Meeting Abstract

P2.55  Monday, Jan. 5  Estimating the cost of ventilation in zebra finches by increasing mechanical work MARKLEY, J.S.*; GOLLER, F.; CARRIER, D.R.; Univ. of Utah, Salt Lake; Univ. of Utah, Salt Lake; Univ. of Utah, Salt Lake markley@biology.utah.edu

The cost of ventilation may be high in birds due to the large mass of the ventilatory system, which must be moved with every breath. To measure this cost we developed a mechanical method to increase the work of breathing in small, readily available zebra finches. Birds were surgically outfitted with velcro sutured to the distal end of the sternum, around the sternal ribs, and to the skin covering the synsacrum (back). A custom built mask with a screen pneumotach was used to measure ventilation, and oxygen consumption (Vo₂) was measured via flow-through respirometry. Weights of approximately 7, 9 and 13% of body mass were added alternately to the sternum and back. The mass of the sternum and associated flight muscles in zebra finches is 14% of body mass. Mean oxygen consumption values for 3 minute periods were used to calculate minute ventilation, frequency, Vo₂. Preliminary results indicate that changing the location of these masses from the back to the sternum produced no change in Vo₂. Birds may have been forced to change their mode of breathing or their perching posture when faced with these loads. The actual cost of ventilation remains equivocal, nevertheless, this result potentially reveals plasticity in ventilatory mechanics of passerines, which allows birds to mitigate the cost of added sternal mass.