Determinants of Home Range Size for Polar Bears (Ursus maritimus)

The mean home range size of female polar bears (Ursus maritimus; 125 100 km2 ± 11 800; n = 93) is substantially larger than the predicted value (514 km2) for a terrestrial carnivore of similar weight. To understand this difference, we correlated home range size and sea ice characteristics. Home range size was related to […]

Breathing frequency in ruminants: a comparative analysis with non-ruminant mammals

In cattle, sheep and goats, during resting conditions, breathing frequency (f) greatly exceeds the value expected for their body weight (W, kg) from the allometric curve of other land mammals. It was postulated that this was the effect of the production of CO2 during rumen fermentation. If this were the case, a high f should […]

The scaling of eye size with body mass in birds

We developed a simple method that uses skulls to estimate the diameter, and hence the mass, of birds’ eyes. Allometric analysis demonstrated that, within five orders (parrots, pigeons, petrels, raptors and owls) and across 104 families of flying birds, eye mass is proportional to (body mass)0.68 over a range of body masses (6 g to […]

Metabolism and thermoregulation during fasting in king penguins, Aptenodytes patagonicus, in air and water

We measured oxygen consumption rate (O2) and body temperatures in 10 king penguins in air and water. O2 was measured during rest and at submaximal and maximal exercise before (fed) and after (fasted) an average fasting duration of 14.4 ± 2.3 days (mean ± 1 SD, range 10–19 days) in air and water. Concurrently, we […]