The Asian water monitor (Varanus salvator), also called common water monitor, is a large varanid lizard native to South and Southeast Asia. It is one of the most common monitor lizards in Asia, ranging from Sri Lanka and coastal northeast India to Indochina, Malay Peninsula, and Indonesian islands where it lives close to water. It is listed as Least Concern on the IUCN Red List.[1] It was described by Laurenti in 1768 and is among the largest squamates in the world.[2]
The Asian water monitor is also called Malayan water monitor, common water monitor, two-banded monitor, rice lizard, ring lizard, plain lizard and no-mark lizard, as well as simply water monitor. The local name in Sri Lanka is kabaragoya, denoting a subspecies with distinct morphological features.[3]
Description
Walking on pavement
The water monitor is a large species of monitor lizard.
Breeding maturity is attained for males when they are a relatively
modest 40 cm (16 in) long and weigh 1 kg (2.2 lb), and for females at
50 cm (20 in). However, they grow much larger throughout life, with
males being larger than females.[4] Adults rarely exceed 1.5–2 m (4.9–6.6 ft) in length,[5] but the largest specimen on record, from Sri Lanka, measured 3.21 m (10.5 ft). A common mature weight of V. salvator can be 19.5 kg (43 lb).[4][6] However, 80 males killed for the leather trade in Sumatra
averaged only 3.42 kg (7.5 lb) and 56.6 cm (22.3 in) snout-to-vent and
142 cm (56 in) in total length; 42 females averaged only 3.52 kg
(7.8 lb) and 59 cm (23 in) snout-to-vent and 149.6 cm (58.9 in) in total
length,[4]
although unskinned outsized specimens weighed 16 to 20 kg (35 to
44 lb). Another study from the same area by the same authors similarly
estimated mean body mass for mature specimens at 20 kg (44 lb)[7] while yet another study found a series of adults to weigh 7.6 kg (17 lb).[8] The maximum weight of the species is over 50 kg (110 lb).[9]
In exceptional cases, the species has been reported to reach 75 to
90 kg (165 to 198 lb), though most such reports are unverified and may
be unreliable. They are the world's second-heaviest lizard, after the Komodo dragon.[4]
Their bodies are muscular, with long, powerful, laterally compressed
tails. The scales in this species are keeled; scales found on top of the
head have been noted to be larger than those located on the back.
Water monitors are often defined by their dark brown or blackish
coloration with yellow spots found on their underside- these yellow
markings have a tendency to disappear gradually with age. This species
is also denoted by the blackish band with yellow edges extending back
from each eye. These monitors have very long necks and an elongated
snout. They use their powerful jaws, serrated teeth and sharp claws for
both predation and defense. In captivity, Asian water monitors' life
expectancy has been determined to be anywhere between 11–25 years
depending on conditions, in the wild it is considerably shorter.[10][11]
Distribution and habitat
Head closeup showing split tongue
The Asian water monitor is widely distributed from India, Bangladesh,
Sri Lanka, Myanmar and Thailand, Cambodia, Laos, Vietnam, the Chinese Guangxi and Hainan provinces, Malaysia, Singapore to the Sunda islandsSumatra, Java, Bali, Borneo and Sulawesi. It inhabits primarily lowland freshwater and brackish wetlands. It has been recorded up to an altitude of 1,800 m (5,900 ft).[1]
Asian water monitors are semiaquatic
and opportunistic; they inhabit a variety of natural habitats though
predominantly this species resides in primary forests and mangrove
swamps. It has been noted that these monitors are not deterred from
living in areas of human disturbance. In fact, they have been known to
adapt and thrive in agricultural areas as well as cities with canal
systems (such as in Sri Lanka, where they are not hunted or persecuted
by humans). This species does not thrive in habitats with extensive loss
of natural vegetation and aquatic resources. Habitats that are
considered to be most important to this species are mangrove vegetation,
swamps, wetlands, and altitudes below 1000 meters.[12]
V. s. salvator with full belly at Kandy Lake, Sri Lanka. Possibly obese or gravid, maybe both.
Water monitors defend themselves using their tails, claws, and jaws.
