Screening Global Positioning System Location Data for Errors Using Animal Movement Characteristics

Bjørneraas, Kari; Moorter, Bram Van; Rolandsen, Christer Moe; Herfindal, Ivar

doi:10.2193/2009-405

Cited by 69 publications

(69 citation statements)

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“…Some of the approaches discussed in this study may reduce the effect of GPS location error, such as using the MSD to smooth trajectories, using a mean starting location or using a mean or median location per day. A number of modelling approaches have also been developed to remove GPS location errors and improve GPS accuracy, thus reducing the effect of GPS location errors [ 45 , 46 ].…”

Section: Discussionmentioning

confidence: 99%

Quantifying Migration Behaviour Using Net Squared Displacement Approach: Clarifications and Caveats

2016

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Estimating migration parameters of individuals and populations is vital for their conservation and management. Studies on animal movements and migration often depend upon location data from tracked animals and it is important that such data are appropriately analyzed for reliable estimates of migration and effective management of moving animals. The Net Squared Displacement (NSD) approach for modelling animal movement is being increasingly used as it can objectively quantify migration characteristics and separate different types of movements from migration. However, the ability of NSD to properly classify the movement patterns of individuals has been criticized and issues related to study design arise with respect to starting locations of the data/animals, data sampling regime and extent of movement of species. We address the issues raised over NSD using tracking data from 319 moose (Alces alces) in Sweden. Moose is an ideal species to test this approach, as it can be sedentary, nomadic, dispersing or migratory and individuals vary in their extent, timing and duration of migration. We propose a two-step process of using the NSD approach by first classifying movement modes using mean squared displacement (MSD) instead of NSD and then estimating the extent, duration and timing of migration using NSD. We show that the NSD approach is robust to the choice of starting dates except when the start date occurs during the migratory phase. We also show that the starting location of the animal has a marginal influence on the correct quantification of migration characteristics. The number of locations per day (1–48) did not significantly affect the performance of non-linear mixed effects models, which correctly distinguished migration from other movement types, however, high-resolution data had a significant negative influence on estimates for the timing of migrations. The extent of movement, however, had an effect on the classification of movements, and individuals undertaking short- distance migrations can be misclassified as other movements such as sedentary or nomadic. Our study raises important considerations for designing, analysing and interpreting movement ecology studies, and how these should be determined by the biology of the species and the ecological and conservation questions in focus.

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Section: Discussionmentioning

confidence: 99%

Quantifying Migration Behaviour Using Net Squared Displacement Approach: Clarifications and Caveats

2016

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“…If the animal was captured or recaptured during the 43 day time window around the APEX flights, the first and last days of data collection were excluded from analysis. GPS data were screened for unrealistic movement following the method of Bjørneraas et al [ 80 ], with limiting parameters set to α = 1.5 km/h and cos θ = − 0.97 (velocity and turning angle defining erroneous turnarounds, i.e. spikes in the data), μ = 50 km (possible distance travelled within 20 h) and Δ = 200 km (distance impossible to travel within 20 h; for details see [ 80 ]).…”

Section: Methodsmentioning

confidence: 99%

Foraging ecology of three sympatric ungulate species – Behavioural and resource maps indicate differences between chamois, ibex and red deer

Schweiger

Schütz

Anderwald³

et al. 2015

Mov Ecol

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BackgroundThe spatial distribution of forage resources is a major driver of animal movement patterns. Understanding where animals forage is important for the conservation of multi-species communities, since interspecific competition can emerge if different species use the same depletable resources. However, determining forage resources in a spatially continuous fashion in alpine grasslands at high spatial resolution was challenging up to now, because terrain heterogeneity causes vegetation characteristics to vary at small spatial scales, and methods for detection of behavioural phases in animal movement patterns were not widely available. We delineated areas coupled to the foraging behaviour of three sympatric ungulate species (chamois, ibex, red deer) using Time Local Convex Hull (T-LoCoH), a non-parametric utilisation distribution method incorporating spatial and temporal autocorrelation structure of GPS data. We used resource maps of plant biomass and plant nitrogen content derived from high-resolution airborne imaging spectroscopy data, and multinomial logistic regression to compare the foraging areas of the three ungulate species.ResultsWe found significant differences in plant biomass and plant nitrogen content between the core foraging areas of chamois, ibex and red deer. Core foraging areas of chamois were characterised by low plant biomass and low to medium plant nitrogen content. Core foraging areas of ibex were, in contrast, characterised by high plant nitrogen content, but varied in plant biomass, and core foraging areas of red deer had high plant biomass, but varied in plant nitrogen content.ConclusionsPrevious studies carried out in the same study area found no difference in forage consumed by chamois, ibex and red deer. Methodologically, those studies were based on micro-histological analysis of plant fragments identifying them to plant family or functional type level. However, vegetation properties such as productivity (biomass) or plant nutrient content can vary within vegetation communities, especially in highly heterogeneous landscapes. Thus, the combination of high spatial resolution resource maps with a utilisation distribution method allowing to generate behavioural maps (T-LoCoH) provides new insights into the foraging ecology of the three sympatric species, important for their conservation and to monitor expected future changes.Electronic supplementary materialThe online version of this article (doi:10.1186/s40462-015-0033-x) contains supplementary material, which is available to authorized users.

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“…We therefore treated each trajectory between two recapture events as an independent raccoon dog trajectory. Each trajectory was screened for errors following the method described by [ 32 ].…”

Section: Methodsmentioning

confidence: 99%

Individual and Temporal Variation in Habitat Association of an Alien Carnivore at Its Invasion Front

et al. 2015

Self Cite

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Gathering information on how invasive species utilize the habitat is important, in order to better aim actions to reduce their negative impact. We studied habitat use and selection of 55 GPS-marked raccoon dogs (30 males, 25 females) at their invasion front in Northern Sweden, with particular focus on differences between males and females, between movement states, and between seasons and times of the day. Daily movement pattern was used to classify GPS-locations into dispersing and settled. We focused on both anthropogenic and natural landscape characteristics. Since we did not have any a priori knowledge about the spatial scale of raccoon dog habitat selection, we first assessed how landscape characteristics of random points changed with distance from the GPS-location they were paired to. Because changes in habitat use became less pronounced at approximately 5 km for all variables, we focused on habitat use at two spatial scales: fine (500 m) and coarse (5 km). Habitat selection was strongest at the coarse scale, and reflected the results found for habitat use. Raccoon dogs selected agricultural areas and wetlands, lower altitudes, and shallow slopes, and avoided forests, open natural areas, and areas close to water and roads. There were no differences in habitat selection between males and females, or between movement states. This lack of sexual segregation increases the probability of encountering potential mates during dispersal, and therefore the likelihood for reproduction in new areas. The seasonal and diurnal pattern of habitat use may provide guidance for where and when to aim management efforts.

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Screening Global Positioning System Location Data for Errors Using Animal Movement Characteristics

Cited by 69 publications

References 0 publications

Quantifying Migration Behaviour Using Net Squared Displacement Approach: Clarifications and Caveats

Quantifying Migration Behaviour Using Net Squared Displacement Approach: Clarifications and Caveats

Foraging ecology of three sympatric ungulate species – Behavioural and resource maps indicate differences between chamois, ibex and red deer

Individual and Temporal Variation in Habitat Association of an Alien Carnivore at Its Invasion Front

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