Observing animals directly in the field provides the most accurate understanding of animal behaviour and resource selection. However, making prolonged observation of undisturbed animals is difficult or impossible for many species. To overcome this problem for the Tasmanian devil (Sarcophilus harrisii), a cryptic and nocturnal carnivore, we developed animal-borne video collars to investigate activity patterns, foraging behaviour and social interactions. We collected 173 hours of footage from 13 individual devils between 2013 and 2017. Devils were active mostly at night, and resting was the most common behaviour in all diel periods. Devils spent more time scavenging than hunting and exhibited opportunistic and flexible foraging behaviours. Scavenging occurred mostly in natural vegetation but also in anthropogenic vegetation and linear features (roads and fence lines). Scavenging frequency was inversely incremental with size e.g. small carcasses were scavenged most frequently. Agonistic interactions with conspecifics occurred most often when devils were traveling but also occurred over carcasses or dens. Interactions generally involved vocalisations and brief chases without physical contact. Our results highlight the importance of devils as a scavenger in the Tasmanian ecosystem, not just of large carcasses for which devils are well known but in cleaning up small items of carrion in the bush. Our results also show the complex nature of intraspecific interactions, revealing greater detail on the context in which interactions occur. In addition, this study demonstrates the benefits of using animal-borne imaging in quantifying behaviour of elusive, nocturnal carnivores not previously seen using conventional field methods.
Devils were trapped in custom built pipe traps (diameter 315 mm x length 875 mm, constructed from solid PVC pipe; N. Mooney and D. Ralph, unpublished data) baited with meat. Nearly all of the devils on the study site (n = 142) were already microchipped as part of a long term study on devil movement [16, 27]. Only devils that have been trapped several times before were fitted with a camera, to ensure a high probability of recapture for collar retrieval. Several males were trapped frequently, which led to us collaring more males than females. Animals were not sedated and were released immediately following fitting of collars. Devils that were fitted with a timer collar or with a video collar that was turned on during the day were released from traps early in the morning. To fit devils with a video collar that was turned on during the night, traps were set at dusk and checked a few hours later, and the devils released immediately after they were fitted with a collar. Eight devils were released with the video collar turned on during the day, 12 were released in the night, and 10 animals were fitted with timer collars that turned the video on 11 hours after release. The different types of collar were randomly deployed on devils. As collars recorded footage for a maximum of 12 hours, devils were re-trapped as soon as possible thereafter and the collars removed.
1080p hd video animals interacting
First, we reviewed all footage and recorded the start and finish time of all behaviour states observed (moving, scavenging, hunting, interacting with other devils, drinking and resting). Scavenging was defined as when a devil was feeding on an animal that was already dead when the devil found it. Hunting was defined for the purposes of this paper as active pursuit and capture of live prey, regardless of whether the prey was killed or not, although devils are probably actively hunting every time they are moving. An interaction was defined as the presence of another devil in close proximity to the video-collared devil, or if vocalisations could be heard. Resting included sleep, grooming and digging (as devils dug only while in their burrows). To give context to later analyses and the timing of certain behaviours, we calculated the average proportions of time the devils spent in each state and compared this across three periods of the diel cycle: midnight to sunrise, sunrise to sunset and sunset to midnight. These time periods were based on phases of devil activity determined from GPS data at this study area [27], which showed that most devils became active at sunset, movement rates gradually reduced after midnight, and most devils were stationary by sunrise. The first hour of footage following the release of a devil from the trap was considered likely to be atypical and was excluded.
The footage collected on video collars carried by devils in coastal northwest Tasmania, Australia, provide the first quantification of foraging behaviour and social interactions throughout all aspects of daily life, a goal that has been previously unattainable using existing methods. Devils are predominately nocturnal and spend most of their time resting at any time of day. Agonistic interactions with other devils occur occasionally and mostly when devils are travelling. Devils at this site scavenge more than they hunt. The video collars documented evidence of killing behaviour by devils for the first time. The two hunting and killing events recorded on the video collars are of small prey animals. They appear to be opportunistic, involving only a short pursuit while the devils were travelling, with no extended approach or pursuit.
