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The
Elements of Habitat: A Home
Habitat is composed of four very important elements: food,
water, shelter and space. Basically, healthy habitat provides
everything that an animal needs to survive.
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Food
Wildlife food varies from animal to animal. Some animals,
like vultures,
help clean up the environment by eating dead things. Others,
like the pelican,
will live near large bodies of water where they can find
fish. The American White Pelicans, like we have at Salt
Plains, live in flocks. They make a big circle in the water
and as they get closer together, making the circle smaller,
fish are pushed to the center for a feast.
Deer
usually eat forbes found close to the ground. Opportunistic
eaters like the raccoon
will eat almost anything they can find in the wild - including
discarded human food. Dragonflies
feed on mosquitoes
when they're adults, but small fish
when they're young.
Animals
eating a variety of food means that there is more food to
go around. All the animals aren't competing for the very
same patch of seed. |
Water
This is a pretty easy element of habitat to describe. Wildlife
need water the same way that we do. This is why wetlands
are such important habitats. They provide a lot of food
sources, such as fish, plants, aquatic bugs and other animals,
but they also provide the very important source of water.
Shelter
Shelter can describe many things. From underground fox
dens to hollow logs, woodpecker
holes and deer
simply bedding down into the tall brush. |
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Shelter
provides a place for an animal to make a nest, but also
a place to hide from predators or get out of bad weather.
Wildlife like shelter to be close to food and water so that
they have a safe place to be. Many animals will spend warm
summer daytime hours sheltered in the shade, choosing to
come out into open areas where we might see them at dawn
and dusk.
Space
Space is often left out of habitat definitions, because
it isn't as easy to define as food, water and shelter. Space
is a very important element of habitat and the amount of
space needed varies among wildlife species.
The
bald eagle
is a good example of a species that needs a lot of space.
A bald eagle has very specific habitat requirements. They
prefer clean water, with an abundant amount of fish,
need trees, up to 100 ft tall, for perching and nesting
and plenty of space in which to fly. A bald eagle may fly
up to 200 miles in a single day!
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In addition to space in which to fly, the bald eagle needs
space, un-invaded by humans. This is the type of space that
becomes difficult to define; the
amount of space an animal needs before it runs/flies/crawls
away.
For
bald eagles, this may be 100 yards. Meaning, if you get
within 100 yards of a perching bald eagle, the eagle will
fly away.
Sandhill
cranes will sleep the night away in open
water, where predators cannot easily sneak up on them.
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Whooping
cranes, an endangered species, require almost
twice as much water around them before they will rest for
the night.
As
you spend more time around wildlife, you will notice a difference
in space requirements. Along the nature trails, you will
notice that herons
and ibis will
fly off before you get within 100 ft, but geese
will often allow you to walk right by the marsh without
flying away. |
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If
you got off of the trail and moved closer, they might fly,
but they are comfortable with the distance from the trail
to the water. Being quiet and moving slow will improve your
chances of seeing wildlife before you scare them off.
Another
space need is space for migration.
Wildlife migrate south, to warmth and food, when it gets
cold in the north. And then, they fly back north, in the
spring.
Let's look at the Killdeer
migration, to the left. This 10.5 in. bird spends summers
in the U.S. It then migrates to the S. United States, Mexico
or Central America in winter and flies, each spring, to
the Artic Circle to breed. This round-trip journey exceeds
20,000 miles!
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The
biggest problem for wildlife came when the land became obstructed
with housing developments and buildings, wetlands were drained
or filled and habitat was converted to farmland - making
available habitats and home ranges so small that some animals
populations began to decrease because they simply didn't
have enough habitat.
"Wild
creatures, like men, must have a place to live. As civilization
creates cities, builds highways, and drains marshes, it
takes away, little by little, the land that is suitable
for wildlife. And as their space for living dwindles, the
wildlife populations themselves decline. Refuges resist
this trend by saving some areas from encroachment, and by
preserving them, or restoring where necessary, the conditions
that wild things need in order to live".
- Rachel
Carson |
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