They are excellent swimmers, using the raised fin on their tails to
steer through water. They are carnivores, and consume a wide range of
prey. They are known to eat fish, frogs, rodents, birds, crabs, and snakes.[13] They have also been known to eat turtles, as well as young crocodiles and crocodile eggs.[14] Water monitors have been observed eating catfish
in a fashion similar to a mammalian carnivore, tearing off chunks of
meat with their sharp teeth while holding it with their front legs and
then separating different parts of the fish for sequential consumption.[15]
In dominantly aquatic habitats their semiaquatic behavior is
considered to provide a measure of safety from predators. Paired with
their generalist diet, this is thought to contribute to their ecological
plasticity.[12] When hunted by predators such as the king cobra (Ophiophagus hannah)
they will climb trees using their powerful legs and claws. If this
evasion is not enough to escape danger, they have also been known to
jump from trees into streams for safety, a tactic similar to that of the
green iguana (Iguana iguana).[10]
Like the Komodo dragon, the water monitor will often eat carrion.[13][16]
They have a keen sense of smell and can smell a carcass from far away.
They are known to feed on dead human bodies. While on the one hand their
presence can be helpful in locating a missing person in forensic
investigations, on the other hand they can inflict further injuries to
the corpse, complicating ascertainment of the cause of death.[17]
The first description of the water monitor and its behaviour in English literature was made in 1681 by Robert Knox, who observed it during his long confinement in the Kingdom of Kandy:
“There is a Creature here called Kobberaguion, resembling an Alligator.
The biggest may be five or six feet long, speckled black and white. He
lives most upon the Land, but will take the water and dive under it:
hath a long blue forked tongue like a sting, which he puts forth and
hisseth and gapeth, but doth not bite nor sting, tho the appearance of
him would scare those that knew not what he was. He is not afraid of
people, but will lie gaping and hissing at them in the way, and will
scarce stir out of it. He will come and eat Carrion with the Dogs and
Jackals, and will not be scared away by them, but if they come near to
bark or snap at him, with his tail, which is long like a whip, he will
so slash them, that they will run away and howl.”[18]
Water monitors should be handled with care since they have many
sharp teeth and can give gashing bites that can sever tendons and veins,
causing extensive bleeding. The bite of a large pet water monitor was
described by its American owner as being worse than that of a
rattlesnake.[19]
Venom
The possibility of venom in the genus Varanus is widely debated. Previously, venom was thought to be unique to Serpentes (snakes) and Heloderma (venomous lizards). The aftereffects of a Varanus bite were thought to be due to oral bacteria alone, but recent studies have shown venom
glands are likely to be present in the mouths of several, if not all,
of the species. The venom may be used as a defensive mechanism to fend
off predators, to help digest food, to sustain oral hygiene, and
possibly to help in capturing and killing prey.[20][21]
Predation
Adult water monitors have few natural predators, and are only know to be preyed on by saltwater crocodiles.[22]
Monitor lizards are traded globally and are the most common type of
lizard to be exported from Southeast Asia, with 8.1 million exported
between 1998 and 2007.[23]
The Asian water monitor is one of the most exploited varanids; its skin
is used for fashion accessories such as shoes, belts and handbags which
are shipped globally, with as many as 1.5 million skins traded
annually.[1] Other uses include a perceived remedy for skin ailments and eczema,[24] novelty food in Indonesia,[25] and a perceived aphrodisiac,[26] and as pets.[27]
Conservation
In Nepal, it is a protected species under the Wild Animals Protection Act of 2002. In Hong Kong, it is a protected species
under Wild Animals Protection Ordinance Cap 170. In Malaysia, this
species is one of the most common wild animals, with numbers comparable
to the population of macaques there. Although many fall victim to humans
via roadkill and animal cruelty, they still thrive in most states of Malaysia, especially in the shrubs of the east coast states such as Pahang and Terengganu. In Thailand, all monitor lizards are protected species.[27]
It is still common in large urban areas in Thailand and is frequently
seen in Bangkok's canals and parks. Because of this, it is currently
listed as Least Concern in the IUCN Red List and in CITES Appendix 2.
