Monday, September 30 -- Film: Chimpanzees of the Mahale Mountains

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There are about 40 members to a group. There are 100 chimps in Mahale Mountains National Park. In this group, there are 10 males, 40 females, and 50 juveniles. They move daily in large groups. When food is scarce, they move in small groups. The males stay in groups more but females stay alone with their kids more often. They wean their kids at 4-5 years old.
Sometimes a chimp will eat the leaf of some plant, but they don't chew it, just swallow it and it is thought that they do so for medicinal rather than nutritional purposes. They also lick salt from nearby rocks. Chimps will eat meat 2-3 times/week. They especially like to eat leaf-eating red colobus. They also eat bushbucks, bushpigs, and rodents. Among primates, they will eat blue monkey, red monkey, and galago. Galago is nocturnal so during the day if they find one they'll eat it. Once they have caught some meat, males will share with another male or a female if she's in heat. A female who gets meat will usually only share with her young.
Babies ride underbelly first year, then in jockey position until 4 or 5 years old. Females make a bed to nap in during the day and another to sleep in during night, but males only do it at night. Babies learn how to do it from their moms. Making your own bed is a final stage in a juvenile's education. If a new female shows up and was in between two group' ranges for a while, the males from the group that adopts her might kill her baby since they're not sure that it wasn't someone from the other group who sired it. This was a really sad part in the movie 'cause they were kind of graphic about it.
Babies begin playing hard at about 3 years, but they play lightly from 3 months. They continue playing 'til about 7 yrs old. Baby chimps, like human babies, chew on anything that catches their eye. They stick their fingers in holes etc. At age 6 months to 1.5 years, when baby switches from underbelly to jockey position, the babies often dangle from shoulders and things while they're learning. Chimps nurse about 2 min/hr until they're about 5 years old.

I didn't like this movie nearly as much as the other ones. The narrator had a really strange speech pattern which kept distracting me from what he was trying to say.

Wednesday, October 2 -- Primate Conservation

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(First we finished up on gorillas, but I've put those notes on the day they are really attached to, Sept. 27)

Last Friday marked the end of the taxonomic study of primates, and now we're going to do several topical lectures.


Think about the fact that most political decisions don't last too long. Political systems come and go, even horrible wars' effects are gone in a few generations, but if you don't conserve, the effects will last forever. This is probably the biggest and most rapid phase of extinction that has ever seen before. As in, to what we're doing now, the dinosaurs all being wiped out was nothing! And it's different because it's not due to natural forces. We're changing the environment so quickly and so drastically that things can't adapt quickly enough to it.

The Current Status of Primate Conservation

A third to a half of all primate species are endangered because of overexploitation and habitat destruction. As an estimate, it's maybe at 42% right now, but it'll go up in the future. It will probably be the next generation or two who will decide how many primate will survive.

Basic Factors Affecting Primate Conservation

(inherent facts about primates which make them difficult to conserve)

Geographic distribution: Primates are just tropical animals, found mostly in the tropics of the southern hemisphere. This means that primates live mainly in third-world countries, so economics is a factor 'cause home countries are poor and have a lot of demands on their resources.

"All discussion about Africa must begin and end with a recognition, however grim, of the continent's underdevelopment and poverty."

--John Bonner, 1993

Low reproductive potential: Take for example the chimp; they only produce a baby every 5-6 years, and there's a very high infant mortality- 50% die in their first two years. This means that populations can't bounce back very quickly. Also, they live in low population densities, so to save a large population you need a lot of ground!

