Species of the Month

Introduction: World Elephant Day is next week, so to celebrate we’re profiling one of the world’s three

elephant species. In addition to the Asian elephant, did you know there are two different African

elephants? There’s the forest elephant and the more commonly known bush elephant, the August

Species of the Month.

African bush elephant (Wikipedia)

 

Scientific name: Loxodonta africana

Kingdom: Animalia (animals)

Class: Mammalia (mammals)

Order: Proboscidea (elephants)

Range: Central and southern Africa

Habitat: Savannah, forest, deserts

Lifespan: 60-70 years

Diet: Grasses, herbs, fruit, tree leaves, and tree twigs, roots, and bark

Predators: Lions, African wild dogs, hyenas, crocodiles, humans

Mother and calf (Wikimedia Commons)

Conservation Status: Elephants are listed as vulnerable on the IUCN red list. They are threatened under

the US Endangered Species Act.

Other Information: The African bush elephant is the largest land mammal in the world. An adult male

can weigh over six tons with a shoulder height of ten feet. Adult males live alone or in small groups,

while females and calves will form a larger herd led by a matriarch. Calves are raised communally

and are totally dependent on maternal care for several months. They reach full independence around

eight years old. Elephants don’t grow their tusks until after they’re a year old and the baby teeth fall

out. They also have a conveyor belt of six molars that wear out and fall out, allowing the next in line

to move forward. After losing the last molars, they can no longer eat properly. The large ears are great

for hearing, but also dissipate heat. Elephants are very mobile with a large range because of the

massive amount of food they need to eat. They can drink up to 50 gallons of water a day. Mud and

dust baths help them keep cool. Predators mainly go after small calves that fall behind the rest of the

herd. The greatest challenges facing elephants are caused by humans. Development has caused habitat

loss, and keep in mind these giants need a lot of room to roam. Poaching is also a serious threat. Most

elephants are confined to protected areas, limiting their population sizes. However, even at a protected

reserve elephants aren’t safe from poachers.

Young elephants at the watering hole (Sierra Club)

This week’s information comes from Animal Diversity Web.

Amazing Okavango

Ever hear of the Okavango River in Africa? You probably haven't. It's a rare river that flows into an inland delta rather than the ocean. During the winter, it floods the glassland and creates a seasonal wetland that attracts wildlife from all over Africa in one of the world's greatest migrations. It is an amazing oasis in the Kalahari Desert.

Flooded Okavango (Natural World Safaris)

The annual flood occurs at the height of Botswana's dry season, so it offers welcome relief to the plants and animals in the area, in addition to welcoming migratory animals of all shapes and sizes. The abundance of water boosts the growth of plants, drawing in herbivores. The herbivores attract large predators.

Elephants (Royist)

Safari cruise through the grasslands (National Geographic)

Among the many different animals who take advantage of the situation are elephants, lions, cheetahs, zebras, rhinos, 89 fish species, and 24 globally threatened birds. Not only is the Okavango key to survival of individual animals, it is crucial habitat for entire species.

Lion and buffalo (National Geographic)

A safari in the Okavango is like watching "The Lion King" live and in person. This weeks information comes from UNESCO World Heritage.

Nature Minute Book Club

While it's not as cold as it was this time last year, I'm still hunkered down for winter. Even though temperatures are more seasonable this year, it's still a good time to curl up with a good book. Here are a few I read in the last year.

The Soul of an Octopus by Sy Montgomery

Naturalist Montgomery spent time at the New England Aquarium in Boston, where she got to know the aquarists and their charges. Getting up close and personal with the octopus (several over the course of a few years). In that time, we explore animal personalities and intelligence. As the aquarium loses and acquires new octopuses we learn about their life cycles. Overall, the book does a good job of breaking down the stigma against this odd-looking mollusk.

The Gulf by Jack E. Davis

Part history, part geology, part ethnography, and part ecology, this book examines every facet of the Gulf of Mexico. Beginning with the Gulf’s prehistoric origins to its modern day exploitation and ecological disasters, Davis shares his intimate knowledge of what he terms “the American Sea”. Meet some of the colorful characters who shaped Gulf culture as we know it today: from Colusa chieftains to Spanish conquistadors to tarpon fishermen, oil barons, feather hunters, and conservationists.

