Mecistops cataphractus and Osteolaemus tetraspis tetraspis:

Captive Breeding for Re-Introduction into Native Gambian Ecosystems

A Conservation Initiative

By

Crocos Ark Trust

Republic of the Gambia

2008
Mecistops cataphractus and Osteolaemus tetraspis tetraspis:

Captive Breeding for Re-Introduction into Native Gambian Ecosystems

Purpose:  The purpose of this proposal is to make known the intent of the Crocos Ark Trust to establish a captive breeding program for two species of crocodiles once commonly found throughout the Gambia’s riverine, swamp, and mangrove habitats:   Mecistops cataphractus (formerly classified as Crocodylus cataphractus, Slender-snouted Crocodile, and Osteolaemus tetraspis tetraspis (West African Dwarf Crocodile).  The ultimate goal of the project will be the successful reproduction and re-introduction of both species into native Gambian ecosystems.  Historically, three species of crocodiles existed within the Gambia: the two aforemention species as well as Crocodylus niloticus, Nile Crocodile (Figure 1).  Due to multiple factors, but not limited to uncontrolled hunting and habitat loss, both species are now endangered (and possibly locally extinct) within their native ranges within the Gambia.  It is for the benefit of native ecosystems, international wildlife conservation, and Gambians alike that this initiative is proposed.

Figure 1.  Map illustrating presence and number of crocodilian species in Africa.

This proposal outlines the objectives and basic methodology associated with the initiative in conjunction with a brief account of the species involved.  This proposal is not designed to be construed as an actual management plan.  The development thereof shall be complete in due course with the acquisition of support for the project.

Goals:  The goals of the initiative are the successful reproduction (captive) and introduction of M. cataphractus and O. t. tetraspis into their historical territories within the Gambia.  In conjunction, affiliated and necessary research regarding species ecology, status of wild populations, and status of suitable habitat will be conducted.  Sensitization and education of the public (Gambian and ecotourist alike) regarding crocodile conservation shall be addressed.  It is the aim of the parties involved to re-establish self-sustainable populations of these two species of crocodiles that, with monitoring and government protection, may thrive with minimal intervention.  (Photo of O. tetraspis hatchlings courtesy of www.reptilia-import.de)

Species in Question:  Both species referred to in this plan are listed as CITES Appendix I animals, and unfortunately, both are seriously understudied in regards to even their basic ecologies, specific reproductive biologies, and even specific habitat preferences.  Initial priority for both species lies in conducting population surveys so overall species management agendas may be developed.

Figure 2.  Mecistops cataphractus.  Photo from the Central Florida Zoo.

Mecistops cataphractus:  Figure 2.  A mid-sized, highly aquatic crocodile species averaging 2.5m in length, with reports of some specimen reaching up to 4 meters.  Past surveys indicate a preference for riverine habitat and a tolerance for mildly brackish water with dense vegetative cover.  Its historical range includes much of central and west Africa, ranging from Mauritania and Mali south to the coast and east to Zambia.  Historical accounts indicate a diet preference of fish and aquatic invertebrates, amphibians, and larger items (such as birds) when available.  The decline of the species is attributed to over-hunting, particularly as C. suchus populations began to decline.  The species is possibly extinct within the Gambia; a survey in 1991 found zero specimen.

 
Figure 3.  Osteolaemus tetraspis spp.  Photo from DK Images.

            Osteolaemus tetraspis tetraspis:  Figure 3.  A small crocodile species that is not known to attain lengths of even 2 meters.  Survey data is limited, but prior research indicates that O. t. tetraspis is more terrestrial, preferring permanent and semi-permanent swamp pools or slow moving rivers near dense vegetative cover.  They are nocturnal and will dig elaborate tunnels where they hide during the day.  Data on this species is limited, and their status is unknown.  The last recorded specimen was seen 12 years ago in Abuko Wildlife Reserve.

The initiative proposes working with M. cataphractus and O. t. tetraspis together as the species are sympatric in nature.  When conducting surveys/research for one species, it is likely to require little extra effort and resources to extend research to encompass the other.  It is also worthwhile to note that there have been no recorded attacks upon humans by either species in the wild that we are aware of.

