Although moss is commonly found in the feces of arctic herbivores, we do not know the digestible value of this forage for ruminants. We compared grass hay (Bromus sp.) with moss (Hylocomium splendens, Tomenthypnum nitens) from 2 locations in Alaska, USA: Cape Krusenstern National Monument and Fairbanks. We evaluated forages by digestion in ruminally fistulated muskoxen (Ovibos moschatus) by suspending forages in polyester bags before and after the rumen was acclimated with moss for 15 consecutive days. Ruminal degradation was not affected by acclimation to moss. Hay lost dry matter during 48 hours of ruminal incubation (À49%), whereas moss gained dry matter (þ44-57%). Incubated moss gained nitrogen (þ435-680%), as well as fiber (þ18%), and one moss gained ash (þ121%). Mass gained by moss in the rumen was probably due to the combined effect of microbial colonization and adsorption of fibrous particles onto the sponge-like matrix. We evaluated postruminal degradation of forages by incubation in acid-pepsin. Ruminally incubated mosses lost little nitrogen in acid-pepsin even though ruminally incubated hay lost 23% nitrogen on acid digestion. Consumption of moss during winter may be a net cost of selecting plants within moss communities when lichens and graminoids are scarce. Moss in feces may, therefore, indicate low availability of favored foods for muskoxen and other arctic ruminants that are confined to small winter ranges. Increasing concentrations of moss in the feces and, thus, the diet of muskoxen may alert wildlife managers to shifts in winter range quality or forage access due to changing snow conditions. (JOURNAL OF WILDLIFE MANAGEMENT 71 (3):752-758; 2007)
In social ungulates particular individuals or cohorts, such as adult females, can lead or initiate foraging movements. We use muskoxen (Ovibos moschatus) as a model system to test hypotheses regarding the sex and age class of leaders and the potential costs of leadership in 3 different behavioral contexts: activity initiation, foraging-bout movements, and spontaneous group movements. We conducted research on approximately 160 muskoxen at Cape Krusenstern National Monument adjacent to the coast of the Chuckchi Sea in northwestern Alaska. We observed free-ranging, mixed-sex groups of muskoxen from the ground during 5 June-22 September 2002. Adult females emerged as leaders in all 3 contexts, and other group members were more likely to follow adult females than adult males during initiations of activity. Half of successful initiations by adult males included aggressive behavior toward females. Males took a more active role during rut (the mating season) by provoking females to initiate group activity and by actively manipulating spontaneous movements led by females through herding and blocking activities. Leaders incurred no obvious costs in terms of lost foraging time. Costs and benefits of leadership can be subtle and difficult to measure in the field and can include foraging and reproductive trade-offs and increased risk of predation.
I investigated local and regional differences in percent moss in the feces of muskoxen (Ovibos moschatus) and reindeer or caribou (Rangifer tarandus) in northwestern Alaska, USA, and related fecal moss to forage availability, snow conditions, animal density, and terrain ruggedness on wintering areas. Reindeer are a partially domesticated form of Rangifer tarandus originating from Europe and Asia and differ physiologically and ecologically from caribou. Percent moss in feces of muskoxen differed locally among individual wintering areas. Because of the large local variation in moss content of muskox feces, regional differences between the 2 study areas were difficult to resolve. Percent of moss in the feces of reindeer-caribou did not differ between wintering areas within the same study area but did differ between study areas. On muskox wintering areas, fecal moss correlated negatively with graminoid cover and snow hardness and positively with moss cover and muskox density, but fecal moss did not correlate with snow depth or terrain ruggedness. On reindeercaribou wintering areas, fecal moss correlated positively with moss availability but not with lichen cover or snow depth or hardness. Because muskox groups in Alaska are isolated from each other in winter, even groups wintering on neighboring hills may face different foraging availability and might, therefore, exhibit differences in growth or productivity. Reindeer-caribou are more mobile than muskoxen in winter, and fecal samples may not be representative of vegetative and snow conditions at the wintering area where I collected them. I conclude that managers can use fecal moss as an indicator of overgrazed ranges, severe snow conditions, or crowded conditions on muskox wintering areas, but that the association between fecal moss and range conditions has to be drawn with caution for the more mobile reindeer-caribou.
Problem statement: Muskoxen (Ovibus moschatus) are distant relatives of sheep (Caprinae) and have roamed the Arctic for a million years, with populations reaching North America between 150,000 and 250,000 years ago. Muskox populations could be negatively influenced by climate change and increased exposure to contaminants. Since the snow depth is a critical factor in their ecology, effects could occur throughout their distribution. Muskox typically feed on plants on hilltops and upper slopes where shrubs are increasing at the expense of graminoid and lichen species. Besides changes in plant species composition, wildfires and flooding, as well as renewed mining developments, can lead to an increased incidence of total Hg (THg) bioavailability. Approach: In this survey THg concentrations were measured in the hair of muskox at several sites on Seward Peninsula of Alaska, USA. Results: Muskox exhibited mean THg levels in the hair of 29. THg levels are relatively low and helping establish a baseline for Hg exposure in muskoxen.
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