Two of the owls with tufts on their heads, Great Horned Owls and Screech Owls, are often seen as the most uncanny and most dangerous owls. In fact, some Indian tribes believe that individual examples of these owls may not even be real birds at all, but instead are actually transformed witches or the unquiet spirits of the dead.
There are a number of reasons these owls might be seen as particularly powerful. First, they have tufts or horns on their heads, and horns are often signs of spiritually powerful beings for many tribes. Horned water serpents are just one example, which are seen as leaders of the underworld powers by many tribes. So the tufts or horns on these owls likely connect them to underworld powers.
Second, like most owls, Great Horned Owls and Screech Owls are active mainly at night, locating their prey in the darkness, flying on noiseless wings, and communicating with other owls through their weird sounding hoots, unlike most other birds, which are active in the day. Because many tribes associate night with death and the underworld, it is no surprise that some tribes often associate nocturnal owls with death and the underworld, too.
Finally, specific characteristics of these owls make them stand out from other owls. Great Horned Owls are the largest owl around the Plains, and can take much larger prey than other owls, such as opossums and skunks instead of mice or voles, for instance. The calls of Great Horned Owls can also be especially disturbing to some. Occasionally it utters sounds resembling the half-choking cries of a person nearly strangled, and is sometimes attracted by a campfire and will fly over it, shrieking as is goes.
Screech Owls, although much smaller than Great Horned Owls, also have ample claims to their weird behavior. First, they come in two color phases; red and gray, and red is often seen as a spiritually powerful color among many tribes. They also utter disturbing cries at night, which have been described by some as screeching and by others as wails. Small wonder then, that many of the positive traits of owls are seen to belong to more normal-seeming species, such as the Barred Owl of the woodlands, also known as the Hoot Owl, or the Short-Eared or Burrowing Owls of the plains.
Both the Oto and the Ioway had a Hoot Owl Clan for instance, and the Ioway name for that clan, 'Mankoke,' is the same as the Ioway word for the Barred Owl.
The Ponca once had an Owl Sub-clan and the Osage also are said to have had an Owl People or 'Wapunka inihkacina,' although I do not know if it was a Clan or a Sub-clan.
Among the Cheyenne, contemporary members of the tribe only considered one kind of owl to be a bird, the Short-Eared Owl, which they know as the "snake-eating owl," an important source of medicine power for doctors or healers. All other owls the Cheyenne class as 'mista,' or "spirits of the night." Even the Cheyenne Contraries or 'hohnuhke' in the Buffalo Days wore the feathers of the "little prairie owl" in their headdresses, but not the feathers of the Great Horned Owl or the Screech Owl.
Among the Hidatsa, I know of one warrior who had a guardian spirit in the form of a Burrowing Owl or Prairie Dog Owl, which is said to have protected him from being shot.
Warriors often sought to draw upon owl powers. For instance, Cheyenne warriors attached owl feathers to their shields, or wore them on their arms, to impart the owl's special powers, such as the ability to see in the dark and move silently and unnoticed.
In a similar way, Creek warriors carried owl feathers so that they would have extraordinary night vision in battle.
Among the Cherokee, one of four scouts on a war expedition, whose task it was to locate the enemy, wore an owl skin and imitated the owl's cry. The Cherokee also observed Screech Owls closely while they were out looking for the enemy, because these owls were said to be able to foretell victory or defeat in battle.
Members of many of the warrior societies of the Plains tribes, such as the various Dog Soldier Societies, also wore owl feathers or used them on their ceremonial objects, such as the Arikara Young Dogs Society, and the Hidatsa Dog Society. Several tribes had sacred owl bundles that they used while out looking for the enemy, including the Ioway and the Fox tribes.
Among the Lakota, there was a 'Miwa'tani' or Mandan warrior society, sometimes referred to as the "Tall Ones" or the "Owl Feather Headdress" society, or the "No Flight" society. The members of this society were "exempt" from serving Aki'cita duties. The society was very old, even in the Buffalo days, and was said to have originated by a man who dreamed of an owl being. Admission into the society was difficult, because one of the requirements was that each member pledged to sacrifice his own life in battle if need be, to save a wounded member.
The owl's predatory prowess was important to hunters also. The Pawnee have several stories of owls that gave some of their power to individuals so that they could become excellent hunters, with the ability to see at night.
Among the Hidatsa, a large speckled owl was said to be the chief of the spirits controlling the game, and the bundle used in the Hidatsa Earth naming ceremony to call for buffalo contained the head, two wings, and two claws of a speckled owl.
The Menominee were also gifted with hunting power from the owls known as the Spotted Fawn Medicine.
