干旱区生态环境知识资源中心(Arid): Head-started Agassiz's desert tortoises Gopherus agassizii achieved high survival, growth, and body condition in natural field enclosures

Arid

DOI	10.3354/esr01067
	Head-started Agassiz's desert tortoises Gopherus agassizii achieved high survival, growth, and body condition in natural field enclosures
	Nagy, Kenneth A.; Henen, Brian T.; Hillard, L. Scott
通讯作者	Nagy, KA (corresponding author), Univ Calif Los Angeles, Dept Ecol & Evolutionary Biol, Los Angeles, CA 90095 USA.
来源期刊	ENDANGERED SPECIES RESEARCH
ISSN	1863-5407
EISSN	1613-4796
出版年	2020
卷号	43 页码:305-321
英文摘要	We measured survival, growth, and body condition of 8 hatchling cohorts of desert tortoises Gopherus agassizii (living in predator-resistant outdoor pens in the Mojave Desert, California, USA) over 11 yr to evaluate head-starting methods. At 11 yr of age, 7 times as many of the first cohort had survived than if they had been free-living tortoises. Subsequent improvements in predator control, food and water supplementation, and pen structure increased survival from 7 to 10 times that under wild conditions in younger cohorts. Annual survival averaged 96%. Carapace length (CL) increased 6.95 mm yr-1, similar to that of free-living tortoises. Annual growth rates varied with calendar year (possibly reflecting food and water supply), age, cohort (year hatched), mother, and in 4 dry years, with crowding. Most of the first cohort grew to a releasable size (CL > 100 mm) by their 9th year. Body condition indices remained high, indicating little dehydration despite droughts in 8 of the 11 years, because irrigation offered drinking opportunities. Headstarted tortoises developed fully hardened shells (>= 98% of adult shell hardness) earlier (10.1 vs. 11.6 yr), but at a larger CL (117 vs. 104 mm) than did free-living tortoises. Selective feeding in head-start pens decreased subsequent germination of favored wildflower species, apparently by reducing the natural seedbank. Consequently, we reseeded and irrigated each autumn to promote subsequent spring food supply. We irrigated in early summer to enable drinking and ensuing consumption of dry, dead plants and Bermuda grass hay, a supplement. These procedures can greatly improve juvenile survivorship, and increase numbers of hard-shelled, midsized juveniles to help augment wild populations.
英文关键词	Survivorship Predation Emergence success Density effects Condition Index Shell hardness index
类型	Article
语种	英语
开放获取类型	Green Submitted, gold
收录类别	SCI-E
WOS记录号	WOS:000619516900023
WOS关键词	FREE-RANGING DESERT ; MOJAVE-DESERT ; NUTRITIONAL QUALITY ; CLIMATIC VARIATION ; EGG-PRODUCTION ; 2 POPULATIONS ; SHORT-TERM ; SIZE ; JUVENILE ; WATER
WOS类目	Biodiversity Conservation
WOS研究方向	Biodiversity & Conservation
来源机构	University of California, Los Angeles
资源类型	期刊论文
条目标识符	http://119.78.100.177/qdio/handle/2XILL650/348818
作者单位	[Nagy, Kenneth A.; Hillard, L. Scott] Univ Calif Los Angeles, Dept Ecol & Evolutionary Biol, Los Angeles, CA 90095 USA; [Henen, Brian T.] MAGTFTC MCAGCC, Environm Affairs, Twentynine Palms, CA 92278 USA
推荐引用方式 GB/T 7714	Nagy, Kenneth A.,Henen, Brian T.,Hillard, L. Scott. Head-started Agassiz's desert tortoises Gopherus agassizii achieved high survival, growth, and body condition in natural field enclosures[J]. University of California, Los Angeles,2020,43:305-321.
APA	Nagy, Kenneth A.,Henen, Brian T.,&Hillard, L. Scott.(2020).Head-started Agassiz's desert tortoises Gopherus agassizii achieved high survival, growth, and body condition in natural field enclosures.ENDANGERED SPECIES RESEARCH,43,305-321.
MLA	Nagy, Kenneth A.,et al."Head-started Agassiz's desert tortoises Gopherus agassizii achieved high survival, growth, and body condition in natural field enclosures".ENDANGERED SPECIES RESEARCH 43(2020):305-321.