Table of Contents
Appearance and Physical Characteristics of Stump Tailed Macaques
When a troop of Stump-tailed macaques face you from a distant opening in the rain forest, mouths gape at the sight. These stocky old world monkeys appear like miniature gorrillas due to their heavily built arms and clear social bonding. Younger animals have striking pink or red faces while as they age their skin darkens. Stump-tailed macaques have distinctive physical features that set them apart from other primates. These unique macaques are quadrupedal, meaning they move on all four limbs.
Stump-tails are medium-sized, weighing between 7 and 14 kilograms, and have short, stubby tails, hence their name. The adults fur is brownish-gray or dark brown, and they have hairless faces with black skin. They have long, powerful limbs and grasping hands and feet that are well-suited for climbing trees and swinging from branch to branch.
Behavior and Social Structure
Stump-tailed macaques are highly social animals, living in groups that can range from 10 to 70 individuals. Known for their largely peaceful interactions with peers, conflicts often pas with out aggression. Within these groups, there is a strict hierarchy with dominant males at the top. They communicate with a variety of vocalizations and facial expressions and also use body language to convey emotions and intentions. They are highly intelligent and have been observed using tools such as stones to crack open nuts and shells. As omnivores Stump-tails will often hunt the many types of frogs that live in rain forests.
Habitat and Distribution
Widely dispersed in the National parks of Thailand such as Kaeng Krachan National park, Stump-tails exist in South East Asia from Northern Himalayian India to as south as Malaysia and Indonesia. They, too, can be found in liited numbers in Laos, and Cambodia. Secondary forests, old-growth forests and rainforests allow these old world monkeys to live in moist conditions where food and water is abundant.
Stump-tails, like most macaques, do not live exclusively with partners. The females in the group will often mate with the dominant male and give birth to his offspring. The females will also care for the young macaques until they are old enough to fend for themselves.
Males typically leave their natal group when they reach maturity, and they will often travel long distances in search of a new group.
Mating in stump-tailed macaques typically occurs during the dry season. After a female becomes pregnant, she will give birth to a single infant after a gestation period of around 170 days. Infants are born with black fur, which will eventually turn to the typical brownish-red color of adult macaques.
Stump-tailed macaques are social animals that live in troops of up to 30 individuals. The social structure of these troops is complex, with a clear hierarchy based on age and gender. Within a troop, there are usually several smaller groups consisting of related individuals. Females typically outnumber males in a troop, and adult males are usually more dominant than females.
The diet of stump-tailed macaques consists primarily of fruits and leaves, but they will also consume bugs, small vertebrates, and eggs. These macaques are known to be very opportunistic eaters, and they will take advantage of whatever food is available to them, like most omnivores.
Why Do Stump-tail Macaques Have Two Breeding Seasons?
According to a study conducted on a population of female stump-tailed macaques, it was observed that there were increased levels of steroid sex hormones, specifically 17β-estradiol and progesterone. These hormones play an important role in the regulation of the female reproductive cycle and are essential for fertility and successful pregnancy.
The study found that 17β-estradiol levels were significantly greater during the summer and fall seasons. This suggests that the female macaques experience increased levels of ovarian activity during these seasons, which could be due to changes in food availability or environmental factors such as temperature and humidity. These changes in hormone levels could signal the onset of the breeding season for these macaques.
Similarly, progesterone levels were found to be significantly greater during the summer, fall, and winter seasons. This suggests that the female macaques are capable of sustained levels of reproductive activity throughout the year. This could be due to the fact that they have evolved to have two mating seasons per year, which allows them to maximize their reproductive success and increase the likelihood of survival for their offspring.
It is important to note that the stump-tailed macaque is currently classified as Vulnerable by the International Union for Conservation of Nature (IUCN, 2015) and is listed on the IUCN Red List of Threatened Species. This means that the species is at a high risk of extinction in the wild.
The population of stump-tailed macaques is projected to decline over the next 30 years due to various threats, including hunting and habitat loss. These macaques are hunted for their meat and for use in traditional medicine, which has resulted in significant population declines in some areas. Additionally, habitat loss and fragmentation due to human activities such as deforestation and agriculture have also had a negative impact on the species.