Seasonal foraging behavioural compensation in reproductive wapiti hinds (Cervus elaphus canadensis)

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.

Elk Distributions Relative to Spring Normalized Difference Vegetation Index Values

Rocky Mountain elk (Cervus elaphus) that winter near San Antonio Mountain in northern New Mexico provide important recreational and economic benefits while creating management challenges related to temporospatial variation in their spring movements. Our objective was to examine spring distributions of elk in relation to vegetative emergence as it progresses across the landscape as measured by remote sensing. Spring distributions of elk were closely associated with greater photosynthetic activity of spring vegetation in 2 of 3 years as determined using NDVI values derived from AVHRR datasets. Observed elk locations were up to 271% greater than expected in the category representing the most photosynthetic activity. This association was not observed when analyses at a finer geographic scale were conducted. Managers facing challenges involving human-wildlife interactions and land-use issues should consider environmental conditions that may influence variation in elk association with greener portions of the landscape.

Effects of grass and browse consumption on the winter mass dynamics of elk

Much of the research into herbivore ecology and evolution has focused on patterns and mechanisms of niche partitioning in the diets of specialized grazers and browsers, but the significance of the balance of grazing and browsing within intermediate feeders present unique questions that have received less attention. We explored the nutritional effects of varying the balance of grass and browse in the winter diets of elk (Cervus elaphus). We compiled published data from three similar studies that monitored the mass dynamics of captive elk fed diets of pure grass, pure browse or 1 of 14 mixed diets in winter feeding trials. Elk lost mass (up to 22% of initial body weight) in 29 of 33 feeding trials, similar to wild elk in winter. We used regression models of mass dynamics, considering the linear, quadratic or logarithmic effects of the proportion of the diet that was grass ( approximately 1 - proportion of the diet that was browse) and the additive and interactive effects of nitrogen intake. Diet composition had strong effects on mass dynamics, and all models explained > or =73% of the variation (adjusted r (2)) in mass dynamics. Nitrogen intake had uniformly positive effects on mass balance, and increasing grass intake caused improved maintenance of body mass up to a point, but further increases in the proportion of grass in the diet had neutral or negative effects on body mass. Overall, the data suggest that elk are adapted to consuming mixed diets. Nonetheless, data on the foraging behavior and diet selection of wild elk in many populations show that elk often consume grass-dominated diets and sometimes consume browse-dominated diets, but rarely consume mixed diets. Physiological adaptations to mixed diets may place unique spatio-temporal constraints on diet selection in intermediate feeders and impose large penalties for a sub-optimal balance of grazing and browsing.

Fecal steroid analysis of female giraffe (Giraffa camelopardalis) reproductive condition and the impact of endocrine status on daily time budgets

Gestation and lactation can impose substantial energetic costs on female mammals. We developed a non-invasive means to determine reproductive condition in female giraffe using fecal steroid analysis. Giraffe may be especially challenged during their reproductive cycle because of two characteristics: they are impregnated while lactating and they do not breed seasonally. We studied the social behavior and endocrinology of seven female giraffe in a large naturalistic outdoor enclosure in order to chart connections between maternal physiology and behavior across the reproductive cycle. We found that giraffe gestation averages 448 days among females producing a calf that survived, with fecal pregnane concentrations reaching a zenith during the last trimester of pregnancy. Resumption of ovarian cyclicity following parturition was accelerated after neonatal calf mortality, but ovarian cycles resumed as early as 39 days postparturition while nursing. Although time spent feeding was unaffected by reproductive state, pregnant females significantly reduced time allocated to social behavior and had a tendency to locomote less than when cycling or acyclic. We suggest that modifications in foraging strategies as a function of reproductive state among wild giraffe derive from antipredator activity rather than from metabolic demands. Female giraffe probably cope with simultaneous lactation and gestation by producing high quality milk for neonatal calves commensurate with slow fetal growth and accelerating fetal growth simultaneous with weaning of nursing calves.