Apologies to Ian for keeping this thread alive. I promise this will
be my last word.
I realise now that I haven't completely answered Anthony's
question.
About 30 years ago I had the pleasure of monitoring the development of 65
A. stuartii from birth to 3 months old. From the time they
detached from the nipple, I handled each of them for a short time every
day. Quite quickly, I was able to recognise each individual based
on its reaction to being handled. Each of them seemed to have a
distinctive personality which emerged from very young and remained stable
throughout the 3 months.
Among the males there was a wide range of personality types. At the
extreme ends of the spectrum there were males that cowered every time I
handled them, and males that attacked me the moment I opened their
cages. The 38 males included everything from wimps to dorks, snags,
and jocks.
In the wild, juvenile antechinus mortality is about 80%. It's my
guess that the surviving 20% is biassed towards the jock end of the
spectrum. These males would include those who are most successful
in learning to hunt (which they do by stealing from their mother as she
hunts and from one another), and those that survive being kicked out of
her nest as summer progresses (the young females continue to live with
mum and their sisters, and may raise their own litters in a female group
nest of sisters, aunts and cousins - hence Shaun's antechinus
hive).
If the males survive the dispersal, they would then need to be successful
at competing with other young males to establish a nest site and a
feeding territory. By the time the breeding season comes around,
the only remaining males would be jocks and expert dancers.
Daryl King
At 01:27 PM 22/02/2007, Bron King wrote:
Anthony,
Mating among antechinuses is horrendously competitive, and only the
strongest and fittest males 'get lucky'. Contrary to popular
folk-lore, it is not the sex act that kills them, it is the stress of the
long and arduous mating season. Every male is frantically engaged
in searching for mates and brawling with other males. They neglect
their diets, and are super-charged with hormones. All of these
stresses cause their immune systems to collapse. The proximate
cause of death is generally bacterial infections and run-away increases
in their endoparasite load. For the lucky ones, one or more 5+ hour
copulations provide a bit of compensation.
Male antechinuses in captivity, provided with regular good-quality food
and spared the horrors of breeding, can live for 3 years. But in
the real world, their entire lives are lived out in exactly 11
months.
The antechinus you saw at Barren Grounds would be A. stuartii
(Brown Antechinus). I have also seen A.stuartii
sun-basking at Jervis Bay, but as far as I know it is not common
behaviour. A. stuartii is a bigger and bolder critter than
A. agilis. I have seen many more of them in daylight than
any other species. But I have never seen a basking female with
pouch-young . Well spotted!
Daryl King
At 11:31 AM 22/02/2007, Overs, Anthony \(REPS\) wrote:
Daryl
That?s a most informative answer. Thank you for sharing that with
us.
A question. Does EVERY male get ?lucky?? Are there any males (you know,
those awkward, shy types that can?t dance?) that would miss out on mating
and survive a second (or even third) year?
Also an observation. At Barren Grounds I would sometimes see an
antechinus out during the day. Once I saw from the visitor?s centre
window a female with little pink peanut-like babies attached to her belly
lying in the garden bed catching a few rays.
Cheers
Anthony
-----Original Message-----
From: Bron King
Sent: Wednesday, 21 February 2007 6:57 PM
To: Alastair Smith; 'Philip Veerman'
Cc: Canberrabirds
Subject: RE: [canberrabirds] Warks Road Antechinus
Alastair,
A. agilis and A. swainsonii (Dusky) are both common in the
Brindabellas. They are both possibly more common at Warks Road than
anywhere else in the ACT. The junction of Warks Road and Blundells
Creek Road is the type locality for A.agilis, which was described
in 1998.
A. flavipes (Yellow-footed) is a woodland specialist and has never
been trapped in that part of the ACT (it used to be reasonably easy to
find on Black Mountain a few decades ago, but no longer).
A. agilis is the most arboreal of all antechinuses. It lives
in tree-holes and hunts in trees and on the ground. A.swainsonii
adults are strictly terrestrial, nesting and hunting in areas of
friable soil. Young swainsonii (less than 6 months old)
occasionally hunt on fallen trees and in lower branches of coppiced
trees.
Both species breed in winter, with the young dispersing over summer to
coincide with food abundance. 80+% of antechinuses on the ground at
the moment would be current-year juveniles.
Both species are occasionally seen in early morning or late afternoon
daylight hours, especially juveniles (which no doubt accounts in part for
the high mortality of dispersing juveniles). Both species may be
abroad around the clock during the winter breeding season.
>From the point of view of climbing behaviour your antechinus could be
either a juvenile A. swainsonii or an A. agilis. At
this time of year, most juvenile A. agilis are about House Mouse
size, so you can rule them out. A juvenile A. swainsonii
would be roughly the same size as an adult female A. agilis.
Bear in mind that the only adult antechinuses in the population in
summer are females (the males all having died in August following
mating), so the possible size range is less than you quote (head and body
for female A.agilis is 75-95mm). Brindabella antechinuses
are smaller than coastal animals - closer to the median of 90mm in the
case of A. agilis. If, in the unlikely event it is an adult female
A.swainsonii, it is unlikely to be larger than 116mm.
I think it is more likely to be A. agilis. The 2-metre burnt
stump you describe is a typical nest-site for agilis. Even
an adult would risk a short daylight excursion from its nest if it
detected a small skink or other high-value prey in the vicinity.
Climbing down head-first, antechinuses flatten themselves against the
trunk with their hind-feet turned backwards and widely spaced. This
gives the impression of a larger animal than they appear on the
ground.
Although antechinuses are the most numerous of marsupials, they are so
cryptic that very few people will ever see one. To spot one at
Warks Road, in daylight, is a privileged experience.
Daryl King
At 08:19 PM 19/02/2007, Alastair Smith wrote:
Philip,
I omitted the fact that it appeared to be a similar size (as well as
colour) to the White-browed Treecreeper (160-175mm) would indicate that
it was a largish species of antechinus (my initial reaction was that is
was another white-brow climbing down the stump). As such, this which
would probably rule out Agile (80-116mm) and point to yellow-footed
(90-160mm) or dusky (90-185mm). I presume both species a re found in the
ACT but interesting I cannot find a list of mammal species for the ACT
(nor birds/retiles for that matter) under the Environment ACT
website.
Many thanks to all those who have replied on and offline ? we?ll nail
this identification yet.
Cheers
Alastair
From: Philip Veerman [
Sent: Monday, 19 February 2007 6:16 PM
To: Alastair Smith
Cc:
Subject: [canberrabirds] Warks Road Antechinus
I don't think that colour is enough
of a guide. They are all pretty much brownish. The size and shape are the
issues. Most of the people who identify these critters have them in hand
whilst doing so. Although just looking at a reference book now, suggests
that size range within species is much greater than between species.
Although a lot of that is sexual dimorphism, so if you don't know what
sex it is, it is pretty hard to know what size it should be. They are all
mostly nocturnal but of course during the breeding season, these critters
go beserck and can be seen occasionally during the daytime.
I once observed (and caught) a Pygmy
Possum at Warks Road (about 22 years ago), I have a photo of myself
holding it.
Philip
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