Moustached Tamarin (S. mystax) from The Bronx Zoo, New York City. Photo from Wikipedia.

S. mystax belong to the Callitrichid family, and like all Callitrichids has an interesting reproductive strategy unlike those of other primate families. Callitrichids form multimale-multifemale group and has a polyandrous (one female, multiple male) mating system. Callitrichids are the only primate family that consistently give birth to twins. The gestation period for S. mystax is 6 months. Usually, only one dominant female is reproductively active and shares offspring rearing responsibilities with multiple males in the group. However, an unstable dominance hierarchy among females might lead to multiple births within the group and will compromise the survivability of both the group and the offspring from stress, less parental investment and lack of food resources.

The researchers were studying how help from male moustached tamarins in the same group and the absence of female competition ensure the survival of offspring when they observed a female cannibalizing an infant. Necropsy and genetic analyses were used to rule out diseases and to determine paternity. They found that the infant has no diseases and did not die from trauma (falling from tree). Instead, it was a healthy infant and was being cannibalized by its own mother.

The mother was seen biting and then eating the head of its own infant during a period when another female was pregnant and gave birth just 1 month later. Before that, the perpetrator had given birth to twins three times successfully when four to five adult and subadult males were present in the group. Although we do not know for certain that the infant was alive when the mother started biting it, our field observations preceding the event suggest it probably was. The possible infanticide case and the two cases of births and early death of the infants occurred while only two to three adult males were present in the group. This could be the second case of maternal infanticide reported in the genus Saguinus and the similar circumstances suggest a common pattern. Culot et al. (2011).

Five common hypotheses proposed by Hrdy (1979) were used by the authors to try to explain maternal infanticide and cannibalism in this scenario. These hypotheses are resource competition, sexual selection, social pathology, exploitation, and parental manipulation.

The resource competition and sexual selection hypotheses were rejected because it was maternal infanticide, and not infanticide from another female. The social pathology hypothesis was rejected because it predicts infanticide restricted in areas that are disturbed by humans. The study group was habituated and had many successful births, therefore social pathology was ruled out. The exploitation hypothesis was also reject because the mother did not kill her infant to exploit its meat. Observation shows that the mother only consumed the brain and parts of the infant’s neck.

The parental manipulation hypothesis was accepted because the authors think that it best explains the scenario. The offspring was not pathological nor did it fell from the tree. Instead, it was a healthy infant that was killed by its own mother. According to Hrdy (1979), victim of parental manipulation does not necessarily have to be defective but also born “at the wrong place in the wrong time”.

The authors concluded that parental manipulation is the best explanation for this possible maternal infanticide scenario. Parental manipulation strategy can happen in a group with poor capacity to raise the offspring from multiple breeding females, birth intervals that are shorter than 3 months, and low infant survival probability due to physical injuries or weakness.

References:

Lingual view (side that touches the tongue) of Mescalerolemur horneri partial mandible.
Scale bar equals 2 mm. Photo from Kirk & Williams (2011).

Anywho … A fossil primate from the Eocene Epoch was discovered in Devil’s Graveyard badlands of West Texas by Anthropologists Christopher Kirk and Blythe Williams. Named Mescalerolemur horneri, this new fossil primate lived about 43 million years ago is a member of the extinct group, adapiforms, that are found all over the Northern Hemisphere. Mescalerolemur looked like a modern-day greater dwarf lemur and weighs about 370 grams.

Interestingly enough, Mescalerolemur are more closely related to Eurasian and African adapiforms than those from North America. Darwinius masillae, famously known as Aunt Ida, was a Eurasian adapiform. Another interesting fact to point out is that Mescalerolemur had unfused mandibular symphysis, similar to those of Strepsirrhines (lemurs, lorises and galagos). The authors posit that this is definitive evidence that adapiforms are more similar to Strepsirrhines than Haplorrhines (humans are Haplorrhines). Kirk &Williams (2011) published their findings on Journal of Evolution: New adapiform primate of Old World affinities from the Devil’s Graveyard Formation of Texas (PDF). You can also read more about the discovery at EurekAlert: Anthropologist discovers new fossil primate species in West Texas.

