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Effects of maternal characteristics and climatic variation on birth masses of Alaskan caribou

January 1, 2005

Understanding factors that influence birth mass of mammals provides insights to nutritional trade-offs made by females to optimize their reproduction, growth, and survival. I evaluated variation in birth mass of caribou (Rangifer tarandus) in central Alaska relative to maternal characteristics (age, body mass, cohort, and nutritional condition as influenced by winter severity) during 11 years with substantial variation in winter snowfall. Snowfall during gestation was the predominant factor explaining variation in birth masses, influencing birth mass inversely and through interactions with maternal age and lactation status. Maternal age effects were noted for females ≤ 5 years old, declining in magnitude with each successive age class. Birth mass as a proportion of autumn maternal mass was inversely related to winter snowfall, even though there was no decrease in masses of adult females in late winter associated with severe winters. I found no evidence of a hypothesized intergenerational effect of lower birth masses for offspring of females born after severe winters. Caribou produce relatively small offspring but provide exceptional lactation support for those that survive. Conservative maternal investment before parturition may represent an optimal reproductive strategy given that caribou experience stochastic variation in winter severity during gestation, uncertainty of environmental conditions surrounding the birth season, and intense predation on neonates.

Publication Year 2005
Title Effects of maternal characteristics and climatic variation on birth masses of Alaskan caribou
DOI 10.1644/1545-1542(2005)86[506:EOMCAC]2.0.CO;2
Authors Layne G. Adams
Publication Type Article
Publication Subtype Journal Article
Series Title Journal of Mammalogy
Index ID 70029576
Record Source USGS Publications Warehouse
USGS Organization Alaska Science Center