|
That
is a curious suggestion Harvey. I wonder why you should think the two species
should follow the same trend. I wouldn't know if you are right or partly right
or whatever. Although you are saying they don't and suggest the difference as
due to releases. Is there much difference in the rate of captivity / release /
escape between the two species? I don't know. I've seen both in captivity. All
it would take is for the Rainbow Lorikeet to have more of a tendency to stay
when conditions are good than the Musk Lorikeet and that alone could create a
difference between the population trends between the two. I do agree with your
last sentence.
I
believe the increase in the Rainbow Lorikeet in Melbourne followed a few years
behind a similar but less dramatic increase in the Musk Lorikeets in Melbourne.
But that is based on my impressions, rather than number
evidence.
Philip
further musing on the occurrence of Rainbow
Lorikeets in Canberra...
I would have expected that the natural incidence
of Rainbow Lorikeets in the Canberra region would be at about the same level as
the natural incidence of Musk Lorikeets. As Canberra is marginal to the main
(coastal) distribution of both species, birds occurring here naturally would
likely be birds moving about (ie west, as Tonya inferred) due to either
local/regional seasonal flowering or population pressure movements. These birds
are likely, for the most part, to occur in small numbers and stay for only brief
periods of time.
Musk Lorikeets are quite scarce in
Canberra, so to my mind, the most likely explanation for the
recent establishment of the small local population of Rainbow
Lorikeets is that it evolved from a small nucleus of non-naturally occurring
birds, either released (eg Tidbinbilla releases) or aviary escaped birds, or
both, which with the assistance of artificial feeding managed to survive
Canberra winters. From there the population is slowly increasing, and slowly
spreading, perhaps with the occasional incorporation of further escaped birds
and possibly wild nomadic birds originating from outside the
region.
If this is the case I
would anticipate the population would continue to grow, albeit slowly. Increased
availability of food from cultivated year-round flowering garden plants and
artificial feeding, and the impacts of climate change, would assist this
growth.
Harvey
Harvey Perkins
CRC Selection Rounds
Section
_______________________________________
Department of Innovation, Industry, Science and
Research
| 