Avian phenotypic transitions; acting constraints, mechanisms and consequences

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The long-term objectives of this program are to identify the mechanisms that limit phenotypic flexibility in birds facing high energy demands and to determine the consequences of these limits on fitness. Over the next 5 years, we will study the trade-offs resulting from phenotypic mismatches occurring during transitions between life-history stages, and during changes in environmental conditions. We will (1) examine the mechanisms underlying slow adjustments in avian cold endurance following rapid changes in temperature. This will be conducted at the UQAR Avian Facility by tracking individual physiological adjustments in black-capped chickadees (Poecile atricapillus) after a sudden drop or increase in temperature. We will also (2) examine physiological consequences of limited flexibility in extreme phenotypes. This will be done under experimental conditions by comparing the physiological responses of warm and cold acclimated pine siskins (Pinus Spinus) exposed to increased thermoregulatory demands and also across the Canadian Arctic (East Bay 62°N, Alert 82°N), where cold specialized snow buntings (Plectrophenax nivalis) encounter temperatures rising above their heat tolerance limit. Working with chickadees at the Macpès Research Forest and snow buntings at both Arctic sites provides the opportunity to (3) determine how metabolic performance and responses to thermal constraints relate to the reproductive component of fitness. This will be done in chickadees by comparing winter metabolic performance to reproductive success and by studying body temperature and provisioning rates of breeding buntings in relation with microhabitat temperatures and use of thermal refugia. Working at Alert with long distance migrant red knots (Canutus islandica) and ruddy turnstones (Arenaria interpres), we will also (4) investigate how conflicting demands can shape recovery from, and preparation for migration in these birds. This program will provide an integrated comprehension of the interplay between ecological and physiological constraints that shape adaptive phenotypic flexibility in birds. The impact of this program will be major because each project is designed to fill knowledge gaps that are critical to predict how animals cope with environmental changes. Trainees will acquire the skills and perspectives needed to tackle today's environmental issues, through fundamental research and/or applied work in conservation physiology. These scientists, able to work with actors from a variety of disciplines, will help understand how organisms adjust to rapid environmental alterations and climate change, a matter of increasing importance for Canada.