Hanuman langurs Flashcards
Why is it difficult to keep colobines in captivity?
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
Hanuman langurs can be found in a diverse range of habitats across the Indian subcontinent. Give 4 examples.
- Mountains
- Flood plains
- Forests
- Urban landscapes
Due to this ecological flexibility Hanuman langurs can be socially flexible. Give 3 examples of social organisation.
- Polygyny in provisioned or non-seasonal areas
- All-male bands excluded from mating in provisioned/non-seasonal regions
- Polygynandry in seasonal areas
What part of the country experiences seasonality?
The North
In the north of India langur births occur throughout the year. True or false?
False: the seasons restrict births to 3-5 months of the year
What part of the country does not experience seasonality?
The centre/south and Sri Lanka
In the centre/south/Sri Lanka do births occur throughout the year?
Yes, as they are not restricted by the environment.
Why are langurs provisioned for?
They are holy to Hindus
De-synchronisation to the environment allows for polygyny. Why?
Mate-guarding: the males are physically able to guard one or two fertile females from their competitors.
Cooperation occurs between female langurs in baby-sitting, home range defence and defence against infanticidal males. Why?
Females are philopatric and so they are all closely related.
Do male langurs cooperate? Why?
No, there is little relatedness between all-male band members due to the high degree of turnover
Is infanticide common in langurs?
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.
Why do langurs have show such impressive geographical range?
Their diet is highly generalised; they can eat leaves, shoots, blossoms and gum
Can langurs eat poisonous plants?
Yes, like strychnoid plants that quickly kill animals of the same size.
Why are langurs sacred to Hindus?
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.
Langurs’ ecological adaptability is second only to which primate?
Humans
Why must langurs sleep a lot?
Their food does not provide many calories
How does provisioning help the harem resident to guard his females?
He wastes less time searching for and eating food.
Sometimes the landscape facilitates mate-guarding for the harem resident. How? Give an example.
In the semi-arid area around Jodhpur there is little tree/shrub cover and harem residents can easily spot invading males.
Why are bachelor males disadvantaged in foraging?
Because harems take all the food and water.
Why don’t related juvenile males, all ousted from the troop at the same time by a new resident, join forces and take over?
Males rarely survive long in bachelor groups due to a lack of resources and thus decreased fitness.
So do males in a bachelor group work together to invade a harem?
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.
What proportion of infants are killed during harem take overs?
1/3 (at Jodhpur)
Of the average 17 infants a female at Jodhpur will have in her lifetime, how many will she see murdered?
4
Synchronising fertility would protect against infanticide as it causes paternity confusion. Why then do female langurs not do it?
More males in a polygynandrous system increases food competition for females, thus increasing inter-birth intervals and lowering reproductive output.
Monopoly of females in polygyny is facilitated by? Give 2 things.
- De-synchronisation of females to the environment (lack of seasonality or provision)
- Sparse environments, e.g. forests system generally show polygynandry
In less human-dominated landscapes facilitate polygynandry. Why?
Because weaker bachelor males have increased survival and can grow up together, forming strong bonds and infiltrating female groups together.
Humans and langurs are similar in their ecological and social flexibility. What can be said of their reproductive output?
It is correspondingly high.
What adaptations do colobines have for eating vegetation and unripe fruit? List 3.
- molars with sharp, high cusps
- saliva that helps to neutralise toxic tannins
- large, multi-chambered stomachs that break down plant fibres
Why are colobine stomachs often distended?
Because they must eat large quantities of food and digestion takes a long time.