Originally posted on The Prancing Papio.

Coquerel-Sifaka at the Maryland Zoo in Baltimore, Photo: Kristin Abt

Read the press release for more information!

The Duke Lemur Center manages the United States’ Coquerel’s Sifaka population and provides more information about the species: Coquerel’s Sifaka

Although experimentation testing these types of numerical skills are not new, previous studies used edible items where the subject may eat the amount of food on the plate in which they choose – this experiment yielded only a 69% success rate in this study, and showed that the impulsiveness to gain a reward that they could see impaired their judgement when making a choice. Therefore previous studies may have underestimated the animals’ ability.

More information at; BBC – Earth News

Schmitt, V. & Fischer, J. Representational format determines numerical competence in monkeys. (2011). Nat. Commun. 2:257 DOI: 10.1038/ncomms1262.

A vervet monkey. Photo from Wikipedia.

Here’s what the researchers did in the field. They used playbacks of recorded vervet monkey (subjects) alarm calls from concealed speakers. Equal amount of alarm calls for leopard, eagle and snake were used. These alarm calls were recorded from known adult male, adult female and juvenile vervet monkeys in the field. Trials were done when subjects were on the ground and also when they were in the trees. These trials were conducted in the absence of predators to eliminate visual cues from the caller.

Alarm calls were broadcasted in different amplitudes to mimic natural alarm calls. In succession from loudest to lowest amplitudes are alarm calls for leopard, eagle and snake. Subsequently, leopard calls have the lowest pitch while snake calls have the highest pitch. To control for the possible effects of amplitude, the researchers broadcasted alarm calls that do not differ significantly in the amplitudes for all three predators.

Table from Seyfarth et al. (1980). Click on illustration for its original size

The alarm call playbacks showed two types of responses. First, subjects of any sex and age looked at the direction of the speaker and spent more time scanning their environment once an alarm call was made for more than 10 seconds. The researchers believe that they might be scanning for additional cues from the “caller” and the subject’s surrounding.

Second, each alarm calls seem to elicit a distinct response from the subjects. Remember the trials were done when the subjects were on the ground and on the trees? When subjects were on ground, leopard calls were more likely to make them run up into the trees and eagle calls made them look up and run into cover (bushes) Snake calls made them look down. When subjects were on the trees, leopard calls were more likely to make them run higher in trees and to look down. Eagle calls made them look up and sometimes run out of trees. Snake calls made them look down.

From the results, Seyfarth et al. (1980) posit that vervet monkey alarm calls alone do elicit different responses. It’s hard to tease out whether these alarm calls symbolize the predator ”leopard” or a command ”run up tree”. However, we can postulate that these alarm calls are rudimentary semantic signals used to warn other conspecific of impending danger. For those that are not familiar with semantics, it refers to the meaning of a symbol, sign, word or phrase. In this case, vervet monkey alarm calls are semantic signals because it conveys a specific meaning.

Reference:

Seyfarth, RM. Cheney, DL. Marler, P. 1980. Monkey responses to Three Different Alarm Calls: Evidence of Predator Classification and Semantic Communication. Science 210(4471): 801-803.

Originally posted on The Prancing Papio.

Alarm calls are typically high frequency sounds because these calls are hard to localized by predators. On the other hand, low frequency sounds are easier to localized by predators. Calls that are hard to localized by predators are selected for because conspecific can pick up on the warning but predators cannot identify the location of the caller. If an individual successfully alert its social group of approaching predator yet does not reveal its location, it will significantly decrease the chance of the caller to be detected and increase the chance of its social group to avoid predation.

Here, I will focus on the study of predatory alarm calls in vervet monkey (Chlorocebus pygerythrus) by Seyfarth et al. (1980) in the Amboseli National Park, Kenya. Vervet monkeys are Old World monkeys that range between Eastern and Southern Africa. These monkeys are diurnal and live in closely-knit social groups. They are quadrupedal and are both terrestrial and arboreal. Like all Old World monkeys, vervet monkeys have the characteristic cheek pouches that enables them to forage and store food to be eaten later. Male vervet monkeys have blue scrotal area and a red penis. Males and females are sexually dimorphic, with males slightly larger than females.

