Fate of ousted male residents of one-male bisexual troops of Hanuman langurs (Presbytis entellus) at Jodhpur,Rajasthan, India

Little is known about the fate of adult male residents after they are ousted from bisexual one-male troops of Hanuman langurs (Presbytis entellus) in the course of adult male replacements. In a long term study at Jodhpur, Rajasthan, it was possible to reconstruct partial life histories of several ousted residents. One resident was killed during the male change. Ousted residents did not regain residency despite their continued invasions into bisexual troops. It is assumed that the males' chances to take over and to defend a troop are restricted to an age of 9–14 years, when the males are in prime physical condition. One male became solitary for some months while trying to regain residency of his old troop, before joining some “alien” males. As a rule, males are likely to rejoin their own male bands if they are ousted after short periods of residency. If the residency exceeds 3 months then the ongoing structural change in the former band may prevent their reintegration. However, in such cases, ousted residents which belonged to the same band may reunite and mingle with another male band which lacks prime males. Weaned sons may follow their fathers after ousting. In the case of numerous weaned offspring, fathers and sons may together form at least temporary new male bands.     

On the dynamics of the hanuman langur populations of jodhpur (Rajasthan,India)

The city of Jodhpur (26°18′N, 73°8′E) supports a population of about 900 hanuman langurs (Presbytis entellus) divided into 24 bisexual troops and 12 all-male bands in an area of 60 km². This population has been censused from 1968 to 1978. Over this period the population of bisexual troops has remained stable around 700, while the population of all-male bands has increased from 160 to 230 individuals. The bisexual troops show a tendency towards a reduction in population growth rate with increasing troop size, with troops over 50–60 tending to split. Very small troops may grow by large scale immigration. Although a number of male changes and mortality through infanticide have been recorded, there is no evidence of a regular periodicity in the occurrence of initial, growth and mature phases in the life history of a bisexual troop. Unlike the bisexual troops, the all-male bands show no tendency towards a reduction in growth rate with the increase in band size, but show a continuous growth of band size over the study period. Langurs of Jodhpur rely heavily on cultivated fields for their sustenance. This cultivation has been on increase over the study period, and since the males invade cultivation more readily, they may have been able to take fuller advantage of these increasing resources and affect a population increase that has not been possible for the bisexual troops.     

The process of weaning in hanuman langursPresbytis entellus entellus

Twelve langur infants (seven males and five females) of three focal bisexual unimale troops of Hanuman langurs,Presbytis entellus entellus living near Kailana, Jodhpur, Rajasthan (India) were observed for their weaning behaviour. Weaning starts between 7.0 to 10.0 months of age, average 8.6 months. The process of weaning lasts between 3.2 to 5.6 months, average 4.2 months. A 13-month-old infant is fully weaned. Infants are independent at this age. Male infants are weaned earlier compared to females. Males react to their mothers' rejections more fearlessly and are more vocal compared to females. By and large, infants were found in stress during this period as their mothers are often very harsh, hostile, punitive, and indifferent to their infants. By severing ties with their infants, mothers serve dual purpose of allowing their infants to become independent and may be to become ready to bear offspring.     

Abortions in free ranging Hanuman langurs (Presbytis entellus) — a male induced strategy?

During a 10-year long term study, 6 eye-witnessed and 1 pressumed cases of abortions occurred in 3 one-male bisexual troops of free ranging langurs (Presbytis entellus) near Jodhpur, Rajasthan, India. The age of the unborns varied from 35 to about 200 days. The subsequent birth interval ranged between 7.1–21.1 months. 2 miscarriages occurred during stable periods of residency of a single male. 5 cases occurred prior to or after infanticide in connection with male changes. In one case a female was attacked by the new male before she aborted. In one case a female presumably aborted after attacks on her semiweaned infant. Most of the reproductive losses hence seem to be related to psychical and physical stress exerted by new males on pregnant females. As part of their reproductive strategy, males reduce their waiting time to insemination in this way. Abortions may likewise represent an adaptive reproductive strategy of females, who prefer to abort instead of investing in a foetus which is likely to be killed after birth.     