Parties Involved: The crocodile breeding and re-introduction initiative will require the cooperation of numerous individuals and groups, including:

            - Crocos Ark Trust and its Affiliates

- The Gambia Department of Parks and Wildlife Management

            - Local and international wildlife conservation organizations

            - Other parties involved/interested in crocodile and wildlife conservation

Why Re-Introduce Crocodiles to the Gambia?  Presently, the Gambia is striving to establish itself as a center for ecotourism.  Wildlife conservation initiatives such as that which is proposed here are likely to help encourage ecotourists to visit the Gambia to display support for the cause, and Gambians do recognize the economic potential of crocodiles as a tourist attraction. Already, a large proportion of tourists to the Gambia are ecotourists, including many amateur ornithologists and other wildlife enthusiasts.  It is fair to presume that by striving to learn about and conserve local herpetofauna, a new face of ecotourism within the Gambia may arise in the form of amateur herpetologists.  Additional tourist potential may also be derived from the need for ecological research within West Africa and the Gambia.

Gambia is considered an ideal location for a crocodile re-introduction for multiple reasons other than just the potential of increasing tourism.  Firstly, Gambians don’t associate crocodiles with aggression or death.  Instead, crocodiles have a sacred place within the culture.  For example, three crocodile pools exist in the Gambia: Kachikally Crocodile Pool in Bakau, Mama Folonkoo in Kartong, and the Crocodile Pool in Berending.  These pools are held in high regards by indigenous Gambians, and women often frequent the pool for prayer and for blessings of enhanced fertility or improved chances for conceiving a male child.  The value of crocodiles within the culture may be seen even on the national currency: the dalasi coin is imprinted with a crocodile, and the water mark on the paper money of the Gambia is a side view of a crocodile head.

Prior research on crocodilians indicates that human health and overall ecological benefits may be derived from the re-introduction of these two native species.  Research conducted by Ernst Josef Fittkau in South America suggests positive effects on local fish populations for local fishermen.  His research indicates that fish are a significant portion of the diet of small to mid-sized crocodiles, and part of their consumption is of unhealthy specimen, allowing for an increased harvest stronger and healthier fish by fishermen.  Additionally, he concluded that through the culling of unhealthy fish specimen and the natural cycle of defecation by the crocodiles into the river, a healthy electrolyte balance may be re-established.  Other research, conducted in Madagascar by J. Milot, notes a positive correlation in the increase of rabies outbreaks with the decline of crocodile populations.  This may be due to the fact that crocodiles tend to eat smaller, easily caught food items from the waters edge, and sick animals, such as those infected with disease such as rabies are likely to provide a more easily caught meal.  Thus with the re-introduction of crocodile population, the chances of controlling diseased wildlife may be enhanced.

Another potential benefit of these mid-sized predators is their effective control on the populations of rapidly reproducing and pest species.  And other positive effects associated with crocodile re-introduction that necessitate some research include a positive effect of crocodile digging/burrowing in semi-permanent or seasonal pools.  Thus, introduction of two once native species will help to rebalance the natural systems between predators (large versus small predators), it will increase the likelihood that tourists will have the opportunity to view a crocodile on their trip to the Gambia (an occurrence which is becoming increasing more uncommon), and may even potentially help to discourage crocodile poaching within the country.

The species in question, M. cataphractus (Figure 4 and 5) and O. t. tetraspis (Figure 6 and 7) are native species in the Gambia.  Over the previous century, over-hunting, habitat loss, and other human influences have resulted in the decline of their population to a level where we now must consider the potential that one, possibly both, of these species is locally extirpated.  Due to a lack of survey data, their status cannot be known for certain.  However, as the Gambia attempts to conserve its natural resources, it must consider all ecological niches as valuable.  The goal of the Gambia is to restore its ecology to that of approximately the mid-1900s, with maintenance of forest habitats in an attempt to decrease the encroaching desert.  As M. cataphractus and O. t. tetraspis were once common within its ecosystems, the Gambia must consider these species as an important factor in maintaining ecological stability. 

