Good morning T & D
The relationships between species, as affects distribution, does
not seem to be all that well understood. Some species occur ‘with’
other species; some species avoid other species. May I
speculate?
The R Wattlebird is a very aggressive species. I think it
might be responsible for absence of the Noisy Miner from the strongly-defended
garden territories of the wattlebird. That is not to say that both
species might not occur together in some places.
Let’s face it, from a bird point of view the ANBG is a strange
place. The available food and variety of habitats allows a concentration
of adjoining and overlapping territories. Students of the relevant
species will know much more about that. Fierce tussles between RWBs
are commonplace, sometimes in the form of death grapples on the ground, where locked-together
combatants can almost roll under your feet. I have seen two examples of apparently
permanent eye injuries (to wattlebirds, not birdwatchers) that I attribute to
this. Wattlebirds constantly chase other species.
I think koels are in suburbs where there is most food, but they
will probably spread to other suburbs eventually. However, they are
harassed by wattlebirds, particularly the female koel. I have seen
several examples of wattlebird attacks causing koels to leave an area, at least
temporarily - typically the female followed by the male. Although
koels are attracted to RWB nesting territories, I think the bot gardens are
just too hot for them, from that point of view.
Another point is that calling male koels are birds of
habit, even using the same calling perch for weeks on end. Therefore you
are either in a koel calling territory or you are not. It is not as
if the birds fly around calling all over the place, more or less randomly.
From: Dimitris Bertzeletos
[
Sent: Monday, 24 January 2011 11:56 PM
To: canberra birds
Subject: RE: [canberrabirds] Koels - why so patchy?
Heya
Tonya
I did my special topics on the range expansion of the Common Koel into South
Eastern Australia. Me and Dr. Naomi Langmore discovered that the colonization
of Red Wattlebirds by the cuckoo is partly to blame. If my memory is right the
two species met (Koels expanding south, Red Wattlebirds expanding north) round
~1950 in the Sydney area from which point their spread took off. Urban habitats
also favour Red (and Little Wattlebirds) in addition to having many fruit
bearing trees. Add a warming climate and this tropical species is fairing very
well indeed.
The species has increased on the south coast as well and though it is also
found in more natural settings. There are three youngsters that I know off
within 300 meters of my house this season, all fed by Red Wattlebirds.
Now as to why the species is patchy in the ACT. It's a recent colonist the
first breeding records being in 2009. So perhaps the species hasn't colonised
all suitable areas, or as you say, only prime urban areas suit the needs of the
adults.
Hope this helps :-)
D.
From:
Date: Mon, 24 Jan 2011 22:01:48 +1100
To:
Subject: Koels - why so patchy?
Hi all,
I just moved to O'Connor, where there is a Koel that calls constantly,
and I've noticed that Koel are fairly common in the Inner North. But I
spend quite a lot of time in the botanic gardens (like all day most days for
much of the breeding season), and have for the past few years, and I've only
rarely ever heard a koel there, despite the fact that there are tons of
wattlebirds and orioles that could serve as hosts. Does anyone know why
Koel are more abundant in the suburbs - perhaps a diet of planted trees serves
better than natives, and that's more important than host abundance? Any
thoughts of opinions would be appreciated!
Cheers,
Tonya
--
Tonya Haff
PhD candidate
Evolution, Ecology and Genetics
Research School of Biology
Australian National University
Mobile:+61-4-3331-2908
Lab: +61-2-6125-5651