Video collars provide a new tool for observing a range of natural behaviours in animals, unimpeded by biases from observation. First, video collars allow distinguishing carrion from kills, which is difficult to do from scat remains unless there are blowfly maggots present or odour of rotting meat carries through. Second, video collars also allow direct quantification of diet composition, without the biases of scat analysis [47], although ground vegetation and low lighting can limit prey identification. Third, aspects of behaviour can be directly quantified in a way that has not been previously possible for cryptic, nocturnal species. While distance, habitat, and speed and tortuosity of travel can be quantified from GPS tracking, allowing inferences about foraging behaviours, video collars can reveal the context of scavenging and hunting behaviours. The video collars revealed that when devils are active, they run at a constant pace and rarely walk, and they constantly and opportunistically forage (for carrion or live prey). The majority of scavenging occurs in natural vegetation, although devils also scavenge in pasture and along roads, and hunting was observed in both native vegetation and pasture. Finally, video collars enable new detail of intraspecific interactions.
Interacting with animals has been shown to decrease levels of cortisol (a stress-related hormone) and lower blood pressure. Other studies have found that animals can reduce loneliness, increase feelings of social support, and boost your mood.
Another study found that children with autism spectrum disorder were calmer while playing with guinea pigs in the classroom. When the children spent 10 minutes in a supervised group playtime with guinea pigs, their anxiety levels dropped. The children also had better social interactions and were more engaged with their peers. The researchers suggest that the animals offered unconditional acceptance, making them a calm comfort to the children.
While pets may bring a wide range of health benefits, an animal may not work for everyone. Recent studies suggest that early exposure to pets may help protect young children from developing allergies and asthma. But for people who are allergic to certain animals, having pets in the home can do more harm than good.
These inconsistencies are further confounded by a lack of consensus about the mechanisms through which HAI may improve human well-being [9]. Researchers have often referred to the biophilia hypothesis [29,30], which proposes that humans have an innate affiliation with other forms of life. This perspective suggests that because human evolution occurred almost exclusively in natural environments, people are predisposed to respond positively to aspects of nature that would have increased fitness in the ancestral environment, and negatively to those which would have decreased fitness [31]. For example, people typically respond positively to natural landscapes providing sources of food, water or shelter, and negatively to animals which pose a threat, such as spiders or snakes [31]. Although the biophilia hypothesis has been criticised for offering too broad a perspective and for lacking falsifiability [32], researchers have drawn on these ideas to develop theories with more explanatory power. For example, the biophilia-effect suggests that because the behaviour of animals is indicative of the presence or absence of threats in the environment, interaction with a calm or friendly animal may support human well-being by promoting relaxation and reducing physiological arousal [33,34].
Alternatively, HAI may operate via distraction, whereby attention is diverted away from a perceived stressor to lessen the experience of negative mental states; this may be of most relevance in the context of AAI [25]. Research has indicated that young children preferentially attend to images or videos of animals compared to non-living objects [43], and will choose to interact with real (but caged) animals over toys resembling those animals [44]. Similarly, adults have been found to more rapidly identify changes in the location of living targets (animals and people), compared to inanimate objects [45]. These findings suggest that animals may be particularly effective at attracting human attention. However, animals are not unique in being an effective source of distraction, and so similar benefits may be achieved through the use of alternative, and possibly more cost effective, stimuli [25,42].
This brief overview is by no means exhaustive and several other theories have been proposed [9,33,42]. Despite these divergent approaches however, one model provides a framework which may potentially incorporate some, or all, of the above discussed mechanisms. The biopsychosocial model [46] proposes that health is a continuum influenced by interacting biological, psychological and social factors; changes in one factor may influence the others and in turn impact health. For example, psychosocial stresses may lead to physiological responses including increased heart rate and blood pressure, or reduced immune function. Ultimately, these responses may have a negative effect on health, resulting in increased morbidity and mortality [47,48]. Equally however, some psychological and social factors may have a protective influence on health; higher levels of social support for example, have been linked to a reduced risk of cardiovascular disease [47]. In the context of this model, there are numerous ways in which interaction with companion animals may impact human health. For example, owning a dog may lead to improved health through increased physical activity, while animals may provide social support either directly, or indirectly by facilitating social interactions with other individuals [49,50]. Conversely however, the grief associated with the loss of a companion animal may have a detrimental effect on human well-being [50]. Thus, while the biopsychosocial model provides a potential framework for integrating multiple theories, it also highlights the likelihood that no one mechanism can account for the diverse effects of HAI. One area which warrants further consideration is whether the observed benefits are influenced by the type of animal involved in the interaction [26,51]. 2ff7e9595c
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