CENSUS AND MONITORING OF PUFFINS FRATERCULA-ARCTICA ON ROST, N-NORWAY, 1979-1988

A new census and monitoring method for populations of breeding Puffins was developed and applied to the population on the island of Hernyken. The method is based on a star-shaped model of evenly spaced sampling plots throughout the topographic surface area of the colony. The main advantages of this approach are that all areas are equally represented, the variance of the estimates can be calculated, and it reveals changes in breeding density in any part of the colony as well as changes of the total colony area. The method can easily be used to survey other resources, even when operating on highly different scales. The number of apparently occupied Puffin burrows on Hernyken decreased from 119700 in 1979 to 43 160 in 1988. This was presumably the result of very few chicks being reared by the Rost Puffins during 1969-1982. In 1983-1987, when no recruitment was expected, the annual population decline of 13.7% was independent of burrow density and probably equalled the adult mortality rate. In 1988, there was a significant recruitment of first breeders, and these birds settled in the most densely populated areas.