|Subject:||Re: Still on the Regent Honeyeater at Newstead, Vic!|
|Date:||Thu, 12 Jun 2003 14:42:10 +1000|
Chris opened the can of worms! "You mentioned in an earlier posting that you can notice a difference in the calls of Victorian and NSW birds, yet there is evidence, through sightings of banded birds from Chiltern, that Vic. birds travel to NSW (Capertee Valley). Did the Chiltern bird then start talking the NSW lingo? And, is there reason to believe that if there are state populations of Regents, that they occasionally 'mix', or is there just the one single population of the species occurring throughout Vic, NSW and SE Qld, and that the birds are highly nomadic in their pursuit of suitable foraging pastures, and thus could turn up anywhere?"
Well, this a very long story and I conveniently omitted mentioning the movement patterns of Regents when discussing dialects for that reason.
OK, Chris asked - blame him!!.
It was once thought (at least by me) that there were discrete "populations" of Regent Honeyeaters. This was/is a matter of some importance to the Recovery Program as it potentially impacts on how we manage the population/s. We can either manage for three populations (northern NSW, central NSW and north-east Victoria) or one population. If we adopt the latter approach then it doesn't matter (in a relative sense) if we lose the Victorian birds as they would be considered "merely" the southern limit of a much more broadly distributed taxa. If we recognised three "populations" we might give equal weight to ensuring the survival of each of the taxa.
If adopting the one taxa approach we could, theoretically at some stage, supplement the failing Victorian population with birds from the much healthier (in terms of numbers) central NSW population using captive breeding to build up numbers. If there are, in actual fact, three populations then such an approach would be fraught with danger.
In 1995 we had scientists compare the DNA of Regent Honeyeaters from northern NSW, central NSW, the ACT and north-east Victoria. The conclusion? They could detect no significant difference between the four sample groups. I do not have a good enough understanding of the techniques used to comment on this other than to suggest that the critical points here are the ability to detect a significant difference. This is not the same as saying there was no difference. I understand that major advances have been made in this field since 1995.
Now back to the main point! (see why I decided to omit this aspect of the discussion).
There are confirmed records of individually identifiable, ie colour-banded, Regent Honeyeaters moving between the three main breeding areas (these have been published in Recovery Round-up in various issues of Corella - the journal of the Aust Bird Study Association). The one Chris alluded to was a bird banded in the Capertee Valley (central NSW) on 26-10-1994, resighted in the Capertee Valley Aug 1997 and then at Chiltern on 21-07-2001. This was a movement of at least 472km.
Other movements include two birds (of only nine banded) marked in the ACT in December 1995 and resighted in the Capertee Valley (~ 270 km to the north) on 08-10-1997 and 08-03-1998 respectively.
On 17-07-2002 a colour-banded Regent HE was sighted on the NSW Central Coast (a non-breeding refuge area). This bird was banded near Barraba on 08-04-1995, a movement of at least 355 km. This movement is of significance because it was a member of a flock that contained at least three other Regent HEs colour-banded in the Capertee Valley (109km to the west).
So what does all this mean? Yes, there are movements between the remaining core breeding areas albeit of only a very small number of individuals. We have a large number of colour-banded birds that are repeatedly seen back in the same breeding area where they were banded or at sites 80 or so km away (there is regular interchange of birds breeding in the Capertee Valley and the Munghorn Gap - Wollar area for example but that's another story). This small exchange of genetic material between areas might not be enough to affect things such as dialect and I think it is perfectly acceptable to think that a bird from the Capertee Valley can "talk" to a bird from Chiltern.
So, do we have one or three "populations" of Regent Honeyeaters. I'm still sitting on the fence.
Regent Honeyeater Recovery Coordinator
NSW National Parks & Wildlife Service
P.O. Box 2111
Dubbo NSW 2830
Ph: 02 6883 5335 or Freecall 1800 621 056
Fax: 02 6884 9382
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