Conservation ecology of kea - Kea Conservation Trust website

Information Criterion (AIC; Lebreton et al. 1992), with the best models having a low
AIC value and a high model weight calculated from the differences in AIC (Buckland et
al. 1997). We examine the significance of specific terms included in the models using
likelihood ratio tests (LRT). This approach involves calculating the difference in –2.log
likelihood values between a model that includes the term in question and one that does
not. The resulting statistic follows a chi-square distribution with one degree of freedom
(Hosmer & Lemeshow 1989).
Results
We monitored 36 kea nests between 1993 and 1998 (Fig. 2). In 1998 we were able to
find more nests because more birds were radio-tagged and because some unmated radio-
tagged males led us to previously unknown pairs on the periphery of the study site. We
failed to find any nests in 1996, despite visiting all known nest holes three times over the
spring, and despite an intensive radio tracking effort. Nests were found at all stages of
the breeding cycle from egg laying until just before fledging, although 74% were found
before the eggs hatched (Fig. 1).
Figure 2. Kea nests found at Nelson Lakes from 1993-1998.
Number of nests
14
12
10
8
6
4
2
0
1993
1994
1995
Year
1996
1997
1998
13
In progress at end of field
season
Fledged
Nest contents
disappeared/preyed upon
Accidents