Meeting Abstract
Hematocrit – or the percent volume of red blood cells in whole blood – is often referred to in papers as an indicator of body condition, yet it is responsive to a seeming myriad of factors, including factors that aren’t necessarily related to body condition (e.g., elevation, metabolic demand and hydration). Some ambiguity may also arise from the fact that few studies directly investigate hematocrit but rather measure hematocrit because it is easy to do so and might prove interesting. We used an experimental approach to investigate the impacts of water availability, food availability and cage size (as an indirect manipulation of flight activity) on hematocrit levels in captive red crossbills (Loxia curvirostra). We found effects of food treatment and housing on changes in hematocrit and no difference following a short-term water restriction. We discuss these results in light of hypotheses about hematocrit and body condition.
