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

Journal of Mammalogy



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 type Article
Publication Subtype Journal Article
Title Effects of maternal characteristics and climatic variation on birth masses of Alaskan caribou
Series title Journal of Mammalogy
DOI 10.1644/1545-1542(2005)86[506:EOMCAC]2.0.CO;2
Volume 86
Issue 3
Year Published 2005
Language English
Publisher American Society of Mammalogists
Contributing office(s) Alaska Science Center
Description 8 p.
First page 506
Last page 513
Online Only (Y/N) N
Additional Online Files (Y/N) N
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