Status and Distribution of Macaca fascicularis umbrosa in the Nicobar Islands, India

We surveyed the distribution and status of the long-tailed macaque (Macaca fascicularis umbrosa) in the Nicobar Islands of India. Long-tailed macaques live on 3 islands: Great Nicobar, Little Nicobar and Katchal. There are a total 788 groups. Group size ranged from 25 to 56 individuals with a mean size of 36. Long-tailed macaques are a multimale-multifemale society. Adult males, adult females and immatures constituted 9.7 per cent, 43.2 per cent and 47.1 per cent of the population, respectively. A fairly high ratio of immatures to adult females indicates a healthy population turnover. Vegetation parameters including tree density, canopy cover, canopy height and basal area indicated a still healthful habitats on all the 3 islands. We observed a few threats to the macaques. Measures should be undertaken to ensure survival of the Nicobar subspecies.     

Infanticide and juvenilicide in Hanuman langurs (Presbytis entellus) around Jodhpur,India

Ten cases of infant killings and 2 cases of juvenile killings were observed in two troops of Hanuman langurs, (Presbytis entellus) around Jodhpur, India. Fatal attacks on infants and juveniles are classified into four categories. The process of infanticide was observed from start to end and is described in detail for 3 cases. The age of the victims ranged from 0.2 to 48 months. The interbirth interval among females whose infants were killed is significantly shorter compared to females whose infants survived. In ourt study, 7 cases support the reproductive advantage hypothesis, that infanticide is an adaptive behaviour to increase male reproductive success. The remaining 5 cases do not fit into the reproductive advantage hypothesis. In these cases, victims are over 8 months old, and as such their deaths could not shorten the interbirth interval. It appears that by killing older infants and juveniles the males obtain an advantage in resource competition for their offspring. An alternative is that new males chase or peripheralise the older infants and juveniles, which leads to 97% predominant uni-male troop structure in Jodhpur.     

Birth dynamics in Hanuman langurs,Presbytis entellus of Jodhpur,India

Ten years data on birth peak, birth rate and interbiith interval inPresbytis entellus of Jodhpur have been presented. Although Hangman langur females breed round the year, there is some concentration of births during January–March while fewer births occur during October–December. It seems that provisioning and crop raiding together may provide better feeding opportunities to breed year round. However, it remains unclear whether environmental factors allow langur females to deliver more infants during January–March. During 1984–86 the birth rate was uniform for the whole population (0.63). While there was a variation within the troops from year to year, data suggest that resident male replacements do alter birth rate. It goes down when resident males are replaced frequently. The interbirth interval ranges between 7.0 and 76.5 months (average, 16.88 months;n = 112). Abortions and still-births reduced the interbirlh interval to 7.1 months (range 7.1-21.1; average, 11.4 months;n= 8) compared to the normal inlerbirth interval following infant survive its first 4.1 months of life (range 10.7-76.5 months; average, 17.28 months;n = 86). However, infant loss under the age of 4.1 months did not reduce the interbirth interval except in two cases (range 7.0-51.8 months; average, 17.27 months;n = 18). Maternal rejection or weaning begins at about 8 months of age and lasts until infants are 12 months old. In this population, the probability of twin births was worked out to be 0.79 per 100 births.     

Sanctuary in the City: Urban Monkeys Buffered against Catastrophic Die-off during ENSO-related Drought

Large-scale climatic drivers such as El Niño Southern Oscillation (ENSO) can overwhelm factors that ordinarily govern local population dynamics. We recently documented an ENSO-related die-off of mammals in the Kumbhalgarh Wildlife Sanctuary (KWS), Rajasthan, India. This die-off coincided with the La Niña-induced drought of 2000, which followed two consecutive monsoon failures. Hanuman langurs suffered a population crash of nearly 50% from 1999 to 2001. A Multivariate ENSO Index explained 80% of the variability in population size during the time series, and predicted the mass mortality and/or recruitment failure associated with the major La Niña event spanning 1999. Here, we ask whether langurs in a large Rajasthani city, Jodhpur, were buffered against drought because humans provisioned them with food—for religious reasons. Unlike the KWS population, the Jodhpur population suffered no significant decline. In 2001, this urban population remained 95% as large as in 1999, before the drought. Variability in population size was also vastly reduced in Jodhpur. Thus, the impact of drought was dampened in a major urban area compared with an officially protected area. In this case, high human population density was not anathema for conservation. Wildlife sanctuaries in protected areas are undeniably important conservation tools, but our findings reinforce the notion that cities can serve as de facto sanctuaries for some species. This study provides some hope for biodiversity conservation in a rapidly urbanizing world, particularly for holy and commensal species.