Between 1946 and 1993, the number of territorial red kites, which form an isolated relict population in mid-Wales, has increased from 7 pairs to 113 pairs. Population growth has been approximately exponential at a mean rate of 5% per year. Breeding success was generally poor, but improved from an average of 0.53 young per pair in 1946-1960 to 0.71 young per pair in 1991-1993. Annual losses from the whole population (including juveniles) was estimated during 1946-1960 at 22%, reducing to 11% during 1961-1993. As the population grew, the area used for breeding expanded slowly. Despite wandering widely in their first year, birds returned to breed close to their natal area. For the most part, they expanded their breeding range progressively on a `rolling front', rather than striking out into distant unoccupied areas.