Niche blogs, but low CTR? Adsense

t quiet some visitors splitted over mostly 3 different niche blogs. I have around 5k visitors - 7k visitors a month. Tho, my ctr is far below 1. I make like 10 euro a month from these visitors by clicking my adsense. My niches are categorized in quotes, small animals and drugs. Are these just bad niches? So that's why the ctr is low?

Also, I am wondering if there would be any other options to make a little more from those amount of visitors. Help would be appriciated .

Yeah there are more about it
the first two would be:
the niches
the template.