SEASONAL ADAPTATIONS IN THE ENERGETICS AND BIOMECHANICS OF LOCOMOTION IN THE SVALBARD ROCK PTARMIGAN (LAGOPUS MUTA HYPERBOREA)

• Main Author: Lees, John
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: 2013
• Subjects: Respirometry; Birds; Sexual selection; Locomotion; Jumping; Energetics; Arctic; Ptarmigan; Arctic Archipelago; Lagopus muta; Lagopus muta hyperborea; rock ptarmigan; Svalbard; Svalbard Rock Ptarmigan
• Online Access: https://research.manchester.ac.uk/en/studentTheses/867ab906-4d06-4500-a4dc-ac6d27bc1965; https://pure.manchester.ac.uk/ws/files/54536972/FULL_TEXT.PDF

One of the most striking things about many animals is that they can be defined by the ways in which they move. Moving costs metabolic energy and is a significant contributor to the daily energy balance of organisms and therefore fitness. Balancing energy needs is critically important to species inhabiting areas of limited resources. The metabolic cost of locomotion is influenced by physiological, morphological and behavioural factors that vary across species. The influence of these factors within species is less well understood. The objective of my PhD is to elucidate the potential for variation in locomotor performance, in particular the energy consumed and the biomechanics of locomotion within a species, in response to differences in season, sex, age and the nature of the terrain. The Svalbard ptarmigan (Lagopus muta hyperborea) is the only year-round avian resident of the Arctic archipelago of Svalbard. Svalbard is characterized by extreme photoperiodic and climatic conditions, with 24 hours of daylight in summer and continuous darkness in winter, when ice makes food unpredictable. As a result, ptarmigan annually gain significant fat stores, as much as doubling their body mass in winter. The consequences of such large gains in mass upon the metabolic cost and biomechanics of terrestrial locomotion are yet to be quantified. The Svalbard ptarmigan represents a unique opportunity to gain insight into avian adaptations.Using respirometry, I present evidence that winter birds are able to carry their fat stores at no metabolic cost. Using kinematic and force plate data, I show that acquiring fat results in reduced locomotor performance in terms of speed and take-off ability. As well as exhibiting phenotypic variation, male and female Svalbard ptarmigan are behaviourally very different. I present evidence that these behavioural differences are reflected in the metabolic cost of locomotion. In particular, males are both more efficient and faster than female birds during both summer and winter. I suggest that this ...