I am comparing habitat availability vs. use by a bird species using the R compana() function (package adehabitat) which uses Aebischer et al. (1993) method. It is a 3rd order habitat selection analysis, so the availability of habitats is different for each bird.
The compana randomisation test resulted in a nice habitat ranking plus a table with the significance of paiwise comparisons. The only thing I need more, are log-ratio differences or Manly selection ratio's (considering that these are given in almost every paper on habitat selection). Thus, I tried the Wi function that computes Manly's selection ratios. The problem is that the resulting ranking of habitats is very different from the one produced by compana, and the compana result seems to fit much better to the raw data. Apparently the results of these methods cannot be combined.
So now I am a bit lost. I hope someone is willing to explain
- Why these two methods (compana and Manly selection ratio's) produce such different habitat rankings and how they relate to each other.
- If I can obtain log-ratio differences within the compana function.
- How I can view the data tables that compana has used. (I know how to view the tables that I entered myself, but
companareplaced some zero-availability values by the weighted mean lambda, and I would like to see the new availabity table)
...Or any other advice on how to proceed.
