Dichotomous Key to Representative Birds
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
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.
To determine the bird using the provided dichotomous key, we need to follow the steps in the key and match the characteristics of each bird to the options provided.
1. Start with the first set of choices:
a. If the beak is relatively long and slender, the bird is Certhidea.
b. If the beak is relatively stout and heavy, proceed to step 2.
2. For the second set of choices:
a. If the bottom surface of the lower beak is flat and straight, go to Geospiza.
b. If the bottom surface of the lower beak is curved, proceed to step 3.
3. For the third set of choices:
a. If the lower edge of the upper beak has a distinct bend, the bird is Camarhynchus.
b. If the lower edge of the upper beak is mostly flat, the bird is Platyspíza.
Now, let's examine the characteristics of each bird option provided (W, X, Y, and Z) to determine which one matches the Geospiza description.
A. Bird W: No information provided about its beak, so we cannot determine if it matches Geospiza or not.
B. Bird X: No information provided about its beak, so we cannot determine if it matches Geospiza or not.
C. Bird Y: No information provided about its beak, so we cannot determine if it matches Geospiza or not.
D. Bird Z: No information provided about its beak, so we cannot determine if it matches Geospiza or not.
Since no information is given about the beak characteristics of the birds (W, X, Y, and Z), we cannot determine which one matches Geospiza using the provided dichotomous key.
Based on the provided key, if a bird has a relatively stout and heavy beak, and the bottom surface of the lower beak is flat and straight, it would lead us to Geospiza.
Therefore, the correct answer would be:
B. Bird X