黑河林区驼鹿冬季食性研究

1987—1988年在黑龙江省黑河林区,应用粪便显微组织学分析技术,结合野外啃食调查,对驼鹿冬季食物组成、食物选择性和利用率进行了研究。结果表明,冬季驼鹿共采食31种(属)植物,其中柳、榛、桦、红松、杨和紫椴是主要的冬季食物(19.9％、18.0％、16.7％、14.9％、7.3％和6.7％)。驼鹿对杨、柳、红松和紫椴有正选择性,对榛、桦和毛赤杨有负选择性。选择性的强弱顺序为:杨>柳>红松>紫椴>榛>桦>毛赤杨。驼鹿对柳的选用率最高(32.1％),对桦的利用率最低(12.1％)。     

Choice of feeding sites by moose during summer, the influence of forest structure and plant phenology

We observed forage and habitat selection in radio-collared moose at feeding sites in southeast Norway. Use of older forest increased from spring to autumn. Birch Betula spp. and bilberry Vaccinium myrtillus accounted for c. 75% of the diet. Occurrence of important forage plants, height of browse, and difference in phenology between plant species all appeared to play a role in moose selection of feeding sites. Shading influences moose forage by delaying plant phenology and possibly through its effect on leaf content of water and secondary compounds. On single birch trees, feeding was concentrated to the top branches at midsummer; during spring and autumn more leaves from side branches were eaten. Greater discrimination as vegetation matured was also evident from the wider variety of forage species used at midsummer. Selection of feeding sites was not related to density of important browse species. We propose that variations in light/shade conditions may play a role in moose choice of feeding sites and that moose on summer range will benefit from a heterogeneous mixture of plantations and older forest stands.     

黑龙江省胜山林场冬季驼鹿、马鹿和狍的种间关系

1987—1989年的两个冬季在黑龙江省黑河市胜山林场,对驼鹿、马鹿和狍的食性、采食高度和栖息地进行了研究。驼鹿的主要食物是柳(22.4％)、榛(16.0％)、红松(14.3％)和桦(13.8％);马鹿为杨(36.0％)、桦(22.7％)和红松(17.3％);狍为桦(26.5％)、柳(19.0％)、杨(12.7％)。三种动物采食高度的频次为正态分布。驼鹿的采食高度(标准差)为137.4(±39.0)厘米;马鹿为136.2(±37.0)厘米;狍为84.2(±29.2)厘米。驼鹿和马鹿对红松林的利用程度最高,而狍主要利用沼泽植物和红松林。驼鹿与狍在食物维和栖息地维上的生态位重叠最大,驼鹿与马鹿在采食高度维上的重叠最大。三种动物在食物、采食高度和栖息地三维生态位上的重叠大小的顺序为:驼鹿和马鹿>驼鹿和狍>马鹿和狍。     

The Nutritional Balancing Act of a Large Herbivore: An Experiment with Captive Moose (Alces alces L)

The nutrient balancing hypothesis proposes that, when sufficient food is available, the primary goal of animal diet selection is to obtain a nutritionally balanced diet. This hypothesis can be tested using the Geometric Framework for nutrition (GF). The GF enables researchers to study patterns of nutrient intake (e.g. macronutrients; protein, carbohydrates, fat), interactions between the different nutrients, and how an animal resolves the potential conflict between over-eating one or more nutrients and under-eating others during periods of dietary imbalance. Using the moose (Alces alces L.), a model species in the development of herbivore foraging theory, we conducted a feeding experiment guided by the GF, combining continuous observations of six captive moose with analysis of the macronutritional composition of foods. We identified the moose’s self-selected macronutrient target by allowing them to compose a diet by mixing two nutritionally complementary pellet types plus limited access to Salix browse. Such periods of free choice were intermixed with periods when they were restricted to one of the two pellet types plus Salix browse. Our observations of food intake by moose given free choice lend support to the nutrient balancing hypothesis, as the moose combined the foods in specific proportions that provided a particular ratio and amount of macronutrients. When restricted to either of two diets comprising a single pellet type, the moose i) maintained a relatively stable intake of non-protein energy while allowing protein intakes to vary with food composition, and ii) increased their intake of the food item that most closely resembled the self-selected macronutrient intake from the free choice periods, namely Salix browse. We place our results in the context of the nutritional strategy of the moose, ruminant physiology and the categorization of food quality.     

