Hello Everyone! I have recently used the adehabitatHS package in R with Design III (widesIII function) data to estimate overall manly selectivity measures (wi) for two study populations. I am interested in habitat selection and the lands have been categorized into 4 land-use types (pine, hardwood, pasture, ruderal). Approximately half of our GPS collared animals are on a high-fenced preserve and the other half are on state-managed lands located adjacently. I have been having trouble finding a significance test that would allow me to compare population habitat selectivity measures, at each habitat type, between our wild and farmed study populations. Is anybody aware of any significance tests that could be applied in this situation? Any assistance would be much appreciated!
Hi, that kinds of statistics (selectivity, niche overlap) are usually compared using bootstrap measures, as their theoretical distributions are often unknown.
Check:
Article Statistical Inference on Measures of Niche Overlap
Article Bootstrapping Wildfire Selectivity for the Forest Types of C...
https://s3.amazonaws.com/academia.edu.documents/41833573/Habitat_selection_by_invasive_alien_plan20160131-23150-orzbri.pdf?AWSAccessKeyId=AKIAIWOWYYGZ2Y53UL3A&Expires=1553002348&Signature=rnOHsHLPYOWUXJIUW3c%2FXu9hsos%3D&response-content-disposition=inline%3B%20filename%3DHabitat_selection_by_invasive_alien_plan.pdf
Or just type "manly selectivity bootstrap" in GoogleScholar.
Cheers
Obvious, perhaps, but a simple chi-square test can compare use to an expected value based availability in the environment. Also check out Ivlev’s electivity index as a way toncompare these quantities
Hi Jeremy Orange. There is a simple and elegant example of how you can perform these comparisons between habitat availability and use in these articles:
Neu, C. W., Byers, C. R. and J. M. Peek. 1974. A technique for analysis of utilization-availability data. Journal of Wildlife Management 38:541-545.
Byers, C. R., Steinhorst, R. K. and P. R. Krausman. 1984. Clarification of a technique for analysis of utilization-availability data. Journal of Wildlife Management 48:1050-1053.
With GPS track data and quantification of habitat availability this is easy to do.
All the best,
Alexander
We used a log-likelihood ratio tests (similar to a chi-squared test) and something similar to Ivlev's electivity index to compare between groups in examining selection of prey. Either may be useful to you. Details here: Article Diet Selection by a Lizard Ant-Specialist in an Urban System...
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