Step by step: reconstruction of terrestrial animal movement paths by dead-reckoning

Background: Research on wild animal ecology is increasingly employing GPS telemetry in order to determine animal movement. However, GPS systems record position intermittently, providing no information on latent position or track tortuosity. High frequency GPS have high power requirements, which necessitates large batteries (often effectively precluding their use on small animals) or reduced deployment duration. Dead-reckoning is an alternative approach which has the potential to ‘fill in the gaps’ between less resolute forms of telemetry without incurring the power costs. However, although this method has been used in aquatic environments, no explicit demonstration of terrestrial dead-reckoning has been presented.Results: We perform a simple validation experiment to assess the rate of error accumulation in terrestrial dead-reckoning. In addition, examples of successful implementation of dead-reckoning are given using data from the domestic dog Canus lupus, horse Equus ferus, cow Bos taurus and wild badger Meles meles.Conclusions: This study documents how terrestrial dead-reckoning can be undertaken, describing derivation of heading from tri-axial accelerometer and tri-axial magnetometer data, correction for hard and soft iron distortions on the magnetometer output, and presenting a novel correction procedure to marry dead-reckoned paths to ground-truthed positions. This study is the first explicit demonstration of terrestrial dead-reckoning, which provides a workable method of deriving the paths of animals on a step-by-step scale. The wider implications of this method for the understanding of animal movement ecology are discussed

Patterns of livestock activity on heterogeneous subalpine pastures reveal distinct responses to spatial autocorrelation, environment and management

BACKGROUND: In order to understand the impact of grazing livestock on pasture ecosystems, it is essential to quantify pasture use intensity at a fine spatial scale and the factors influencing its distribution. The observation and analysis of animal activity is greatly facilitated by remote tracking technology and new statistical frameworks allowing for rapid inference on spatially correlated data. We used these advances to study activity patterns of GPS-tracked cows in six summer-grazing areas in the Swiss Alps that differed in environmental conditions as well as livestock management. RESULTS: Recorded GPS positions were assigned to the activities of grazing, resting, and walking, and were discretized on a regular grid. Regression models with spatially structured effects were fitted to the spatial activity patterns using Integrated Nested Laplace Approximation. They indicated that terrain slope, forage quality, and stocking rate were the primary factors determining cow activity in the six study areas. Terrain slope significantly reduced livestock activity in five of the six areas and sparse forage availability significantly reduced grazing in all areas. In three areas, grazing pressure imposed by the pasture rotation was observable in the grazing pattern. Insolation, distance to the shed, and distance to water were less important for cow activity. In addition to the main factors identified across all study areas, we found effects operating only in individual areas, which were partly explained by specific environmental and management characteristics. In study areas with few paddocks, environmental variables exerted a stronger control on livestock activity than in areas with a short stocking period per paddock. CONCLUSIONS: The data demonstrated that a strict pasture rotation with short stocking periods is necessary to influence livestock activity, and hence potential effects on ecosystem processes. Without grazing management, livestock activity is primarily determined by the environment. Such insight is indispensable for studying relationships between grazing animals and ecosystem characteristics, and for developing management strategies to optimize ecosystem services. The analysis also highlighted the need for an appropriate statistical treatment of bio-logging data, since various estimates were biased if spatial autocorrelation was ignored. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s40462-015-0053-6) contains supplementary material, which is available to authorized users

Seasonal Migration of Sika Deer in the Oku-Chichibu Mountains, Central Japan

Movements and seasonal home ranges of 6 GPS collared sika deer were investigated at the Oku-Chichibu Mountains, central Honshu, from April 2009 to March 2010. All deer migrated between discrete summer and winter home ranges. The linear migration distance ranged from 2.5 to 31.9 km. Mean elevation during the summer and the winter ranged from 980 to 1,782 m, and from 1,204 to 1,723 m, respectively. Two deer were upward migrants and 4 deer were downward migrants. Taking into consideration of the relatively small snow accumulation in the summer home range, the possibility of autumn migration to avoid deep snow is low. The percentage of steep slope in the winter home range was higher than that in the summer. Bamboo grass was not found in the summer home range, but was predominant in the winter home range. Road density decreased in the winter home range compared to the summer. Only 2 out of 6 deer stayed mainly in the wildlife protection area during the winter. Our results indicate that the autumn migration was affected by winter forage and human disturbance, thereby assured the survival of the deer during winter.ArticleMAMMAL STUDY. 37(2):127-137 (2012)journal articl

The Relationship Between GPS Sampling Interval and Estimated Daily Travel Distances in Chacma Baboons (Papio ursinus)

Modern studies of animal movement use the Global Positioning System (GPS) to estimate animals’ distance traveled. The temporal resolution of GPS fixes recorded should match those of the behavior of interest; otherwise estimates are likely to be inappropriate. Here, we investigate how different GPS sampling intervals affect estimated daily travel distances for wild chacma baboons (Papio ursinus). By subsampling GPS data collected at one fix per second for 143 daily travel distances (12 baboons over 11–12 days), we found that less frequent GPS fixes result in smaller estimated travel distances. Moving from a GPS frequency of one fix every second to one fix every 30 s resulted in a 33% reduction in estimated daily travel distance, while using hourly GPS fixes resulted in a 66% reduction. We then use the relationship we find between estimated travel distance and GPS sampling interval to recalculate published baboon daily travel distances and find that accounting for the predicted effect of sampling interval does not affect conclusions of previous comparative analyses. However, if short-interval or continuous GPS data—which are becoming more common in studies of primate movement ecology—are compared with historical (longer interval) GPS data in future work, controlling for sampling interval is necessary

