Albino chimp baby murdered by its elders days after rare sighting

Researchers in Uganda made a rare sighting of an albino chimp in the wild, but only days before the young ape died at the hands of older chimps in its community.

The scientists described the grisly encounter in a recent study, published July 16 in the American Journal of Primatology, and noted that only a handful of nonhuman primates with albinism have been spotted in the wild in the past. These included a few toque macaques (Macaca sinica), bonnet macaques (Macaca radiata) and spider monkeys (Ateles geoffroyi), and among the great apes, an albino western lowland gorilla (Gorilla gorilla gorilla) was once captured in the wild as an infant and then kept in captivity until its death in adulthood.

The only albino chimp ever reported was a western chimpanzee (Pan troglodytes verus) named Pinkie, who was found as an infant and sheltered in the Tacugama Chimpanzee Sanctuary in Sierra Leone until her unexpected death at age 9. Because Pinkie was collected from the wild at just a few weeks old, scientists didn't have the opportunity to observe her interactions with wild chimps. Now, the new study provides a unique glimpse into the brief life of an albino ape in the wild.

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The albino chimp was spotted among a population of eastern chimpanzees (Pan troglodytes schweinfurthii) in Uganda's Budongo Central Forest Reserve. At the time of the young chimp's birth in summer 2018, the chimp community consisted of about 75 individuals.

A 19-year-old female chimp, which the researchers referred to as "UP," was known to be pregnant in January 2018, and on July 15 of that same year, she was seen carrying a "white" infant, later confirmed to be a male. Judging by the infant's size and the last recorded sighting of UP, the team estimated that the albino newborn was about 2- to 2-and-a-half weeks old.

Later on July 15, a pair of adult chimps encountered UP and the albino infant and began producing "alarm hoos and waa barks," sounds that chimps often make when facing potentially dangerous animals, like snakes and bush pigs, the authors wrote. Another male chimp heard these hoos and barks, as well as UP screaming, and rushed into the area; he struck UP before clambering up a tree and starting to produce alarm hoos and waa barks, as well. 

Over the next few minutes, several more adult chimps entered the area and joined in the ruckus. But a few adult chimps remained quiet and simply watched UP and the infant attentively; one calm individual even approached and reached out to UP with its hand. At some point, UP rushed up a tree, with the infant clinging to her chest, and stayed there for some time before climbing down and ducking from sight inside a dense thicket. Researchers spotted her and the infant a few more times that morning. On one occasion, an adult male let out a "tantrum scream on encountering (likely unexpectedly) UP and the baby at a close distance."

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Just days later, on July 19, the young chimp met his end. 

In the early morning, field assistant Bosco Chandia of the Budongo Conservation Field Station and researcher Maël Leroux, who holds positions with the field station and University of Zürich, came upon a large group of chimps erupting in a chorus of hoos, waa barks and screams. Sounds of physical aggression and the screams of an infant drifted from the thicket, but the team could not see the individual chimps involved in the encounter.

Soon, a male known as "HW" emerged from the vegetation, clutching the albino infant to his chest. The infant's left arm was missing, and the wound appeared fresh. Six adult chimps and three younger chimps of various ages followed HW, and the researchers also spotted UP in the throng. All were producing waa barks at HW as he climbed a tree, infant in hand, and started "biting the fingers, legs and the right ear of the infant." At this point, UP was chased from the party by one of the adult males.

A few minutes later, an adult female took the infant from HW and began biting its limbs and head while other chimps sniffed the body. The female then "bit the infant's head repeatedly, apparently causing its death, as the infant remained silent and stopped moving after the bite," the authors wrote.

Following the infant's death, an adult male draped the carcass over a branch. Over the course of the next few hours, 10 of the chimps approached the body, sniffing, inspecting and sometimes grooming or stroking the dead infant. Eventually, the chimps left, and the research team collected the body for an autopsy, noting that the infant's skin, hair and eyes lacked pigmentation. The 4.6-pound (2.1 kilograms) chimp had sustained "substantial injuries," including deep gashes in its head and a crack in its skull, revealing damaged brain tissue beneath.

Reflecting on the community's reaction to the albino chimp, the authors noted that "the initial reaction of community members towards the infant appeared to be different from a typical situation in which chimpanzees encounter females with a newborn for the first time." 

Normally, chimps react with curiosity to newborns, touching and grooming the infants and also grooming their mothers. On occasion, chimps may respond with excitement or aggression, particularly in communities where infanticide is common, but reactions of apparent fear toward a newborn are "unusual," the authors wrote. The group's way of inspecting the albino infant after death was also unusual; whereas the mother or close kin of an infant typically might groom its body after it's been killed, in this case, the careful inspections of the carcass hinted that the chimps perceived it as a novel object, or at least as an individual from outside their territory, the authors suggested. 

The chimp's white coloration also somewhat resembled that of black and white colobus monkeys (Colobus guereza), which chimps in the reserve prey upon; the infant's "prey-like" color, combined with its chimp-like smell and appearance, "could explain the behavior of some of the individuals towards the infant."

Of course, "it is not possible to draw firm conclusions from this one observation," and this particular community of chimps has a history of infanticide, so it's possible that the young male would have been killed "regardless of its appearance," the authors wrote. Pinkie, the captive albino chimp, lived among other chimps at the Tacugama Chimpanzee Sanctuary for some time, but no official account of her introduction to the group has been published. Therefore, it's unclear whether this community's reaction to an albino infant can be considered typical or odd.

Originally published on Live Science.