4. RESULTS & DISCUSSION   continued

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4.6 Impact of disturbances at nesting sites

	4.6.1 Human disturbances Human activities which have a direct impact on breeding pairs include: climbing; hang gliding; quarrying; walking tracks; research activities carried out near cliffs including this study. Some peregrines are quite accepting of human activities around them whilst others are definitely not. Acceptance of humans by peregrines seems to be determined by the individual birds' disposition and the frequency both in and out of the breeding season that humans are encountered. Cliff size and height seem to affect peregrines' tolerance to disturbance. The bigger and better the cliff, the safer they appear to be from human intervention. Peregrines nesting on small cliffs are vulnerable and the cliff may be abandoned easily.
		4.6.1.1 Recreation: The peregrines that nest at the most popular climbing and caving area in Northern Kosciuszko are committed to breeding well before visitors are able to access the area. Seasonal closures of the area limits visitor access early in the breeding season. These peregrines have been through site selection, scraping of ledge, copulation, and egg laying well before gate opening. These eggs are very close to hatching by the time people access this site and the birds have bonded to the cliff. In the four years of this studying these birds they have reared young. This may not be the case if the area was accessed all year by visitors as this added impact may impair breeding success or the site may be abandoned. In the Australian Capital Territory (ACT), at one local climbing cliff it was found that the breeding peregrines moved approximately two kilometres (J Olsen personal comments) away to a new cliff. These birds were lucky to have other options available. Some may not. Again birds in KNP produce young, so it may be better to say nothing and monitor success of the eyrie. Hang-gliders are of less problem in KNP due to the normal hang-gliding "season" which is after the breeding season. back to top 4.6.1.2 Research: Being on a cliff for an extended period of time can jeopardise the eggs or young where they are less than ten days old through possible chilling or overheating. If it is early in the season and the parent bird is agitated, it is wise to retreat after about 10 minutes if the nest is not located and return later in the season. It is good practice to take a note of the time the parent bird started attacking or making noises, as generally it is necessary to be out of sight before the adult will return to the nest. In some instances the female bird will escort an intruder out of the area. Other research work can have an impact on peregrines. These include mammal trapping and hair tubing around cliffs. This type of research requires daily checking of traps and regular replacement of tape on hair tubes and may have a direct impact on the breeding success of peregrines. Since starting this project it appears that the peregrines have adjusted to human presence. During the first year of surveying, the peregrines were generally more vocal and more game in the defence. With each year some peregrines appeared to have accepted human presence more readily. back to top 4.6.1.3 Other disturbances: It seems incredible that peregrines can tolerance being close to machinery. At one of the sites trains pass within eight metres of the eyrie. The peregrines reared young each year of the survey. back to top
	4.6.2 Disturbance by animals Peregrines can be driven out of the eyrie by a whole range of animals and birds, such as wedge tailed eagles, owls, goats, goannas and possum. In fact, possum scats were observed in eyries during the study. On numerous occasions the eviction of wedge tailed eagles from around eyries was witnessed. In two of these instances the attacks were so fierce that the peregrines put the eagle to ground. At one of the nesting ledges, a goanna was observed descending the cliff towards the three young in the eyrie. The adult peregrines evicted it by actually striking the goanna around its tail area. back to top
		4.6.2.1 Goats and peregrines: At all the cliffs visited in the Lower Snowy area, goats were either present or using the cliff at different periods. Many cliffs were used by goats as camps for the night. The effects of goats on nesting peregrines needs to be broken down into individual issues, as follows: When goats first inhabited the area. As goats started to disperse into KNP from neighbouring areas, there climbing ability would have enabled them to target cliffs for protection. Consequently, goats tend to spend large amounts of time around cliffs. In the beginning, the presence of the goats could have been detrimental to the success of the peregrines' breeding. It is not known for how many seasons this may have impaired breeding. Individual pairs could have accepted this disturbance quickly. Others may have abandoned the site. Cliffs that were easily negotiated by goats would certainly have been abandoned due to the goats accessing the nest ledge or being so close to it. We may now have less breeding pairs in this area than prior to the introduction of the goats. What is happening now Given that only two weeks were spent in the area over the last two seasons (1998 and 1999), observations of goat impact were made at only a few active nest ledges. At site 25 during the 1998 survey, goats were present on the cliff. Male and female falcons were at the cliff but were behaving as a non-breeding pair. A thorough search of the cliff did not reveal an active nest. During the 1999 survey, it was apparent that the goats had not used the cliff for some time. One of the ledges contained one egg, although no parent bird was spotted in the short time of the visit. At site 24, goats were present on the cliff during the 1998 survey and again in 1999. At this particular cliff, the peregrines were breeding both years. During one evening, the cliff was observed (using the spotting scope) from approximately 1km away. Goats were observed climbing above and around the eyrie. This activity seemed to have no impact on the incubating female. It appears that this pair had accepted the goats' presence. It should be pointed out however that the nest ledge was in a very secure place with the goats out of sight most of the time. It was interesting that the female reacted to the presence of humans by the usual diving and screaming, but did not react this way with the goats' presence. It would seem that the peregrine could distinguish between humans and the goats. On arrival at site 29, goats were camped adjacent to the cliff. Again, the peregrine (a male only was seen) reacted to human presence but not to the presence of the goats. No active nest was located at this site, however there was evidence of previous use of ledges. back to top Impact by goats on replacement male or female peregrine. Given that it seems some of the peregrines accept the goats, it would be interesting to assess acceptance of the goats when one of the pair, or the pair, is replaced. It is suggested that this eventual replacement of birds would impede breeding for some time, until the new bird(s) became accustomed to the goats. Of course the replacement bird may have been in the area for some time and already be accustomed to the goats, but perhaps not at such close quarters as will be the case whilst breeding. Conclusion Although peregrine eggs have been sighted on ledges, young peregrines have not been sighted in the nest. The Lower Snowy area is surveyed early in the season to avoid the hotter weather of November. Because young peregrines have not actually been sighted, it cannot be concluded that breeding at these sites has been successful. It may be that the goats are having an impact. It is possible that they are causing disturbances resulting the female peregrine being off the eggs repeatedly. This could lead to embryo cooling and overall reduced hatching. In any case, removal of the goats is the preferred option. back to top