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BIOL 4240Field Ecology

Ecologists are often interested in spatial data…Plant ecologists, distribution of individuals.

Animal ecologists, distribution of individuals AND movements

Which way did they go?

What purpose can movement/telemetry studies serve?


* 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


N

10 Random WalksMinimum Convex PolygonObserved Movement Path

1 0 1 2 Kilometers

• Home ranges – Various models (polygons, parametric and non-parametric)








• Home ranges – 2 variables have big influence…1) How many animals

2) How many points per animal


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



• 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


• Survival –

– Use computer software SURVIV by White (1983)

– Program MARK?– Various other methods…

Mayfield, Kaplan-Meier, Cox’s


• Questions necessary to determine…

– What type of study?

*Observational (descriptive or correlative)

*Manipulative



– Hypothesis testing or Model building?

*Which type of study is more appropriate for model building?



– What level of inference?• What is the population?• Time of day?• Scale?



– 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



– Sampling design?

– Sampling intensity?• Preliminary estimates of means/variances• Determining biological significance• Choosing desired power• Calculating necessary N



– 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)



– Are Radio-marked animals an unbiased sample?*Effects of non-random capture*Marking-induced or relocation-induced changes in

behavior and survival



– Are location errors addressed?*PDOP*Remote estimation



– Are biases in observation rate identified and corrected?

*remote estimation (GPS collars etc.) important

• Preliminaries…

– How many dimensions do tracking data have?


• Coordinate Systems…Explain UTM and why it is preferred*Advantages of Lat./Long.?

*Disadvantages?


• 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)...


• 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


• Coordinate Systems… * N or S then UniversalPolar Sterographic (UPS) used.



– What other data are important to include with location data?



– Cause and Effect can ONLY be determined through which type of experiment?



– 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?