These classifications have been made on the basis that this species
maintains a geographically wide distribution, can be found in a variety
of habitats, adapts to habitats disturbed by humans, and is abundant in
portions of its range despite large levels of harvesting.[1]
Loss of habitat and hunting has exterminated water monitors from
most of mainland India. In other areas they survive despite being
hunted, due in part to the fact that larger ones, including large
females that breed large numbers of eggs, have tough skins that are not
desirable.[3]
In Sri Lanka, it is protected by local people who value its
predation of "crabs that would otherwise undermine the banks of rice
fields".[3] It is also protected as it eats venomous snakes.[28]
Taxonomy
Asian
water monitors fall within the kingdom: Animalia, phylum: Chorodata,
class: Reptilia, order: Squamata, family: Varanidae, genus: Varanus, and species: V. salvator.[12] The family: Varanidae contains nearly 80 species of monitor lizards, all of which belong to the genus: Varanus. This genus has been proven to show the widest size range of any vertebrate genus.[29]
There is a significant amount of taxonomic uncertainty within this
species complex. Morphological analyses have begun to unravel this
taxonomic uncertainty but molecular studies are needed to test and
confirm the validity of this evidence. Research initiatives such as
these are very important for changes in conservation assessments.[12]
Subspecies
V. s. salvator
The Asian water monitor, V. s. salvator, the nominate subspecies, is now restricted to Sri Lanka, where it is known as the kabaragoya (කබරගොයා) in Sinhala and kalawathan in Tamil.
The Andaman Islands water monitor, V. s. andamanensis, is found on the Andaman Islands; the type locality is Port Blair, Andaman Islands.
The two-striped water monitor, V. s. bivittatus, is common to Java, Bali, Lombok, Sumbawa, Flores, Ombai (Alor), Wetar, and some neighbouring islands within the Sunda arch, Indonesia; the type locality is Java (designated by Mertens 1959).
Melanistic V. s. macromaculatus
The black water monitor, V. s. komaini, from Thailand
(type locality: Amphoe La-ngu, Satun Prov., Thailand, and
Thai-Malaysian border area), was formerly a subspecies, but now is
regarded as a junior synonym and melanistic population of V. s. macromaculatus.[2] It is known as the "black dragon" or "black water monitor" (มังกรดำ, เหี้ยดำ) in Thai[30]
The Southeast Asian water monitor, V. s. macromaculatus (type
locality: Siam [Thailand]), is found in mainland Southeast Asia,
Singapore, Sumatra, Borneo, and smaller associated offshore islands.[2]
Ziegler's water monitor, V. s. ziegleri, is from Obi Island.
The generic name Varanus is derived from the Arabicwaral (ورل), which translates as "monitor". The specific name is the Latin word for "saviour", denoting a possible religious connotation.[13] The water monitor is occasionally confused with the crocodile monitor (V. salvadorii) because of their similar scientific names.[32]
In Thailand, the local word for a water monitor, hia (เหี้ย),
is used as an insulting word for bad and evil things, including bad
persons. The word is also thought to bring bad luck, so some people
prefer to call the animals 'silver-and-gold' (ตัวเงินตัวทอง) to avoid the jinx.[citation needed]
The origin of this offensive meaning can be traced back to a time when
more people lived in rural areas in close proximity to monitor lizards.
