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.
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
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Lecture] | [Discussion]
(First we finished up on gorillas,
but I've put those notes on the day they are really attached to, Sept.
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
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
(inherent facts about primates which make them
difficult to conserve)
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
--John Bonner, 1993
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
(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:
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.
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.
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.
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
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.
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
...to 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.
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.
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
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.
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.
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
American Society of Primatologists
Friday, October 4 -- Feeding
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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.
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
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
Differences in Food Dispersion and
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.
better illustrate clumping in time, look at how many months in a year
these food items are available:
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
Types of Food Used and Prototypical Users
New World Monkey: spider monkey
Old World Monkey:
World Monkey: howler monkey
Old World Monkey:
World Monkey: squirrel monkey (saimiri)
Old World Monkey: none,
Ape: none, really, although chimps eat some
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.
Insectivores and gummivores are smallest
Frugivores who also eat insects are bigger
who eat leaves are even bigger
Gramnivores and folivores
are the biggest of all.
(Gramnivore means you eat stems and
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
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
Insects are rare, but are of high quality.
Leaves are abundant but of low quality, and fruit is in between on both
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.
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
Behavioral Consequences of Food Choice
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.
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.
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
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
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
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.
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
Used by local people in these cases:
schistosomiasis (blood flukes)
|Other uses; |
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got back our papers on natural selection, discussed next week's paper,
took a quiz, and discussed the midterm.
Let me know your thoughts: email@example.com
October 9, 1996