Problem Set:

This homework will involve 2 parts. In the first part you will present analyses of your line transect and point count data.  For the second part you will analyze a published application of distance sampling methods.

Part I.

Field data analyses

For this portion of the problem set you will have to perform 2 analyses.   The first analysis will be done on the line transect data set you collected in the old Arboretum.   The second analysis will use your point count data.  Use program DISTANCE to analyze this data in an appropriate fashion [i.e. stratify the habitat, and use intervals and truncate as you see fit].  You will also need to change the area units in the data entry section as warranted.  Total area surveyed in the line transect exercise was 500m².  Area surveyed in the point count was 1962.5m².  (Remember: circular area=pi*r²)

(10 pts) Write a short scientific paper to report your findings (Body of text [items 1-4] should be a maximum of 2 pages double spaced; not including the table).  Your lab should have these sections:

1.  Introduction -  Briefly describe distance sampling.   State the objectives of the lab (Explore distance sampling using line transect and point count analyses).

2.  Methods - Briefly describe the field methods used to collect the data and how you analyzed both data sets (models and data filter used).

3.  Results - Create a table that compares all the method/strata combinations.  Report the key function and series expansion chosen, density, f(0) or p(0), and effective width/radial distance.  Include each estimate's 95% CI.  Report any other relevant results from this lab.

4.  Conclusions - Compare and contrast the results you obtained using the line transect and point count methods (make sure to comment on all information listed in the results section).  Include any relevant assumptions, possible violations to those assumptions, and consequences of violating those assumptions.  Which method seemed to give the most reasonable results?  Why?

5.  Literature Cited - Background information that you include should be cited here.

6.  Appendix - Include your raw data (either field notes or spreadsheet form). Copy all relevant output (e.g., graphs) from Program Distance into this section.  Do not include all of the output, only the parts that are applicable.

Part II.

Distance sampling case study

For this part of the homework, we expect you to find 1 example of an application of distance sampling methods published in the peer-reviewed literature.  Draw on your previous literature searching experience (Lab 1) to find the paper you will use for your case study analysis. (Good keyword choices might be: distance sampling, line transect, or point count) Because you will need to read the article thoroughly, you should either print out the full article or pull the journal from the stacks and photocopy the article.  

(10 pts) You will summarize your analysis of the chosen case study in short essay format (max. 2 pages, double-spaced).  At a minimum, your essay must address the following points:

• At the top, give the full citation for the article you used.

• Where was the study area and what habitat types were present?

• What was the study organism, or group of organisms. (For example, you might find a paper on "grassland birds")

• How did the study environment (e.g., forest cover, deep ocean) and study animal characteristics combine to affect the investigator's choice of methods?

• What were 2-3 of the key results obtained in the study via distance sampling methods?

• Discuss the merits and potential flaws in the investigator's application of distance sampling methods.  For example:  Were the core assumptions met?  Were the methods the best choice for the situation? Were the analyses conducted properly and presented clearly? 

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Revised: 25 August 2011