Temporal patterns of territory settlement and detectability in mated and unmated Nightingales Luscinia megarhynchos

In many bird species the sex ratio of adults is male-biased, which is likely to have consequences for the ecology as well as for the conservation of a species. For example, when some males remain unpaired in a population, there should be strong selection on behavioural traits that enhance pairing success. A surplus of males is also likely to have important implications for the interpretation of breeding bird survey data. In our study population of Nightingales Luscinia megarhynchos, about half of the males stayed unpaired, suggesting that the number of males encountered singing was greater than the number of breeding pairs. Furthermore, the detectability (the probability of encountering a male singing) of mated males was only two-thirds that of unmated males when censused in the morning or late in the breeding season. The relative detectability was more similar early in the season and during the twilight periods before sunrise and after sunset. Males that arrived earlier on the breeding grounds were more successful in attracting a mate than males arriving later. Some of the unmated males deserted their territories and prospected areas up to 4000 m distant, whereas others settled on the study site only late in the season and may actually have changed territories. We suggest that adult sex ratios and the time of the census should be taken into account when interpreting the results of breeding bird surveys.

Rethinking the early medieval settlement of woodlands: evidence from the western Sussex Weald

The assumptions underlying the interpretation of the early medieval settlement of woodland are challenged through a detailed study of the Weald in western Sussex. The patterns of usage of woodland in England were very varied, and each area needs to be looked at individually. Systems of woodland exploitation did not simply develop from extensive to intensive, but may have taken a number of different forms during the early medieval period. In one area of the Weald, near to Horsham, the woodland appears to have been systematically divided up between different estates. This implies that woodland settlement may not always have developed organically, but this type of landscape could have been planned. It is argued that the historical complexity of woodland landscapes has not been recognised because the evidence has been aggregated. Instead, each strand of evidence needs to be evaluated separately.