Species of the Month

This week we're taking a break from understanding energy sources and trying to understand a species. When you think about lizards, you probably imagine them basking under the hot desert sun or on a tropical island. If that's the case, then June's Species of the Month will surprise you by showing up in some unexpected locations. Say hello to the eastern fence lizard.

Eastern fence lizard (University of Georgia)

Scientific name: Sceloporus undulatus

Kingdom: Animalia (animals)

Class: Reptilia (reptiles)

Order: Squamata (scaled reptiles)

Range: New York south to Florida, west to the Rockies

Habitat: Grasslands and forest edges

Lifespan: Unknown, thought to be four years average

Diet: Insects, some plant matter

Predators: Birds, snakes, other larger lizards, domestic dogs and cats

Conservation Status: No special protection

Other Information: The eastern fence lizard is a widespread reptile. They live under rocks and logs
where they have protection overnight. Cold-blooded, they bask in sunlight during the day to raise their
body temperatures. Normally, they bask close to where they call home. They are little guys. Adults
only grow as long as 19 centimeters. Color varies, but they are usually gray or brown. Males have a
blue patch on the throat and belly. A male will display the throat patch to attract a mate or warn other
males away from his territory. He will also do head bobs and push ups if threatened.
Fence lizard eggs grow after hatching. Mating season begins in April, with hatching taking place from
June to September. The eggs doubles in size between laying and hatching, and babies are half the size
of adults when they emerge. There is no parental care.

Male lizard showing blue throat and belly (University of California, Berkeley)

This week's information is courtesy of the Animal Diversity Web at University of Michigan. Next week
we return to our energy series with a look at wind power.

Tidal Energy

Continuing the series on alternative energy sources, this week features tidal energy. It is similar to
hydroelectric power: it uses the same principles of water in motion and is also a “clean” energy source.
However, tidal power relies not on the temperamental flow of a river which is subject to effects of
weather and climate but on the timeless and ceaseless pull of the sun and moon on the world’s oceans.
Because of its reliance on ocean tides, this is considered a renewable energy source because it does
not diminish the amount of tides in the ocean.

Tidal power is also similar to wind power. Tidal turbines look like miniature underwater windmills.
Tidal turbines can be smaller and more densely spaced than windmills because water is denser than air;
less surface area is required to generate a comparable amount of electricity. While the wind may not
always blow, the tides are always in motion. 

Tide turbines (Forbes)

Another device to harness the energy of the tides is called a barrage. It is similar to a small submerged
dam that blocks the incoming and outgoing tides at the mouth of an estuary. A sluice in the dam opens
to collect the tidewater, which flows though and turns turbines to generate electricity.

One drawback of tidal energy is the tides themselves. Generation capacity is limited by the tidal cycle,
meaning peak demand will frequently be missed. Also, the change in tides must be at least seven
meters for this to be economically efficient. 

Barrages are limited by location. Not all estuaries are suitable sites. The equipment used for generation (either barrages or tide turbines) must be highly durable due to the unforgiving nature of the undersea environment.

Tidal barrage (Britannica)

Like the other energy sources previously mentioned, tidal power has negative impacts on the environment. However, due to limit use of this technology, these impacts are still being studied and at present are not certain to be occurring. The possible impacts include altered waves, currents, substrate, and sediment movement; loss of habitat for benthic organisms; noise that may interfere with biosonar; generation of magnetic fields; introduction of toxins in paint, lubricants, and antifouling; hindrance of fish passage; and fish being struck by blades or sucked into turbines.

This week's information comes from Marine Current Turbines, Ocean Energy Council, and Pacific Marine Energy Center. After a brief break for a look at June's Species of the Month, this series will resume with wind energy.

Pros and Cons of Hydroelectric

Hydroelectric power generates the most electricity of all renewable energy sources in the US, about
7% of the total production. It is a truly renewable source as the same water can flow through a series of dams on a single river, and it is renewable. It is also “clean”, producing no carbon emissions outside of those during the dam building process. 

Water held back by a dam goes through an intake pipe and turns turbines as it passes through the dam.
Faster flowing water will produce more power. Hydroelectric power is about 90% efficient, making it a
great source of power. Due to controls at the dam, the flow of water can be adjusted to meet peak
demands much more quickly than at a nuclear or coal-fired plant. Some dams are equipped with a
pump and can pump water to a higher level during times of low energy usage. The water is then
released back through the dam at peak times to generate additional power.

Not all dams are generating stations, but hydroelectric dams often serve other purposes such as flood
control, irrigation, drinking water supply, and recreation. Because the water is naturally occurring and
free, hydroelectric power is among the cheapest on the market, less than a penny per kilowatt hour on
average. An electric utility can earn additional income through recreational fees, keeping utility rates
low.

