Habitat use and population dynamics of the Azure-Winged Magpie ...

Based on visual estimations of total colony sizes in early autumn (September), I estimated that
55.4% of the colony was banded in 2007, 83.1% in 2008, 92.9% in 2009, and 68.6% in 2010
(Table 3.8). I took into account the ca. 20 birds that left the colony just after the breeding season
in 2009.
Table 3.8 Proportion (%) of the colony that was banded each year. No visual estimation was done
for 2006. Visual estimations in early autumn (September) each year was used.
Estimation methods 2006 2007 2008 2009 2010
Visual (%) - 55.4 83.1 92.9 68.6
The number of birds born into this colony showed a marked decrease over four years (2006-
2010) (r 2 = 0.942, P = 0.020; Fig. 3.10). The number of fledged chicks also showed a significant
decline, although only marginally (r 2 = 0.864, P = 0.046).
Although group size in the beginning of the 2010 breeding season was the lowest amongst the
four years for which we have data, the number of individuals present in the beginning of the
season did not differ significantly across the years (r 2 = 0.645, P = 0.127; Table 3.5, Fig. 3.11).
Although the number of chicks hatched in 2009 was more than in 2010, the number of chicks that
fledged in 2010 was similar to 2009 (Table 3.6; Fig. 3.10). Six breeders fledged chicks
successfully in 2010 compared to 10 in 2009 (Table 3.5; Fig. 3.16). Although the number of birds
visually estimated in the colony in autumn was comparable in both years (2009 & 2010), the
starting population only consisted of 18 birds in June 2010 compared to 41 birds in May 2009
(Table 3.5).
Assuming the adult birds that were banded in 2006 and 2007 were yearlings, six birds in our
colony were at least four years old when they were re-sighted in 2009 and 2010 (four and two
respectively).
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