4. RESULTS & DISCUSSION   continued

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4.7 Egg laying

Infertile and/or eggs not incubated properly were identified in two eyries during 1997 and four during 1996. Jerry Olsen (personal comments) found one in four eyries contain addled eggs. Eggs that are addled are sometimes still in the eyrie long after the remaining young have fledged. These eggs tend to become bleached out. In one instance during the study, a female peregrine was still trying to incubate an addled egg which was 16 days overdue (see photograph). At this nest site, the live young present was in poor condition. This may have been due to the female placing higher priority on egg incubation rather than caring for the live young. Some addled eggs disappear. These may be crushed by the young in the eyrie. It is therefore difficult to determine a ratio of fertile to infertile eggs for a particular season.