No abstract

A high level of dopaminergic activation such as that produced by a high dose of amphetamine suppresses eating, whereas a low level such as that produced by a low dose can have the opposite effect. Like a high dose of amphetamine, a high level of wheel running also suppresses eating. It was hypothesized that this suppression is due to dopaminergic activation produced by wheel running. If so, a relatively small amount of wheel running should produce a low level of dopaminergic activation and thus have the same effect as a low dose of amphetamine: facilitation of eating. In the present experiment, nondeprived rats were allowed to run in a wheel for 30 min before a feeding test. As predicted, a little wheel running facilitated eating in these rats relative to appropriate controls. The present results may be relevant to an understanding of eating disorders in humans.

Behavioural interactions between Harbour seal mothers and pups at Miquelon revealed that the following behaviour of the pup generally ensures that the pair stay together, though the mother takes over this rôle when necessary. This relationship held true when the animals were hauled out on the sandflats, and when they were in the water. Our results imply, contrary to suggestions in the literature, that the pup is able to distinguish its mother from other females. The tendency of the pup to follow its mother is discussed in the context of imprinting as a bonding mechanism.

No abstract

Many pinnipeds travel long distances between breeding and feeding grounds in some cases showing remarkable homing abilities (James & Dykes, 1978). Very little is known about the methods they use to plot their course but if they were aware of their rate of movement, this ability could conceivably assist them. The following procedure which was undertaken with a captive male harbour seal (Phoca vitulina Linnaeus) demonstrated that the animal was able to determine his swimming speed.The seal was first trained to swim at any speed through ten hoops 48 cm in diameter submerged at equal intervals around the periphery of an 8 m oval tank filled with sea water to a depth of 1.2 m. Each trial consisted of one circuit of the tank, and always began at the same hoop. A screen preventing the seal from going through this start hoop was removed to indicate the onset of each trial. The seal was then trained to swim the 17 m course maintaining a speed of 6 km/h. The experimenter observed from a bridge suspended over the tank, and measured the animal's speed by listening to a series of tones. These tones were audible only to the experimenter and were timed such that if the seal were swimming at 6 km/h, he would reach each hoop at the same moment the experimenter heard the tone. A buzzer was sounded whenever the animal swam at less than the required speed, and a whistle was blown if he were moving too quickly.