Nest-building in primates

In the primate order, nest-building behaviour is displayed by prosimians and the great apes. Prosimians build nests instinctively for long durations and these are used not just for sleeping but also raising for families. Great apes build nests for sleeping at night, and in some cases the nests are built for sleeping in the day as well. Nest-building by great apes is learned by infants from the mother and others in the group and is considered a matter of tool use, not just animal architecture.^[1][2]

It has been speculated that a major evolutionary advance in the cognitive abilities of hominoids may first have occurred due to the development of nest-building behaviour and that the transition from nest-building to ground-sleeping led to "modifications in the quality and quantity of hominid sleep, which in turn may have enhanced waking survival skills through priming, promoted creativity and innovation, and aided the consolidation of procedural memories".^[3]

Nest building in prosimians

Prosimians may be nocturnal, diurnal, or crepuscular.^[4] Some may either occupy holes in trees or build nests.^[4] Unlike the great apes, prosimians build nests by instinct and use them for breeding purposes.^[1]

Amongst lemurs, smaller species, such as mouse lemur and giant mouse lemurs, build leaf nests for the protection of young while in larger lemur species such as Verreaux's sifaka, ring-tailed lemur and common brown lemur the young cling to the mother and nests are not built.^[4] Nests are made from locally collected material and may be lined with hair plucked from its own body.^[5] Leaf nests in golden-brown mouse lemurs may provide thermoregulation benefits.^[3] In some species, such as dwarf galagos, the day-sleeping nests may be shared by groups of females or occasionally by visiting males.^[6]

Aye-ayes, being nocturnal, build oval-shaped nests from nearby branches and lianas for day time use. These may be built in a tangle of lianas or in a fork of a tree, at a height of 7 to 20 metres (23 to 66 ft) above the ground. These nests may be re-used by other aye-aye once the original occupant moves on. A single occupant uses a nest for a few days at a time refreshing it regularly with fresh vegetation.^[7]

Nest building in great apes

Gorilla night nest constructed in a tree.

Great apes construct nests by day or by night, primarily for resting. The nests are not built using instinct but through behavioural patterns which are learned by the young from their mother. Nest building is habitual behaviour,^[8] and nest-counts and faecal analysis at each nest site can be used to estimate great ape population counts and composition.^[9] In the case of orangutans and chimpanzees, social influences are probably essential for the animals to develop successful nesting-behaviour.^[1]

Gorillas

Gorillas construct nests for daytime and night use. Day nests tend to be simple aggregations of branches and leaves on the ground while night nests are more elaborate constructions in trees. The nests may be 2 to 5 feet (0.61 to 1.5 m) in diameter and are constructed by individuals. The young nest with the mother but construct nests after three years of age, initially close to that of their mother.^[10] Gorilla nests are distributed arbitrarily and use of tree species for site and construction appears to be opportunistic.^[2]

Chimpanzees and bonobos

Chimpanzee nest in Kenya

Nest-building is seen in chimpanzees and bonobos who construct arboreal night nests by lacing together branches from one or more trees. It forms an important part of behaviour, especially in the case of mothers who teach this trait to infants. Nests consist of a mattress, supported on a strong foundation, and lined above with soft leaves and twigs. Nests are built in trees which have a minimum diameter of 5 metres (16 ft) and may be located at a height of 3 to 45 metres (9.8 to 148 ft). Day as well as night nests are built. Nests may be located in groups.^[11]

Orangutans

An orangutan nest in Sabah, Borneo.

Orangutans build day as well as night nests. These are carefully constructed; young orangutans learn from observing their mother's nest-building behaviour. In fact, nest-building is a leading cause in young orangutans leaving their mother for the first time. From six months of age onwards, orangutans practice nest building and gain proficiency by the time they are three years old.^[1]

Construction of a night nest is done by following a sequence of steps. Initially a suitable tree is located, orangutans being selective about sites even though many tree species are utilised. The foundation is then built by pulling together branches under them and joining them at a point. After the foundation has been built, the orang bends smaller, leafy branches onto the foundation; this serves the purpose of and is termed as the "mattress". After this orangutans stand and braid the tips of branches into the mattress. This increases the stability of the nest and forms the final act of nest building.

