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Normal Intestinal Flora Of Wild Nile Crocodiles In The Okavango Delta, Botswana

Normal Intestinal Flora Of Wild Nile Crocodiles (Crocodylus niloticus) In The Okavango Delta, Botswana

Owing to the difficulty in obtaining biological specimens from wild crocodilians, very little is known about their normal intestinal flora. The intestinal tract flora isolated from wild-caught African dwarf crocodiles (Osteolaemus tetraspis) has been reported.

Salmonellae isolated from wild Nile crocodiles from Lake Kariba, and from wild American alligators (Alligator mississippiensis) have also been documented. Other studies have dealt with captive crocodilians, including the normal intestinal flora of captive gharials (Gavialis gangeticus), and the prevalence of salmonellae in healthy captive crocodilians.

Farmed crocodile hatchlings often fail to develop a normal mixed intestinal flora. In other species, the rapid establishment of bacterial  communities of normal flora in the gastrointestinal tract (GIT) is thought to be essential for GIT homeostasis and the prevention of colonization by pathogenic bacteria. A deficient intestinal flora is likely to be one of the factors predisposing farmed crocodiles to enteritis. Enteritis, and associated septicaemia, is one of the main causes of mortality in farmed crocodilians.

Determining the normal intestinal tract flora of wild Nile crocodiles is the 1st step towards developing a probiotic for use in farmed Nile crocodiles.

Crocodiles were captured in thePanhandle of the Okavango Delta during summer (February 2005). Capture was done at night, using a 4.8 m flat bottomed aluminium boat propelled by a 60 hp engine. Crocodiles were located using a powerful spot-light which, when shone into the crocodile’s eyes, reflected back a red glow due to the presence of a retinal tapetum lucidum. Once spotted, the beam of light was kept focused on the crocodile’s eyes, making it possible to approach the animal with the boat. Crocodiles estimated to be smaller than 1.2 m total length (TL) were captured by hand. Crocodiles between 1.2 m and 2.3 m were captured using a swivelling noose (Animal Handling Co., USA) which was placed over the snout and pulled tight in the neck region. Crocodiles were then brought onto the boat, jaws were taped shut and the animals were physically restrained.

Twenty-nine animals were randomly selected for cloacal swab collection. Each crocodile was blindfolded and restrained in dorsal recumbency. A cloacal swab was taken by inserting a sterile cotton swab (Transwab, Medical Wire & Equipment Co. Ltd., UK) into the cloaca to a depth of 50–100 mm, rotating the swab, withdrawing it and placing it directly into the sterile transport medium supplied.

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About Grant Reed

Grant Reed is a founding Director of Okavango Guiding School. Grant has a post-graduate degree in Nature Conservation and is a FGASA Level 3 guide with SKS Birding, Wildflowers and Dangerous Animals. He is a passionate naturalist, conservationist and educator.