Hi, any suggestions will be welcome as the title reads.
- Four habitats to compare, one which is a control
- Bird data (categorical and quantitative, traits, abundances, microhabitat uses, nesting categories) for breeding and non-breeding seasons
- Various tree characteristics measured.
Which tests could I perform with what data to understand how bird communities use the different habitats?
This sounds like a similar problem to one I studied, except mine was plants (as opposed to birds) in restoring fields (equivalent to your habitats) with land use and flooding variables (environmental data, same as your tree characteristics). I found fourth corner modelling the best approach and used the mvabund package in R to implement it (relatively simple and good details in the package manual). In our analysis we used all the fields in the same model as one of the environmental gradients captured the difference between them, but perhaps if you are comparing between habitats you might need to fit a model for each one. Here are the links for my paper and another that have used this method and some of the background for the type of fourth corner models and mvabund (the Brown et al. is a good starting point):
http://onlinelibrary.wiley.com/doi/10.1111/1365-2664.12922/full
http://onlinelibrary.wiley.com/doi/10.1111/2041-210X.12163/abstract
https://link.springer.com/article/10.1007/s00442-016-3700-8
http://rpubs.com/dwarton/68823
Sounds like a GLM - GAM approach type problem. in R you can use the standar stats library (for glm) or mgcv for gam.
First, it is meaningless to call a habitat a 'control' because all habitats are different – just say you have four habitats. Then, as David said in Prometheus, 'your answers depend on what you hoped to achieve'. So you need some definite questions (or hypotheses) that you require answering before you start analysing your data. It seems that your main question is 'habitat use by birds', the categories of which will be things such as foraging, roosting (or perching), and nesting. So, use the tree characteristics to define your habitats. Then, as Emigdio stated, you can perform GLM with post-hoc tests to determine if bird data differed significantly between habitats in breeding and non-breeding seasons. Your factors are 'habitat' (characterised by tree traits) and 'season', both of which are fixed, and your variables are the bird data. Canonical ordination is also an option. I hope this helps :)
Thanks Samantha, Emigdio and Andrew fro the insights. I wasn't clear on the first point: I sampled three sub-habitats that are part of an original, unique and overarching habitat and a fourth outside that we considered the usual, common and non-unique habitat. hence, the control affiliation. The questions are there, I was just wanting to see which stats. tests are going to be suggested to answer habitat-use questions. Thanks again as I have been led astray by some supervisors of mine and that is now obvious seeing your suggestions.
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