Good evening, LK.
Your observations of turkey mounds and young do not translate into an
absence of predation. I quote from a study by Jones and Everding: "the
large number of mounds (in some suburban areas)does not necessarily
correlate with large numbers of recruits". They go on to state that
hatching success from suburban mounds is lower than in wild mounds, and that
mortality of hatchlings is high. Eggs and hatchlings are probably more
vulnerable to predation than adults. Thus, if adults live for many years,
it may appear as if the birds are "holding their own". If eggs are not
hatching, or if there is little recruitment of new birds because young are
taken before they mature, older birds may persist for years, then suddenly,
populations may disappear as old birds die. The study lists a number of
populations in urbanised areas of Brisbane that have disappeared. The
weight of evidence shows that Brush Turkeys in urban areas are vulnerable.
I have lived in an area where Turkeys are seen daily; there are several
mounds in use in my street. I have been making careful observations of the
birds here for years. Adult birds have maintained local mounds, and laid in
them. However, on only 2 occasions in the last 5 years have I seen any
chicks. In both instances, chicks were seen for several days only, and not
seen again. I have never seen any immature or juvenile birds. Only adults.
I have however, seen a cat taking a chick, and I have seen a chick run over
by a lawn mower. The only birds in this street are adults. I do not expect
them to be replaced by young growing up in this area. If adult birds die
and happen to be replaced, I expect this to occur when juveniles move out of
the forest areas on the flanks of Mt Coot-ha, along creeks and gullies.
Not that it matters too much, because it does not affect what I have said
about foxes, but... personnel from BCC animal control have quoted a figure
of about 50,000 dogs in Brisbane.
Scott O'Keeffe
-----Original Message-----
From: Laurie & Leanne Knight
Sent: 16 August 2001 18:54
To: Scott O'Keeffe
Cc: birding-aus
Subject: 1080
Scott O'Keeffe wrote:
>
> Your original post suggested that cats or dogs are several orders of
> magnitude more abundant than foxes. If there are 50,000 dogs in Brisbane,
> your assessment implies that there are about 500 foxes in Brisbane. There
> would certainly be more than 500 foxes in Brisbane. In suggesting that
> foxes are very common in Brisbane, I mean that, for a top level predator,
> they are very common. Compared with estimates of fox density from other
> locations, it can also be said that foxes are very common in Brisbane.
> 10,000 is not too likely, but I wouldn't rule this out as a possibility
for
> greater Brisbane. As far as I know, no exhaustive surveys have been
> undertaken for GB.
>
> As far as diet goes, few studies have been done in the Brisbane area, and
> not many have been done in urban areas generally. Best work comes from
> Melbourne. One study I was involved in looked at scat samples from the
> Boondall wetlands and surrounds. The most common vertebrate remains in
fox
> scats in that study were bandicoot. Still common around Brisbane, but in
> southern populations centres, disappearing, and foxes are heavily
> implicated. Surprisingly, the remains contained no evidence of hares.
>
> Brush Turkeys? As I understand it, recruitment for Brush Turkeys in
> suburban Brisbane is low, and it has been suggested that the birds seen in
> the outer suburbs move into these areas from outlying forest. I havn't
seen
> any evidence to prove or disprove the idea that foxes take Brush Turkeys.
> The fact that we see Turkeys around the 'burbs is not necessarily evidence
> of a lack of predation. Foxes could be picking the Turkeys off, providing
> vacant territories for birds dispersing from outlying forest areas.
Perhaps
> these vacant territories are rapidly filled by 'new' birds, conveying the
> impression that individual birds survive in an area year after year. Are
> the Turkeys we see from one year to the next the same birds, or 'new'
birds
> which have taken up vacant territories? I also repeat what I said
> previously about eggs. Foxes love eggs, and eggs in a large heap of
> decaying organic material....? You can't tell me that isnt likely to
> attract foxes.
>
I doubt the Mt Gravatt turkey population is heavily predated - I used to
live in a different street and had a long term mound the other side of
the back fence [see references to Lord Jim, sire of many young turks in
the archives]. I remember seeing three young turks moving through my
yard in convoy, and I saw another emerge from the mound.
As for the number of pet cats and dogs in the Brisbane metro area, I
would expect there to be a couple of hundred thousand ...
LK
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