Key to B.C. Frogs and Toads
How to use the key:
Dichotomous keys are very commonly used in biology – you may have seen one before.
Dichotomous means two-branched, and these keys are a useful way to break down an
identification process into a number of simple steps. There are paired descriptions
of different traits, each numbered. For each pair (beginning at no. 1), click the
option (a) or (b) that best fits your animal, and go to the numbered characteristic
given by that option. Choose the best option again, and so on until you come to a
species. Click on the name to see the species description, and see whether the
description fits what you saw. If it doesn’t, try the key again, especially if you
were not sure of one or more of your choices.
For example, suppose I have seen a small frog in the Lower Mainland. I look at its
eyes and see that it has horizontal pupils, so I click on 1(b). This directs me to no.
3; I choose (b) again because my frog has smooth skin. In no. 4 I choose (a) because
my frog has a dark eye stripe and sticky pads on its toes. I discover that I have
seen a Pacific Chorus Frog (and a cute little creature it was, too).
Illustrations taken from: Green, D.W. and R.W. Campbell. 1984. The Amphibians of British Columbia.
British Columbia Provincial Museum, Handbook 45. Used with permission of RBCM.
Pupil of eye vertical when contracted … go to 2
Pupil of eye horizontal when contracted … go to 3
No parotoid glands or warts present, skin smooth or with scattered tubercles …
go to 4
Toe-pads absent or inconspicuous … go to 5
Dark side and dorsal stripes absent, dorsolateral folds and/or skin fold around
ear membrane present … go to 6
No large, rounded spots on back … go to 7
Colour green or olive green, no dark facial mask present.
Adult males with deep yellow throats and ear membranes larger than diameter of eye.
… go to 8
Colour brown or tan, may have black, irregular spots on back, dark facial mask
more or less obvious … go to 9
Red, orange or yellow colouration underneath, especially in older
individuals, dark spots present on back, facial mask present but not intensely
dark … go to 10
This key is used here by permission of the
Royal British Columbia Museum. It is modified from the key appearing in their handbook,
The Amphibians of British Columbia by David Green and R. Wayne Campbell, which was
published in 1984.
Photo © Russ Haycock. No reproduction or distribution without permission.