I would like to analyse three breeding grounds, one active, one recently abandoned and one abandoned for several years. The predictors are continuous, rough percentage of the coverage of a particular habitat type. Their distribution is quite skewed, many times only either 100 or 0%. The units are patches, altogether around 300, with 30 predictors. The dependent variable is therefore multinomial (three classes exactly). Which would be a good statistical technique to analyse this situation? I thought of multinomial boosted regression trees but cannot find any good instructions to do it. Thanks!!!