contrary to the belief that those who have a high degree of cognitive impairment, such as an intellectual disability, are unable to process the loss of those around them, those with cognitive impairments are able to process grief in a similar manner to those without cognitive impairment. one of the main differences between those with an intellectual disability and those without is typically the ability to verbalize their feelings about the loss, which is why non-verbal cues and changes in behavior become so important, because these are usually signs of distress and expression of grief among this population. it is important when working with individuals with these such impairments that caregivers and family members meet them where their level of functioning is and allow them to process the loss and grief with assistance given where needed, and not to ignore the grief that these individuals undergo. an important aspect of treatment of grief for those with an intellectual disability is family involvement where possible, which may take the form of a biological family or a family created in a group home or clinical setting. by having the family involved in an open and supporting dialogue with the individual it helps them to process. however, if the family is not properly educated on how these individuals handle loss, their involvement may not be as beneficial than those who are educated. the importance of the family unit is very crucial in a socio-cognitive approach to bereavement counseling. in this approach the individual with intellectual disability has the opportunity to see how those around them handle the loss and have the opportunity to act accordingly by modeling behavior. this approach also helps the individual know that their emotions are acceptable and normal. in animals in august friedrich schenck's 1878 painting anguish, held at the national gallery of victoria, a grieving ewe mourns the death of her lamb. previously it was believed that grief was only a human emotion, but studies have shown that other animals have shown grief or grief-like states during the death of another animal, most notably elephants, wolves, apes, and goats. this can occur between bonded animals which are animals that attempt to survive together (i.e. a pack of wolves or mated prairie voles). animals are bonded species like humans. there is evidence that animals experience grief in the loss of their group member, a mate, or their owner for many days. some animals show their grief for their loss for many years. when animals are grieving, their life routines change the same as humans. for instance, they may stop eating, isolate themselves, or change their sleeping routine by taking naps instead of sleeping during the night. after the death of their group member or a mate, some of the animals become depressed, while others like the bonobo keep the dead bodies of their babies for a long time. cats try to find their dead fellow with a mourning cry, and dogs and horses become depressed. since it is more difficult to study emotion in animals because of the lack of clear communication, in effort to study grief, research has been done on hormone levels. one study found that "females showed significant increases in stress hormones called glucocorticoids". the female baboons then increased grooming, promoting physical touch, which releases "oxytocin, which inhibits glucocorticoid release". mammals mammals have demonstrated grief-like states, especially between a mother and her offspring. she will often stay close to her dead offspring for short periods of time and may investigate the reasons for the baby's non-response. for example, some deer will often sniff, poke, and look at its lifeless fawn before realizing it is dead and leaving it to rejoin the herd shortly afterwards. other animals, such as a lioness, will pick up its cub in its mouth and place it somewhere else before abandoning it. when a baby chimpanzee or gorilla dies, the mother will carry the body around for several days before she may finally be able to move on without it; this behavior has been observed in other primates, as well. the royal society suggests that, "such interactions have been proposed to be related to maternal condition, attachment, environmental conditions or reflect a lack of awareness that the infant has died." jane goodall has described chimpanzees as exhibiting mournful behavior toward the loss of a group member with silence and by showing more attention to it. and they will often continue grooming it and stay close to the carcass until the group must move on without it. one example of this goodall observed was of a chimpanzee mother of three who had died. the siblings stayed by their mother's body the whole day. of the three siblings the youngest showed the most agitation by screaming and became depressed but was able to recover by the care of the two older siblings. however, the youngest refused behavior from the siblings that were similar to the mother. another notable example is koko, a gorilla who was taught sign language, who expressed sadness and even described sadness about the death of her pet cat, all ball. elephants, have shown unusual behavior upon encountering the remains of another deceased elephant. they will often investigate it by touching and grabbing it with their trunks and have the whole herd stand around it for long periods of time until they must leave it behind. it is unknown whether they are mourning over it and showing sympathy, or are just curious and investigating the dead body. elephants are thought to be able to discern relatives even from their remains. when encountering the body of a deceased elephant or human, elephants have been witnessed covering the body with vegetation and soil in what seems to be burial behavior. an episode of the seminal bbc documentary series life on earth shows this in detail – the elephants, upon finding a dead herd member, pause for several minutes at a time, and carefully touch and hold the dead creature's bones. birds some birds seem to lack the perception of grief or quickly accept it; mallard hens, although shocked for a moment when losing one of their young to a predator, will soon return to doing what they were doing before the predator attacked. however, some other waterbirds, such as mute swans are known to grieve for the loss of a partner or cygnet, and are known to engage in pining for days, weeks or even months at a time. other species of swans such as the black swan have also been observed mourning the loss of a close relative. monogamous animals another form of grief in animals is when an individual loses its mate; this can be especially brutal when the species is monogamous. so when a pair bonding species, such as a black-backed jackal, loses its mate it can be very difficult for it to detach itself from its dead mate.