3.4. Characterising the wild−domestic interface
In a camera trap study conducted around NPA communities (Ward et al., 2021), wild dogs and unsupervised domestic dogs accounted for the majority of dog triggers, 40.7% and 44.5%, respectively (N = 2,317 photo series). Wild dogs were most frequently observed at night around a waste site and less frequently around campground and beach locations. They were generally observed with other wild dogs, as well as domestic dogs occasionally. This observational study demonstrates that wild dogs are active in peri-urban community areas in northern Australia.
In the camera trap survey used to monitor the wild dog population in the NPA, Gabriele-Rivet et al (2020) also found the spatial use and daily activity patterns of wild dogs and free-roaming community dogs showed substantial temporal activity overlap and spatial correlation, especially during the dry season. This highlights the potential risk of disease transmission at the wild–domestic interface in an area of biosecurity risk in equatorial northern Australia.
Data from this camera-trap study were further used to explore spatial and seasonal opportunities for interactions between wild dogs and unsupervised domestic dogs (Gabriele-Rivet et al., 2021b). A detection event was defined as the capture of one individual in a photograph. For each dog type (wild dog versus unsupervised domestic dog), the (standardised) relative activity index (detection events ÷ capture effort) was calculated at each camera station and for each season.
Unsupervised domestic dogs were mostly (86% and 84% in the dry and wet seasons, respectively) active in proximity (< 1 km) to the five Indigenous communities in the NPA. A peak of unsupervised domestic dog activity was noticeable in areas that lay further away from the communities towards the tip of the peninsula, which was more pronounced during the wet season compared to the dry season. This finding is most certainly related to hunting excursions (Gabriele-Rivet et al., 2019a).
Compared to unsupervised domestic dogs, the activity of wild dogs was more spatially homogeneous across the study area, although more activity was found around the communities, especially during the dry season, and in distant areas where hunting trips frequently occur, especially during the wet season.
The higher level of wild dog activity around the communities during the dry season implies a higher risk of interaction with free-roaming domestic dogs; indeed, significant spatial correlation between wild dogs and unsupervised domestic dogs has been found early in the dry season (Gabriele-Rivet et al., 2019a). In contrast, wild dogs are 1.6-times more active >10km from the communities in the wet season. This coincides with domestic dog activity in these areas due to hunting, increasing the likelihood of interactions between both populations. Thus, the location and nature of the domestic−wild interface varies by season in this equatorial climate zone.
3.5. Hunting increases the wildlife−domestic dog interface
Cooperative hunting (most commonly for feral pigs) involving several hunters and their domestic dogs is common across Australia, and within Indigenous communities is a traditional practice that contributes to food security. Contact opportunities between wild and hunting dogs during hunting can create a wildlife–domestic interface for disease transmission of shared pathogens (Fiorello et al., 2006; Hughes and Macdonald, 2007), such as canine parvovirus (Meers et al., 2007; Kelman et al., 2020). Generally, hunting provides an opportunity for spatial translocation of disease over large distances (Sparkes et al., 2016), contributing to disease spread and complicating disease control. Hunting dogs can also provide a link between wild dogs (and other wildlife) and humans.
To further investigate this potential interface, a cross-sectional survey of 13 hunters from communities of the NPA was undertaken (Gabriele-Rivet et al., 2019a). More than half these hunters had experienced at least one wild dog encounter during hunting in the year prior to the interview. Wild dogs were seen mostly on the roads when driving before or after their hunting trip, and during hunting trips wild dogs were reported to keep their distance from the hunting group (hunting dogs often barked at or chased wild dogs during encounters). Generally, 1–2 wild dogs travelling together were observed, but sometimes packs of 3–6 wild dogs, including puppies, were seen. Hunters reported practicing hunting activities more frequently during the wet season compared to the dry season (median of 12 vs 7.2 hunting trips per season, respectively). Mapping of the relative risk of interactions between wild and hunting dogs during hunting trips allowed the identification of high-risk areas in the NPA, based on the combination of high wild dog density and frequency of hunting trips. These areas, towards the tip of the NPA region, are characterised by dense rainforests. Results from this study, when combined with those from a camera trap survey in the NPA in which a peak of unsupervised domestic dog activity was noticeable in areas that lay further away from the communities towards the tip of the peninsula in the wet season (Gabriele-Rivet et al., 2019a), support the potential for disease transmission at the domestic–wild dog interface through contacts between hunting dogs during hunting activities.