Dichotomous Key to Representative Birds

Question

1. a. The beak is relatively long and slender.................Certhidea
b. The beak is relatively stout and heavy.................go to 2
2. a. The bottom surface of the lower beak is flat and straight.......Geospiza b. The bottom surface of the lower beak is curved.................go to 3
3. a. The lower edge of the upper beak has a distinct bend.........Camarhynchus
b. The lower edge of the upper beak is mostly flat.................Platyspíza

Using the key above, which of the following is Geospiza?
A. Bird W
B. Bird X
C. Bird Y
D. Bird Z

Answer 1

Based on the given key, Bird Z is most likely to be Geospiza because it has a relatively stout and heavy beak with a curved bottom surface of the lower beak. Therefore, the correct answer is D.