FrogLog 103 PDF here - Amphibian Specialist Group

Frogs About Town: Ecology and
Conservation of Frogs in Urban
Habitats of South Africa
By Donnavan J. D. Kruger & Louis H. Du Preez
The global distribution of frogs, together with the human
race’s own need for water, has resulted in a close association
between humans and frogs. The human race has
reached a historic turning point, as it is transforming from a mostly
agrarian to a predominantly urban species (1). The global human
population has grown exponentially over the past two millennia
and is expected to reach eight billion by 2025. The world urban
population has increased much faster than the rural population,
and has now reached a stage where the growth in the rural population
has essentially stopped with all future population growth to be
expected in the urban environment (1). The picture for South Africa
doesn’t look much different with 62% of the population living in
urban environments and a 1.2% annual increase rate (2).
To date very little research
has been done on
frogs in the urban environments
of South Africa.
In the greater Cape
Town area, populations
of the Western leopard toad (Amietophrynus pantherinus) (Fig. 1)
and the Micro frog (Microbatrachella capensis) (Fig. 2) have been
monitored by Cape Nature and a research group based at SANBI.
There has also been public involvement in conservation of frogs
in the city, with several environmental groups helping to remove
Leopard toads from the roads in Cape Town each year to prevent
them being squashed in the city traffic.
Fig. 1: The Endangered Western leopard toad, Amietophrynus pantherinus.
Photo: L. du Preez.
Fig. 2: The Critically Endangered Micro frog, Microbatrachella capensis.
Photo: L. du Preez.
Urbanization has a number of harmful effects on the ecosystem.
These include increased temperature, severe effects on wetlands
and water availability, water usage and water quality, habitat
destruction or alteration and establishment of exotic plants and
animals (3, 4). Urbanization is also one of the main causes of the
degradation of freshwater systems in South Africa (5).
In addition to these noticeable changes in the physical structure of
the environment, urbanization also causes a striking change in the
acoustic environment (6). This change may possibly hinder the capability
of male frogs to attract females by decreasing the distance
in which males can be heard by females (7). These disturbances
in female perception of male calls may lead to reduced breading
success (6).
African Amphibian Conservation Research Group, North-West University,
Potchefstroom, South Africa. Email: donnavan.kruger@nwu.ac.za
Fig. 3: Green female pattern of Pickersgill’s reed frog, Hyperolius pickersgilli.
Photo: L. du Preez.
24 | FrogLog 20 (4) | Issue number 103 (July 2012)