Vervet monkeys are known to elicit predator-specific alarm calls. Three well-documented vervet monkey alarm calls are those for leopard, martial eagle and python. Leopard alarm calls are short tonal calls produced in a series of inhalations and exhalations. Eagle alarm calls are low pitched grunt while python alarm calls are high pitched “chutters”. Different alarm calls seem to evoke different responses to individuals that heard the alarm calls. However, the first reaction of a vervet monkey upon hearing an alarm call is to look at the direction of the caller. Looking at the direction of the caller gives them clues as to why the alarm calls were made and also where the caller is facing reveals the direction of the approaching predator. You can listen to these different alarm calls on this site.

As we said before, different alarm calls evoke different responses. Leopard alarm calls would make the monkeys run up into the tree to avoid being ambushed by the leopard. Also, these monkeys would sit on the branches further away from the tree because, even though leopards can climb trees, the branches could not support the leopard’s weight. When an eagle alarm call is given, vervet monkeys would make them look up, run for the nearest bush or both to avoid an approaching aerial attack. Python alarm calls would the monkeys stand bipedally and look down on the ground.

Adult vervet monkeys are more discriminatory when eliciting alarm calls. Infants and juveniles calls however, are less discriminating as they attribute most terrestrial mammals with leopard calls, flying birds with eagle calls and stick-like figures with snake calls (although, compared to infants, juveniles are more discriminant when making alarm calls). In spite of that, adult vervet monkeys seem to elicit eagle alarm calls to different species of raptors and non-raptors (see illustration below). We can infer that adult vervet monkeys attribute eagle alarm calls to birds with the same silhouette as martial eagles. As vervet monkeys get older, they seem to have a better association between predator species and types of alarm calls. Vervet monkeys generally pay more attention to adult alarm calls than those of juveniles or infants.

The study of vervet monkey alarm calls by Seyfarth et al. (1980) laid an important ground work to better understand the complexity of animal communications. By showing that vervet monkeys make different alarm calls to different predatory species, we can posit that vervet monkeys have the ability to categorize different species. The ability to discriminate between terrestrial mammal, flying birds and snake-like objects starts during infancy in vervet monkeys. As they get older, they are better at associating predators with specific alarm calls.

The ability to over generalize during infancy is evident in both vervet monkeys and humans. For example, upon learning the word “dog”, human infants would refer to quadruped mammals they see as “dog”. As the infant grows, so does the ability to associate the semantic meaning of words they learned. However, the acquisition of alarm calls in vervet monkeys is different than the acquisition of speech (language) in humans. Alarm calls in vervet monkeys are instinctual and not learned. Humans, however, have to learn their language. Failing to do so during the “critical period” generally will result in the inability to learn language in later years. Feral child are examples of human infants that lack linguistic input during their critical period of language acquisition.

Most of us interpret animal alarm calls as an uncontrollable auditory response to fear or pain, akin to humans yelping if we had our finger caught in a door. While this is not entirely false, some animal calls actually convey information from the caller to the listener. Seyfarth et al. (1980) posit that vervet monkey alarm calls are actually basic semantic signals or symbolic signals because each alarm calls seem to mean something to these vervet monkeys. While we don’t know if these alarm calls actually mean “leopard” or “run up to the tree”, we do know that it conveys specific information to their conspecific about approaching predators.

I will be blogging Part II of this post later this week, where I will explain in details the experiments done by Seyfarth and Cheney on vervet monkey alarm calls.

References:
Cawthon Lang KA. 2006 January 3. Primate Factsheets: Vervet (Chlorocebus) Taxonomy, Morphology, & Ecology. http://pin.primate.wisc.edu/factsheets/entry/vervet. Accessed 2011 March 9.