Traditionally, Thai villagers lived in two-story houses; the top floor
was for living, while the ground floor was designed to be a space for
domestic animals such as pigs, chickens, and dogs. Water monitors
entered the ground floor and eat or maim the domestic animals, also
hence the other name dtua gin gai (ตัวกินไก่ ‘chicken eater’) or nong chorakae (น้องจระเข้ ‘younger brother of crocodile’, ‘little crocodile’) and even sometimes called ta kuat (ตะกวด), which in fact refers to a Bengal monitor (V. bengalensis), a different species.[33]
In Indonesian and Malay language, the Asian water monitor is called biawak air.[34]
The golden lion tamarin gets its name from its bright reddish orange
pelage and the extra long hairs around the face and ears which give it a
distinctive mane.[8] Its face is dark and hairless. The bright orange fur of this species does not contain carotenoids, which commonly produce bright orange colors in nature.[9] The golden lion tamarin is the largest of the callitrichines.
It is typically around 261 mm (10.3 in) and weighs around 620 g
(1.37 lb). There is almost no size difference between males and females.
As with all New World monkeys, the golden lion tamarin has tegulae, which are claw-like nails, instead of ungulae or flat nails found in all other primates, including humans.[10]
Tegulae enable tamarins to cling to the sides of tree trunks. It may
also move quadrupedally along the small branches, whether through
walking, running, leaping or bounding.[11] This gives it a locomotion more similar to squirrels than primates.
Habitat and distribution
The
Golden Lion Tamarin has a very limited distribution range, as over time
they have lost all but 2%–5% of their original habitat in Brazil.[12] Today, this tamarin is confined to three small areas of the tropical rain forest in southeastern Brazil: Poço das Antas Biological Reserve, Fazenda União Biological Reserve, private land through the Reintroduction Program.[6]
The first population estimate made in 1972 approximated the count at
between 400 and 500. By 1981 the population was reduced to less than
200. Surveys from as recently as 1995 suggested that there may only have
been at most 400 golden lion tamarins left in the wild; they have made a
nice comeback and now number 3200 in the wild. Tamarins live along the
far southeast border of the country in the municipalities of Silva Jardim, Cabo Frio, Saquarema, and Araruama.[13] However, they have been successfully reintroduced to the municipalities of Rio das Ostras, Rio Bonito, and Casimiro de Abreu.[14] Tamarins live in coastal lowland forests less than 300 m (984 ft) above sea level.[15] They can be found in hilltop forests and swamp forests.
Behaviour and ecology
The golden lion tamarin is active for a maximum of 12 hours daily. It uses different sleeping dens each day.[16][17]
By frequently moving their sleeping nests around, groups minimize the
scent left behind, reducing the likelihood of predators finding them.[18]
The first activities of the day are traveling and feeding on fruits. As
the afternoon nears, tamarins focus more on insects. By late afternoon,
they move to their night dens. Tamarin groups use hollow tree cavities,
dense vines or epiphytes
as sleeping sites. Sites that are between 11 and 15 m (36 and 49 ft)
off the ground are preferred. The golden lion tamarin tends to be active
earlier and retire later in the warmer, wetter times of the years as
the days are longer.[16] During drier times, it forages for insects longer as they become more scarce.[16][17]
Golden lion tamarins are characterized by using manipulative foraging under tree barks and epiphytic bromeliads.
Their sites of foraging are usually distributed around their home
ranges, which are large territories (averaging 123 hectares) in which
multiple foraging sites are located, to find sufficient resources over
long periods of time. These areas are sufficient enough in size so that
even if there is overlap in between the home range of two different
groups, the interactions are minimal due to the distribution of the
foraging sites (they spend 50% of their time in approximately 11% of
their home range).[19]
The golden lion tamarin has a diverse, omnivorous diet consisting of
fruits, flowers, nectar, bird eggs, insects and small vertebrates. They
rely on microhabitats for foraging and other daily activities and
tamarins will use bromeliads, palm crowns, palm leaf sheaths, woody
crevices, lianas, vine tangles, tree bark, rotten logs, and leaf
litters.[16][17] The golden lion tamarin uses its fingers to extract prey from crevices, under leaves, and in dense growth; a behavior known as micromanipulation.[20]
It is made possible by elongated hands and fingers. Insects make up to
10–15% of its diet. Much of the rest is made of small, sweet, pulpy
fruits. During the rainy season, the golden lion tamarin mainly eats
fruit, however during drier times, it must eat more of other foods like
nectar and gums.[16] Small vertebrates are also consumed more at these times as insects become less abundant.
