SummaryAutumn migration of Quail was studied on the northern coast of Sinai in 1972 and 1973. Arab Quail nets were used to catch totals of 4863 and 1823 in the two years, respectively. Of 1761 Quail ringed in 1973, 0–4% have been recovered from the extensive area predicted by earlier ringing results.Quail started to enter nets 10 min after first light, and continued to do so until 0800–0900 h, local time. The quantity netted per day varied greatly, producing waves of migration which were inversely correlated with the barometric pressure over Europe prior to the arrival of each wave. Each of the arriving waves was apparently a discrete (group of) populations) from one area. The very close similarities in the arrival dates of each wave for both the 1972 and 1973 passages has been interpreted as showing that the timing of autumn migration in Quail is mainly dependent on exteroreceptive time–setters and/or biological clocks.Sex and age ratios of each day's catch varied greatly and were related to the rise and fall in numbers of Quail arriving each day. The approximate sex and age ratios for all Quail crossing the coast after dawn during the 1973 passage was 58% male, 75% young, and 7–2 young per adult female.The 26 Quail analysed for fat and water content were definitely not suffering from dehydration, but many of them would not have been able to reach their wintering grounds without additional food. The ‘average’ Quail had 75% of the fat reserves required, while less than 20% of the Quail had the required amount.The daily temporal pattern of netting suggests that a proportion of the Quail cross the coast before dawn and alight at dawn well dispersed within the Sinai desert. This, together with the observed inverse correlation between the amount of fat at arrival and the time of netting, suggest that it is the Quail in poorer physiological condition that arrive later in the day, and that these may stand smaller chances of completing their autumn migration even if not netted by man.More than three times the number of Quail were caught per metre net in 1972 than 1973 (2–43 Quail/metre net/season and 0–73 Quail/metre net/season, respectively. This decline cannot be attributed to hunting. Rough quantitative data during the years 1900–1959 shows that the abundance of Quail in any year was not dependent on abundance in the preceding year. On the other hand, fluctuations in Quail abundance were associated with long–term climatic changes, i.e., netting success in Egypt was negatively associated with rainfall in the Sahel, and shooting in Luxembourg was positively correlated with temp