贺兰山同域分布岩羊和马鹿的夏季食性

2008年78月贺兰山对同域分布的岩羊和马鹿粪便进行采集,利用粪便显微分析法对二者夏季食性进行了研究。从10个沟系中一共收集了297堆岩羊和305堆马鹿粪便,每堆中捡拾2粒粪粒,组成40个复合样本进行分析。结果表明,夏季在岩羊采食的19科35种(属)植物中,针茅(29.74%)、早熟禾(18.82%)、内蒙古邪蒿(10.30%)、灰榆(7.76%)、冰草(7.47%)是其主要食物,针茅是岩羊夏季的大宗食物;夏季在马鹿取食的11科18种(属)植物中,小红柳(36.26%)、山杨(23.10%)、灰榆(16.84%)等是其主要食物,小红柳为马鹿夏季的大宗食物。夏季岩羊采食植物中,乔木占8.67%,灌木占3.97%,禾本科草本占69.43%,非禾本科草本占17.94%;马鹿采食植物中,乔木占89.61%,灌木占5.38%,禾本科草本占1.03%,非禾本科草本占3.99%。从食物多样性和食物生态位宽度来看,岩羊的Shannon-Wiener指数高于马鹿,而马鹿的Pielou均匀性指数和食物生态位宽度指数高于岩羊,岩羊和马鹿共有9种食物重叠,生态位重叠指数为65.17%。     

Selectivity by moose vs the spatial distribution of aspen: a natural experiment

Patch use theory predicts that herbivores perceive food as patches and spend more time in high quality patches, i.e. feeding sites providing a high net rate of intake of energy and/or limiting nutrients. The herbivores should accordingly not discriminate among food items in such high quality patches, and food items should thus be eaten in proportion to availability. In contrast, classical diet theory assumes food selection to take place at the level of individual plants, and predicts that the forager should concentrate on the most profitable item until availability drops below some critical threshold.
Here we address how the spatial distribution of European aspen Populus tremula , a highly preferred browse species, affects the selectivity by moose Alces alces at the patch and the tree level. The study was performed in a managed boreal forest landscape in coastal northern Sweden, where aspen occurs highly aggregated almost exclusively in discrete patches. We compared moose' selectivity for aspen and browsing intensity on aspen ramets and other browse species in aspen patches versus at randomly located sites.
Random sites and aspen stands were utilised equally by moose in terms of overall use of forage. There was no difference in total coverage of forage species and relative moose density. Selectivity for aspen was stronger at random sites than at aspen sites, and the browsing intensity on aspen was similar. We conclude that moose did not perceive aspen stands as discrete patches, and used aspen ramets more in accordance with diet theory. These findings agree with the idea that large generalist herbivores strive to maintain a mixed and balanced diet, causing rare species to be over-utilised (negative frequency-dependent food selection). By such selective feeding, moose may reinforce the aggregated distribution of aspen in the managed boreal forest landscape.     

Effects of willow nutrition and morphology on calving success of moose

Across much of North America, populations of moose (Alces alces) are declining because of disease, predation, climate change, and anthropogenic-driven habitat loss. Contrary to this trend, populations of moose in Colorado, USA, have continued to grow. Studying successful (i.e., persistent or growing) populations of moose can facilitate continued conservation by identifying habitat features critical to persistence of moose. We hypothesized that moose using habitat with higher quality willow (Salix spp.) would have a higher probability of having a calf-at-heel (i.e., calving success). We evaluated moose calving success using repeated ground observations of collared individuals with calves in an occupancy model framework to account for detection probability. We then evaluated the impact of willow habitat quality and nutrition on moose calving success by studying 2 spatially segregated populations of moose in Colorado. Last, we evaluated correlations between willow characteristics (browse intensity, height, cover, leaf length, and species) and willow nutrition (dry matter digestibility [DMD]) to assess the utility of using those characteristics to assess willow nutrition. We found willow height and cover had a high probability of being positively associated with higher individual-level calving success. Willow DMD, browse intensity, and leaf length were not predictive of individual moose calving success; however, the site with higher mean DMD consistently had higher mean estimates of calving success for the same year. Our results suggest surveying DMD is likely not a useful metric for assessing differences in calving success of individual moose but may be of use at population levels. Further, the assessment of willow morphology and density may be used to identify areas that support higher levels of moose calving success.     

