Improved communication systems, shrinking battery sizes and the price drop of tracking devices have led to an increasing availability of trajectory tracking data. These data are often analyzed to understand animals behavior using mixture-type model.In this work we propose a new model based on the Logistic-Normal process. Due to a new formalization and the way we specify the coregionalization matrix of the associated multivariate Gaussian process, we show that our model, differently from other proposals, is invariant with respect to the choice of the reference element and of the ordering of the components of the probability vectors. We estimate the model under a Bayesian framework, using an approximation of the Gaussian process needed to avoid impractical computational time.We perform a simulation study with the aim of showing the ability of the model to retrieve the parameters used to simulate the data. The model is then applied to the real data where a wolf is observed before and after the procreation. Results are easy interpretable showing differences in the two phases.We record a time series of spatial locations of the female wolf called F24 (2-3 years old), that was live-trapped in May 2009 in the Abruzzo, Lazio and Molise National Park (central Apennines, Italy) and equipped with a Vectronic Pro Light-1 collar (Vectronic Aerospace GmbH, Berlin, Germany). Details on wolf capture and handling are provided in [36]. During winter months (January -April), fix attempts were scheduled every 30 minutes for 10 days, and every 3 hours for 20 days for the rest of the year. The lower acquisition interval during winter months was programmed with the aim to estimate wolf kill rate through field investigations of GPS clusters [58].When first captured, F24 was a member of the Villa pack, where it remained for 7.9 months before dispersing and establishing a new pack (i.e., Bisegna pack) in January 2010. The wolf reproduced in May 2010 and, using information derived from its GPS locations, we were able to determine the actual position of the den. Between May 28th and June 4th, F24 restricted its movements in the proximity of the den. We therefore assumed that F24 entered the den on May 28th and reproduced in the following days. Until collars failure on June 16th, F24 systematically revisited the den to feed and attend the cubs. We collected locations from F24's collar with a mean acquisition rate of 91.5%. We decided to
The modelIn a mixture-type model the clustering is generally encoded using a discrete (latent) random variable z = {z t } t∈T , where z t ∈ {1, 2, . . . , K} ≡ K is a membership variable such that z t = k indicates the behavior at time t.