Fichtel, C. Perry, S. Gros-Louis, J. 2005. Alarm calls of white-faced capuchin monkeys: an acoustic analysis. Animal Behaviour 70(1): 165-176. doi: 10.1016/j.anbehav.2004.09.020.

Gould, JL. Gould, CG. 1999. The Animal Mind. Scientific American Library.

Ouattara, K. Lemasson, A. Zuberbühler, K. 2009. Campbell’s Monkeys Use Affixation to Alter Call Meaning. PLoS ONE 4(11). doi:10.1371/journal.pone.0007808.

Seyfarth, RM. Cheney, DL. Marler, P. 1980. Monkey responses to Three Different Alarm Calls: Evidence of Predator Classification and Semantic Communication. Science 210(4471): 801-803.

Zuberbühler, K. Jenny, D. Bshary, R. 1999. The Predator Deterrence Function of Primate Alarm Calls. Ethology 105: 477–490. doi: 10.1046/j.1439-0310.1999.00396.x.

Zuberbuhler, K. 2000. Referential labelling in Diana monkeys. Animal Behaviour 59(5): 917-927. doi: 10.1006/anbe.1999.1317.

Free conservation biology textbook

Sodhi, N. S. and P. R. Ehrlich (Eds.). 2010. Conservation Biology for All. Oxford University Press.
Available online at: http://www.mongabay.com/conservation-biology-for-all.html

“The authors published Conservation Biology for All in a free and open access format in an effort to make conservation knowledge available to as many people as possible.”

Free conservation biology textbook: Conservation Biology for All

mongabay.com

Orangutan at Sepilok (Photo: Kristin Abt)

A recent article “Fostering Appropriate Behavior in Rehabilitant Orangutans (Pongo pygmaeus)” published online in the International Journal of Primatology discusses research on the behavior of rehabilitant orangutans (Pongo pygmaeus and P. abelii) at the Orangutan Care and Quarantine Centre in Pangkalan Bun, Kalimantan (Indonesian Borneo). Much past research has focused on postrelease behavior of rehabilitated orangutans and on the behavior of wild individuals; therefore, this research is especially timely and useful for the number of centers currently attempting to rehabilitate the ever-increasing number of displaced great apes and other fauna (Descovich et al., 2011).

Orangutans (n=40) in this study included males and females, mass classes ranging from 5 to 25 kg, and good, moderate, and poor health distinctions. Individuals were observed continuously for a period of 5 hours during 3 separate forest excursions each.  A number of behaviors relevant to postrelease success in the forest habitat were recorded (type of locomotion, social behavior, such as play, human caretaker interaction, point of height in tree or on ground, feeding and food choice, grooming, etc.).

Results from this study showed that rehabilitant individuals’ masses were associated with the amount of time spent at the centre. Authors note this finding as a result of the early age of admittance to the centre for most individuals. Further, orangutans in better health spent an increased amount of time consuming food and less time resting than other categories. In terms of locomotion (>30% of overall time), quadrupedal movement in trees was the dominant method (again, with orangutans in better health doing so more often). Individuals who had been at the Care Centre longer spent more time on the ground rather than swinging or other locomotion. As the day in which focal individuals were observed continued, human interaction increased.

As rehabilitation of orphaned individuals is a component of the long-term species survival of orangutans, research regarding the behavior of these individuals is important for increasing the chance of postrelease survival and success. Additionally, as their habitat is lost as a result of a number of conservation threats, land protection is necessary to provide habitat in which the released individuals and their wild conspecifics can live.

Reference

Descovich, K. A., Galdikas, B. M., Tribe, A., Lisle, A., & Phillips, C. J. 2011. Fostering appropriate behavior in rehabilitant orangutans (Pongo pygmaeus). International Journal of Primatology. doi:10.1007/s10764-011-9491-1

Orangutan Foundation International (a 501(c)3 nonprofit organization) supports the work of the Orangutan Care and Quarantine Centre and other crucial efforts to promote orangutan conservation, including land protection, research, and education. Visit www.orangutan.org to donate directly to OFI. If you would like to donate items specifically to enhance the lives of individuals at the Care Centre, visit this wishlist to select items that orangutans, such as those in this study, will greatly benefit from. If you would like to learn more, look for the upcoming IMAX© movie Born to Be Wild to be released in theaters April 8, 2011.