Diet composition and foraging ecology of Asian elephants in Shangyong, Xishuangbanna, China

The composition of the diet and the foraging ecology of the Asian elephant in its natural habitat were studied from 1998 to 2000 in the Shangyong National Natural Reserve located at Xishuangbanna, China, using field observation and dung analysis. A total of 106 plant species were recorded as being eaten by Asian elephants, 83 of which were identified in the elephants' dung. The plant families that contributed to a major proportion of the elephants' diet in the study area were: Gramineae (8 spp., 10.0%), Moraceae (7 spp., 9.9%), Papilionaceae (4 spp., 8.4%), Araliaceae (3 spp., 6.6%), Vitaceae (3 spp., 5.7%), Apocynaceae (3 spp., 4.6%), Musaceae (1 spp., 4.2%), Zingiberaceae (3 spp., 3.7%), Myrsinaceae (3 spp., 3.6%), Rosaceae (3 spp., 3.6%), Euphorbiaceae (5 spp., 3.3%), Ulmaceae (2 spp., 3.0%) and Mimosaceae (4 spp., 2.9%). The most important plants in the elephants' diet were Ficus spp. (Moraceae, 9.0%), Dendrocalamus spp. (Gramineae, 4.5%), Musa acuminata (Musaceae, 4.2%), Microstegium ciliatum (Gramineae, 3.5%) and Amalocalyx yunnanensis (Apocynaceae, 3.1%). Asian elephants consumed a variety of plants in terms of life forms, including trees, vines, shrubs and herbs. Early successional plant species constitute a higher proportion of the diet than late successional plants (42 spp. taking 59% vs. 32 spp. taking 37%). Browsing species accounted for a larger proportion of the diet compared to grazing species (77 spp. taking 91% vs. 6 spp. taking 9%). The number of plant taxa (species, genus, family) in elephants' diet each month negatively correlated with monthly rainfall and mean temperature. The study may help to develop proper strategies for wildlife management especially with regard to the human-elephant conflict, which is now a serious issue in the conservation of Asian elephants in this area.     

Effect of Roadside Vegetation Cutting on Moose Browsing

Moose (Alces americanus ) vehicle collisions (MVCs) are an issue throughout the distribution of moose. Many mitigation strategies have been tested and implemented to reduce the number of MVCs, but there have been few empirical analyses of the effectiveness of roadside vegetation cutting. The goal of this study was to determine if roadside vegetation cutting attracted moose into roadside areas to browse on the vegetation regrowth. We hypothesized that moose would be attracted to roadside areas with cut vegetation. Consequently, we predicted that there would be higher levels of browsing in cut areas compared to uncut areas. To determine if moose were browsing more in cut or uncut areas, we measured the number of plants browsed by moose in paired treatment (cut on or after 2008) and control (not cut since at least 2008) sites, along with a suite of potential environmental covariates. Using a model selection approach, we fit generalized linear mixed-effects models to determine the most parsimonious set of environmental variables to explain variation in the proportion of moose browse among sites. In contrast to our hypothesis, our results show that the proportion of moose browse in the uncut control areas was significantly higher than in the cut treatment areas. The results of this study suggest that recently cut roadside areas (7 years or less based on our work) may create a less attractive foraging habitat for moose. The majority of the variance in the proportion of moose browse among sites was explained by treatment type and nested plot number within site identification (34.16%), with additional variance explained by traffic region (5.00%) and moose density (4.35%). Based on our study, we recommend that vegetation cutting be continued in roadside areas in Newfoundland as recently cut areas may be less attractive browsing sites for moose.     

Moose summer and winter diets along a large scale gradient of forage availability in southern Norway

Studies on dietary functional responses in large herbivores are traditionally conducted by following individual animals. The method is very time-consuming, and hence, typically provides only a narrow array of forage species compositions. Here we use a range level approach to look at moose (Alces alces) selectivity for and utilization of forage species in relation to availability in both summer and winter. We compare 12 Norwegian ranges representing a large scale gradient in plant communities. The most important forage species in the diet were birches (Betula spp., comprising 43% of all trees browsed in summer and 27% in winter), rowan (Sorbus aucuparia, 25% of trees browsed in summer, 37% in winter), and bilberry (Vaccinum myrtillus, 42% of herbaceous epidermal fragments in summer feces). Selectivity for birches was positively related to its availability and negatively related to availability of rowan, Salix spp., and aspen (Populus tremula) together (all more selected for than birches). Multiple regression models including availability of several forage species were thus superior to single-species models in explaining the diet content of main forage plants. Selectivity for birches was also stronger in summer than in winter, while the opposite pattern was found for rowan. The finding is relevant for our evaluation of the quality of summer and winter ranges, and hence, their relative influence on population productivity. Our study underlines the need to incorporate species composition of available forage when quantifying dietary functional responses in selective herbivores such as moose. Furthermore, care should be taken when extrapolating data on moose diet across ranges or seasons.