Threats to Primate Populations

(external factors affecting primate conservation)

Overharvesting: Some older forms include hunting for food, for example bonobos and cebids; Hunting for trophies or ornaments, like when black and white colobus are made into rugs for tourists; And hunting of pest species such as when farmers don't like troops of monkeys harvesting their crops so they shoot them. Baboons and macaques especially like to raid crops. Primates are also affected by indirect hunting; they get caught in snares set for other species like deer or whatever.
Primates are also 'harvested' by live capture- especially for biomedical research. Primates are so closely related to humans, and have much the same diseases, that they make good models for medical research. For example, the only non-human primate who can support the AIDS virus is the chimp so they're being used for AIDS research. You have heard of blood types Rh positive and Rh negative, right? Well the "rh" stands for Rhesus monkeys in which blood types were first discovered. Most biomedical research is done on live caught primates, instead of captive-bred ones. Primates are also caught live for the pet trade; the cebus monkey or organ-grinder monkey is popular, as well as squirrel monkeys. Recently young apes have begun to be hot pet items especially in Asia, where people keep orangutans or gibbons or even bonobos as exotic pets (the babies, anyway). In 1991, in Taiwan there were 283 orangutans registered as pets. This is just the registered ones, so the real number is probably more like 700-800. The total orangutan population in Borneo is only about 16,000. So, the number as pets in Taiwan is like 5% of total population in Borneo! Also, you must remember that in order to capture an infant, you've got to kill the mom, and then in transport and holding, about 9 out of 10 die. So, for every baby that ends up being a pet another 9 to 10 have probably died along the way.
For the most part, overharvesting targets only 1 or 2 specific species. This is in contrast to:

Habitat destruction: This is much less selective in that it affects several species in a single area. It is also irreversible; you can't captive breed rainforests. If you deplete an animal's population (without making them extinct), they can recover but if their habitat is gone they can't ever recover. Habitat destruction is more difficult to combat than overharvesting, because humans don't NEED pets but they do need more space so they intrude on the monkeys' habitats.
Habitat destruction is divided into two types; small-scale and large-scale. Small-scale woodcutting is for example, hand logging; someone finds a nice mahogany tree and goes in and cuts it up. It would also include cutting wood for firewood. Most of the world's population still uses wood for heat and cooking, and as the population grows, there is more need for wood. Also as populations grow, they clear more and more for agriculture. You may have heard of slash and burn agriculture- People will clear out a whole forest, burn it off, plant a crop, get 1-2 years and then the soil will get depleted so they move on and cut some more. Before, this practice was ok because there was so little going on that the forest could grow back up but now it's getting cleared too fast for the forest to catch up.
Large-scale destruction is like commercial logging- clearing out complete forests. A lot of the forests go to make paper. Much of the SE Asian rainforests are used to supply paper for Japan. Also, cattle ranching is big in S America to produce beef for export for places like Macdonalds. Oil refineries in Asia also take up space once covered in rainforests. This kind of behavior is irreversible because rainforests can't just grow back like a field. The soil is really thin and doesn't have much nutrients. Rainforests have a complex ecosystem in which the nutrients are very efficiently recycled. However, when the trees are all cut down, the rain washes the soil with all the nutrients away and it all ends up in rivers where it just becomes pollutants. So, when a large area is cut and then left it just becomes poison to the surrounding area.
So now we know that some destruction is from multinational corporations and some is from local people needing firewood or food. You might think that the damage from commercial use is worse, that it's all the big companies who have no heart who are the bad guys. In actuality, in Africa for example, 1/3 of the forest clearing is from corporations but 2/3 is from the local people, mostly for agriculture. It's really the exponentially expanding human race that is making life so difficult for the rainforests.

Regional Surveys

Neotropics: Contains 6 genera and 64 species, with 27 of those species endangered. The most highly endangered is the muriqui or woolly spider monkey. They have the misfortune to live in the Atlantic rainforest of E Brazil which is really heavily settled. Only 1-5% of this rainforest still exists. Also, the uakari is very endangered. They used to live in the Amazon basin.

Madagascar: Contains 13 genera and 28 species, with all species endangered. In fact, 14 lemurs are already extinct. (They disappeared within the last 1000 years or so, basically since humans first populated the place.) One was huge, like gorilla-sized, it just hung around in trees like a koala. But now it's gone. Madagascar is improportionally important for its acreage because its species don't occur anywhere else in the world.

