Attachment behaviour is a behaviour which is observed when an animal forms a strong bond to either a human or another animal. The behaviour of the animal that is seeking to be close to its either a human or another animal is characterized as attachment behaviour. Bowlby and Ainsworth were the first to describe attachment behaviour in humans. Since then the theory has been applied to other animals and their caregivers and to animal relationships with each other. This bond is often formed as the caregiver provides the essentials for life, such as food and security. Many studies have shown that dogs show attachment behaviour to their human caregivers. Wolves are highly social animals and their social interactions in their packs fit the criteria of attachment behaviour. As dogs are closely related to wolves many investigators have studied wolf attachment behaviour to humans. Wolves that were raised for 3–7 weeks showed attachment behaviour to their human caregivers. This attachment behaviour was characterized by preferring to be close to their human caregiver, by seeking contact, and by greeting the caregiver more frequently compared to a stranger. As the wolf is a non-domesticated animal this is an example of attachment behaviour without domestication. Another study showed that wolves that were hand-reared for 16 weeks of their lives by human caregivers showed attachment behaviour to a stranger rather than their caregiver.
Wolves are animals which live in social groups referred to as packs and are known for forming affiliative bonds with others in their packs. Wolves in packs are known for initiating play with one another. It has been observed that wolves initiating play are not doing so randomly. It may be a reflection of the relationships present in the pack and will reflect the tension, cooperation, and competition present. Tensions are noted to become higher around breeding season where the cost and benefits are weighed against each other.[clarification needed] Female wolves are known for being the main initiators of affiliative interactions though a small percentage of males will initiate affiliative interactions. The omega male was not a target of any affiliative interaction. In other studies researchers have separated the most dominant wolf and the most subordinate wolves. It was recorded that the dominant wolf spent less time sleeping and showed more behavioural stress compared to the omega wolf. The dominant wolf was reported to rest in the section of his enclosure closest to his pack. It has been noted by researchers that the younger subordinate wolves seem to have less attachment to their pack compared to their higher ranking compatriots.
Wolves' cooperation is essential for tasks such as hunting and protecting young though the level of attachment present in the pack are not necessarily equal. It should noted that the majority of wolves are known for dispersing from their birth pack, this makes measuring attachment behaviour present in the packs to be difficult. Though there are cases in which when wolves leave their pack they accompany siblings with the same sex as them. This behaviour has been mentioned to be a form of adaptive behaviour that benefits both pack mates in future conflict.
When studying wolf attachment behaviour it was found that there are specific criteria for a wolf to exhibit attachment behaviour to a human. Wolves that were removed from the den around 10 days of age and were raised for 3–7 weeks by a human caregiver were shown to display attachment behaviour to their human caregiver. The pups were with their caregivers 24 hours a day for the first 1.5–2 months of their lives. Then the pups were present with their human caregiver for 16 hours a day and the caregivers were responsible for feeding the pups. The pups were tested with a novel stranger and their caregiver present in a novel room, this was done by using a modified Ainsworth Strange Situation Test. Prior to testing the wolf pups were observed to show no preference between their caregiver and a novel stranger. After the wolf pup's 2 minutes of isolation phase they were shown to more likely greet their caregiver compared to the stranger. Wolf pups were even observed to show an effect of reunion by having greater proximity with their caregiver compared to a novel stranger. Though this does not necessarily mean that all wolf pups will exhibit attachment behaviour as different variables may impact the attachment behaviour present in the wolves.
Wolves who have been hand reared for 16 weeks showed a different behaviour compared to those hand reared for 3–7 weeks. The wolves that were tested were separated from their mothers and littermates 3–5 days after birth. The wolves were in close contact with their caregiver for 20–24 hours for the first 16 weeks. The wolves were socialized with other wolves and were exposed to novel situations to the extent that they were used to traveling in cars and on public transportation. Due to the hand rearing the wolves lacked wariness and did not actively avoid humans. It was noted that the wolves had a strong interest in strangers. The experiment was tested over seven episodes where the wolves were first exposed to their caregiver, their caregiver and a stranger, just a stranger, their caregiver, were left by themselves, with a stranger and finally their caregiver. The hand reared wolves studied seemed to seek physical contact with the stranger and did not discriminate between following their caregiver or stranger. This result was theorized to be due to the wolves being of a more independent age at the time of testing. After the study the wolves used were able to re-socialize and were allowed to enter into a pack of wolves.
Wolves are different than dogs when it comes to their ability to understand where a human is looking. In a study wolves were socialized with humans for an extended period of time to determine if they would react the same way that dogs do. When a dog is trying to find something that a human has hidden they will look at the human to determine where they are looking and thereby where they should be looking. This behaviour is not seen in wolves no matter how much socialization occurs. The wolf does not look back at the human, but rather looks for it by themselves without looking to the human for help. This can be explained as the wolf not communicating with the human when it is not initiated by the human. Since wolves do not exhibit attachment behaviour if they were not raised by that specific human, they do not communicate with them if it is not initiated by the human.
Wolves who have been raised by humans vary in how they respond to novel humans. If they were raised by a human by had never met another human outside of their primary caregiver, they typically react differently than those who were socialized with many different humans during their formative years. While just about all wolves raised by humans will form an individualized relationship with that human, not all wolves will form an attachment relationship with that human or any other human. Wolves also may not form a dependency on their human caregiver even if they do have a good relationship with the caregiver. Most times the wolf will form a closer relationship to the primary caregiver than to any other human who may have been present during their life.