Figure 4.   Historic Distribution of Mecistops Cataphractus. Central and West Africa: Angola, Benin, Burkina Faso, Cameroon, Central African Republic, Chad, Congo, Equatorial Guinea, Gabon, Gambia, Ghana, Guinea, Guinea Bissau, Ivory Coast, Liberia, Mali, Mauritania, Nigeria, Senegal, Sierra Leone, Tanzania, Togo, Zaire, Zambia

Figure 5.  Present Distribution of Mecistops cataphractus according to UNEP-WCMC Species Database.  Red regions denote countries where the species is presumed locally extirpated.

Figure 7.  Distribution of Osteolaemus tetraspis spp. according to UNEP-WCMC Species Database. Red regions denote countries where the species is presumed locally extirpated.

Necessary Infrastructure:  Through funding via donations and grants, the Crocos Ark Trust plans to design and construct a series of pools and enclosures for both species; Separate enclosures for each species will be designed to follow German guidelines for crocodile husbandry.  Additionally, a series of quarantine pools shall be constructed.  The goal is to create a sustainable series where water utilized for each pool will be used for other functions and in other capacities around the facility.

Initially, the construction of eight pools is proposed (Figures 8, 9 and 10).  Six mid-sized enclosures are proposed, including four pools at 3 meter diameter and two pools of 4 meter diameter.  Two large enclosures at 7 meter and 10 meter diameters are proposed as well.  As necessary, and as funding permits, additional pools shall be constructed.

Figure 8.  Aerial view and layout for proposed crocodilian enclosures.

Figure 9.  Cross-section view of 10m and 7m diameter pools.

Figure 10. Proposed enclosusures.

Enclosure walls shall be constructed of concrete and access to the enclosures shall be restricted via the use of plastic-coated wire fencing.  The total estimated expenditure for initial set-up and preparation for the project is 906190 dalasis.  The proposed budget for construction and development is outlined in Appendix I.

Research:  With the advent of construction and funding, and throughout the entirety of the timeline projected for the project, various research activities shall be initiated to increase our scientific understanding of the species in question.  Research and investigation may include, but is not limited to:

-          Survey of status via nest counts within the Gambia (census data)

-          Assessment of availability of preferred habitat for both species and identification of potential release/re-introduction sites

-          Reproductive Ecology

-          Population dynamics and estimation of minimum viable population (MVP) levels to ascertain a finite goal for the project

Breeding/Re-Introduction: All specimen shall be monitored within Crocos Ark Trust and husbandry and breeding protocol as recommended by German legislation/guidelines, the Crocodile Specialist Group (CSG), and the AZA Crocodilian Taxonomic Advisory Group (TAG) shall be followed.  After introduction into wild ecosystems, introduced specimen shall be monitored utilizing appropriate technologies.  At present, microchipping to maintain data in accordance with international zoological facilities and records is considered ideal.  However, radio-tracking technology is in consideration for post-release monitoring.  Release/re-introduction is not expected for a minimum of seven years from the date of submittal of this proposal and available affordable technologies are subject to change; thus, the appropriate method of monitoring shall be assessed at a date nearer to re-introduction.

Acquisition of Stock/Specimen:  Acquisition of breeding stock is anticipated from a variety of sources including: international zoological facilities, private collectors, and customs offices within Europe. 

-          Zoological facilities may be able to provide captive bred specimen, thus ensuring health and genetic diversity of stock.

-          Private collectors throughout Europe and the United States often encounter instances where they cannot keep an animal due to cost, intensity of maintenance requirements, legal issues or family reasons.  In these situations, zoological facilities cannot always adopt the animals in question, in which case the animals are either killed or illegally released into the wild.

-          Customs offices occasionally confiscate illegally transported animals and subsequently have nowhere to remove the animal to.

All animals shall be subject to permitting and quarantine as necessitated by the regulations of the Gambia, the by-laws of CITES, and the animals’ own well-being.

Proposed Timeline:  A basic timeline is proposed to guide construction, research, and breeding initiatives.  It should be understood, however, that timetables shall vary according to funding and the availability of reproductively ready stock and the availability of suitable habitat for release.

Year 1

Year 2

Year 3-7

Year 7 à

Appendix I.  Estimated Budget and Supplies for Proposed Infrastructure and Development in Gambian Dalasis.