 |
 |
 |
 |
 |
 |
 |
Twenty-Third Annual Meeting and Symposium of the
Desert Tortoise Council, April 3-5, 1998
Abstracts
Reproductive Output of Large-For-Age Desert Tortoises (Gopherus agassizii)
Terry E. Christopher*1, Brian T. Henen1, Ellen M. Smith2,
Mary E. Allen1,3, F. Harvey Pough2, and Olav T. Oftedal1
Smithsonian Institution, National Zoological Park, 1Department of Zoological Research
and 3Department of Nutritional Resources, 3001 Connecticut Avenue, Washington, D. C.
20008;
2Department of Life Sciences, Arizona State University West, 4701 W. Thunderbird Road,
PO Box 37100, Phoenix, AZ 85069-7100;
and The Desert Tortoise Conservation Center, Las Vegas, Nevada 89117
Small juvenile desert tortoises maintained on a high plane of nutrition since 1991 had reached an adult body size (> 180 mm carapace length) by 1995. Are such large-for-age (LFA) tortoises reproductively competent? In 24 outdoor pens, ten LFA females and eight LFA males (sex assessed from plasma testosterone and estradiol levels) were paired with ten adult males and eight adult females, respectively, and six adult females were paired with six adult males to serve as a control group. Following initial behavioral observations, follicular development was monitored with ultrasonagraphy in Fall 1995 and Spring 1996, and clutch size was measured with radiography in Spring 1996. In Spring 1996, all 14 adult females laid eggs. However, only two LFA females produced eggs (one clutch per female, two eggs per clutch). Every adult female had some eggs hatch. Only one of the two clutches from LFA females was found and the eggs showed no signs of development.
LFA females remained paired with adult males throughout 1996 and Spring 1997. In 1997, five LFA females laid a total of six clutches. Eggs from two clutches, both from one LFA female, hatched. LFA females that had laid eggs in 1996 also laid eggs in 1997, but these were infertile. LFA males were reproductively competent but LFA females were not.
| 1998 Abstracts | | | Abstracts Index | | | Home |