Social structure
Family groups may consist of up to eight members.
Golden lion tamarins are social and groups typically consist of 2-8
members. These groups usually consist of one breeding adult male and
female but may also have 2–3 males and one female or the reverse.[21]
Other members include subadults, juveniles and infants of either sex.
These individuals are typically the offspring of the adults. When there
is more than one breeding adult in a group, one is usually dominant over
the other and this is maintained through aggressive behavior. The
dominance relationship between males and females depends on longevity in
the group. A newly immigrated male is subordinate to the resident adult
female who inherited her rank from her mother.[22]
Both males and females may leave their natal group at the age of four,
however females may replace their mothers as the breeding adult, if they
die, which will lead to the dispersal of the breeding male who is
likely her father. This does not happen with males and their fathers.
Dispersing males join groups with other males and remain in them until
they find an opportunity to immigrate to a new group. The vast majority
of recruits to groups are males.[23]
A male may find an opportunity to enter into a group when the resident
male dies or disappears. Males may also aggressively displace resident
males from their group; this is usually done by two immigrant males who
are likely brothers. When this happens, only one of the new males will
be able to breed and will suppress the reproduction of the other. A
resident male may also leave a vacancy when his daughter becomes the
breeding female and he must disperse to avoid inbreeding.[24] Golden lion tamarins are highly territorial and groups will defend their home range boundaries and resources from other groups.[25]
Tamarins emit "whine" and "peep" calls, which are associated with alarm and alliances respectively.[26] "Clucks" are made during foraging trips or during aggressive encounters, whether directed at conspecifics or predators.[27]
"Trills" are used to communicate over long distances to give away an
individual's position. "Rasps" or "screeches" are usually associated
with playful behavior. Tamarins communicate though chemicals marked
throughout their territories. Reproductive males and females scent mark
the most and their non-reproductive counterparts rarely do so. Dominant
males use scent marking to show their social status and may suppress the
reproductive abilities of the other males.
Reproduction
The mother provides transportation at the early stages of the infant's life.
The mating system of the golden lion tamarin is largely monogamous.
When there are two adult males in a group only one of them will mate
with the female. There are cases of a male mating with two females,
usually a mother and daughter.[21]
Reproduction is seasonal and depends on rainfall. Mating is at its
highest at the end of the rainy season between late March to mid-June
and births peak during the September–February rains.[28] Females are sexually mature between of 15–20 months but it isn't until they are 30 months old when they can reproduce.[27] Only dominant females can reproduce and will suppress the reproduction of the other females in the group.[29] Males may reach puberty by 28 months.[28]
Tamarins have a four-month gestation period. Golden lion tamarin groups
exhibit cooperative rearing of the infants. This is due to the fact
that tamarins commonly give birth to twins and, to a lesser extent,
triplets and quadruplets. A mother is not able to provide for her litter
and needs the help of the other members of the group.[30]
The younger members of the groups may lose breeding opportunities but
they gain parental experience in helping to rear their younger siblings.[22]
In their first 4 weeks, the infants are completely dependent on their
mother for nursing and carrying. By week five, the infants spend less
time on their mother’s back and begin to explore their surroundings.
Young reach their juvenile stage at 17 weeks and will socialize other
group members. The sub-adult phase is reached at 14 months and a tamarin
first displays adult behaviors.
Ecosystem roles
Vocalizing.
