title: Annual variation in maternal age and calving date generate cohort effects in moose (Alces alces) body mass.
abstract: A general feature of the demography of large ungulates is that many demographic traits are dependent on female body mass at early ages. Thus, identifying the factors affecting body mass variation can give important mechanistic understanding of demographic processes. Here we relate individual variation in autumn and winter body mass of moose calves living at low density on an island in northern Norway to characteristics of their mother, and examine how these relationships are affected by annual variation in population density and climate. Body mass increased with increasing age of their mother, was lower for calves born late in the spring, decreased with litter size and was larger for males than for female calves. No residual effects of variation in density and climate were present after controlling for annual variation in mother age and calving date. The annual variation in adult female age structure and calving date explained a large part (71-75%) of the temporal variation in calf body mass. These results support the hypotheses that (a) body mass of moose calves are affected by qualities associated with mother age (e.g. body condition, calving date); and (b) populations living at low densities are partly buffered against temporal fluctuations in the environment.
authors: Norwegian Institute for Nature Research, Tungasletta 2, 7485, Trondheim, Norway.
authors: Erling J
authors: EJ
authors: Solberg
authors: Morten
authors: M
authors: Heim
authors: Vidar
authors: V
authors: Grøtan
authors: Bernt-Erik
authors: BE
authors: Saether
authors: Mathieu
authors: M
authors: Garel
mesh_terms: D000367:Age Factors; D000818:Animals; D001835:Body Weight; D003670:Deer / Q000502:physiology*; D005260:Female; D005843:Geography; D016013:Likelihood Functions; D008423:Maternal Age; D009664:Norway; D011156:Population Density; D012621:Seasons
references: J Theor Biol. 2007 Jan 21;244(2):308-17
references: 16978654
references: Trends Ecol Evol. 1999 Sep;14(9):343-348
references: 10441307
references: Trends Ecol Evol. 1997 Apr;12(4):143-9
references: 21238011
references: Evolution. 1989 May;43(3):485-503
references: 28568400
references: Oecologia. 2004 Jan;138(1):135-42
references: 14564502
references: Anim Behav. 1998 Aug;56(2):301-307
references: 9787020
references: J Anim Ecol. 1998 Nov;67(6):979-86
references: 26412376
references: Proc Biol Sci. 2002 Apr 7;269(1492):747-53
references: 11934368
references: Proc Biol Sci. 1997 Sep 22;264(1386):1317-24
references: 9332016
references: Proc Biol Sci. 1999 Aug 22;266(1429):1655-61
references: 10501037
references: Science. 2001 May 25;292(5521):1528-31
references: 11375487
references: Oecologia. 2001 Aug;128(3):400-405
references: 24549909
references: J Mammal. 1978 Nov;59(4):857-8
references: 750641
references: Proc Biol Sci. 2000 Mar 7;267(1442):471-7
references: 10737404
references: Oecologia. 2001 Apr;127(2):230-238
references: 24577654
references: Evolution. 2003 Dec;57(12):2879-92
references: 14761065
references: Ecology. 2006 Mar;87(3):745-58
references: 16602303
references: J Anim Ecol. 2006 Sep;75(5):1110-8
references: 16922846
references: Nature. 2004 Jul 1;430(6995):71-5
references: 15229599
references: Am Nat. 1999 Dec;154(6):730-46
references: 10600616
references: Science. 1995 Aug 4;269(5224):676-9
references: 17758812
references: Trends Ecol Evol. 1998 Feb 1;13(2):64-9
references: 21238202