Abstract: Groups of 3-5 homing pigeons individually recognizable by different colours of their plumage were followed by helicopter on their way home. In most cases the animals flew together as a group with frequently changing leadership. Flight formations in terms of leadership were noted every minute. It was examined statistically whether the flight order varies at random or whether there are leading and led birds. In 6 out of 7 experiments with groups of 4-5 pigeons flight order was far from random, one or two pigeons proving to be leaders. In only one experiment leadership did not differ from a random distribution. No correlation could be found between the tendency to lead within a group and homing performance of the single pigeon when released individually.

Abstract: Summary Utilization of waterholes by wildlife was studied between April, 1973 and July, 1974 in Tsavo National Park (East), south of the Voi river. Seasonality was an important factor which influenced the various aspects of waterhole utilization. The numbers of the herbivores utilizing the waterholes increased during the dry season but fell during the rains. Some ungulates also moved near to the artificial waterholes in the dry season but moved away from them during the rains when they drank from natural water-holes formed in clay pans filled with rain water. A basic pattern of waterhole utilization dominated by small (adult-size) species during day-time 06.00–18.00 hours and larger species at night 18.00–06.00 hours is described. The separation in times of arrival and deparature peaks of waterhole utilization, and average coincidence of percentages of paired species populations are used to show that big-game attained a measure of time-spaced ecological separation at the waterholes. The water relations of some day-time and night-time drinkers are discussed. From the baseline study the management implications of the development of additional waterholes in the park are discussed.

Abstract: The reaction of Euglena gracilis cytochrome c-552 (cytochrome f) with the nonphysiological reactants potassium ferrocyanide, potassium ferricyanide, sodium ascorbate, sodium dithionite, and Chromatium vinosum high potential nonheme iron protein was studied by stopped-flow and temperature-jump kinetic methods. The reaction of the purified, water-soluble protein with the reactants was investigated as a function of ionic strength, pH, and temperature. The results demonstrated that reduction and oxidation takes place at a negatively charged site on the cytochrome c-552 surface. Participation of specific amino acid residues in electron transfer is implicated from the pH results. The results obtained for the nonphysiological reactions of cytochrome c-552 are compared with available data for horse heart cytochrome c and Rhodospirillum rubrum cytochrome c2. The results strongly suggest that Euglena gracilis cytochrome c-552 undergoes nonphysiological oxidation and reduction by a mechanism different from that found for cytochrome c or cytochrome c2.