Meeting Abstract
P1.67 Sunday, Jan. 4 Don’t put all your eggs in one basket: Growth, self-maintenance, and fledgling survival in Savannah sparrow (Passerculus sandwichensis) chicks raised in experimentally manipulated broods ERICKSON, P.A.**; NICHOLS, K.S.; MITCHELL, G.W.; MAUCK, R.A.; HAUSSMANN, M.F.; Kenyon College, Gambier, OH; Bowdoin College, Brunswick, ME; Univ. of Guelph, ON; Kenyon College, Gambier, OH; Bucknell Univ., Lewisburg, PA ericksonp@kenyon.edu
Early environmental conditions can have profound and long-lasting effects on the life history trajectory of an organism. Individuals face tradeoffs as they allocate available energy to the competing demands of growth and self-maintenance, and poor environmental conditions may compromise both physiological and life history traits. We manipulated brood size in a wild population of Savannah sparrows (Passerculus sandwichensis) nesting on Kent Island, New Brunswick, Canada, to create reduced (2-chick) and enlarged (6-chick) broods in order to alter food availability via intra-nest competition. Chicks were moved between nests at age 2 days, and we collected a blood sample and measured wing length, tarsus length and weight at age 7 days. We recaptured fledglings 3-6 weeks post-hatch to collect a second blood sample. Compared with reduced-brood and control chicks, enlarged-brood chicks had shorter wings (P=0.01) and lower weights (P=0.05) at age 7 days. Nestlings were recaptured as fledglings in a higher proportion from reduced broods (42%) than from either control (22%) or enlarged (11%) broods (P=0.04). Preliminary analysis suggests that catalase activity, a measure of investment in self-maintenance, did not differ between groups but was positively correlated to day 7 weight (P=0.04). We will also present data on lipid peroxidation and telomere length, but our initial results suggest that chicks allocate energy to self-maintenance rather than growth when faced with limited resources in the wild, and this size reduction may lower chances of survival to independence.