They found that the dominant male was approached more frequently when involved in a partnership with an estrous female. But also found that although females gain more attention during estrous, levels of interactions with the female during consortship did not change comparatively to the control. De Marco et al. also found that levels of sleeping and environment manipulation from bystanders were significantly reduced during times of sexual pairing; this study is the first to demonstrate a change of group behaviour in primates during times of sexual consortship.

Read more of the study at;
De Marco, A. Cozzolino, R. Dessì-Fulgheri, F. Thierry, B. 2011. Interactions between Third Parties and Consortship Partners in Tonkean Macaques (Macaca tonkeana). Int J Primatol DOI: 10.1007/s10764-011-9496-9

Woodland Park Zoo Lion-tailed Macaque (Photo: Kristin Abt)

By: Kristin Abt

The Lion-tailed Macaque (Macaca silenus) is an endangered cercopithecine primate native to the Western Ghats region of India, described as one of the primary hotspots of biodiversity in the world (Kumara & Singh, 2004).  IUCN (2010) estimates a mere 2,500 mature individuals with a total population size of 4,000 individuals.  Furthermore, these monkeys (LTMs) exist in an estimated 47 subpopulations in 7 locations.  Their serious status merits continuing intense and collaborative research on their demographics, current pressures, and the effects of habitat fragmentation, which appears to be the primary concern for their long-term survival in the wild.

Ecology and Distribution

These Old World monkeys have cheek pouches with simple stomachs, long, non-prehensile tails, an opposable hallux and pollex, hardened ischial callosities, and close, downward facing nostrils.  They are diurnal with complex, matrilineal social systems normally with one adult male and one subadult male to multiple females and their offspring.  Males disperse and females display estrus swellings to advertise their reproductive status.  They have an average group size of 18 with a range of 7 to 40 individuals (Umapathy & Kumar, 2000b).  Compared to other macaque species, Umapathy and Kumar point out that they have a slower life history with females reproducing first at 6.6 years and having a birth rate of 0.31 infants/female/year thereafter.  This overall low prolificacy with delayed sexual maturity, long interbirth interval, and low population turnover presents an additional challenge when groups must respond to external survival pressures.

The LTM differs from other macaque species additionally through its primarily arboreal nature.  Menon and Poirier (1996) emphasize this characteristic through the documentation of 3 falls and one subsequent death from tree gaps.  In places with incontiguous canopy cover, individuals exhibited a strong preference to exert considerable effort to cross large holes in the canopy without descending to the ground.  Ramachandran and Joseph (2000) discuss the conservation and sustainability implications of this in that LTMs failed to range into adjacent areas disrupted by fire or eucalypt and teak plantations in order to exhaust nearby resources in neighboring forest fragments.

Individuals are found only in the Western Ghats region in the three states of Kerala, Karnataka, and Tamil Nadu and have been studied extensively in such national and private evergreen forests as Silent Valley in the Palghat district (Ramachandran & Joseph, 2000), the Indira Gandhi Wildlife Sanctuary in Anamalai Hills (Umapathy & Kumar, 2000a & b), Brahmagiri-Makut and Sirsi-Honnovara (Kumara and Singh 2004), the Puthuthotam Cardamom Forest (Menon & Poirier, 1996), and the Kudremukh Forest Complex (Kumara & Singh, 2008).  Within these locations, it has been found that the LTMs prefer habitat primarily between 300m asl – 900m asl (Kumara & Singh, 2008).  It is estimated that almost 40% of the remaining population exist as small groups found in isolated, highly fragmented forests in these areas (Umapathy & Kumar, 2000a).  As one goes from South to North within their range, group size has been shown to increase (Kumara & Singh, 2004).