In many tribes, owls were seen as most closely allied with medicine men, rather than warriors or hunters. Lakota medicine men or 'peju'ta wica'sa' respected the owl because it moved at night when people slept, and the medicine men get their power from dreams at night. Clear dreams, like the owl's sight. Therefore, many Lakota medicine men wore owl feathers and promised never to harm the owl, or else it was believed their powers would leave them.
Creek medicine men often carried an owl skin or feather as a symbol of their calling.
Ponca medicine men also used owl feathers in their healing ceremonies, and Ojibwa medicine men placed a stuffed owl near them while they were making medicine, so that it could "see if they do it right."
The Pawnee used an owl medicine, and among the Pawnee it is said, "the owl is the leading medicine-man among the birds."
Finally, owls were said by the Alabama, the Caddo, the Cherokee, and the Lakota, to bring prophetic news, either of the future or of events happening at a great distance, to the few medicine men that could understand them.
The owl's association with medicine men can also be bad news for ordinary folks. If a medicine man used owl power on your behalf to heal, it was great. However, if the medicine man of an enemy tribe used his powers against you, then it was said he could be an 'evil witch' or 'dark' medicine man trying to steal your soul.
Because witches or 'dark' medicine men were believed to be able to transform into owls, or to use owls to send death or disease, one could never quite be sure if an owl was a real owl, a transformed witch, or an owl sent on a mission by a witch. The owls most often believed to be shape-shifted witches were, the Great Horned or Screech Owls. So among the Cherokee, the same word, 'skili,' was used to refer to both witches and Great Horned Owls.
The Alabama, Caddo, Catawba, Choctaw and Menominee also associated Great Horned Owls and/or Screech Owls with witches, and the Wisconsin Ojibwa also link witches and owls.
Its not unusual then that among many tribes, seeing or hearing an owl is believed to be a bad omen, often signaling serious illness or death to come, especially when a night owl is seen during the day, or an owl is found hanging about the home or village instead of the woods. In other words, acting in an anti-natural manner.
It is the owl's connections with death, the afterlife, and rebirth that truly mark owls as a force to be reckoned with for most tribes.
First, owls are either considered to be embodied spirits of the dead, or associated with such spirits, by a very wide range of tribes, including the Lakota, Omaha, Cheyenne, Sauk & Fox, Ojibwa, Menominee, Cherokee and Creek. Several of these tribes also have stories of an "owl being" that stands at a fork in the road in the sky, or the Milky Way, that leads to the land of the dead, letting some souls pass, but condemning others to roam the earth as ghosts forever.
Among the Lakota, the Old Owl Woman or 'hiha'n winu'cala' who guards the road to the afterlife at the end of the Milky Way assesses the merits of the souls of the dead with their deeds on earth, letting the good through and sending the bad over the edge and out of the afterlife to wander earth as a ghost or 'wana'gi' for all eternity.
A similar belief among the Cheyenne is that the Old Owl Woman, who is the gatekeeper to the land of the dead, sits atop the junction at the fork in the Milky Way and decides which souls are shunted onto the dead-end branch.
Among the Ojibwa, one word for the bridge over which the dead had to pass to the afterlife is the Owl Bridge. The Lake Superior Ojibwa also mention a spirit being with horns called 'Pacugu' which might refer to the tufted "horns" of a Great Horned or Screech Owl, that stands at a fork in the road to the afterlife, blocking the way for evil souls, but helping good ones along on their journey. Another Lake Superior Ojibwa story mentions that the last obstacle the soul must pass on its way to the land of the dead is an old woman, perhaps an Owl Woman, who questioned the soul about its life and decided which souls to turn back, punish, or let pass. The Wisconsin Ojibwa have a story that relates how the brother of a culture hero called Nanabozho, placed an owl being as the second test for souls as they pass along the road to the afterlife.
The Sauk & Fox tribe also speaks of a soul-bridge that leads to the land of the dead. They say that there are two paths at the soul-bridge, one is red and one is gray. Men follow the red path, the gray by women. It has been suggested that this is in reference to the two color phases of the Screech Owl, which are also red and gray.
However, owls were not just connected with death and the afterlife, but also with rebirth through the Calumet ceremony, and the Midewiwin ceremony. Owl feathers encircle the stems of the calumet pipes used for adoption ceremonies among the Omaha, Osage, Kansa, Oto, Ioway and Pawnee. It is said that these owl feathers hanging in an arc, symbolized deer lungs, and together with the stem of the calumet, which represented a windpipe, they were used to symbolically to blow life back into the person being adopted in the Calumet ceremony.
"Old Bear" - Mandan (painted by George Catlin in 1832) holding a pair of Calumets
Owls are also connected with rebirth through their role in the Ojibwa Midewiwin or Medicine ceremony. Not only were owl skin pouches used by various Midewiwin society members, but owls were also carved atop poles that a candidate passed during their initiation into the third and fourth degrees of the Midewiwin.
Hope this helps.