otters to 10 miles of stream.' In the Upper Thames I should be inclined to say that there must be fully one otter to every 5 miles of river, which is a somewhat higher estimate than that for the north of the county. A curious fact about otters, which seems only to have been realized of late years, is that they breed at any time of year, although they do not have more than one litter in about a twelve- month. Certain animals, such as some of the rodents, breed nearly all the year round under favourable conditions ; and the gray- seal breeds exclusively in the autumn, which appears also to be the custom of the dor- mouse, though rather earlier, and with greater range of date ; while for a wild animal only reproducing about once in twelve months, to have no special season, appears to be a unique arrangement. The female otter comes in season with the greatest regularity every month from the time she is ten months old. The most common number of young in my own experience is two, but frequently three, a larger number being exceptional ; but Mr. Uthwatt says, ' Three is about the usual number of the litter, though they often have four or five, and occasionally six.'
My friend Mr. Thomas Southwell, M.B.O.U., F.Z.S., was the first really to grasp the fact that otters have young at any time of year, and published notes on it in the Zoologist for 1877 (p. i 72) and 1888 (p. 248) ; the first of these being a reply to a note of mine in the same volume (p. 100). It may now be asserted with some confidence that while the young are born during any month of the year, yet that more litters are born between October and February, both inclu- sive, than during the remaining seven months of the year. Mr. Uthwatt says on this point : ' They breed all the year round, but probably more cubs are born in January, February, and March, than at any other time.' Though differing most reluctantly from one with so great a practical experience, I believe this is not the case.
I have noticed by observation of otters in captivity, that the females when in season have a curious habit, which seems to be designed to attract the attention of any pass- ing male. This is that they collect little mouthfuls of short straws and deposit them here and there. In a state of liberty short bents or dead aquatic plants would doubtless be substituted for the straws ; but outside a cage these little tufts would be very difficult for a human eye to recognize. Having once noticed this habit among my otters in cap- tivity, it is now easy to tell when one is in season, without further observation. I began keeping otters in captivity in 1869, and during the last thirty years have, with one short in- terval of a few months, kept them continu- ously, seldom having fewer than two in my possession at any one time, and sometimes a larger number.
The story of the breeding of a litter in my collection was told originally in a note pub- lished in the Proceedings of the Zoological Society, 1 88 1, p. 249 ; repeated with additions in the Zoologist, 1882 (p. 20 1) ; and also copied into the Live Stock Journal in the former year. The facts noted are briefly as follows : Pair- ing took place while swimming in the tank early on 12 August, and after a gestation of sixty-one days (during the last ten or twelve of which the female was obviously gravid) young were born on the afternoon of 12 October. The mother had been hand-reared with a feeding-bottle, and was extremely tame, so I ventured to look at the cubs on the 25th (when thirteen days old), finding them to be two in number and about 8 inches in total length. Though the mother made not the smallest objection to my looking at the cubs, yet on returning to them her instinct came in, and within a couple of hours she transferred them to the other bed-box. From that day they were constantly (often daily) shifted backwards and forwards from one box to the other. They were in every case I think removed by the most direct route across the tank ; and the greater part of the way they were under water, being carried by the scruff of the neck. They were blind for about thirty days. On 9 December, when they were eight weeks two days old, they first voluntarily emerged from the shelter of the bed-box and made a little tour of inspec- tion of the cage (about 28 feet long) ; they went into the water both intentionally and accidentally as was supposed. One had hung half out of the box four days previously. The next day I first saw the mother carry fish into the box, to try to tempt the cubs to begin a more solid diet ; and on the afternoon of the same day the cubs were anxious to take a little walk, but the mother hearing the garden men grubbing some bushes, in spite of her extreme lameness, felt nervous on their behalf, and would not allow them out of shelter. She kept pulling them back as first one and then the other crawled towards the exit. At last losing patience with one which was specially insubordinate, she seized it by the side of the neck and carried it to the tank, in which she gave it a thorough sousing and thence straight back to bed, where, after a further short demonstration of independence, it subsided. Two days later, one of the cubs
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