Academic journal article The American Midland Naturalist

Display of Animal Location Data and Kernel Home Range Contours in Google Earth Pro

Academic journal article The American Midland Naturalist

Display of Animal Location Data and Kernel Home Range Contours in Google Earth Pro

Article excerpt

ABSTRACT.

This paper presents step-by-step instructions for taking an animal location data set, creating a set of kernel home range utilization distribution contours, and formatting and manipulating those contour files for display in Google Earth. The intent of this paper is to assist researchers studying animal movement and habitat use patterns in overcoming common problems of interoperability of data between the various software programs. I also highlight the features of Google Earth Pro that add useful information on habitat and terrain characteristics to the display of animal location and home range data, as well as those features that permit analyses of home range and habitat use.

Researchers studying animal movement and habitat use patterns often encounter difficulty formatting and transferring data files among the various software programs used for home range creation, analysis and display. For example, in the mid 1990s I used the DOS-based KERNELHR program (Seaman et al, 1998) to compute home ranges of southern flying squirrels (Glaucomys volani) but had to have a programmer write a script to import those contour files into the UNIX Geographic Resources Analysis Support System (GRASS) (USACERL, 1993) geographic information system (GIS), where I conducted habitat selection analyses using habitat layers digitized from aerial photography of study areas (Taulman and Smidi, 2004). Graphic display of those habitats overlain with home ranges required furtiier complex manipulations and conversions of data files. In this paper I will provide instructions for taking an animal location data set, creating a set of kernel home range utilization distribution contours, and formatting and processing those contour files for ultimate display in Google Earth Pro (Google, 2009). Google Earth Pro's color satellite landscape imagery and spatial analysis tools allow the user to easily display and examine animal locations and home ranges, as well as to conduct rigorous habitat selection analyses.

In studies of animal home range and habitat use researchers have several metíiodological options to address: (1) the home range model and software to employ to create range boundaries from location data, (2) whether to incorporate information on habitats contained within die home range in the analysis and (3) how to display home range and habitat data to enhance interpretation, analysis and communication of results to others.

The kernel home range model has been in use in wildlife studies for over 20 y (Worton, 1987, 1989). The kernel method is a nonparametric function applicable to multimodal location data and it produces a probability density estimate unaffected by grid size (Seaman and Powell, 1996; Hansteen et al, 1997). The earlier and simpler minimum convex polygon (MCP) home range model (Mohr, 1947) provides no information on the differential use of areas within the home range boundary (Laver, 2005). Ecological questions addressed using the MCP mediod are limited to comparing size and overlap of ranges among a group of animals (Pratt et al, 2001). Neverdieless, some researchers continue to attempt habitat selection analyses using this method, assuming a uniform use of all habitats enclosed by die range polygon (Ramier and Gipson, 2000; Foerster and Vaughan, 2002).

The increased information provided by the kernel mediod on an individual animal's use or avoidance of areas within its range (and the possibility of performing a valid habitat selection analysis) , compared with the simpler MCP mediod, have led to increased use of the kernel mediod in ecological studies in recent years (Grinder and Krausman, 2001; Hidalgo-Mihart et al, 2006). But habitat data must be layered with the home range contours to accurately assess an animal's habitat use patterns. Without incorporating habitat data into home range analyses, much of the information contained in die kernel utilization distributions is lost and the researcher is again limited to discussing range size and overlap (McCullough et al, 2000; Benson et al. …

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