How do free-ranging domestic herbivores reduce competition within owner-determined herds?

Review: A theoretical framework to define foraging behaviour syndromes in ruminants using wearable technologies

Due to intensification processes that have had negative impacts on environmental externalities, pastoral farmers, worldwide, are facing increasing scrutiny and pressure from consumers, governments, and the public to reduce the environmental footprint of their operations. Developing tools and systems that farmers can use to maintain profitability and productivity while decreasing the negative externalities of their operations is important for the vitality of rural sectors. Capitalising on individual animal variation has been promoted as an opportunity to increase animal productivity and enhance welfare while decreasing the negative environmental impacts of pastoral farming. Of particular interest are behaviours that are associated with foraging, as these are the primary drivers of variation in animal performance in pastoral farming. Developing a methodology that can identify consistent foraging behavioural variations across individuals is a critical step in making this a practical solution for farmers and herders. As with all behavioural research, the fundamental challenge is selecting the appropriate behaviours to measure. Understanding the contextual drivers of behavioural expression is a major development in this process. Herd management and composition, environmental variables and many more contexts alter the expression of behaviours, so how do we capture behaviours of interest? We propose the use of a systematic methodology to capture behaviours of significance from large groups of foraging ruminants using wearable technology, namely Global Positioning System and accelerometers. This contrasts with traditional reductionist methodologies used in behaviour research and has the benefit of providing large objective datasets from undisturbed animals. Statistical analysis of the data will inform behaviours of interest that are clustered together to inform a three-factor foraging behaviour syndrome model adapted from the animal five-factor model (activity, aggression, boldness, exploration, sociability) of personality. Syndromes, unlike personalities, include correlated suites of behaviours that are expressed across spatial and temporal contexts. By capturing foraging behaviour syndromes, selection can be used to match appropriate syndromes to different pastoral farming landscapes, thereby potentially improving the system's productivity while reducing their negative environmental impact.

Behavioural Indicators of Intra- and Inter-Specific Competition: Sheep Co-Grazing with Guanaco in the Patagonian Steppe

Simple Summary

In extensive livestock ranching, where animals are maintained at high numbers, competition between individuals is expected, but not generally assumed. To compensate for reduced food availability, herbivores modify their feeding behaviour, which can be used as an indicator of competition. We investigated behavioural changes of domestic sheep in Chilean Patagonia in response to herd size, food availability, and the presence of a wild competitor, the guanaco, considered a problem for sheep production by ranchers. Large sheep herds were associated with a decrease in sheep grazing, while food availability increased time spent feeding. Guanaco had no effect on sheep behaviours. Behavioural changes were mostly associated with competition between individual sheep and not with guanaco. We suggest that to improve sheep production, ranchers should focus on sheep management at appropriate herd sizes according to grassland capacities.

Abstract

In extensive livestock production, high densities may inhibit regulation processes, maintaining high levels of intraspecific competition over time. During competition, individuals typically modify their behaviours, particularly feeding and bite rates, which can therefore be used as indicators of competition. Over eight consecutive seasons, we investigated if variation in herd density, food availability, and the presence of a potential competitor, the guanaco (Lama guanicoe), was related with behavioural changes in domestic sheep in Chilean Patagonia. Focal sampling, instantaneous scan sampling, measures of bite and movement rates were used to quantify behavioural changes in domestic sheep. We found that food availability increased time spent feeding, while herd density was associated with an increase in vigilant behaviour and a decrease in bite rate, but only when food availability was low. Guanaco presence appeared to have no impact on sheep behaviour. Our results suggest that the observed behavioural changes in domestic sheep are more likely due to intraspecific competition rather than interspecific competition. Consideration of intraspecific competition where guanaco and sheep co-graze on pastures could allow management strategies to focus on herd density, according to rangeland carrying capacity.