Home Range Calculations
Student Name: SCIN 401 Mammalogy
Case Study Assignment Week 7: Home Range Calculations
Read the following information about home ranges and the case example. Follow the directions for the calculations. Answer the essay question completely using thoughtful ideas, the course text, and outside reference sources. Proofread answers for potential writing errors.
Part A. Background on Home Ranges
Intraspecific competition for resources and other behavioral interactions can drive territoriality and establishment of home ranges. Many mammal species exhibit forms of territoriality that result in home ranges.A home range is defined by Burt (1943) as “that area traversed by the individual in its normal activities of food gathering, mating, and caring for young.” Mammals known to exhibit territoriality occur in the orders Perissodactyla, Carnivora, Lagomorpha, Rodentia, Primates, Chiroptera, and Socicomorpha (Vaughan et al. 2011). Study of home ranges can increase knowledge about the species ecology, including habitat quality, and behavior.
Calculation of home ranges from raw location data is beyond the scope of this case study; however, it is valuable to know in general terms how home ranges are calculated. Generally individuals are marked and then location data is gathered by capture-recapture, observation capture, radio-telemetry, and/or satellite data (e.g., collars with GPS transmitters have been used on large species like polar bears [http://alaska.usgs.gov/science/biology/polar_bears/tracking.html]). Location data is graphed usually with the aid of mapping software like ArcGIS (http://www.esri.com/software/arcgis/index.html) or even Google Earth Pro (Taulman, 2010). Statistical techniques are used to calculate and analyze home ranges such as minimum convex polygons, bivariate ellipses, adaptive and fixed kernels, and even a Brownian bridge technique (Mitchell, 2006). Home ranges can be overlayed with other GIS data layers (e.g., habitat cover type, elevation, water sources, etc.), to create powerful analyses and hypotheses for further research.
Reference Sources
Burt, W. H. (1943). Territoriality and home range concepts as applied to mammals. Journal of Mammalogy, 24:346-352
Mitchell, Brian R. 2006. Comparison of programs for fixed kernel home range analysis. Remotely Wild (Issue 21, June 2006).
Taulman, J.F. (2010). Display of Animal Location Data and Kernel Home Range Contours in Google Earth Pro. The American Midland Naturalist 164(1):157-164. 2010 doi: 10.1674/0003-0031-164.1.157
Vaughan , T.A., Ryan, J.M., &Czaplewski, N.J.(2011)Chapter 23, Territoriality and Home Range. Mammalogy(course text), Jones & Bartlett, Sudbury MA
Part B. Case Example
( Photo Credit: Sally King, U.S. National Park Service )In this case example, three populations of Abert Squirrel (Sciurusaberti) also called the tassel-eared squirrelwere studied. Sciurusaberti is found in ponderosa (Pinuspondersa) forests inWyoming, Colorado, New Mexico, Arizona, Utah, and northern Mexico(Mejia, 1999).There are up to eight recognized subspecies that are distinct due to geographic isolation and discontinuous ponderosa forest distribution (Lamb et al. 1997). They have an integrated ecology with ponderosa pine which they rely on for feeding, nesting, and cover(Grotheret al. 2005). Optimal habitat for Sciurusabertiis late successional mixed age ponderosa pine forests. A combination of management practices such as logging, grazing, and wildfire suppression haveresulted in homogenous even age stands that are suboptimal squirrel habitat (Grotheret al. 2005). In this case example, home range distributions of three isolated populations of Sciurusaberti in Colorado were measured by radio telemetry and observation catching. Data was analyzed using ArcGIS software with resulting average home range sizes for radio tagged individuals.
Reference Sources
Grother, C. Vazquez, M. & Spicer, L. (2005) Abert’s Squirrel (Sciurusaberti) Species Assessment.US Forest Service. Retrieved from http://www.fs.usda.gov/Internet/FSE_DOCUMENTS/stelprdb5199814.pdf
Mejia, J. 1999. “Sciurusaberti” (On-line), Animal Diversity Web.Retrieved from http://animaldiversity.ummz.umich.edu/site/accounts/information/Sciurus_aberti.html.
Lamb, T. Jones, T.R.&Wettste, P.J.(1997) Evolutionary Genetics and Phylogeography of Tassel-Eared Squirrels (Sciurusaberti).Journal of Mammalogy 78(1): 117-133
Other Reference Sources
http://www.nps.gov/band/naturescience/aberts-squirrel.htm
http://www.mnh.si.edu/mna/image_info.cfm?species_id=300
http://www.wildlife.state.nm.us/education/wildlife_notes/documents/Abertssquirrel.pdf
Part C. Data
Individuals for each population were marked with radio telemetry devices and locations were taken multiple times daily for six months (April-October). Data was recorded in the field with GPS devices then downloaded and analyzed using fixed kernel algorithm. The results of the home range size and graphical representation are given here.
| Population A | |
| Individual | Home Range Size(ha) |
| 1 | 226 |
| 2 | 172 |
| 3 | 204 |
| 4 | 159 |
| 5 | 197 |
| 6 | 184 |
| 7 | 178 |
| 8 | 148 |
| Population B | |
| Individual | Home Range Size(ha) |
| 1 | 74 |
| 2 | 66 |
| 3 | 97 |
| 4 | 105 |
| 5 | 76 |
| 6 | 88 |
| 7 | 72 |
| 8 | 110 |
| 9 | 83 |
| 10 | 78 |
| Population C | |
| Individual | Home Range Size(ha) |
| 1 | 357 |
| 2 | 343 |
| 3 | 368 |
| 4 | 377 |
| 5 | 246 |
| 6 | 255 |
Part D. Home Range Calculation
For this case study use the data for each population to calculate the average (mean) home range and standard deviation. Calculations can be done manually or by Excel (use Summary Statistics).
An arithmetic mean is calculated by the sum of the elements divided by the total number of elements. In this assignment take each home range size for each individual and sum then divide the sum by the number of home ranges.
The standard deviation is a measure of central tendency or variation in the data. Standard deviation is calculated as the difference of each element from the mean:
| Results | ||
| Population | Mean Home Range Size(ha) | Standard Deviation (s) |
| A |
183.5 |
33.5 |
| B |
84.9 |
22 |
| C |
324.3 |
65.5 |
Part E. Home Range Conclusions and Analysis
Utilizing and specifically citing the data and results of home range data and compare and contrast the three populations. Propose at least two alternative hypotheses (reasons) for the differences in the data.Propose how each hypothesis could be tested. Discussion should be a minimum of 300 words and contain significant thought and analysis and utilize at least two reference sources in APA. Some questions you should answer include:
· What could cause the spatial pattern observed in each population?
· What could cause the difference in the average home range size?
· What data would you collect to test your hypothesis?
SCIN 401
Case Study Assignment Lesson7
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