SOCIAL ORGANIZATION AND BEHAVIOR
In general, the majority of douc langur groups are multi-male/multi-female,
usually with more females than males (usually around 2 adult females for every
adult male), although one-male groups have been observed in P. nemaeus
(Lippold 1995; 1998; Nadler et al. 2003; Lippold & Vu 2008; Minh 2008). The
group core consists of related females, as well as a lesser number of males and
immature individuals including juveniles and infants (Lippold 1999). Group size
is variable by location (from only several individuals up to 51), and is
affected by the degree of habitat disturbance, with group sizes larger in lesser
disturbed habitats which are larger in size (review in Lippold 1998). P.
nigripes group sizes average 20 individuals, while P. nemaeus
group sizes average 19 individuals (Lippold 1998). Groups are trending towards
smaller size as habitats are disturbed further (Nadler et al. 2003). Fission
and fusion of P. nigripes groups has been observed in the wild (Minh
Photo: Anna Halko-Angemi
In the wild, allogrooming occurs more often than autogrooming and adult
females groom each other often. Most allogrooming occurs before rest periods or
sleep, and especially in the afternoon. Allogrooming sessions may last up to an
hour (Lippold 1977).
In the wild, there is a loose dominance hierarchy within douc langur groups,
with adult males always dominant to all other group members (Lippold 1977).
Hierarchies also occur in captive douc langurs (Lippold 1977; Kavanaga
In captivity, both females and males between 2 and 4 years old are sometimes
forced out of their natal groups (Lippold 1977; Ruempler 1998).
In captive P. nemaeus, agonism is rare, and usually is short-lived
when it does occur. Staring and growling indicate aggression and grimacing,
twittering and squealing show submission (Kavanagh 1978).
In the wild and in captivity, both adults and immature individuals engage in
social play, but adults far more infrequently than the immature individuals, and
play is often accompanied by a characteristic play-face (Lippold 1977; Kavanagh
1978). To solicit play, often the head is thrown back with a pseudo-smile on
the face, but also by tail pulling, running, jumping, and pulling the ears of
another individual. Play may consist of wrestling, chasing and jumping and
usually occurs after feeding and before periods of rest (especially in the late
morning, early afternoon, and before sleep in the evening). Solitary play is
also seen (Lippold 1977).
The female reproductive cycle in P. nemaeus averages 26.4 days, with
estrus lasting 1-3 days (Ruempler 1998; Heistermann et al. 2004). Multiple
copulations occur during estrus (Ruempler 1998). The rump area changes from
white to a red color during estrus (while pregnant, it remains this red color)
and copulations continue through pregnancy (Hick 1972; Brockman & Lippold
1975; Lippold 1977; 1998; Ruempler 1998). Interestingly, the male rump also
changes to a redder color, responding to females in estrus (Lippold 1998).
During pregnancy in captivity, females become more peripheral from the group and
spend much time nearby the adult male (Ruempler 1998).
Reproduction and births occur year-round, but there appear to be birth peaks
influenced by environmental factors, and within individual groups, several
births may occur around the same time (Lippold 1977; 1999).
To solicit mating, a female may face the male and move her head back and
forth by pushing her chin forward or she may crouch, facing her anogenital
region towards the potential mate, sometimes looking back over her shoulders
(Kavanagh 1978; Ruempler 1998). However, either sex may solicit copulation
(Lippold 1998). Copulations are dorsal-ventral, with the male mounting the
female from behind and grasping the female with his forearms. In captivity, a
male will mate with more than one female in the group (Kavanagh 1978).
In captivity, P. nemaeus males reproduce for the first time between
5-8 years old while females reproduce first between 5-7 years old (Ruempler
1998). Gestation can only be estimated at between 180 and 200 days, due to
multiple copulations between partners in a single estrus, although a single
captive female in one study had a gestation of 210 days (P. nemaeus)
(Brockman & Lippold 1975; Lippold 1981; Ruempler 1998). The average
inter-birth interval is 24 months in captivity (Ruempler 1998).
At birth, a P. nemaeus male weighed 324g (11.4 oz), while females
average 463g (16.3 oz) (Ruempler 1998; Smith & Leigh 1998). P.
nemaeus infants are hairy at birth (chestnut-colored with black hands and
feet), but in contrast to adults their face is black, with only lighter stripes
below their eyes. This coloration changes to adult coloration between 8-12
months old (Hick 1972; Ruempler 1998). The eyes are open at birth and infants
are usually singletons (Hick 1972; Ruempler 1998). In captivity, P.
nemaeus births occur mostly in the early evening and not during the day
(Ruempler 1998). Infants are carried ventrally both by the mother and other
members of captive douc langur groups (Kavanagh 1978; Ruempler 1998). Climbing
starts by day 7 of life, and hanging by the feet at 14 days. In captivity, by
18 days old, infants start grasping solid food and are eating leaves and fruit
by 60 days old (Brockman & Lippold 1975; Ruempler 1998). Weaning starts at
around 12-15 months (Ruempler 1998).
Allomothering is observed in wild P. nigripes (Rawson 2006).
In P. nemaeus, threats are communicated by flattened ears and a
forward stretched neck (Ruempler 1998). Aggression is signaled by the "stare"
in which the eyes are opened all the way, raised eyebrows, and sometimes
thrusting forward of the jaw (Kavanagh 1978). Submission or non-hostility is
indicated by the "grimace" in which the eyes and mouth are opened so the teeth
are visible (Kavanagh 1978).
P. nemaeus emit a "threat bark" when they are surprised, grunts when
satisfied, excitement calls, and screams when frightened (Lippold 1977; Ruempler
1998). Twittering and squealing indicate submission, while growling indicates a
threat (Kavanagh 1978).
Content last modified: September 3, 2009
Written by Kurt Gron.
Cite this page as:
Gron KJ. 2009 September 3. Primate Factsheets: Douc langur (Pygathrix) Behavior . <http://pin.primate.wisc.edu/factsheets/entry/douc_langur/behav>. Accessed 2015 September 1.