water sample and invertebrate organisms back where you got
them.
No matter what size pond you have, there are ways to improve it
for wildlife. For example, birds and other wildlife are attracted
to the sounds, movement, and the flashing light of moving water.
Falling water is also soothing to the human ear and masks noise.
A small dribble or trickle over a log or rock is all you really
need.
Here are
some other ways to improve a pond for wildlife:
- Add a floating
log anchored to the shore. Fish tend to gather under such logs.
- Include a
multi-forked stick that protrudes above the water’s surface.
(You can stick it in a sand-filled coffee can.) Songbirds and
dragonflies will use the branch as a perch.
- Include a
large rock that protrudes above the water’s surface. Turtles,
frogs, and butterflies will use it for basking.
- Submerge
a small brush shelter in shallow water as a place for turtles,
salamanders, frogs, toads, and aquatic insects to attach their
eggs and to serve as a hiding place for fish or tadpoles (Fig. 2).
- Add a rock
shelter next to or around part of the pond for animals such as
salamanders (Fig. 2). Add a group of large rocks in the pond as
hiding places for fish and/or amphibians.
- Create a
gentle slope and a better beach around a portion of your pond
by adding sand, small rocks, or soil in steep areas.
- Install nest
boxes nearby for cavity-nesting birds, such as violet green swallows
and wood ducks. A bat house will help control a pond’s mosquito
population.
Algae are free-floating microscopic plants without true roots, flowers,
or leaves. They are an essential food for fish, tadpoles, ducks,
and snails, as well as providers of dissolved oxygen for all aquatic
creatures. In a balanced pond system, algae growth is controlled,
creating at most a moss-like coating on the surface of the liner,
which gives it a natural look.
An overabundance
of nutrients (decayed vegetation, fish wastes, fertilizer runoff)
will increase algae and color the water brown, yellow, pea-soup
green, or even red. When this occurs, the pond is said to be “blooming.”
Algae blooms also occur in new ponds and in the spring before pond
plants get big enough to shade the water adequately.
In the wild,
birds get water from moist food sources, snow, dew, rain puddles,
ponds, lakes, and streams. But water can be scarce during summer
dry spells and inaccessible during winter freezes. Species that
are not otherwise likely to visit a yard may drop by a birdbath,
especially during hot summer months and during spring and fall migrations.
Since birds carry water to their young in their beaks, a birdbath
also may encourage nest construction nearby.
A birdbath can be almost anything that holds water - from an upside
down frisbee to a backyard pond. Whatever form it takes, certain
features are crucial.
Birds prefer
a birdbath with margins that slope gradually, allowing them to wade
in to a comfortable depth (Fig. 4). A dry edge or beach gives birds
a dry place to land before entering the water.
Many birdbaths
go unused because they are too deep. Keep the water shallow - typically
1 to 3 inches at its deepest point - since most birds bathe in water
that is no deeper than their legs are long.
Few birds will
try to bathe in a bath that has a slippery surface, though they
may perch on the edge to drink. A rough-textured bowl is much preferred.
In winter, some
birdbaths can crack because, when water freezes, it expands about
10 percent. Because ice will exert pressure against an edge, this
is another reason to avoid baths with edges that turn up sharply.
If you fall
in love with a birdbath that is too deep, steep, or slippery for
birds, you may be able fix the problem by adding flat rocks or gravel.
Bathtub stickers or caulk sprinkled with sand also provide traction
on slippery surfaces.
Any size birdbath
may be used by birds. However, the bigger the birdbath the more
birds will use it at the same time. For communal bathing, a birdbath
should be at least 18 inches in diameter.
 |
| Figure 4. Birds need a gradual slope that allows
them to wade in and find a comfortable depth. An 18"-high
wire fence can be added to keep cats from ambushing the
bathing birds. |
|
|
A wide variety of ready-made birdbaths are available from local
nurseries, garden centers, and specialty wildlife stores. All have
advantages and disadvantages: Concrete baths are widely available,
have the feel of stone, fit into most landscape settings, and stay
put even in strong winds. Birds like concrete baths because of their
rough surface; wide, gently sloping bowls; and stability. Plastic
birdbath bowls placed in iron-rod or wood supports are lightweight
and easily moved, hence; easy to clean. However, the bowls often
have steep sides and a slippery surface. Plastic may also crack
if water is allowed to freeze in it. While ceramic birdbaths can
be quite ornamental, glazed ceramic is extremely slippery. Hanging
birdbaths have the advantage that they can be placed where it might
not be convenient to locate a birdbath that rests on the ground.
