THE BREEDING OF A PARADISE FLYCATCHER

Summary. 1. At Amani, Tanganyika Territory, the Paradise Flycatchers use the softest moss for their nests and make them durable by oversewing the rim with cobweb. Sites are on the forest edge nearly always over water. Theree hours of observation were made at three nests in spells of about eight hours at a time. 2. On the whole the males and females shared the care of the eggs and the young about equally, but there were wide differences in this respect from day to day 3. The eggs were covered for over 90% of the observed time, and a high proportion of spells “on” were terminated by thc mate's arriving to take over. Duration of individual spells “on” varied up to two hours, but the favourite duration (nearly half of all the spells) was about 30–40 minutes. This applied both to spells “on” terminated by the initiative of the sitting bird and to those terminated by the arrival of the mate. The possibility suggests itself that an internal rhythm was operating, irrespective of whether a bird was on or off the nest. Nevertheless, out of 39 occasions (all short) when the eggs were uncovered through the sitter's departure without relief, the same bird returned on 18, which suggests that when off the nest both parents “keep an eye on it” and react to the situation “nest uncovered”. 4. Brooding of the young amounted at first to nearly the same high percentage of time as the brooding o f the rggs, but was in much shorter spells. It stopped abruptly about the fifth day. others followed a parent. 5. Each nestling of a brood of two in a nest received more food (largely butterflies) than each in two broods of three, 2.6‐5.4 feeds per hour compared with 14‐2.5 and 1.3‐1.8. 6. Some of the young that wcre seen to fly left the nest in the absence of the parents, All left between dawn and noon. Nestling period about 11 days irrespective of the amount of food received.