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ROOSTING PREFERENCES OF A WHISKERED BAT
Having accustomed the bat to roosting in these vertical crevices one of the sheets of glass was covered on the outside with black enamel, the bat side of both being still piain glass. The bat showed no preference as between piain or dark glass. If it hung up under the piain glass and the dark was substituted it was in the same place in the morning and vice versa, this substitution being made as often when it was hanging in one of the crevices or in the other so that there was no question of " crevice preference " affecting the result. In fact such crevice preference as appeared seemed to be purely conservative. T h e bat would sleep in the left-hand crevice, go down to feed, return and stay there whether under dark or clear glass only to do the same if removed and put under the right-hand one. Light seemed to make no difference. On two nights in each of the two crevices under clear glass and with dark glass on the other the bat was left with a 60 watt lamp shining on it from a distance of 18". In every case the bat was found still under the clear glass in the morning, having certainly gone down to feed on two of the nights, when it emptied its food dish. T h e other cage used was a box 200 X 250 X 250 mm. high. T h e door was ]" wire netting boarded on the outside to prevent draughts, the sides of wood too smooth for a bat to climb. There was a false back, triangular in horizontal cross section and 10 mm. shorter in height than the true back. There was therefore at the top of the false back a horizontal crevice 10 mm. deep and, due to the triangular cross section, varying in width from 5 to 35 mm. In front of the upper part of the false back was fixed, from side to side and parallel with the true back, a sheet of glass 100 mm. deep making, below the horizontal one, a vertical crevice 90 mm. deep and varying in width from front to back between 0 and 30 mm. T h e false back was faced with perforated zinc to make a uniform and easily climbing surface. The bat therefore had a number of alternative roosting sites :— 1. Hanging vertically on the wire netting front, either against the boards or in a free draught. 2. Hanging in a vertical crevice of varying widths or on the back in the open below the crevice. 3. Creeping into a horizontal crevice of varying widths but uniform depth. When first introduced into the cage the bat rapidly explored it throughout, pressing into the narrowest parts of both the horizontal and vertical crevices. It would do the same when re-introduced after spending a night or two in another cage. When thoroughly at home however it settled down into pretty regulär roosting habits.