I am comparing rate of capture (animal captures per hour) between two years. I'm interested in determining whether there is a difference between rate of capture between the two years. A survey night represent a sample and measures are independent. Sample sizes are small for each group (n1=18, n2=12), variances are unequal, and QQ plots, histograms, and box plots strongly suggest a non-normal distribution.
Because of the non-normality nature of the data, I have explored using a Mann-Whitney U-test test. I realize others have asked similar questions regarding if Mann-Whitney can be used if variance is unequal and I understand that it can be used, but that interpretation becomes more narrow. Specifically, my understanding is that if variances are unequal (i.e., distributions between the two groups differ) then hypothesis testing addresses differences in distribution, not differences in mean (or median).
My two questions are as follows:
1) Can I interpret the results from a Mann-Whitney U-Test - given the unequal variance of my 2 groups - in the context of difference in means?
2) If not, is there a more appropriate test for my situation?