Time in rehabilitation should always be as short as possible. This is because seal pups develop very rapidly in the wild, and pups in the wild therefore undergo a very steep learning curve during the first months of life, and most particularly during the first weeks after weaning. Harbour (common) seal pups are weaned at 3-4 weeks of age and research has shown that almost all pups have learned how to forage for their own live prey about two weeks after weaning, and are catching enough food to maintain their weight and grow from a month after weaning. If pups are kept in rehabilitation throughout this sensitive age of 4-8+ weeks, they are obviously missing out on this essential learning opportunity in the wild. Feeding per se is also not the sole consideration. Pups at this age are also learning social skills as they integrate into the local population and geographical knowledge of their future home range. By contrast, a pup of this age held in a rehab environment is not only missing out on the natural learning curve, but may be acquiring patterns of behaviour and orientation which could interfere with appropriate behaviour after release.

It is for this reason that we try to release our pups as soon as possible after the natural age of weaning. It is not possible, with the present feeding recipe, to match the natural 3-4 week nursing period for harbour seal pups. Our pups gain on average about 0.3 kg/day, whereas a wild pup gains about 0.5 kg/day, and some of our pups are very underweight to start with. Nevertheless, we have found that it is possible in most cases to get pups to an acceptable release weight (20-21 kg) after 4-6 weeks, sometime between the end of July and the middle of August. This enables the pups to be released at a time when most of their wild pup peers are still close to the haul-out groups of moulting adults, and still at the stage of learning to feed on tiny inshore fish. Thus although our pups are a little late joining in with the others, they are not too, and this ihas been confirmed by our radio-tracking. Wild pups end to disperse to foraging sites further offshore from late August-early September. It is probably important for rehab pups to join this dispersal after they have benefited from a few weeks of inshore feeding and orientation experience.

Our experience has been all with harbour seal pups. It is important to note that the same principles - of dove-tailing rehab pups development with pup development in the wild - will apply to other species, although weaning time and weight