Africa: Contains15 genera and 55 species, with 14 of these species endangered. The most critical is the gorilla. You might think of them as living in very remote areas far away from people, but it's just a small mountain range which hasn't been cleared because it's too steep. The fields and clearings come right up to base of mountains where the gorillas live.

Asia: S and SE Asia, more specifically. Contains 9 to 16 genera and 50 to 56 species, with 16 species considered endangered. The most critical is rhinopithecus- the golden monkey. Also endangered are the orangutan and all 9 species of the gibbon- in other words, all the Asian apes.

Potential Solutions Over-exploitation: This is a little more fixable, because there's no real reason why an animal needs to be exploited. What has had an effect is CITES, an international agreement began in 70's and signed by most countries which limits trade in endangered species. It has been effective in limiting both the pet trade and biomedical research. For research, they can do captive breeding instead of live capture. Since CITES, there is much less wild capture. The pet trade has been curtailed, but much is still illegal. A problem is, what do you do when you seize illegal animals? Zoos often buy them with the justification that otherwise they'll die since they've already been caught, but while this saves the individuals, it encourages people to go and deplete the species more. There are also some rehabilitation centers, especially for apes like the orangutan and chimps. Habitat destruction: This problem is a lot more difficult to solve. A crucial part of the solution is education, especially of young people but also of adults. In a lot of cases it doesn't make any economic sense to destroy- these habitats are more valuable in the long term to conserve than to destroy but in short term they give an immediate relief. Pretty much the only hope at this point is reserve systems- we need big chunks of land set aside. But the countries who have the land to preserve are all pretty poor. What you also may not realize is that developing countries set aside more of their land than first world countries. You can't just sit on your high horse and condemn all those darn countries for being greedy and killing the world's rainforests. Indonesia, for example, has between 12 and 25% of its lands protected.

Some other countries:
KenyaTanzaniaZambiaZimbabweAustraliaCanadaNew Zealand

For example, let us look at Ranamafano National Park in Madagascar. It is 170 square miles and it was established in 1991. In the process, 72,000 people were displaced from in and around the area!!! Think about this happening in the United States! Do you think we'd ever be able to set aside all of Washington and Oregon as a national reserve, and just tell the people there too bad, they'd have to get out now?!
There is a problem with reserves, however; they're not always safe for the animals. When civil war broke out in Rwanda, it wasn't clear whether or not the gorillas would be safe. In many cases parks exist on paper but there's no money for hiring people to protect the areas, so when you go look, people are there clearing land and growing food on it.
More encouraging success stories combine the needs of primates and people, for instance tourism has worked well with gorillas. Up until the war, mountain gorilla tourism was the 2nd largest source of hard currency for Rwanda. Despite close contact between humans and gorillas, and thousands of visitors, there have been no injuries at this site.

The benefits of conservation are international but the costs are borne by the countries where the primates are found. 29 out of the 36 world's poorest countries are in Africa S of Sahara. Nine out of ten Africans live in poverty. The developed countries have to contribute somehow. For example, sometimes the US writes off the debt of a S American country in exchange for them setting up a nature preserve.

Conclusion- Crisis and Opportunity

Currently there is a crisis and it IS depressing. A lot of species will be lost. However, many can be saved, and now is a critical time. The human population growth WILL level off at some point but the question is, what will be left when it does? Right now the choices have to be made about what things will be saved and what will be lost. What sacrifices will we make? What will be the costs?

Some Links Relevant to Primate Conservation

Homepage for the Jane Goodall Institute

Pan Africa News- The Newsletter of The Japan Committee for the Conservation and Care of Chimpanzees and The Mahale Wildlife Conservation Society

A page on primate conservation in Vietnam published by the Institute for Ecology and Biological Resources, National Centre for Natural Sciences and Technology, National University of Hanoi

Environmental and Conservation Research

American Society of Primatologists Conservation Page vation/

Friday, October 4 -- Feeding Behavior

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Even though we separate them for convenience, all of these topical lectures are connected. Feeding behavior is very connected and very basic to social behavior. The two readings that were assigned for this lecture are examples of how feeding ecology affects social behavior.