However, water spills easily from them, especially on windy days.
Ground-level
birdbaths, or dipping pools, are an especially attractive feature
in a garden and may be preferred by some bird species(See Fig. 5.).
They can be made larger than a standard birdbath and may attract
other wildlife, such as treefrogs, that might not visit a birdbath
on a stand. However, because they are at ground level, they may
put birds at greater risk from local cats.
To attract a wide variety of birds, place baths in different locations
around your yard. A bath in a shady area with shrubs or small trees
nearby can attract small, shy birds such as warblers and wrens.
A bath at ground-level can attract bigger, bolder birds such as
juncos, as well as four-legged wildlife. When placing a birdbath,
also think about how you’re going to keep it clean and full.
Proper landscaping
around a birdbath can help to attract birds. A small brush pile
within ten feet of a bath will attract birds that require nearby
shelter. Birds also will use nearby open shrubs and trees with low
branches for this purpose. However, be careful not to put so much
shrubbery so close to the bath that you give local cats the opportunity
to ambush birds while they are bathing. In areas with a lot of house
cats, keep at least ten feet of open space around your dust bath
or birdbath to prevent birds from being ambushed.
Birds are attracted
to the sound and movement of water. Commercial birdbaths equipped
with built-in fountains, drippers, or misters help to attract birds,
but beware that fancy baths rarely have the optimal bowl design.
Modifications with stones or gravel may be needed to make bathing
easier.
Incidentally,
don’t worry if the ground around your bath becomes soggy.
Barn swallows, robins, phoebes, and hummingbirds will use mud under
the birdbath for nesting material, while butterflies will gather
there to drink mineral-rich water from mud or wet sand.
Birds need to drink and bathe even on the coldest days. Although
birds can eat snow and melting ice to get water in winter, a birdbath
will be used and appreciated. To be sure it is a reliable source
of water, keep it from freezing between dawn and nightfall, when
birds are active. The water need only be kept just above freezing.
|
| Figure 5. A ground-level birdbath can be made
with
concrete, plastic or other synthetic pond liner. |
|
|
You can keep
a birdbath free of ice by pouring warm water into the bowl, but
this is tedious in extreme cold weather, as the water freezes rapidly.
A stick of wood left in the water during cold snaps can help you
pop out ice so you can add fresh water. (If the water does freeze,
the stick will also help to prevent the birdbath from cracking.)
Birdbaths equipped
with submersible, thermostatically controlled heaters will save
you time. Small heaters designed to operate at a depth of one to
three inches are available at garden stores and hardware centers,
and through mail-order catalogs.
You will need
a source of electricity to run your birdbath heater. Exercise caution
here. Outdoor outlets should be on a circuit or outlet protected
by a ground fault circuit interrupter (GFCI), which will cut off
the flow of electricity in the event of a short. Most outlets in
newer homes are protected by GFCI. If yours isn’t and you
are comfortable with wiring and electricity, you can install your
own. Otherwise, consult a qualified electrician. If you are not
sure whether your outlets are protected, have them checked by a
qualified electrician.
When using a
heater, keep the birdbath full of clean water or you may ruin the
heater and your birdbath.
Diseases can
spread quickly and easily in an untended birdbath. Change the water
every few days in a small bath, and rinse a dipping pool every week
with your hose, to get rid of regurgitated seeds and other debris.
Change water more often if many birds are using the bath. (Locating
your birdbath near a hose bib will make refilling and cleaning easier.)
Scrub small
baths a few times each month with a plastic brush to remove algae
and bacteria. Never add chemicals to kill algae or insects or to
keep the water from freezing in your birdbath.
Even
a bath that is refilled automatically must be monitored at least
weekly for cleanliness; however— more frequently during the
summer months. |
