Kristin A. Descovich

A welfare assessment of methods used for harvesting, hunting and population control of kangaroos and wallabies

In Australia, several macropod species are subjected to commercial harvesting, recreational hunting and population management, using both lethal and non-lethal measures. Some techniques for killing macropods can cause prolonged and/or severe suffering, and of particular concern is the welfare of remaining pouch young or young-at-foot, when females with dependent young are killed. Non-lethal methods are more widely supported by the general public and include reproductive control and relocation. These methods, however, also have significant associated welfare challenges. This review outlines the welfare concerns for each current method, and concludes that an accurate head-shot by an experienced shooter is least likely to inflict suffering. However, this assumes best practice shooting, which may not be representative of field conditions. Furthermore, many aspects of macropod control and killing still require significant research. These include, but are not limited to: accurate statistics for pouch young and young-at-foot mortality and morbidity in Australian states; data on field-based compliance with National Codes of Practice; safe and remote administration of reproductive control measures; and the impact of using dogs and trapping in wallaby destruction and hunting.

Facial expression: An under-utilised tool for the assessment of welfare in mammals

Animal welfare is a key issue for industries that use or impact upon animals. The accurate identification of welfare states is particularly relevant to the field of bioscience, where the 3Rs framework encourages refinement of experimental procedures involving animal models. The assessment and improvement of welfare states in animals depends on reliable and valid measurement tools. Behavioral measures (activity, attention, posture and vocalization) are frequently used because they are immediate and non-invasive, however no single indicator can yield a complete picture of the internal state of an animal. Facial expressions are extensively studied in humans as a measure of psychological and emotional experiences but are infrequently used in animal studies, with the exception of emerging research on pain behavior. In this review, we discuss current evidence for facial representations of underlying affective states, and how communicative or functional expressions can be useful within welfare assessments. Validated tools for measuring facial movement are outlined, and the potential of expressions as honest signals is discussed, alongside other challenges and limitations to facial expression measurement within the context of animal welfare. We conclude that facial expression determination in animals is a useful but underutilized measure that complements existing tools in the assessment of welfare.

Intrasample variation and the effect of storage delay on faecal metabolite concentrations in the southern hairy-nosed wombat (Lasiorhinus latifrons)

Faecal hormone metabolite analysis offers a non-invasive alternative to blood sampling that is particularly relevant to wild animal populations. It has been used for reproductive and adrenal hormone monitoring in captive wombats, but no information exists on its accuracy when sample storage is delayed or on whether variation exists within samples. This study aimed to quantify the effect of storage delay and intrasample variation on faecal metabolite concentrations of testosterone, progesterone and corticosterone in southern hairy-nosed wombats. For all metabolites, intrasample variance was 15% or less of total variance. Delays in storage significantly changed metabolite concentrations, with progesterone showing a progressive decrease over time (0–72 h: t24 = 2.14, P = 0.05), testosterone showing a significant increase after 6-h delay (0–6 h: t21 = 2.83, P = 0.01), and corticosterone showing an initial increase (0–6 h: t48 = 3.60, P = 0.001), followed by a reduction to original concentrations by 72 h (0–72 h: t48 = 0.91, P = 0.38). Although changes caused by storage delays may not obscure large hormonal fluctuations, this study outlines the importance of immediate storage and consistent sampling to allow the most accurate results to be obtained.

Auditory laterality in a nocturnal, fossorial marsupial (Lasiorhinus latifrons) in response to bilateral stimuli

Behavioural lateralisation is evident across most animal taxa, although few marsupial and no fossorial species have been studied. Twelve wombats (Lasiorhinus latifrons) were bilaterally presented with eight sounds from different contexts (threat, neutral, food) to test for auditory laterality. Head turns were recorded prior to and immediately following sound presentation. Behaviour was recorded for 150 seconds after presentation. Although sound differentiation was evident by the amount of exploration, vigilance, and grooming performed after different sound types, this did not result in different patterns of head turn direction. Similarly, left–right proportions of head turns, walking events, and food approaches in the post-sound period were comparable across sound types. A comparison of head turns performed before and after sound showed a significant change in turn direction (χ2 1=10.65, p=.001) from a left preference during the pre-sound period (mean 58% left head turns, CI 49–66%) to a right preference in the post-sound (mean 43% left head turns, CI 40–45%). This provides evidence of a right auditory bias in response to the presentation of the sound. This study therefore demonstrates that laterality is evident in southern hairy-nosed wombats in response to a sound stimulus, although side biases were not altered by sounds of varying context.

Long-term measurement of body temperature in the southern hairy-nosed wombat (Lasiorhinus latifrons)

The southern hairy-nosed wombat (Lasiorhinus latifrons) is a nocturnal, fossorial marsupial that has evolved a range of physiological and behavioural adaptations to its semiarid environment. This study describes long-term core body temperature (Tb) of L. latifrons in a population with opportunities for behavioural thermoregulation through burrow use. Tb was measured hourly in 12 captive L. latifrons using implanted dataloggers over a 9-month period from late winter to late autumn. Data were examined for daily patterns, seasonal changes, sex differences and the relationship with environmental conditions (ambient temperature, den temperature and relative humidity). Tb ranged from 30.9 to 38.8°C, and had a distinct nychthemeral rhythm, with peak temperatures occurring at night in line with nocturnal activity. Females had a higher mean Tb (34.9°C) than males (34.4°C). The relationship between external ambient temperature and body temperature was negative, with body temperature decreasing as ambient temperature increased. This study is an important step towards a comprehensive picture of thermoregulation in L. latifrons, which may become vulnerable in the future if environmental temperatures rise and water availability decreases.

The effect of group size on vigilance in a semi-solitary, fossorial marsupial (Lasiorhinus latifrons)

Prey species that congregate gain protection against predatory attacks and this advantage is often reflected by a reduction in vigilance behaviour by individuals in larger groups. Comparatively few studies have investigated vigilance in solitary animals, but those that have, found that vigilance increases as group size increases because of the threat posed by conspecifics and/or competition for resources. The southern hairy-nosed wombat (Lasiorhinus latifrons) is a large fossorial, nocturnal marsupial that is neither strictly solitary nor gregarious, sharing warren systems with multiple conspecifics. We investigated the effects of conspecific presence on vigilance behaviour in this semi-solitary species. We observed wild-born, adult L. latifrons wombats in three group sizes (Large (1♂, 3♀), Medium (1♂, 2♀) and Small (1♂, 1♀)) in a captive, naturalistic environment that allowed above-ground and den behaviour monitoring. Vigilance behaviours were performed less frequently by wombats in large groups (e.g. scanning, counts/day, Large: 55, Medium: 69, Small: 115, P=0.002) and more frequently as the distance from their nearest conspecific increased (r64=0.30, P= 0.016). Vigilance within burrows was also affected by social influences, with solitary wombats significantly more vigilant than those denning with a conspecific (e.g. scanning: conspecific absent: 0.13/5min, present: 0.03/5min, P<0.0001). It is concluded that the presence of conspecifics reduces vigilance in L. latifrons wombats, even within burrows, and this may partially explain the occurrence of warren sharing in the wild.