Nature of Food Supply Available to Primates

The first thing to remember is that primates are found in the tropics. What kind of food is available in the tropics? Things which are quite different from what you'd find in temperate climates.
Tropical rainforests have leaves (lots of 'em!), tree sap and gums (some species make their own holes to get gum while others take advantage of trees previous injuries), fruits, flowers, insects, and small vertebrates (anything small enough to catch). Note that most of these things are tree products. However, animals are also important sources of protein. From their food source, primates need two main things; protein and energy. Their ordinary protein source is trees and vertebrates.

Differences in Food Dispersion and Availability

There are two important parameters needed to describe a food source; how much is there and where it is. In the tropics, food is usually dispersed patchily. It is often clumped in time as well as in space. For instance, we have data from an island in Costa Rica; 65% of the trees in the area occurred less than once per hectare. So there must be an awful lot of species!! Compare this to a Michigan forest where you could find hundreds of trees of the same species all together.
To better illustrate clumping in time, look at how many months in a year these food items are available:
young leaves6.8
ripe fruit1.1

As you get closer to the equator, you get less seasonality, but in some places where primates live, there is a lot of seasonality. Leaves and stems, obviously, are very abundant. Fruits, on the other hand, are more clumped and less available overall. They are often locally abundant, however. Plant material is generally more abundant than animal material. The distribution and availability of food makes a difference in behavior.

Types of Food Used and Prototypical Users

Prosimian: ring-tailed lemur
New World Monkey: spider monkey
Old World Monkey: red-tailed monkey
Ape: gibbon
Prosimian: indri
New World Monkey: howler monkey
Old World Monkey: leafmonkey/colobine/langur
Ape: gorilla
Prosimian: tarsier
New World Monkey: squirrel monkey (saimiri)
Old World Monkey: none, really
Ape: none, really, although chimps eat some
Prosimian: bushbaby
New World Monkey: marmoset

Feeding Behavior and Anatomy

The title of this section should really be "You eat what you are" because you can look at some of a primate's physical characteristics and see what its diet is.

Body size:

Insectivores and gummivores are smallest

Frugivores who also eat insects are bigger

Furgivores who eat leaves are even bigger

Gramnivores and folivores are the biggest of all.

(Gramnivore means you eat stems and leaves)

Why are they bigger? There are two main reasons. If you're bigger you need to eat more, right? So if your choice of food is rare, you can't be too big 'cause then you can't find enough. Animals who like food that is abundant can be pretty big. A chart plotting body weight vs. metabolic rate slowly levels off- it's not linear- so even though bigger animals need more calories, if you actually measure it per pound they need less. If you graph body mass vs. relative metabolic rate, you'd get a line with a negative slope. For example, orangutans and gibbons both eat fruit and live in similar habitats. The orangutan is about twenty times the size of gibbon but it doesn't eat 20 times as much 'cause its metabolic rate per pound of body mass is slower. Orangutans do spend a little more time feeding during a day than gibbons do, but not that much!
How does this affect what kind of diet they can eat? Small animals don't need a lot of food but they need a lot relative to their size. It needs to be moved through the body pretty quickly so that they can get the nutrients quickly enough to keep them supplied. This means that they need high quality food that is easy to digest. Big animals need a lot of food 'cause they're big, but they don't need to move it through so fast since their metabolic is slower.

To put it another way,

Given their higher energy needs per unit weight, smaller animals must eat easily-digested foods that can be processed quickly. Foods don't have to be abundant since small animals require small amounts of food in absolute terms.

In contrast, large animals with smaller energy requirements per unit wight can process food more slowly, but their total requirements are great. Thus food must be abundant but not necessarily easy to digest.

Insects are rare, but are of high quality. Leaves are abundant but of low quality, and fruit is in between on both axes.

