Dominance effects on grazing patterns in horses in nature reserves

Nature reserve managers aim to evaluate the spatial position and presumed behavior of a group of introduced large herbivores by using telemetric data of one randomly selected individual. We hypothesized that dominance effects can cause variations in grazing patterns. A group of five Konik horses was observed during summer in a Belgian coastal dune reserve Westhoek-Zuid of 60 ha. All agonistic interactions were scored and the hierarchy was analyzed. For each horse 25 focals of 15 minutes were conducted to score behavior and position with 90 seconds intervals. The horses stayed predominantly in the dune-grassland (34,10 %), in woody areas (25,30 %), rough scrub areas (14,20 %) and in rough grassland vegetation (11,60 %). The horses foraged during 59,85 %, rested (standing and lying) during 36,80 % and moved only during 3,35 % of their time budget. The horses diet was composed for 87.73% of grasses, i.e. 66.90% long grasses (average count: 96, SD=39.35) and 33.10% short grasses (average count: 47.8, SD= 13.44). Short grasses were rarer but they were most preferred and were consumed more frequently by higher ranking horses (rank-short grass intake: rs=-0.98), whereas long grass was consumed more by low ranking horses (rank-long grass intake: rs= 0.94). This implies rank related monopolization of better quality grass when groups move in patchy landscapes. Often the poorer long-grassed vegetation types are targeted by nature managers, although these are least preferred by the animals. The choice of an adequate group size should be such that the low ranking animals are forced into eating the suboptimal vegetation, without harming their nutritional welfare. To evaluate the grazing behavior of a group of horses, the selection of both the lowest and highest ranking individual, will give a better view than the selection of a random animal.status: publishe