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

(Dendrocopus spp. and Picus canus) were present and/ or feeding in the same area. C. cyanus
may exert some aggressive dominant behaviour (e.g. chasing off other species) towards other
smaller species such as wagtails (Motacilla spp.) if both are competing for food. Hosono (1975)
found similar behaviour in his study in Nagano, Japan.
No obvious territorial behaviours towards conspecifics and other species were observed in this
colony of C. cyanus, even during the breeding season. I also did not observe any sort of obvious
aggression amongst group members. Reports from observations in Iberia and Japan show a mix
of results, with some populations showing territorial behaviours, such as chasing (Komeda et al.,
1987; Snow et al., 1998; S Imanishi, pers. comm.), but others not (Valencia et al., 2000). This
non-territorial behaviour may stem from relatedness of group members, but kinship has not yet
been studied in these populations.
Behavioural observations were limited by the difficulty of observing C. cyanus when they
foraged in dense bushes (e.g. Padus asiatica and Salix spp.). There is no other way around this
problem, or to improve it without alarming the whole colony, apart from conducting many, or
chance observations regarding the activities of C. cyanus in dense scrub. Observation events of
areas on the true right of Eroo River (i.e. the Main Breeding Area and Sharlan Meadows) were
limited when the water level was high, as it was impossible to cross by foot or horse. Therefore,
when this happened (about two to three days in 2009 and one week in 2010), observations were
limited to the true left of the Eroo, on the true right river bank and ca. 20 metres inland from the
true right of the river.
4.2 Radio-tracking
VHF radio tracking was employed in this study because it is by far the cheapest tracking method
and had reasonable accuracy. As far as I can determine, no VHF radio tracking research has been
published for this species before. Overall, the radio-tracking attempts were not successful on C.
cyanus, as I had difficulties getting accurate signal positioning from transmitters and securing
transmitters onto the tail-feathers of C. cyanus.
Using VHF radio tracking is not without its problems. Tests of radiotelemetry accuracy have
shown signal reception and location accuracy to be affected by several factors, amongst them
reflected signals (“signal bounce”) and attenuation resulting from vegetation cover (Withey et al.,
2001), which I think were the main reasons for difficulties in getting signals from the radio-
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