%0 Journal Article %1 frederickbturner1986production %A Turner, Frederick B. %A Hayden, Page %A Burge, Betty L. %A Roberson, Jan B. %D 1986 %I Herpetologists' League, Allen Press %J Herpetologica %K demography natural_history desert_tortoise %N 1 %P 93-104 %T Egg Production by the Desert Tortoise (Gopherus agassizii) in California %U http://www.jstor.org/stable/3892240 %V 42 %X Egg production by desert tortoises was estimated at two sites in San Bernardino, California: Ivanpah Valley in 1980 and 1981 and Goffs in 1983, 1984 and 1985. Mean clutch frequencies were estimated for 1980 (1.60) and 1981 (1.10) from mass changes observed among sexually mature females weighed every 1-2 wk. Mean clutch frequencies in 1983 (1.89), 1984 (1.57) and 1985 (1.75) were estimated from periodic X-rays of females. Clutch sizes were also determined from radiographs. Tortoises at Goffs typically laid 1-2 clutches during May and June, but one female failed to lay eggs in 1984 and single tortoises laid three clutches in 1983 and 1985. If tortoises laid two clutches, the second was faintly visible in X-rays within 9-10 days after the first was laid. Eggs were laid about 22 days after they were visible in X-rays. Goffs data showed that tortoises <196 mm in body length were more likely to lay one clutch than larger females. Mean clutch frequencies were positively correlated with winter rainfall, but summer rains also apparently contribute to reproductive energetics of tortoises. Clutch sizes were positively correlated with body size. With this effect removed, the following generalizations emerged: (1) clutch size did not differ between years, (2) if two clutches were laid, first and second clutches did not differ in size, (3) females laying but one clutch of eggs laid larger ones than those laying two clutches, and (4) variation in clutch sizes of different individuals was greater than comparable variation within the same tortoises. The overall mean clutch size at Goffs (4.50) is low-relative to clutch sizes reported in the literature. This may be related to the fact that the mean body size of adult females at Goffs (220 mm) is significantly less than mean sizes of adult females in 13 of 16 other populations in California. Only 26 (46 percent) of 57 eggs moved to predator-proof nests in May-June 1984 hatched by the end of October. None of 17 apparently viable eggs left in protected nests until 3 May 1985 hatched.

@article{frederickbturner1986production, abstract = {Egg production by desert tortoises was estimated at two sites in San Bernardino, California: Ivanpah Valley in 1980 and 1981 and Goffs in 1983, 1984 and 1985. Mean clutch frequencies were estimated for 1980 (1.60) and 1981 (1.10) from mass changes observed among sexually mature females weighed every 1-2 wk. Mean clutch frequencies in 1983 (1.89), 1984 (1.57) and 1985 (1.75) were estimated from periodic X-rays of females. Clutch sizes were also determined from radiographs. Tortoises at Goffs typically laid 1-2 clutches during May and June, but one female failed to lay eggs in 1984 and single tortoises laid three clutches in 1983 and 1985. If tortoises laid two clutches, the second was faintly visible in X-rays within 9-10 days after the first was laid. Eggs were laid about 22 days after they were visible in X-rays. Goffs data showed that tortoises <196 mm in body length were more likely to lay one clutch than larger females. Mean clutch frequencies were positively correlated with winter rainfall, but summer rains also apparently contribute to reproductive energetics of tortoises. Clutch sizes were positively correlated with body size. With this effect removed, the following generalizations emerged: (1) clutch size did not differ between years, (2) if two clutches were laid, first and second clutches did not differ in size, (3) females laying but one clutch of eggs laid larger ones than those laying two clutches, and (4) variation in clutch sizes of different individuals was greater than comparable variation within the same tortoises. The overall mean clutch size at Goffs (4.50) is low-relative to clutch sizes reported in the literature. This may be related to the fact that the mean body size of adult females at Goffs (220 mm) is significantly less than mean sizes of adult females in 13 of 16 other populations in California. Only 26 (46 percent) of 57 eggs moved to predator-proof nests in May-June 1984 hatched by the end of October. None of 17 apparently viable eggs left in protected nests until 3 May 1985 hatched.}, added-at = {2016-01-26T08:23:07.000+0100}, author = {Turner, Frederick B. and Hayden, Page and Burge, Betty L. and Roberson, Jan B.}, biburl = {https://www.bibsonomy.org/bibtex/2f329a78ee47196dcc7b9af4c03a8dd5a/peter.ralph}, interhash = {1aec2495bddf1f431492e93112cd0748}, intrahash = {f329a78ee47196dcc7b9af4c03a8dd5a}, issn = {00180831, 19385099}, journal = {Herpetologica}, keywords = {demography natural_history desert_tortoise}, number = 1, pages = {93-104}, publisher = {[Herpetologists' League, Allen Press]}, timestamp = {2016-01-26T08:24:48.000+0100}, title = {Egg Production by the Desert Tortoise ({Gopherus} agassizii) in {California}}, url = {http://www.jstor.org/stable/3892240}, volume = 42, year = 1986 }