Thurber needlegrass: Seasonal defoliation effects on forage quantity and quality

Although Thurber needlegrass (Stipa thurberiana Piper) is an important component of Palouse, sagebrush:steppe, and pine:forest rangelands, little is known of its qualitative and quantitative responses to defoliation. At 14-day intervals one of 7 cohorts of Thurber needlegrass plants was defoliated to a 2.5-cm stubble to describe initial growth rates, determine defoliation effects on subsequent regrowth accumulations, relate regrowth potential to available soil moisture, and determine the nutritional value of initial growth and regrowth for livestock. The study was conducted in 1985 and 1986 with a different group of plants used each year. Although crop-year precipitation for the 1985-86 treatment years was 77 and 111%, respectively, of the long term mean (25.2 cm), growth rates of tussocks were similar between years (P > 0.05). Seasonal yield of regrowth varied between years, however, and was well correlated (r2 = 0.76 to 0.80 P < 0.05) with soil moisture content when treatments were applied. Among 7 defoliation dates (24 April-17 July) only the first 5 yielded regrowth in 1985, and all produced regrowth in 1986. Among treatments regrowth averaged 22% of total herbage yield in 1985 and 50% of total yield in 1986. In both years total herbage accumulations were most suppressed (47-63% reduction) by defoliation during the early-boot stage of phenology. In 1985 when conditions were drier, any defoliation before mid-June depressed (P < 0.05) total herbage yield. Crude protein (CP) of needlegrass herbage was high (19-22%) when growth began in April but declined (P < 0.05) to marginal levels for cattle (6.7-7.7%) by mid-July. Regrowth harvested on 31 July ranged from 7 to 9% CP for the earliest (24 April) treatments and as high as 17% for the latest (17 July). Although Thurber needlegrass can produce highly nutritious regrowth for late-season use, managers face diminishing levels of regrowth as the initial cropping date is delayed later into the growing season. Managers contemplating 2-crop grazing regimes for Thurber needlegrass should base scheduling on plant phenology, soil moisture considerations and historic use rather than specific calendar dates. Further work is needed, however, to definitively determine Thurber needlegrass responses to long-term manipulative grazing regimes.The Journal of Range Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform August 202

Defoliation of Thurber needlegrass: herbage and root responses

Thurber needlegrass (Stipa thurberiana Piper) is an important component of both forested and shrub-steppe communities of the Pacific Northwest and Great Basin regions, and little is known of its tolerance to defoliation. A study was conducted on the Squaw Butte Experimental Range to determine the response of containerized Thurber needlegrass to single defoliations (2.5-cm stubble) throughout the growing season. Dates of treatment spanned vegetative through quiescent stages of phenology. Response variables included: summer regrowth, number of reproductive stems, fall growth, and subsequent spring herbage production, change in basal area, and root mass. Vigor of Thurber needlegrass was reduced most by defoliation during the early-boot stage of development. Impacts were successively less severe from vegetative, late-boot, and anthesis treatments, respectively. Cumulative herbage production the year of treatment was reduced from 38 to 64% by defoliation at the early-boot stage. The same treatment reduced subsequent spring growth by 46 to 51% and root mass the next spring by 34 to 45%. Treatment effects were somewhat reduced when temperature and moisture regimes allowed substantial regrowth after defoliation. Defoliation during or after anthesis had little effect on plant response. Managers should be aware that a single defoliation, particularly during the boot stage, can significantly reduce subsequent herbage production and root mass and possibly lower the competitive ability of Thurber needlegrass.This material was digitized as part of a cooperative project between the Society for Range Management and the University of Arizona Libraries.The Journal of Range Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform August 202

Thurber needlegrass: seasonal defoliation effects on forage quantity and quality.

Although Thurber needlegrass (Stipa thurberiana Piper) is an important component of Palouse, sagebrush:steppe, and pine:forest rangelands, little is known of its qualitative and quantitative responses to defoliation. At 14-day intervals one of 7 cohorts of Thurber needlegrass plants was defoliated to a 2.5-cm stubble to describe initial growth rates, determine defoliation effects on subsequent regrowth accumulations, relate regrowth potential to available soil moisture, and determine the nutritional value of initial growth and regrowth for livestock. The study was conducted in 1985 and 1986 with a different group of plants used each year. Although crop-year precipitation for the 1985-86 treatment years was 77 and 111%, respectively, of the long term mean (25.2 cm), growth rates of tussocks were similar between years (P > 0.05). Seasonal yield of regrowth varied between years, however, and was well correlated (r2 = 0.76 to 0.80 P < 0.05) with soil moisture content when treatments were applied. Among 7 defoliation dates (24 April-17 July) only the first 5 yielded regrowth in 1985, and all produced regrowth in 1986. Among treatments regrowth averaged 22% of total herbage yield in 1985 and 50% of total yield in 1986. In both years total herbage accumulations were most suppressed (47-63% reduction) by defoliation during the early-boot stage of phenology. In 1985 when conditions were drier, any defoliation before mid-June depressed (P < 0.05) total herbage yield. Crude protein (CP) of needlegrass herbage was high (19-22%) when growth began in April but declined (P < 0.05) to marginal levels for cattle (6.7-7.7%) by mid-July. Regrowth harvested on 31 July ranged from 7 to 9% CP for the earliest (24 April) treatments and as high as 17% for the latest (17 July). Although Thurber needlegrass can produce highly nutritious regrowth for late-season use, managers face diminishing levels of regrowth as the initial cropping date is delayed later into the growing season. Managers contemplating 2-crop grazing regimes for Thurber needlegrass should base scheduling on plant phenology, soil moisture considerations and historic use rather than specific calendar dates. Further work is needed, however, to definitively determine Thurber needlegrass responses to long-term manipulative grazing regimes