this isn't too difficult!! it's just an unfamiliar graph which tripped me up for a second, too. what a weird format honestly but anyways
#34 is going to be the red line. you can figure this out by thinking to yourself, "okay, 8 years for 1 cycle" and starting with the horizontal axis. go over 1, because it's 1 cycle, then go up to 8 years... and you run into the red line crossing through. this means that the red line represents 8 years per cycle, and therefore, the red grouse.
#36 is going to be the blue line. you figure it out the same way as above, just with different values: 4 years for 1 cycle. go over 1 for 1 cycle, then go up to 4 years... and it's the blue line crossing through that point. to double-check this one, you could even go over to 2 cycles (which would take 4 years, for the lemming), and you have the blue line crossing through the 8 year mark. that means the blue line is representing the lemmings.