Woodland Park Zoo Exhibit for Lion-tailed Macaques (Photo:Kristin Abt)

Within their habitat, LTMs serve as “one of the most important habitat specialist primates in India” (Ramachandran & Joseph, 2000).  Sushma and Singh (2006) found that compared to other arboreal mammals, such as bonnet macaques (Macaca radiata), Nilgiri langurs (Semnopithecus johnii), and the Indian giant squirrel (Ratufa indica), LTMs have the narrowest niche breadth with some overlap with bonnet macaques, which indicates a degree of competition where these animals must coexist.  Ramachandran and Joseph (2000) point out that they seldom range outside of their evergreen forest even into the deciduous areas.  They also reported that LTMs feed primarily (91%) on plant matter with the remainder consisting of invertebrates, which is a higher amount than other macaque species (Sushma & Singh, 2006).  Ramachandran & Joseph (2000) found that they formed significant associations with 6 major tree species, especially Cullenia.  These are needed in the proper abundance in order to sustain the primates; however, some flexibility is present.  Menon and Poirier (1996) note that, in times of food scarcity, individuals supplement their diet with Artocarpus and Coffea trees in nearby forested plantations. Because they are highly frugivorous and consume large amounts of figs (Sushma & Singh, 2006), they must range significant distances in order to find sufficient food for the group.  Fruit, as a seasonal and patchy resource, offers a lot of carbohydrates, but not a good amount of protein.  As a result, invertebrates comprise a relatively large amount of their diet in order to provide the necessary nutrition for successful reproduction (Umapathy & Kumar, 2000a). Juveniles spend a significantly larger amount of time feeding on these, suggesting their importance for proper growth and development, as well.

Western Ghats, India Map from cepf.net

Conservation Threats due to Habitat Fragmentation

When primate groups are found in highly fragmented habitat, this presents serious survival pressures for themselves and for those individuals in neighboring forests without the opportunity for gene flow.  McGarigal and Cushman (2002) define habitat fragmentation as a “landscape level process in which a specific habitat is progressively subdivided into smaller and more isolated fragments.”  They further discuss how it encompasses a change in landscape composition, structure, and function.  Because habitat fragmentation, along with habitat loss, is considered to be one of the main influences causing the incredible mass extinction of species that is currently occurring, studying the effects of this in order to produce urgent and important management strategies is paramount.

Thus far, a number of studies of the LTM have discovered relevant consequences to the habitat fragmentation continually occurring within their range.  In reference to the demographics of social groups, the effects of habitat fragmentation have been to significantly change the composition naturally found in contiguous and undisturbed sections of forest.  Specifically, Umapathy and Kumar (2000b) found near significance with smaller fragments containing larger group sizes compared to larger fragments.  Also, it appears that there is more likely to be two adult males in a social group of a small fragment than the typical one male: multiple females found in larger fragment sizes.  Significantly, there is a positive correlation between fragment size and the number of immatures and birth rate.  The authors cite possible factors for this as increased predation pressures and resource shortages.  Kumara and Singh (2004) classified health of a population by a high overall presence of groups with the modal group size, favorable sex ratio, and a large percentage of immature individuals; therefore, the findings from the previous study provide further support to their criteria as valid to use when investigating the demographics of LTMs in fragmented areas.

Studies have also investigated how vegetation status in relation to level of fragmentation affects these primates.  Umapathy and Kumar (2000a) found that individuals spent significantly less time feeding on invertebrates, a key component to their diet, in smaller fragments.  Additionally, the least disturbed fragments contained the highest plant abundance.  In areas with colonized species, such as mangos and guava, the macaques added these to their diet, which might slightly compensate for the loss in space and flora diversity; however, it could also contribute to human-wildlife conflict.  Furthermore, these researchers (2000b) also demonstrated a positive correlation between the quality of vegetation and the amount of fragmentation.

