Meeting Abstract

79.7  Monday, Jan. 6 11:30  Elevating antioxidant defence is part of cold acclimatization in a small forest bird wintering in eastern Canada. PETIT, M*; VEZINA, F; Univ. du Québec à Rimouski (Canada), Boréas, CEN, CSBQ; Univ. du Québec à Rimouski (Canada), Boréas, CEN, CSBQ magali.petit@uqar.qc.ca

Resident bird species wintering at northern latitudes increase their heat production capacity (Msum) in response to cold weather conditions. Studies reported that increased oxygen consumption (e.g. sudden activity; cold stress) in animals might also be associated with elevated production of reactive oxygen species (ROS), which are deleterious for the organism. This could therefore represent a cost of elevated metabolic performance in wintering birds. However, animals are also able to adjust antioxidant (AO) levels to balance ROS production and minimize oxidative stress. In this study, we tested whether the increase in Msum associated with winter acclimatization in small passerines was correlated with an elevation in ROS production. We also investigated if this was paralleled by an elevation in AO levels. We captured 175 free-living black-capped chickadees (Poecile atricapillus) over 2 consecutives winters and measured their maximal thermogenic capacity (Msum) as well as their plasma levels of ROS and AO. As expected, wintering chickadees increased their Msum (32%) during the winter and we observed positive relationships between MSUM and both ROS and AO levels. Consequently, Msum was not correlated with oxidative stress (ROS/AO). Our findings therefore suggest that 1) the increase in cold tolerance in small wintering passerines is indeed associated with elevated ROS production but 2) that these birds are able to counterbalance this effect by increasing their AO levels to maintain a stable level of oxidative stress throughout winter. Up-regulation of AO levels therefore seems to be part of seasonal cold acclimatization in chickadees.