BIOL 4240Field Ecology
Ecologists are often interested in spatial data…Plant ecologists, distribution of individuals.
Animal ecologists, distribution of individuals AND movements
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What purpose can movement/telemetry studies serve?
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* Movement patterns, migration, dispersal* Space use and home range size* Resource use and selection* Population abundance and density* Survival* Fecundity
• Movement patterns – assumed to be random through homogenous environment
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N
10 Random WalksMinimum Convex PolygonObserved Movement Path
1 0 1 2 Kilometers
• Home ranges – Various models (polygons, parametric and non-parametric)
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• Home ranges – Various models (polygons, parametric and non-parametric)
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• Home ranges – Various models (polygons, parametric and non-parametric)
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• Home ranges – Various models (polygons, parametric and non-parametric)
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• Home ranges – 2 variables have big influence…1) How many animals
2) How many points per animal
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Confidence level (%)
Bound (%)
N necessary
95 10 386
95 20 98
95 30 45
• Resource use/selection – Describe habitat with discrete categories…– Cover type– Vegetation types– Topography– Successional stage
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• Population Abundance & Density –
– Use telemetered animals as “marked”– Use tagged animals to determine
visibility bias for aerial surveys… helps to minimize underestimation that is common
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• Survival –
– Use computer software SURVIV by White (1983)
– Program MARK?– Various other methods…
Mayfield, Kaplan-Meier, Cox’s
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• Questions necessary to determine…
– What type of study?
*Observational (descriptive or correlative)
*Manipulative
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• Questions necessary to determine…
– Hypothesis testing or Model building?
*Which type of study is more appropriate for model building?
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• Questions necessary to determine…
– What level of inference?• What is the population?• Time of day?• Scale?
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• Questions necessary to determine…
– What is the sample/experimental unit?
*Location point/data
*Animal
* Social considerations
AVOID pseudoreplication (dependence or correlation of sample units, and artificially high estimates of precision) to minimize > type I error
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• Questions necessary to determine…
– Sampling design?
– Sampling intensity?• Preliminary estimates of means/variances• Determining biological significance• Choosing desired power• Calculating necessary N
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• Questions necessary to determine…
– Sampling design?
– Sampling intensity? *Studies suggest that 20-25 animals with ~50 pts
necessary for determining resource selection… AND
*50-300 pts /animal necessary for home range size(Rowland et al. 1997, 1998)
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• Questions necessary to determine…
– Are Radio-marked animals an unbiased sample?*Effects of non-random capture*Marking-induced or relocation-induced changes in
behavior and survival
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• Questions necessary to determine…
– Are location errors addressed?*PDOP*Remote estimation
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• Questions necessary to determine…
– Are biases in observation rate identified and corrected?
*remote estimation (GPS collars etc.) important
• Preliminaries…
– How many dimensions do tracking data have?
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• Coordinate Systems…Explain UTM and why it is preferred*Advantages of Lat./Long.?
*Disadvantages?
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• Coordinate Systems… Explain UTM and why it is preferred*Universal Transverse
Mercator (UTM)…between 84 N and 80 S divided into 6° rectangles (zones 1-60)...
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• Coordinate Systems… Explain UTM and why it is preferred* Example… zone 1 = 180 W Prime meridian = 177 W)
* What are the units in a number AND what do they convey regarding precision?0291923, 4441087 vs. 0291, 4441
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• Coordinate Systems… * N or S then UniversalPolar Sterographic (UPS) used.
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• Preliminaries…
– What other data are important to include with location data?
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• Preliminaries…
– Cause and Effect can ONLY be determined through which type of experiment?
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• Preliminaries…
– Considerations for radio tags…– Smallest size possible– Cryptic coloration– Transmitter effects on behavior/fitness– Requisite time for adaptation– Critical life history periods to avoid– Others?
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