In addition, orangutans may add additional features such as "pillows", "blankets", "roofs" and "bunk-beds" to their nest.^[1] Orangutans make "pillows" by clumping together leafy branches with the leaves in the centre and the twig shoots pointed outward. They bite the twigs ostensibly to blunt sharp ends. Pillows are added to night nests but are usually absent from day nests. A "blanket" consists of large leafy branches with which an orangutan covers himself after lying down. Orangutans may create a waterproof overhead shelter for the nest by braiding together a loose selection of branches. They may also make a "bunk-nest" or "bunk-bed", a few metres above the main nest.^[1]

See also

• Structures built by animals
• Tool use by animals

References

1. ^ ^{a b c d e f} Didik, Prasetyo; Ancrenaz, Marc; Morrogh-Bernard, Helen C.; Atmoko, S. Suci Utami; Wich, Serge A. & van Schaik, Carel P. (2009). "Nest building in orangutans". In Wich, Serge A.; Atmoko, S. Suci Utami; Setia, Tatang Mitra. Orangutans: geographic variation in behavioral ecology and conservation. Oxford University Press. pp. 270–275. ISBN 9780199213276. http://books.google.co.in/books?id=ZHsNfZC3DfYC&lpg=PA270&dq=nest-building%20by%20primates&pg=PA269#v=onepage&q&f=false. Retrieved 5 July 2011. 
2. ^ ^{a b} Marchant, Linda Frances; Nishida, Toshisada (1996). Great ape societies. Cambridge University Press. pp. 226–227. ISBN 9780521555364. http://books.google.com/books?id=iGfjJ4lKb1IC&pg=PA226. Retrieved 4 July 2011. 
3. ^ ^{a b} Coolidge, Frank L.; Wyn, Thomas (2006). "The effects of the tree-to-ground sleep transition in the evolution of cognition in early Homo". Before Farming 2006 (4): Article 11, pp. 11–18. http://www.uccs.edu/~faculty/fcoolidg/Before%20Farming%202006%20Dream%20paper.pdf. Retrieved 6 July 2011. 
4. ^ ^{a b c} Institute for Laboratory Animal Research (U.S.). Committee on Well-Being of Nonhuman Primates (15 June 1998). The psychological well-being of nonhuman primates. National Academies Press. p. 57,63–64. ISBN 9780309052337. http://books.google.com/books?id=Wcx4ASnW0jgC&pg=PA57. Retrieved 5 July 2011. 
5. ^ Bateson, Paul Patrick Gordon (1991). The Development and integration of behaviour: essays in honour of Robert Hinde. Cambridge University Press. p. 206. ISBN 9780521407090. http://books.google.com/books?id=VwMjNXc62wAC&pg=PA206. Retrieved 9 July 2011. 
6. ^ Fleagle, John G. (1999). Primate adaptation and evolution. Academic Press. p. 114. ISBN 9780122603419. http://books.google.com/books?id=PgiGPYeVN0sC&pg=PA114. Retrieved 10 July 2011. 
7. ^ Sauther, Michelle L. (2006). Lemurs: ecology and adaptation. Springer. p. 175. ISBN 9780387345857. http://books.google.com/books?id=nsBtrhsMU5EC&pg=PA175. Retrieved 9 July 2011. 
8. ^ Hansell, Michael Henry (2007). Built by animals: the natural history of animal architecture. Oxford University Press US. p. 211. ISBN 9780199205561. http://books.google.com/books?id=jwUkAM3DvE4C. Retrieved 9 July 2011. 
9. ^ Setchell, Joanna M.; Curtis, Deborah J. (14 March 2011). Field and Laboratory Methods in Primatology: A Practical Guide. Cambridge University Press. p. 126. ISBN 9780521142137. http://books.google.com/books?id=3wRZULBoPg8C&pg=PA126. Retrieved 9 July 2011. 
10. ^ Miller-Schroeder, Patricia (1997). Gorillas. Weigl Educational Publishers. p. 20. ISBN 9780919879898. http://books.google.com/books?id=wSXgVKUYpvgC&pg=PA20. Retrieved 4 July 2011. 
11. ^ Wrangham, Richard W. (1996). Chimpanzee cultures. Chicago Academy of Sciences, Harvard University Press. pp. 115–125. ISBN 9780674116634. http://books.google.com/books?id=IzBIHPeE45IC&pg=PA115. Retrieved 2 July 2011.