The chart below shows estimated lay dates for each eyrie found in the four years (1996 - 1999) against the altitude of each eyrie.
Chart 1:
Many eyries were located in the 800m - 1100m range. This was due to the fact that most cliffs here fall into this altitudinal range.
Elevation of eyries found to date in KNP and Ulandra Nature Reserve range from 350m to 1300m. To date, the 1300m eyrie is the highest known eyrie in Australia. There were indications that the eyrie at 1300m was used in 1996, however it was only discovered during the 1997 survey. Five pigeon rings were taken from the nest scrape - these were all 1995 rings. As pigeons are not raced before they are one year old, this indicates that the earliest these pigeons could have been present in the area was 1996. Peregrine eggshell was also present in the nest. In addition, numerous casts were found above the eyrie on rocks which is a good indication that young were present, as it is common behaviour for fledglings to situate themselves above eyries. However, it is not definite that this site was successful in rearing young.
Dates for egg laying are fairly consistent with the first two weeks in September, the main laying time in KNP. Ulandra tends to be two weeks earlier with 26-27 August being the lay dates for 1996 and 1997. It is interesting to note that sites in KNP range in altitude from 350m to 1300m and there are only slight delay times in relation to higher altitudes for laying as is indicated in the trend line on Chart 1. This is also the case in the Australian Capital Territory (J Olsen, personal comments).
4.3 Peregrine elevation cut-out
