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Global Partners in East Africa
Michael Dorcas, Davidson College
THE STATUS AND CONSERVATION OF AMPHIBIANS AND REPTILES
OF THE CHYULU HILLS - AMBOSELI REGION IN SOUTHERN KENYA
Summary: I spent three weeks in Kenya visiting
and working with faculty and staff at the Center for Wildlife Managment
of the School for Field Studies. My objectives were to investigate the
possibility of initiating long-term studies of amphibians and reptiles
in conjunction with their centers. These sites are located adjacent to
Nairobi National Park and at the base of Mt. Kilimanjaro. I spent a considerable
amount of time meeting with and talking with faculty and the director
of the centers and developed a proposal of potential work that needs to
be done there (see below). After the initial studies are underway, I will
apply for additional funding that will ensure the long-term success of
this project (e.g., Kenya Wildlife Service, NSF).
Proposed Collaborations in Kenya resulting from trip:
Justification
Worldwide declines of amphibians and reptiles have raised concerns throughout
the world during the last decade. Causes of declines have been attributed
to numerous factors including global warming, UV radiation, and disease.
However, experts agree that the primary cause for most amphibian and reptile
declines throughout the world is habitat degradation and destruction.
Due primarily to their cryptic nature, amphibians and reptiles are often
overlooked as important components of most ecosystems. However, amphibians
and reptiles play important roles in most temperate and tropical ecosystems
as both predators and prey, in overall system energy flow, and as major
components of biodiversity. Additionally, due to their sensitive nature,
many amphibians and reptiles can serve as valuable bioindicators of environmental
integrity. Although amphibians and reptiles represent important components
of most ecosystems in east Africa, knowledge of their basic diversity
and distribution is severely lacking and conservation efforts aimed at
amphibians and reptiles are essentially nonexistent.
Between Chyulu Hills and Amboseli National Parks in southern Kenya, habitat
destruction is increasing dramatically due to a change from pastoralism
to agriculture as the primary means of subsistence among indigenous people.
Unfortunately, the best areas for agriculture are within or near aquatic
ecosystems (e.g., swamps) which also contain the highest diversities and
numbers of amphibians and reptiles. Proper evaluation of the impacts of
such habitat destruction and degradation on ecosystems within this region
should include detailed, extensive studies of amphibians and reptiles.
Objectives
We propose to initiate an extensive, long-term evaluation of the impacts
of habitat degradation and destruction on amphibians and reptiles within
the region between Chyulu Hills and Amboseli National Parks. Specifically,
we will 1) determine which species of amphibians and reptiles inhabit
the region; 2) determine the habitats required by selected species; 3)
develop and test fine-scale predictive models of species distribution
within the region; 4) evaluate the impacts of human-induced environmental
degradation; 5) evaluate species as potential bioindicators of environmental
integrity. As the study progresses, selected focal animal studies may
be initiated to provide more detailed understanding of their ecology and
conservation.
This study will become a part of the ongoing SFS research conducts on
the evaluation of land use impacts in the Amboseli-Chyulu Hills region.
Thus far, research by SFS has focused primarily on studies of large mammals
and the interactions of those animals in the ecosystem. Long-term studies
of amphibians and reptiles will add a new dimension to these existing
studies and provide new insights into the effects of anthropogenic impacts
in the region.
Methods
The first step in evaluating the impacts of human disturbance on amphibian
and reptile populations is to determining which species inhabit the region.
Lists of potential species will be developed from available publications
and field guides and from local experts (e.g., Kenyan herpetologists).
Specific records of amphibians and reptiles will be obtained from museum
records (i.e., National Museums of Kenya, Smithsonian, The British Museum
– London, etc.). All known localities will be digitized and incorporated
into a geographical information system (GIS; ArcGIS, ESRI). Due to the
expected scarcity of reliable records, field surveys will be conducted
on a regular basis within various ecosystems in the region to provide
most of the records of amphibians and reptiles. Initial surveys will be
based on habitats selected using aerial photography and interviews with
local people knowledgeable about the amphibians and reptiles of the region.
All records will be provided to the Herpetology Department in the National
Museums of Kenya (Damaris Rotich, Herpetologist). Field surveys will be
conducted in habitats unaffected by human encroachment and in areas impacted
(e.g., agricultural areas). All localities will be recorded with a hand-held
global positioning system (GPS). Habitats where animals are found will
be described based on ground observations and from GIS using image data
(i.e., LandSat imagery, aerial photography). Additional GIS data will
be obtained from various sources where available. Using known localities
and overlaying those with associated habitat data, we will use the GIS
to predict where the species should occur within the entire region. Field
surveys will allow confirmation of these predicted species occurrences.
Evaluation of the impacts of human disturbance will be conducted by using
the GIS to examine the extensiveness of agriculture within the Chyulu
Hills - Amboseli region and comparing those data to information gathered
on amphibian and reptile fine-scale distribution and habitat associations.
Particular species of amphibians and reptiles,
which have geographic ranges encompassing the entire region or substantial
parts of it, will be evaluated for their use as potential bioindicators
of environmental integrity. To do this, we will first evaluate habitats,
by monitoring environmental variables and by determining the extent of
habitat degradation using the GIS. Then, species sensitivity to environmental
degradation will be assessed by evaluating their fine-scale distribution
among habitats of varying degrees of habitat degradation. The presence
or absence of these "bioindicator species" will then be used
as additional evaluation tools for examining anthropogenic impacts on
the ecosystems in the region.
Extensions
Several extensions of the proposed general amphibian and reptile study
could provide additional and unique opportunities for intensive study
and research. For example, long-term mark-recapture studies could be conducted
on particular species or groups of species inhabiting specific areas.
Ideal subjects for such studies include many of the numerous species of
lizards or certain species of turtles and tortoises that inhabit the region.
Such mark-recapture studies would allow evaluation of population sizes
reproductive and life history characteristics, and notable ecological
characteristics of the species.
Radio telemetry studies of particular species could
provide opportunities for exciting and extremely valuable, detailed studies.
Rock pythons (Python sebae) are one of the largest snakes in the world
(reaching more than 5 m in length) but very little is known about their
ecology and natural history. Rock pythons are apparently abundant in Amboseli
National Park and offer an ideal species to study using radio telemetry.
Transmitters lasting 2 years or more would be implanted using standard
techniques and the localities of pythons will be determined and recorded
using a GIS on a regular basis. Data would allow detailed evaluation of
habitat use and determination of home range sizes and activity patterns.
Such a study would garner considerable attention from the media and international
herpetological community.
Dissemination
Because essentially nothing is known regarding the herpetology of the
region, initial publications (e.g., African Journal of Herpetology, Journal
of East African Natural History) describing the species present and their
habitat associations would be expected early on in the study (e.g., 1-2
years). Higher impact publications addressing ecological issues and conservation
implications of the research (e.g., Ecology, Conservation Biology, etc.)
would be expected after 3-4 years of study.
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