The official registration of births, marriages and deaths began in Orkney, as elsewhere in Scotland, on 1 January 1855. These are known as the Statutory Registers. Before that time parish records of births and marriages were kept by parish ministers on a voluntary basis. Some ministers began to keep records much earlier than others and some were more thorough than others in this task. Most recorded births or baptisms as well as marriages but very few recorded deaths in their parishes, and of course there was no such thing as a certificate of birth or marriage. Modern certificates carry a wealth of data but the amount of information recorded by the parish ministers was scant indeed. For a birth it was often only the names of the baby and the parents and for a marriage only the names of the bridal couple. Sometimes other details such as ages or addresses might be given. These records are now known as the Old Parish Records (OPRs).
After official registration began in 1855 the OPRs were called into the care of the Registrar General in Edinburgh. It was then discovered that there were many gaps in them, extending from a few weeks in some cases to many years in others. There is a very long gap in the Rousay records extending to 52 years. The earliest OPRs in Scotland date back to the 1500s but the earliest Rousay ones date from 200 years later, in 1733. So we have records of births and marriages from 1733 to 1746 and then there follows a gap of over 50 years. Because the gap covers two generations it is almost impossible to determine accurate connections between names appearing in the records before the gap with those appearing after the gap.
This long gap in the Rousay OPRs is a severe handicap to those researching their Rousay ancestry. Some information about people who were born during those gap years does come to light if they lived until the beginning of 1855. After that time their deaths were recorded and their ages, as well as the names of their parents and spouses, will appear on their death certificates. Photographs, wills, and documents dealing with land ownership or rentals, can be sources of useful information. In some families old letters and other documents have survived and some family bibles had special pages on which births, marriages, and deaths could be recorded.
The further back in time your search takes you the more difficult it becomes. This is because records beome less numerous. Some people are so eager to trace back to yet another generation that they will not accept the assurances of others who have already gone down that road that there is no way of tracing a particular line further back. They just cannot be persuaded so I am happy to let them go on hunting. They will have to learn the hard way. Or maybe they will come up with a brilliant discovery which all the rest of us had missed.