Teeth & Guts:

Let us compare fruiteaters and leafeaters. (Hereafter called Fruits and Leaves) Fruits have broader, larger incisors because they tend to do more food processing with their front teeth before they get it into their mouths. Leaves' molars have sharp ridges with deep valleys which act like scissors to mash and crush the leaves and cut them into pieces.
Fruits have simple digestive systems with a small intestine to absorb sugars. Leaves have large intestines because leaves have to move their food more slowly since they take a while to digest. Leaves usually also have an adaptation to ferment their foliage; the caecum with its bacteria, or just a complex stomach, as in the colobine, or a larger lower intestine like the howlers and macaques. The bacteria break down complex carbohydrates like cellulose and they also take away toxins, breaking them up.
Gummivores have specialized teeth for gouging into trees to get sap. They need to be clinging to the sides of trees so they have claws for clinging, like the marmoset, for example. Gummivores also have a long caecum to break down their carbohydrates. Insect eaters have sharp cusps for breaking the bugs' exoskeletons. They have short, simple guts since insects are easy to digest.

Behavioral Consequences of Food Choice

Temporal factors

Time of day: They wake up and are hungry, so they eat quite a bit. Then around midday they don't eat so much. In the evenings they need to stock up again for the night, so they feed more again. So, they have two peaks: morning and evening.
Seasonal influences: In orangutans, for example, there's a big dip in percentage of time spent feeding during the months between January and April. This is because food is more scare at these times. Since they don't feed so much, they cut down on activities to save calories.

Spatial factors

Home range size: Remember the graph from an early reading with range size plotted against total weight of group. Note that as groups get bigger they need to wander more widely. However, if you compare leaf eaters to fruit eaters you will notice that fruit eaters have slightly larger home ranges since their food source is less abundant. Example: two species who live in same area, are about the same body size and group size. The red colobus is folvorous and has a small home range size. The patas monkey eats more fruit and has a larger home range.
Day range lengths: You don't have to travel far in a day to find leaves. If you plot percentage of foliage in diet vs. percentage of time spent feeding, those with most leaves in their diets spend the least time moving during day, and they also have shorter day ranges. Species not depending on leaves at all spend more time moving around looking for stuff and have larger day ranges.

Behavioral Adaptations of Folivores

There's really not much energy available to leaf eaters. So how do they adapt to having such low energy sources? They cut down on energy use- like colobus frequently don't move more than a few hundred meters in a day. Howlers are notoriously boring to study because when they move, they don't move too far and even when they're staying in one place they don't spend too much time running or playing or anything- they just lie there conserving energy. Look at the reading on how monkeys spend their time: they spend more than twice as much time resting than any other activity combined.

Medicinal Plant Use

The coursepack article on muriquis and red spider monkeys notes that they have no intestinal parasites, but howler monkeys who live in the same areas have lots of intestinal parasites. So it seems that some leaves do kill parasites. It hasn't been shown, however, that that is the reason they eat those specific leaves.
Chimps, however, show a more thoughtful choice. Researchers will notice that a chimp will begin to not feel well. It will begin dragging, and moving more slowly. It will go out of its way, leaving the group entirely, to find a specific plant. They eat the leaves in a different way than usual, too. Sometimes they'll just lick the leaf, and sometimes they fold it up, put it in the center of their tongue, and swallow it whole without any chewing.

Some drug companies research new drugs by looking at native people's medicinal use of plants. They are now finding that they can learn these kinds of things by watching the monkeys in the area as well.

An example of a plant chimps have been seen to use in this way:Vernonia amygdalina
Used by local people in these cases:

schistosomiasis (blood flukes)
anthelminthic (intestinal worms)
amebic dysentery
intestinal disease
Other uses;

Discussion --

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Today we got back our papers on natural selection, discussed next week's paper, took a quiz, and discussed the midterm.

Let me know your thoughts:
Last modified: October 9, 1996