Along with demographic and dietary changes, significant changes occur in disturbed populations with respect to the groups’ overall behaviors and activity patterns.  Menon and Poirier (1996) studied individuals in a private forest that experienced selective logging and clearing for planting on the floor and found that the primates used the ground often for ranging and foraging out of necessity, but still much preferred the trees – even when travelling in such a manner presented serious and mortal danger due to the lack of sufficient canopy continuity.  They were also forced to cross roads and raid fruit in neighboring plantations, which resulted in human-wildlife conflict and deterrence measures implemented.  Furthermore, the individuals needed to increase their time ranging, which seriously impacted their ability to feed and engage in necessary social behaviors.  Especially relevant to small, isolated populations is the inability to disperse naturally, which Debinski and Holt (2000) discuss and, consequently, suggest corridors for landscape connectivity, especially for highly mobile animals.  Without proper gene flow and the opportunities for appropriate social groups to form, the long-term survival of this species is severely threatened, which is already evidenced by the results of lower numbers of juveniles in these fragmented groups.

In addition to the restriction of available habitat and isolation of existing groups, human-wildlife conflict has placed significant pressure on their survival.  Along with plantations cultivated for teak and eucalypt and areas that are clear felled for tea and coffee, humans also use the forest areas for wood gathering, logging, and hunting of the LTMs and other fauna (Kumara & Singh, 2000b; Menon & Poirier, 1996).  Fragments also increase the likelihood of the macaques coming into human contact and the likelihood that humans will disturb the forest.

Conclusions

As with so many conservation stories, this one can greatly benefit from increased attention, education, and priority at numerous levels. Over recent years, the LTM has featured less prominently in North American zoo collections despite its endangered status, declining populations, charismatic appearance, and active nature (Association of Zoos and Aquariums, 1998). Additionally, few conservation and education efforts are currently in place to support its population (AZA, 1998). While research into its populations and its behavioral ecology are important to further understand the species, additional efforts to increase gene flow between populations, protect its forest habitat, and address conflicts with agriculture are needed for this macaque species to persist.

References

Association of Zoos and Aquariums. 1998. Lion-tailed macaque 98 fact sheet. Retrieved February 8, 2011, from Web site: http://www.nagonline.net/Fact%20Sheet%20pdf/AZA%20-%20Lion-Tailed%20Macaque%20 Species%20Survival%20Plan.pdf

Debinski, D. M. and R. D. Holt. 2000. A survey and overview of habitat fragmentation experiments. Conservation Biology 14: 342–355.

IUCN.  2010 IUCN Red List of Threatened Species.  Retrieved February 8, 2011, from Web site: http://www.iucnredlist.org/details/12559

Kumara, H. N. and M. Singh. 2004. Distribution and abundance of primates in rain forests of the Western Ghats, Karnataka, India and the conservation of Macaca silenus. International Journal of Primatology 25: 1001–1018.

Kumara, H. N. and V. R. Singh. 2008. Status of Macaca silenus in the Kudremukh Forest Complex, Karnataka, India. International Journal of Primatology 29: 773–781.

McGarigal, K. and S. A. Cushman. 2002. Comparative evaluation of experimental approaches to the study of habitat fragmentation effects. Ecological Applications 12: 335–345.

Menon, S. and F. E. Poirier. 1996. Lion-tailed Macaques (Macaca silenus) in a disturbed forest fragment: Activity patterns and time budget. International Journal of Primatology 17: 969–985.

Ramachandran, K. K. and G. K. Joseph. 2000. Habitat utilization of lion-tailed macaque (Macaca silenus) in Silent Valley National Park, Kerala, India. Primate Report 58: 17–25.

Sushma, H. S. and M. Singh. 2006. Resource partitioning and interspecific interactions among sympatric rain forest arboreal mammals of the Western Ghats, India. Behavioral Ecology 17: 479–490.

Umapathy, G. and A. Kumar. 2000a. Impacts of the habitat fragmentation on time budget and feeding ecology of lion-tailed macaque (Macaca silenus) in rain forest fragments of Anamalai Hills, South India. Primate Report 58: 67–82.

Umapathy, G. and A. Kumar. 2000b. The demography of the Lion-tailed Macaque (Macaca silenus) in rain forest fragments in the Anamalai Hills, South India. Primates 41: 119–126.