Spatio-temporal Analysis of Brown Bear (Ursus arctos) Interactions in the Mating Season
Laboratory of Geo-Information Science and Remote Sensing, Wageningen University, 09 June 2011David Haberkorn
“Little is known about the mating related behaviour of the brown bear, for example how individuals find or track down each other, how long they stay together or which bears associate with others in terms of reproductive status or sex. In order to better understand the ecology of the brown bear, the Scandinavian Brown Bear Research Project (SBBRP) uses GPS collars to record the movements of brown bears. I have used these GPS movement data for a spatio-temporal analysis. The objective was to analyse behavioural patterns in order to obtain new knowledge about the brown bear mating system. The first research question aimed at extracting an individual‘s reaction after crossing the track of another individual in terms of changes in speed and direction. In total, 672,118 intersections have been extracted from the datasets and presented regarding changes in speed and direction according to different ages of the crossed tracks (0 – 24 h, 24 h – 72 h, 72 h – 168 h, 168 h – 336 h, > 336 h) and different sex classes. The second research question concerned the extraction of encounters between individuals and determination of their duration. Encounters were defined as positions of two bears within a spatial threshold of either 100 m or 200 m and within a temporal window of ±15 minutes. In total, 628 encounters were extracted for a spatial threshold of 100 m and 793 for the 200 m threshold. They were presented according to different sex and reproductive status class combinations. The analysis was conducted by implementing the spatio-temporal concepts =lagged co-incidence in space and time’ and =co-incidence in space and time‘ (Andrienko and Andrienko, 2007; Andrienko et al., 2008) in a ArcGIS 9.3 with Hawths Tools extension and custom programming in Python. The methods and results of this analysis were validated by experts from the SBBRP and are confirmed to be useful and delivering new knowledge about the mating related behaviour of the brown bear. The analysis developed during this research can also be applied to movement data of other species.”
