Publications

the annual breeding cycle of the high-arctic svalbard ptarmigan (lagopus mutus hyperboreus).	gonadal size, spermatogenesis, egg production, height of the supraorbital comb, moult, and plasma luteinizing hormone (lh) levels were measured during an annual cycle in wild svalbard ptarmigans (lagopus mutus hyperboreus). these birds live permanently at 77-81 degrees n where daylight is continuous from the beginning of april until mid september while the average ambient temperature is above freezing only between early june and mid september. the gonads and comb size began to enlarge in march c ...	1986	3956996
reduced metabolic cost of locomotion in svalbard rock ptarmigan (lagopus muta hyperborea) during winter.	the svalbard rock ptarmigan, lagopus muta hyperborea experiences extreme photoperiodic and climatic conditions on the arctic archipelago of svalbard. this species, however, is highly adapted to live in this harsh environment. one of the most striking adaptations found in these birds is the deposition, prior to onset of winter, of fat stores which may comprise up to 32% of body mass and are located primarily around the sternum and abdominal region. this fat, while crucial to the birds' survival, ...	2010	21125015
evidence for energy savings from aerial running in the svalbard rock ptarmigan (lagopus muta hyperborea).	svalbard rock ptarmigans were walked and run upon a treadmill and their energy expenditure measured using respirometry. the ptarmigan used three different gaits: a walking gait at slow speeds (less than or equal to 0.75 m s(-1)), grounded running at intermediate speeds (0.75 m s(-1) < u < 1.67 m s(-1)) and aerial running at high speeds (greater than or equal to 1.67 m s(-1)). changes of gait were associated with reductions in the gross cost of transport (cot; j kg(-1) m(-1)), providing the first ...	2011	21288943