Hanuman langurs

Question 1

Why is it difficult to keep colobines in captivity?

Answer 1

1) They are folivorous so cannot feed them generalised diet, must be native vegetation
2) They cannot have antibiotics as it disrupts the gut bacteria in their sacculated stomachs

Question 2

Hanuman langurs can be found in a diverse range of habitats across the Indian subcontinent. Give 4 examples.

Answer 2

1. Mountains
2. Flood plains
3. Forests
4. Urban landscapes

Question 3

Due to this ecological flexibility Hanuman langurs can be socially flexible. Give 3 examples of social organisation.

Answer 3

1. Polygyny in provisioned or non-seasonal areas
2. All-male bands excluded from mating in provisioned/non-seasonal regions
3. Polygynandry in seasonal areas

Question 4

What part of the country experiences seasonality?

Answer 4

The North

Question 5

In the north of India langur births occur throughout the year. True or false?

Answer 5

False: the seasons restrict births to 3-5 months of the year

Question 6

What part of the country does not experience seasonality?

Answer 6

The centre/south and Sri Lanka

Question 7

In the centre/south/Sri Lanka do births occur throughout the year?

Answer 7

Yes, as they are not restricted by the environment.

Question 8

Why are langurs provisioned for?

Answer 8

They are holy to Hindus

Question 9

De-synchronisation to the environment allows for polygyny. Why?

Answer 9

Mate-guarding: the males are physically able to guard one or two fertile females from their competitors.

Question 10

Cooperation occurs between female langurs in baby-sitting, home range defence and defence against infanticidal males. Why?

Answer 10

Females are philopatric and so they are all closely related.

Question 11

Do male langurs cooperate? Why?

Answer 11

No, there is little relatedness between all-male band members due to the high degree of turnover

Question 12

Is infanticide common in langurs?

Answer 12

Yes, it is very common in polygynous groups as when the troop resident is overthrown, the predecessor will kill his offspring. This frees up females for mating and ensures his genes are passed on.

Question 13

Why do langurs have show such impressive geographical range?

Answer 13

Their diet is highly generalised; they can eat leaves, shoots, blossoms and gum

Question 14

Can langurs eat poisonous plants?

Answer 14

Yes, like strychnoid plants that quickly kill animals of the same size.

Question 15

Why are langurs sacred to Hindus?

Answer 15

They represent the monkey god Hanuman, which is why their faces, hands and feet are black, because he was burned by demons in The Ramayana.

Question 16

Langurs’ ecological adaptability is second only to which primate?

Answer 16

Humans

Question 17

Why must langurs sleep a lot?

Answer 17

Their food does not provide many calories

Question 18

How does provisioning help the harem resident to guard his females?

Answer 18

He wastes less time searching for and eating food.

Question 19

Sometimes the landscape facilitates mate-guarding for the harem resident. How? Give an example.

Answer 19

In the semi-arid area around Jodhpur there is little tree/shrub cover and harem residents can easily spot invading males.

Question 20

Why are bachelor males disadvantaged in foraging?

Answer 20

Because harems take all the food and water.

Question 21

Why don’t related juvenile males, all ousted from the troop at the same time by a new resident, join forces and take over?

Answer 21

Males rarely survive long in bachelor groups due to a lack of resources and thus decreased fitness.

Question 22

So do males in a bachelor group work together to invade a harem?

Answer 22

Yes, but only the dominant bachelor male is able to challenge the harem resident, and will turn on his cohorts as soon as he establishes among the females.

Question 23

What proportion of infants are killed during harem take overs?

Answer 23

1/3 (at Jodhpur)

Question 24

Of the average 17 infants a female at Jodhpur will have in her lifetime, how many will she see murdered?

Answer 24

4

Question 25

Synchronising fertility would protect against infanticide as it causes paternity confusion. Why then do female langurs not do it?

Answer 25

More males in a polygynandrous system increases food competition for females, thus increasing inter-birth intervals and lowering reproductive output.

Question 26

Monopoly of females in polygyny is facilitated by? Give 2 things.

Answer 26

1. De-synchronisation of females to the environment (lack of seasonality or provision)
2. Sparse environments, e.g. forests system generally show polygynandry

Question 27

In less human-dominated landscapes facilitate polygynandry. Why?

Answer 27

Because weaker bachelor males have increased survival and can grow up together, forming strong bonds and infiltrating female groups together.

Question 28

Humans and langurs are similar in their ecological and social flexibility. What can be said of their reproductive output?

Answer 28

It is correspondingly high.

Question 29

What adaptations do colobines have for eating vegetation and unripe fruit? List 3.

Answer 29

1. molars with sharp, high cusps
2. saliva that helps to neutralise toxic tannins
3. large, multi-chambered stomachs that break down plant fibres

Question 30

Why are colobine stomachs often distended?

Answer 30

Because they must eat large quantities of food and digestion takes a long time.