Hydroelectric dam in Arizona (USGS)

Although hydroelectric power is “clean”, it is not completely “green”. Like the fossil fuels, it also has
negative environmental impacts. Dams affect fish migration, hydrology, and sediment and nutrient
movement. Flooding a reservoir also causes terrestrial habitat loss, which is traded for aquatic habitat.

Fish ladders can be built to aid anadromous fish in passing around a dam. These fish hatch in
freshwater, live as adults at sea, and return to their native streams to spawn. The journey through
natural aquatic habit frequently involves jumping over small waterfalls, which fish ladders mimic.
Different species of fish move at different speeds and therefore have different needs. Fish ladders come
in many different designs, and some even look like a natural stream rather than a flooded staircase.
Intake screens covering the intake pipes can successfully keep most fish from getting sucked into the
turbines, which can kill them.

Fish ladder (Army Corps of Engineers)

Terrestrial habitat is lost at the expense of aquatic habitat gain. However, the reservoir behind the dam
is of lower quality than a natural lake and alters downstream hydrology. Reservoir water stagnates
since there is no outlet and sediments and nutrients from upstream collect behind the dam rather than
enriching downstream areas. Downstream ecosystems can also suffer if not enough water is released
from the dam.

Sediment deposits after a dam removal in Washington (NPS)

This week's information comes from US Bureau of Reclamation, Michigan DNR, and
Union of Concerned Scientists.

Energy Alternatives

Energy is important at a biological level to sustain life, and at a societal level to sustain lifestyle. From
the discovery of fire to the Nuclear Age, energy consumption has changed over the years, and has also
changed the planet. Use of fossil fuels is largely to blame for an increase of atmospheric carbon dioxide
and accompanying changes in climate. The search for reliable, alternative energy sources leads down
many paths, each with its own strengths and weaknesses. Over the next few weeks, we will examine
several energy sources in an attempt to determine which the “greenest” is.

Before examining the benefits and drawbacks of alternative energies, a look at what they are an
alternative to, fossil fuels- petroleum, coal, and natural gas- is in order. Fossil fuels are still in use
because they are relatively cheap, easily refined, and provide many jobs.

Oil drilling (Bureau of Land Management)

The drawbacks of fossil fuels, in addition to the carbon dioxide output, is other environmental
degradation associated with extraction and transport. Finally, because it is a finite source, eventually
the supply will run out. As supply drops, more invasive techniques will be used to extract ever scarcer
supplies and price will go up.

Environmental impacts of drilling for oil and gas include habitat loss at the well site and access roads; noise pollution; air pollution from generators, vehicles, gas flaring, and particle matter; soil disturbance; increased erosion from vegetation loss; increased solid and industrial wastes; degraded water quality from runoff of soil and residues; and oil spills. There are also problems from end-use: air pollution, increased carbon emissions, contamination such as may be found at gas stations, and plastic litter (most plastics are petroleum-based).

Mountaintop removal coal mine (Center for Biological Diversity)

After all the environmental and health issues related to fossil fuels, it seems clear that we need an alternative energy source. There are plenty of green alternatives, which we will explore, starting with hydroelectric next week.

Species of the Month

Introduction: This month we take a look at the badger, a tough little critter that's rarely seen.
Living underground and working mostly at night keeps the American badger off the radar for
most of us. More than just Wisconsin's mascot, they can be found all over the west.

American badger (NPS)

Scientific name: Taxidea taxus

Kingdom: Animalia (animals)

Class: Mammalia (mammals)

Order: Carnivora (carnivores)

Notice the large claws on the forefoot (Fort Hayes State University)

Range: Great Lakes region and Central Canada south to Mexico and west to the Pacific

Habitat: Grasslands- fields, meadows, prairies, or pastures

Lifespan: 4-10 years, oldest in the wild was 14

Diet: Fosorial rodents- gophers, moles, ground squirrels, prairie dogs, mice, rats, voles;
snakes; insects; ground nesting birds

Predators: Humans, golden eagles, bobcats, mountain lions, coyotes, bears, wolves

Conservation Status: No special status, but protected from hunting in British Columbia,
Illinois, Michigan, and Wisconsin.

Other Information: The American badger is a member of the weasel family. A flat body,
stubby legs, and long claws for digging make them an ideal underground predator. They
are one of the few predators that will chase their prey underground, either through
existing tunnels or by making their own as they go. Badgers use several burrows in their
territory, so the unused ones often have other animals living in them.

Mother badger with baby (USFWS)

The American badger mates in late summer or early fall, but embryos don't implant in the
uterus until winter. During winter, badgers are typically inactive in a state of torpor, so the
delayed implantation is likely an adaptation to prevent the females from burning through
fat stores while pregnant. Although coyotes are known to prey on badgers, sometimes they
will hunt cooperatively. Coyotes are more successful catching rodents on the surface, and
badgers are more successful catching them in burrows. Working together, they make more
prey available to each other.

Coyote and badger taking a break (USFWS)

This month's information comes from the Animal Diversity Web at University of Michigan.