Frogs - Identification

Background

Frogs can be found almost anywhere in Australia in many different types of habitats. Most frog species have their own preferred niche e.g. in and around vegetation, on the edges of ponds, swamps and dams, under stones and logs, in trees and foliage, in puddles where water occurs only occasionally, under the eaves of buildings and around water tanks. In order to identify frogs the following methods may be used;

Record frog calls that you hear and then play the calls back to the same frogs. They often respond to the recording enabling you to make a visual identification
Take photos for verifying identifications
Use ‘triangulation’, a method involving 3 people. To pinpoint the frog’s location, participants surround the frog, keeping roughly equal positions from each other. Each person approaches, carefully and slowly, pointing as they move closer to where the frog can be heard in order to locate the frog. The same procedure can be used at night with torches
Listen to the frog’s call and compare it with known frog calls in your region. Every species has a distinct mating call which only the male emits
Survey frogs at night when they are most active. Some frogs such as the Growling Grass Frog may be seen basking during the day in sunny spots near the edge of water.

Aim

The aim of this session is to:

Use an on-line frog identification key to develop skills in identifying the key features of frogs
Use the internet to investigate frog calls
Conduct a survey of frogs in the local area.

Materials

Access to computers and the internet
Key to Victorian frogs website http://frogs.org.au/frogs/key.html#key
The frogs of Victoria http://frogs.org.au/frogs/of/Victoria/
Melbourne Water http://www.melbournewater.com.au/frogs

Notes for teachers

This activity requires internet access for students to the above websites.
The introductory activity involves students using an on-line frog identification key to identify the Growling Grass Frog. Each key feature is recorded by the student.
Key features include:
- Pads present on digits (fingers and toes)
- Pupils horizontal
- Tympanum (ear) distinct
- A distinct dorso-lateral fold. Frog predominantly green
- Back distinctly warty.
Students then access the Melbourne Water Frogs website to determine the frog species within their local Council or suburb from past surveys. They access information relating to distribution, habitat and calls for each species.
Finally, students may plan to conduct their own local survey using information supplied via Melbourne Water. The best time to conduct a local survey is when frogs are breeding and this information can be gained from the previous activity. You may decide that students should register to participate in one of Melbourne Water’s Autumn or Spring Census activities so that they can contribute their own data to the database.