I conducted a study examining bird abundances on and at different distances from an energy development (5 distance “categories” total) over 2 years. I need to determine if there are significant differences in bird abundances 1) for total abundance count and 2) between categories between years (i.e. did bird abundance differ on the entire site, and did bird abundance in category 1 change significantly between year 1 and 2, etc.). I have been using Dunn tests to test for differences in distance categories so far because my data is not normal, but I understand to do a Dunn test I have to use a Levene’s test to look for equal variances between the groups I am testing first. So my problem is that the variances between years are not equal (“av.ab~yr” = “avian abundance by year”):
Levene’st test for equal variances in abundance between years
So are there any recommendations on how I could test for a difference between years given that the variance between years is so unequal? Any help would be much appreciated!!