[MARMAM] Habitat modeling paper

Leigh Torres torr3 at yahoo.com
Fri Oct 10 13:23:47 PDT 2008

Dear Colleagues,

I would like to bring your attention to the following paper that was recently published in Ecological Applications. In particular, I believe this paper will be of interest to those who are working on predictive habitat models of marine mammals. The article may be downloaded from ftp://ecap-18-06-07_07-1455_rfp:1807@ftp.esa.allenpress.com or by request to me.

Leigh Torres

Torres, L., Read, A., and Halpin, P. 2008. Fine-scale habitat modeling of a top marine predator: Do prey data improve predictive capacity? Ecological Applications. 18(7), 1702-1717.


Predators and prey assort themselves relative to each other, the availability of resources and refuges, and the temporal and spatial scale of their interaction. Predictive models of predator distributions often rely on these relationships by incorporating data on environmental variability and prey availability to determine predator habitat selection patterns. This approach to predictive modeling holds true in marine systems where observations of predators are logistically difficult, emphasizing the need for accurate models. In this paper, we ask whether including prey distribution data in fine-scale predictive models of bottlenose dolphin (Tursiops truncatus) habitat selection in Florida Bay, Florida, USA, improves predictive capacity. Environmental characteristics are often used as predictor variables in habitat models of top marine predators with the assumption that they act as proxies of prey distribution. We examine the validity of this assumption by
 comparing the response of dolphin distribution and fish catch rates to the same environmental variables. Next, the predictive capacities of four models, with and without prey distribution data, are tested to determine whether dolphin habitat selection can be predicted without recourse to describing the distribution of their prey. The final analysis determines the accuracy of predictive maps of dolphin distribution produced by modeling areas of high fish catch based on significant environmental characteristics. We use spatial analysis and independent data sets to train and test the models. Our results indicate that, due to high habitat heterogeneity and the spatial variability of prey patches, fine-scale models of dolphin habitat selection in coastal habitats will be more successful if environmental variables are used as predictor variables of predator distributions rather than relying on prey data as explanatory variables. However, predictive modeling
 of prey distribution as the response variable based on environmental variability did produce high predictive performance of dolphin habitat selection, particularly foraging habitat.

Leigh G. Torres
Post-doctoral researcher
National Institute of Water and Atmospheric Research (NIWA)
301 Evans Bay Parade, Greta Point, 
Kilbirnie, Wellington, New Zealand. 
E-mail: l.torres at niwa.co.nz


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