Departamento de Ciencias Agropecuarias y Acuícolas

Organización superior

Facultad de Ciencias

Buscar

Publicaciones

Mostrando 1 - 3 de 3

Some of the metrics are blocked by your
consent settings
DOI 10.3390/ani11113333
Behavioural Indicators of Intra- and Inter-Specific Competition: Sheep Co-Grazing with Guanaco in the Patagonian Steppe
2021-11
Fernandez, Tomas
;
Lancaster, Alex
;
Moraga, Claudio A.
;
Radic Schilling, Sergio Javier
;
von Hardenberg, Achaz
;
Corti, Paulo
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. 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.
Scopus© Citations 6 3
Some of the metrics are blocked by your
consent settings
DOI 10.1016/j.rama.2020.01.006
Midsummer Trophic Overlap Between Guanaco and Sheep in Patagonian Rangelands
2020-5
Pontigo, Felipe
;
Radic Schilling, Sergio Javier
;
Moraga, Claudio A.
;
Pulido, Ruben
;
Corti, Paulo
Diet overlap estimation among species is important to understand interspecific interactions. Through these interactions, one species may extinguish others through competition or adapt through mechanisms such as resource partitioning. The introduction of domestic herbivores in a native assemblage may introduce competition for resources with wild herbivores. In southern Patagonian steppes, guanaco (Lama guanicoe) populations are increasing after a drastic demise during the past century. This is occurring in protected areas and extensive ranching areas for sheep, and in the latter ranchers have rising concerns regarding competition. In this observational study, we measured diet overlap, food selection and preferences, and niche width for guanaco and sheep to compare use of food resources during the summer season. Feces were analyzed through microhistological technique to determine sheep and guanaco diets. Diets of guanaco and sheep were dominated by tussock grass (Festuca gracillima, sheep > 60%, guanaco > 50%), the most abundant plant species. Although food niche widths, measured through Levin's Index, were narrow, guanaco presented the broadest niche (P < 0.001). Of the 17 identified plant species present in guanaco and sheep diets, 5 were always selected by both ungulates and 1 was always avoided at the four study sites. Overlap between diets was high (> 0.90), evidencing potential competition. In addition, diet overlap coupled with our results of small variation in use and selectivity of food resources suggest the absence of resource partitioning. Therefore, both species might share resources or coexist, possibly due to high availability or spatial distribution of food resources and guanaco resilience to cope with numerically dominant competition from sheep. These findings offer new insight into the understanding of these species' interactions. It is also a management challenge to emerging wild and domestic herbivores interactions, as well as livestock production concerns at large. (C) 2020 The Society for Range Management. Published by Elsevier Inc. All rights reserved.
Scopus© Citations 8 2
Some of the metrics are blocked by your
consent settings
DOI 10.1111/jzo.12971
Changes in foraging behaviour suggest competition between wild and domestic ungulates: Guanaco and domestic sheep in southern Patagonia
2022-7
Lancaster, A.
;
Corti, P.
;
Fernandez, T.
;
Moraga, C. A.
;
Radic Schilling, Sergio Javier
;
Hardenberg, A.
Previous attempts to address the presence of interspecific competition between domestic livestock and wild ungulates have focused largely on habitat or dietary overlaps. Although overlaps in habitat or diet create opportunities for competition to occur between species, competition only results from such overlap if it affects one or both species negatively. Less attention has been afforded to possible behavioural modifications induced in wildlife by competition with domestic livestock. Here, we investigated the effects of the presence of livestock on feeding behaviour of guanaco (Lama guanicoe) in southern Patagonia, using focal sampling of individuals during foraging bouts, with instantaneous scan samples to estimate group behavioural budgets. We recorded guanaco bite and step rates, used as proxies of foraging intake and selectivity, from four different study sites over eight consecutive seasons. We also estimated sheep and guanaco densities per site, along with vegetation biomass availability. As in other ungulates, bite rates of guanaco appear to be highly flexible and generally increased with vegetation biomass availability. However, as sheep densities and thus additional grazing pressure increased, guanaco foraging strategy compensated by increasing bite rates when foraging vegetation was scarce, indicating further likelihood of competition. Additionally, scan samples indicated that the probability of guanaco feeding occurring at any one time was higher in areas shared with domestic sheep compared to national parks, suggesting guanaco have to focus more on feeding than other behaviours when sheep are present.
Scopus© Citations 7 2

Departamento de Ciencias Agropecuarias y Acuícolas

Buscar

Ajustes

Filtrar por:

Ajustes

Publicaciones