What a Fish Knows by Jonathan Balcombe

Balcombe dives into what makes a fish different from a mammal or a bird, and what is surprisingly similar. Anecdotal evidence, mixed with lab and field research reveals much about a fish’s sensory and perception, emotion, thought, communication, intelligence, and farts.

Rain: A Natural and Cultural History by Cynthia Barnett

For centuries, mankind has had a love-hate relationship with rain. We curse it for ruining our picnics and parades. We suffer from not enough or too much. Take a journey through time and see how our understanding of rain has changed over the years and how rain (or lack of it) has shaped the course of history and influenced pop culture.

Furry Logic by Matin Durrani and Liz Kalaugher

This book takes place at the intersection of biology and physics, exploring how animals of all shapes and sizes use physics in their daily lives. Learn about how snakes and ground squirrels use thermodynamics; see Komodo dragons and shrimp use force. Marvel as bees defy our understanding of aerodynamics, elephants communicate through seismic waves, and ants find their way home with polarized light. The section on eels will shock you!

Animal Attraction

In a previous episode of Nature Minute we talked about porcupine love. With Valentine’s Day right around the corner it’s time to revisit the subject.

In the human world, success is usually measured in money and power. In the natural world, success is measured by passing on genes to a new generation. Darwin proposed evolution as natural selection by survival of the fittest. Those best equipped to survive their environment will have the most offspring, in theory.

There are two ways in nature to ensure that your offspring will survive to produce offspring of their, furthering your own genes. The first is a high reproductive rate (fecundity) with little to no parental care. The second is lower fecundity with a high rate of parental care.

Some examples of high fecundity animals are insects, which lay thousands of eggs, and mice, which may have multiple litters of a dozen or more in a single year. Surviving mouselings reach sexual maturity at a very early age and have babies that are older than their aunts and uncles. Many plants fall into this category also. Think of how many wishes you’ve made with dandelion seeds. Or if you are like me, think of how many mornings you woke up to a yard full of dandelions that weren’t there the night before.

Lower fecundity breeders are typically larger than high fecundity breeders (this is a general rule, but there are exceptions of course). We fall into this category, along with whales and elephants. We all have a relatively long gestation period (40 weeks for people, 20 months for elephants) and births are commonly single. Sexual maturity takes years to reach and mothers do an excellent job of caring for their young.

Just as there are two ways of breeding, there are also two ways of breeding- monogamy and promiscuity. Monogamy is what we think of in human relationships, a pair mating for life. Bald eagles and barn owls are monogamous.

Promiscuity can be either male or female. Male promiscuity is very common in the natural world (and humans too). A successful male has many offspring, but why should he limit himself to a single female? In these situations, frequently a dominant male will have a harem of females to mate with. Elk and bison are great examples. Going back to a previous Nature Minute on the elk rut, we learned that young males will challenge the older dominant male for the right to mate.

Elk rut, photo by Tom Bartel

Female promiscuity is way to confuse males. In some species, a male will kill any young that are not his own. He wants his own genes, and not someone else’s, to be passed on in perpetuity. To counter infanticide, in some species the female will take multiple mates. Since no one is really sure who the father is, all males assume fatherhood and are unlikely to kill any young since it very well could be their own. It is even possible for all of them to be the father. Bees, hedge sparrows, and garter snake females will all take multiple mates.

In the human world, typically a boy will ask a girl out on a date. Females hold all the power. The same is true in the animal world in many cases. Males will put on a courtship display or perform a courtship ritual, hoping to catch the attention of a lucky lady. Prairie chickens have a lek, which is similar to a middle school dance, but the stakes are higher. Boys on one side, girls on the other. The males strut their stuff and the females pick out their favorites. After it’s over, they all go back to their home territories. Usually there is some desirable trait that females are looking for that demonstrates the male’s fitness (as is “survival of the fittest”, not like a fitness test in gym class). It can be brightly colored feathers, awesome dance moves, the loudest croaking, huge antlers, or any number of other things. The male with the best traits gets to pass those on to the next generation through his genes.

Greater prairie chicken lek, photo by Adrian Binns

So what did we learn today? When it comes to love, people are still pretty much animals. It’s ladies’ choice, and the guys really don’t care as long as she says yes.