The golden lion tamarin has a mutualistic interaction with 96 species of plants found in the Atlantic Forest. This interaction is based on seed dispersal
and food sources for the tamarins. The tamarins show repeat visits to
those plants with abundant resources. They tend to move around their
territories, and therefore, seeds are dispersed to areas far from the
parent shadow, which is ideal for germination. Their seed distribution is important to forest regeneration, and genetic variability and survival of endangered plant species.[31]
Predation
A study has shown that increased predation has caused significant decreases in the population numbers.[32]
A survey conducted in 1992 found the number of wild population of
golden lion tamarins to be 562 individuals in 109 groups. Currently, the
average group size includes 3.6 to 5.7 individuals and densities from
0.39 groups/km to 2.35 groups/km.[33]
These predatory attacks occur at the golden lion tamarin sleeping
sites. The predators make those sleeping sites, which are mainly tree
holes (about 63.6%), larger in order to attack the golden lion tamarins,
sometimes wiping out the entire family. The preferred sleeping sites of
most golden lion tamarins are tree holes in living trees next to other
larger trees with a small percentage of canopy cover. These sleeping
sites not only provide a place for sleep, but also offer protection and
easy access to foraging sites. Most of the tree holes are lower to the
ground, so they are easier to enter. Tree holes that are located in
living trees are drier, warmer, and have a lower number of insects and
therefore a decreased percentage of transmitted diseases. A smaller
percentage of canopy coverage allows the golden lion tamarins to detect
the predators faster, and being surrounded by other large trees allows
them access to escape routes.[32] Due to degradation of their habitats, there are fewer trees that can support entire social groups
and some have to resort to using bamboo (17.5%), vine tangles (9.6%),
and bromeliads (4.7%) as a sleeping site, making them more susceptible
to predators. Golden lion tamarins are known to use different den sites,
but do not change sites often. They are more likely to reuse secure
sites that will offer protection. However, the disadvantage of doing so
is that predators are able to learn where these sites are located.
Golden lion tamarins also scent mark their den holes, so they can
quickly return to them in the afternoon time when predators are most
active. While excessive scent makes it easier for golden lion tamarins
to find their sleeping sites, it also helps predators locate their prey.
Moreover, increased deforestation has decreased habitat space,
providing predators easy access to their prey, causing a decline in the
golden lion tamarin population.[34]
Threats to the golden lion tamarin population include illegal logging, poaching, mining, urbanization and infrastructure development and the introduction of alien species. In 1969, the number of individuals in the Atlantic Forest was found to have dropped to a low of 150 individuals.[35] In 1975 the golden lion tamarin was listed under Appendix I of CITES, given to animals threatened with extinction that may be or are being affected by trade.[36] The species was listed as Endangered by the IUCN in 1982,[3] and by 1984 the National Zoological Park in Washington, D.C. and the World Wide Fund for Nature, through the Golden Lion Tamarin Association, began a reintroduction programme from 140 zoos worldwide.[35] Despite the success of the project, the IUCN classification rose to Critically Endangered in 1996.[3]
By 2003 the successful establishment of a new population at União
Biological Reserve enabled downgrading the species to endangered,[37] but the IUCN
warns that extreme habitat fragmentation from deforestation means the
wild population has little potential for any further expansion.[3]
In an attempt to curb the golden lion tamarin's precipitous decline,
several conservation programs have been undertaken. The intent is to
strengthen the wild population and maintain a secure captive population
in zoos worldwide. The survival rate of re-introduced animals has been encouraging, but destruction of unprotected habitat continues.
Reintroduction
Because of the extensive habitat loss of the golden lion tamarin, the wild population reached endangered
status in the early 1980s. Beginning in 1983, there has been a huge
effort on behalf of scientists and conservationists to reintroduce
captive-born golden lion tamarins back into the wild. With the help of
the Brazilian government, conservationists established the Poço das Antas Biological Reserve
and the União Biological Reserve as sites for reintroduction. The goals
of the reintroduction process include increasing the size as well as
the genetic diversity of the wild population, increasing the available
range to better encompass the historic range of the tamarins in Brazil,
and widening the scope of public awareness and education programs.[38]
The first step of reintroduction begins with zoo free ranging
programs, where tamarins have access to explore the entire zoo. However,
they are kept on zoo grounds by the presence of a nest box, an ice box
like container where their food is kept. When the tamarins are
reintroduced in Poço das Antas Biological Reserve, they require a large
amount of post-release training and veterinary care. For the first 6–18
months the reintroduced groups are monitored. Additionally, 1-2 tamarins
from each group are radio collared to allow careful monitoring, and all
reintroduced tamarins are tattooed and dye marked for easy
identification.[38]
Translocation
Secondly, in an effort to save the golden lion tamarins from extinction,
some of the golden lion tamarins have been removed from small, isolated
unsafe forests and placed into a larger, protected forest; specifically
they were moved to União Biological Reserve and Poço das Antas reserve.
