Observations on the female reproductive cycle of captive giant tortoises (Geochelone spp.) using ultrasound scanning
Publication Type: |
Journal Article |
Year of Publication: |
1997 |
Authors: |
M. Casares, A. Rubel, R.E. Honegger |
Publication/Journal: |
Journal of Zoo and Wildlife Medicine |
Keywords: |
geochelone spp., giant tortoises, ovarian follicles, oviductal eggs, reproduction, ultrasonography |
Abstract:
The reproductive activities of one adult female Galapagos tortoise (Geochelone nigra) and three adult female Aldabra trotoises (Geochelone gigantea) were monitored over 2 yrs using ultrasound scanning. A nonrestraining technique o tactile stimulation was used for all examinations. Developing, preovulatory, and atretic ovarian follicles, as well as eggs at various stages of shell deposition, were identified and measured. In G. nigra, follicles became preovulatory at a diameter of 40-42 mm and eggs were laid 34-84 days (mean = 55.6, n=5) after the thin-shelled eggs were first detected in the oviducts. Geocheloe nigra was capable of retaining eggs, with the shell already formed until the next breeding season. No eggs have been produced by G. gigantea during their stay in Zurich Zoo although follicles of 38-40 mm have been observed requently in two animals.