The subspecific origin of the inland breeding colonies of the cormorant Phalacrocorax carbo in Britain.

The establishment of cormorant breeding colonies inland within south-east Britain since 1981 is a matter of major conservation and pest management concern. This study was initiated to investigate the subspecific origin of two recently established breeding colonies. The analysis examined sequence variation of the control (D-loop) region of the mitochondrial genome. Samples of tissue were obtained from 334 individuals from across the species range in western Europe from both subspecies (Phalacrocorax carbo carbo and P. c. sinensis) and 84 birds from two inland breeding colonies in Britain. Single-strand conformation polymorphism (SSCP) was used to assess mitochondrial variation among samples, revealing four haplotypes. The samples from the traditional breeding colonies clustered into three distinct phylogeographic groupings: Norway-Scotland, Wales-England-Iles des Chausey and the rest of Continental Europe. These results only partly agree with the traditional subspecific taxonomic groupings and are slightly at variance with results using microsatellite DNA frequencies, and a hypothesis using results from both studies is advanced. The subspecific origin of the inland colonies was investigated using maximum likelihood and Bayesian models.

Canada goose (Branta canadensis) droppings as a potential source of pathogenic bacteria.

Canada goose droppings, collected in parks to which the public had access, were screened for a range of bacteria that could be pathogenic in man. Droppings of Canada geese, and other waterfowl, did contain such bacteria, including some that are well-known causes of illness in man. These bacteria, plus a species of Salmonella that was experimentally inoculated into droppings, were shown to survive and multiply in the droppings for up to one month after their deposition by geese. Canada geese ranged further from water than other waterfowl species and thus distributed their droppings over a larger area of park grassland. This more widespread distribution of their droppings leads Canada geese to pose a greater potential health risk than other waterfowl studied here, but variations in human responses to challenge with bacteria, and variations in human and waterfowl behaviour in public parks, renders quantification of this risk impossible.

Soldado virus (Hughes group) from Ornithodoros (Alectorobius) capensis (Ixodoidea: Argasidae) infesting Sooty Tern colonies in the Seychelles, Indian Ocean.

In the summer of 1973, about 5,000 pairs of adult Sooty Terns abandoned a specific part of their breeding grounds on Bird Island in the Seychelles. Incubated eggs and newly hatched chicks were left unattended and the area was not reoccupied in 1974. Numerous Ornithodoros (Alectorobius) capensis occurred in the deserted part in both years, but few or none in the area where bird breeding was normal. Persons visiting the deserted area were bitten by many ticks and experienced severe pruritus persisting for several days. In 1973 and 1974, Soldado (SOL) virus (Hughes serogroup) was isolated from the ticks taken on Bird Island from the ground and from sick and not visibly sick chicks of the Sooty Tern, and also from nests of the Blue-faced Booby on Des Noeufs Island. When ticks from the ground and from Sooty Tern chicks were fed on domestic chicks, they transmitted SOL virus and caused the death of their hosts. Soldado virus was previously known only from O. (A.) capensis-group ticks infesting marine bird colonies on islands off Trinidad and in a lake in Ethiopia. We have also isolated SOL virus from another species of the subgenus Alectorobius from Wales, Great Britain. Marine bird migrations undoubtedly account for the remarkably extensive distribution of SOL virus. The role of migration in the mechanisms and dynamics of tick and virus distribution, and the comparative growth cycles of Hughes serogroup viruses in Ornithodoros ticks, remain to be determined for a better epidemiological understanding of this agent.

The adaptive significance of aggregation behaviour in the dogwhelk Nucella lapillus (L.).

Three kinds of aggregation behaviour were observed in an exposed shore population of Nucella lapillus. Aggregations on the open rock surface during the summer protected dogwhelks from water movement, and were not found on shores where the topography conferred protection. Feeding occurred mainly within these aggregations, probably because individuals experienced less disturbance there than when isolated. Physical contact was important in holding animals together.Winter and pre-breeding aggregations were usually found in clefts or pools. All age groups formed winter aggregations, but those of immature dogwhelks were not as permanent as those of adults, and the latter merged with the prebreeding aggregations. Winter aggregations protected dogwhelks from dislodgment when their ability to regain a foothold was reduced by low temperatures, while pre-breeding aggregations brought the sexes together for fertilization, but the permanence of adult winter aggregations suggested that reproductive activity may have been occurring within them.

Aspects of the ecology of an exposed shore population of dogwhelks Nucella lapillus (L.).

Up to the third year of life Nucella lapillus (L.) could be aged in the laboratory and in the field using shell characters. Monthly counts along transects on an exposed rocky shore have shown that the age groups behave differently, dogwhelks in their first year migrating upshore, and returning to lower levels in the second year. Adults (three years or older) lived and laid egg capsules in the low shore. The most favourable situation for subsequent hatching of these capsules was where they were permanently submerged in sea water.The first requirement of recently hatched young was probably protection from water movement, but they soon gegan feeding on small mussels. The shell height attained by the end of the first winter was related to winter temperatures, but the main growing season was June to November. Adult size was attained in two years, after which the individuals did not usually grow, but those which did grow during the third or succeeding years may have been nonbreeders or have been castrated by the trematode Parorchis acanthus.The age structure of the population suggested that mortality rate decreased with age, and this was confirmed by calculating annual mortality rates for the first three years of life. Heavy mortality in the low shore during the first winter was due mainly to predation by purple sandpipers. In succeeding winters mortality was low, and predation, the main mortality factor, was restricted to the summer months. At this time Cancer pagurus was the most voracious predator, but it was active mainly in the low shore, and the upshore distribution of second year dogwhelks, which were preferred to other age groups, age groups also led to a more economical use of environmental resources, namely food, winter aggregation sites and breeding sites.