This effort to move the golden lion tamarins into União Biological
Reserve in Brazil began in 1991.[39]
The golden lion tamarins faced the potential of getting new diseases
that they had not been previously exposed to. Many were exposed to
callitrichid hepatitis, and contracted the disease.[40]
Despite the challenge of illness, the forty-two translocated
golden lion tamarins' population grew to over 200 in União Biological
Reserve. The number of wild golden lion tamarins is now up in the
thousands in all reserves and ranches combined in Brazil. These numbers
were once down in the 200s in 1991. By 2025, the number of golden lion
tamarins that are protected is projected to be greater than 2000.[39]
Effects of habitat loss
Golden
lion tamarins are native to the Atlantic Forest of Brazil. Their
original habitat was located from the southern part of the state of Rio
de Janeiro to the southern part of the state of Espirito Santo. However,
deforestation of Atlantic Forest for commercial purposes, predation,
and capture of the golden lion tamarins for animal trade and sale as
pets has limited their population to about five municipalities across
Rio de Janeiro. Most of the population is now found in the Poco des
Antas Biological Reserve in Rio de Janeiro.[33]
However, due to the deforestation and fragmentation of the Atlantic forest, their home ranges have decreased in size.[19]
The decrease in size has been reported in terms of fragmentation, and
today the forest consists of thousands of fragments equaling only 8% of
its former size.[41] This directly affects their areas of foraging and subsequently, the amount of resources available.[19]
Effect on juvenile behavior
The
habitat of the tamarins also affects their behavior and social
interactions. For example, the type of trees present has a significant
effect on the behavior of juvenile golden lion tamarins. Their juvenile
behavior is characterized by social play between individuals of
different ages and species. This is a key aspect of their social,
cognitive and motor skill development, and it influences their behavior
when facing competition
and predators; how they play mirrors the way they act when facing
predatory or competitive interactions. Social play is observed more in
large branches (>10 cm) and vine tangles (4m above ground), which is
considered safe for them, as they are less vulnerable to predators,
compared to play in the dangerous areas including canopy branches and
the forest floor. Therefore, deforestation affects the diversity in the
forest and decreases the “safe” areas for play for the juvenile
tamarins. As a result, play decreases and therefore the development of
learned survivorship behaviors does as well. Also, if play is observed
in the dangerous areas, the individuals are more exposed to predators,
leading to a population decline; which resembles the effect of predation
on their sleeping sites. The exposure to predation not only affects the
juvenile tamarins but the adults as well, since it has been observed
that play happens in the center of the group for protection of the
young.[42]
Increase in inbreeding
Additionally, this deforestation and fragmentation also leads to demographic instabilities, and an increased probability of inbreeding, consequently leading to inbreeding depression and a population decline.[43]
In the case of inbreeding, the problem lies in the increase of the
isolated fragments where golden lion tamarins live. Inbreeding leads to
low levels of genetic diversity
and has a negative effect on survivorship; inbred offspring have a
lower survivorship than non-inbred offspring. Fragmentation leads to a
decline in dispersal and as a result, a decline in breeding with
individuals of other groups. Consequently, inbreeding depression is
observed in these populations.[44]
With delay breeding, the decrease and shortage of territory puts
pressure on golden lion tamarins to disperse in order to find necessary
resources and areas suitable for their survival. However, dispersal is
risky and requires a lot of energy that could have been used for
reproduction instead.[45]
.jpg)
Hatchling
Juvenile
With tongue extended (Sunderbans National Park, India)
V. s. macromaculatus resting on tree limb
.jpg)
