Demographic and life cycle characteristics of montane deer mice

Abstract

INNES. 1983. Demographic and life cycle characteristics of montane deer mice. Can. J. Zool. 61: 574-585. Demographic and life cycle characteristics of Peromyscus maniculatus borealis were documented in the wild and in the laboratory. Field studies in the Kananaskis Valley, Alberta, indicated that no mice matured in the summer of their birth, overwintered females produced a maximum of 3 litters each season (average, 1.9), nestling survival was variable (0 to 100%), summer survival of weaned young (average, 0.81 1 2 weeks) was similar to that of summer adults (average, 0.8012 weeks), dispersal rates were low, and winter survival (average, 0.98/semimonthly period) was relatively high. These demographic characteristics are similar to those of other populations in which opportunities for reproduction are limited. Laboratory studies indicated that basic life cycle characteristics such as adult size (20.3 g), litter size (5.2), neonate weights (1.70 g), nestling growth rates (0.34 glday), age at weaning (24.9 days), weight at weaning (9.9 g), and food consumption during lactation (220% of nonbreeding consumption) were not all the same as previously reported for northern P . m. borealis or other Peromyscus. These differences may be related to specific aspects of the annual cycle. MILLAR, J. S., et D. G. L. INNES. 1983. Demographic and life cycle characteristics of montane deer mice. Can. J. Zool. 61:574-585. Les caractkristiques dCmographiques et le cycle biologique ont CtC dCterminCs chez des Peromyscus maniculatus borealis en nature et en laboratoire. Des travaux sur le terrain dans la vallke Kananaskis, Alberta, ont dkmontrC qu'aucune souris n'atteint sa maturitC la Ire annCe, que les femelles qui survivent a l'hiver produisent au maximum trois portCes par saison (moyenne = 1,9), que la survie des jeunes au nid est variable (0,O a loo%), que la survie des jeunes sevrks durant 1'ktC (moyenne 0,8112 semaines) est semblable a celle des adultes durant llktC (moyenne 0,8012 semaines), que les taux de dispersion sont faibles et que la survie au cours de l'hiver (moyenne 0,98/demi-mois) est relativement Clevke. Ces caractCristiques dkmographiques sont semblables a celles d'autres populations dont les chances de reproduction sont 1imitCes. Les Ctudes en laboratoire ont permis d'ktablir que les caractkristiques de base du cycle, telles la masse de l'adulte (20,3 g), le nombre de petits par portCe (5,2), la masse des nouveaux-nCs (1,70 g), les taux de croissance au nid (0,34 g/jour), ]'Age au moment du sevrage (24,9 jours), la masse au moment du sevrage (9,9 g) et la consommation de nourriture durant la lactation (220% de la consommation des individus non reproducteurs) ne sont pas toutes les mcmes c o m e le laissent croire les Ctudes antkrieures sur les P. m. borealis du Nord ou sur d'autres especes de Peromyscus. Ces diffkrences sont peut-ttre reliCes a des aspects particuliers du cycle annuel.[Traduit par le journal]

The effects of dietary protein content on growth and maturation in deer mice

“…Mice from all three diets had high birth masses, and postnatal growth rates that were similar to previously reported values for mice raised on standard laboratory-rodent diets (Millar 1982;Millar and Innes 1983;MacDonald 1997;Woolfenden and Millar 1997). The one difference among the three isocaloric diet treatment groups was the proportion of female mice who were mature at 42 days of age, but patterns of maturation among diets did not reflect protein content.…”

“…Individual growth rates of nestlings (0-21 days) and juveniles (21-42 days) were estimated as the slope of the linear regression of mass on age for each individual. Juvenile growth during these time periods is approximately linear (Millar 1982;Millar and Innes 1983;Woolfenden and Millar 1997). At 42 days, juvenile females were killed by cervical dislocation and their ovaries were excised and stored in 5% neutrally buffered formalin.…”

“…For this reason, deer mice may require a higher dietary protein content than has been estimated for some herbivorous species (see Ditchkoff et al 1998) whose digestive physiologies are more efficient at using low-protein diets (Robbins 1993). Wild-conceived deer mice from the Kananaskis Valley raised in the laboratory on standard rodent chow (~20% protein) have high growth rates (0.30-0.40 g/day ;Millar 1982;Millar and Innes 1983;MacDonald 1997;Woolfenden and Millar 1997) and some females are sexually mature by 42 days of age (MacDonald 1997), but the effects of dietary protein on early growth and sexual development are not known.…”

Inbreeding effects among inbred and outbred laboratory colonies of Peromyscus maniculatus

“…The breeding season is very short relative to that of more southerly populations (review in Millar 1989), and virtually all reproduction is accomplished by overwintered adults (Millar and Innes 1983). Dispersal of young during the breeding season is uncommon in these short-season Peromyscus populations (Galindo and Krebs 1987;Gilbert and Krebs 1981;Millar and Innes 1983), and we suspect that the costs of dispersal are probably very high. Thus, we would suggest that natural populations are probably moderately inbred (Kimura and Ohta 197 1;Shields 1982).…”

Trapping and Marking Terrestrial Mammals for Research: Integrating Ethics, Performance Criteria, Techniques, and Common Sense

“…For most research, these mammals are best live-trapped using box or cage traps (e.g., Bondrup-Nielsen 1987;Getz et al 2001;Gilbert and Krebs 1991;Millar and Innes 1983;Peacock and Smith 1997;Steele and Powell 1999;Stratham and Harden 1982;Wolff and Cicirello 1991) or pitfalls for shrews (e.g., Spencer and Pettus 1966). Because of their high metabolic rates, these mammals (especially shrews) cannot remain in live-traps a long time without food, therefore bait must be of an adequate amount to last between trap checks and must nourish the target animals appropriately.…”