An overview of the impacts of feral cattle, water buffalo and pigs on the savannas, wetlands and biota of northern Australia

Abstract

Since the extinction of the megafauna some 45 000 to 50 000 years ago, grazing pressure on Australian savannas has been relatively low compared to that on savannas in other continents. However, the introduction of several species of ungulate, primarily during the 1800s, and the establishment of large feral populations in northern Australia has resulted in an increase in grazing pressure compared to pre-colonial times when soft-footed macropods were the largest extant grazers. Here, we provide an overview of the introduction of three key ungulates to northern Australia: cattle (Bos taurus, B. indicus), Asian water buffalo (Bubalus bubalis) and pigs (Sus scrofa), and the impact of these populations on both abiotic and biotic elements of savanna habitats in northern Australia. Feral ungulate populations have considerable impacts on soil, water quality, waterhole hydrology, vegetation, fire regimes and the spread of exotic plants, and resulting changes to habitat have flow-on effects for native wildlife. Ungulate impacts on vegetation communities and associated changes in fire regimes are particularly concerning given that sustained grazing can lead to the permanent removal of key grass species and changes in fire intensity and frequency can result in the conversion of grassland to woodland. Native wildlife can be affected by ungulate disturbance in a multitude of ways, but overwhelmingly, habitat loss or degradation is the main driver for declines in biodiversity. Based on current knowledge gaps, we discuss potential directions for future research about how feral ungulate activity affects Australian native species and their impact on savanna habitats.

Population genomic, olfactory, dietary, and gut microbiota analyses demonstrate the unique evolutionary trajectory of feral pigs

“…Sometimes, uncontrolled feral populations can have negative impacts both on indigenous wild and domestic fauna and plants (Abe, 2021; Eldridge et al, 2020; Mihailou & Massaro, 2021; Scandurra et al, 2016).…”

Evaluating the potential for reintroducing the endangered wild water buffalo (Bubalus arnee) in Kanha National Park, central India

“…Therefore, their herbivory would likely reduce dominance of coarse grasses, woody and alien species and facilitate the growth of short vegetation that is preferred by smaller ungulates like chital and swamp deer in Kanha (Sharma et al 2023). Wild buffaloes are known to engineer wallow sites (Mihailou & Massaro 2021), that can likely enhance the sustenance and prevalence of swampy ecosystem and benefit the endangered swamp deer. As a result, buffalo reintroduction can serve as a naturebased solution to multiple restoration challenges and dovetail conservation of other endangered species.…”

“…There is an ongoing decline in the swamp and seasonal swamp ecosystems across the historical wild buffalo range due to altered hydrological regimes and land use changes (Vashistha et al 2021; Paul et al 2023). Wild buffaloes have been observed to engineer wallow sites, thereby sustaining mosaics of swamps, grassy and open areas across different parts of their range (Choudhury 2014; Mihailou & Massaro 2021). Extirpation of a megaherbivore like the wild buffalo can also reduce nutrient cycling, seed dispersal, ecosystem resilience (Ratajczak et al 2022), and availability of large carcasses for scavengers like vultures, who in the absence of wild buffaloes depend on domestic cattle carcasses that are often contaminated with diclofenac and cause deaths and decline in vulture populations (Taggart et al 2007).…”

Causes and consequences of recent degradation of the Magdalena River basin, Colombia

“…Three different breeds of water buffalo have been introduced since the 1960s across the middle and lower basins of the Magdalena for the palm oil industry, meat, and dairy products (ICA 2017). Like hippos and cattle, buffalos are amphibious ecosystem engineers (Mihailou and Massaro 2021). By digging and wallowing on wetland margins, they can destabilize soil, expose large areas to evaporation, and reduce water retention during the dry periods (Skeat et al 1996).…”