Rp. Bennett, Effects of food quality on growth and survival of juvenile Columbian ground squirrels (Spermophilus columbianus), CAN J ZOOL, 77(10), 1999, pp. 1555-1561
Citations number
53
Categorie Soggetti
Animal Sciences
Journal title
CANADIAN JOURNAL OF ZOOLOGY-REVUE CANADIENNE DE ZOOLOGIE
Within a cohort of Columbian ground squirrels (Spermophilus columbianus), m
ost deaths during hibernation usually occur in the first winter. Over-winte
r survivorship of juvenile Columbian ground squirrels is positively related
to prehibernation body mass, which is primarily determined by the growth r
ate after emergence from natal burrows. This study examined how food qualit
y influences growth and survival of juvenile Columbian ground squirrels. Gr
owth and survival of juveniles in three colonies was measured, and biomass,
composition (forb versus grass content), gross energy, crude protein, and
digestibility of the summer forage supply were assessed. Differences in bio
mass and gross energy among colonies did not explain differences in growth
and survival of resident ground squirrels. Growth and survival of juveniles
was enhanced on sites with higher forb content in the forage supply. Forbs
contained 15-40% more protein and were 30-50% more digestible than grasses
, but protein levels on all sites were probably in excess of ground squirre
ls' requirements. This suggests that digestibility was limiting growth and
was a more important food-quality indicator for juvenile ground squirrels t
han either energy or protein.