birding-aus
Brian Fleming wrote:
>
> birding-aus
>
> James Davis wrote:
> >
> > birding-aus
> >
> > Philip:
> >
> > The possibility of snake predation could be why the chicks produce a
> > low
> > sounding growl...this assumes that most snakes can feel vibrations
> > through
> > their jaw bones or ...I can't recall where I learned snakes pick up
> > low-ampitude vibrations. Just a thought.
> >
> > Cheers, Jim
> >
> > Dr. Wm. James Davis, Editor
> > Interpretive Birding Bulletin
> >
> > On Wed, 17 Feb 1999, Philip A Veerman wrote:
> >
> > > birding-aus
> > >
> > > Is it not true that the African Harrier Hawk (Gymnogenys typicus) is
> > a
> > > specialist hunter of things in cavities? I'm sure you have thought
> > of that
> > > one yet you say "there appear to be few natural enemies while the
> > chicks are
> > > still in the cavity". What about snakes but that defence would not
> > work as
> > > (as far as I know) snakes are deaf.
> > > -----Original Message-----
> > > From: Peter Thompson <>
> > > To: <>
> > > Date: Tuesday, 16 February 1999 23:56
> > > Subject: birding-aus (Fwd) Defence calls in cavity nesting birds
> > >
> > >
> > > birding-aus
> > >
> > > ------- Forwarded Message Follows -------
> > > Date sent: Tue, 16 Feb 1999 13:52:02 +0200
> > > From: "Craig Symes" <>
> > > To:
> > > Subject: Defence calls in cavity nesting birds
> > >
> > > Information Wanted: Cavity Nesting Birds and Defense Vocalisation
> > > Calls.
> > >
> > > While attending the I.O.C. in July 1998 I in Durban, I had the
> > chance
> > > to discuss and share various ideas concerning my own and other
> > > researchers studies worldwide
> > >
> > > The Cape Parrot is a secondary cavity nester in the Afromontane
> > > forests of south-eastern South Africa. Juveniles and adults make a
> > > characteristic growling sound if threatened in their nest cavity,
> > yet
> > > there appear to be few natural enemies while the chicks are still in
> > > the cavity. The cavity is usually quite deep and inaccessible from
> > the
> > > ground in an upright forest canopy or canopy emergent tree.
> > >
> > > This form of vocalisation made by any bird species in the nest would
> > > nonethelesss serve as an effective defensive mechanism for a cavity
> > > nesting species. A mammal like growling sound emanating from a dark
> > > cavity would surely raise suspicions to the actual occupant of the
> > > hole to any intruder/predator. My question is, does it occur in
> > other
> > > cavity nesters or species constructing an enclosed nest? The
> > > threatening defensive vocalisations of this species has driven my
> > > interest in investigating the phenomenon in birds worldwide and
> > > investigating and reviewing where such defensive mechanisms may be
> > > utilised. I did post a similar request a while back on SABirdnet and
> > > had a few responses. Thank you to those who did respond.
> > >
> > > I am unaware of any publications directly confronting this issue and
> > > would appreciate views and input on various species that different
> > > subscribers may have studied or encountered.
> > >
> > > Please bear in mind the following points when replying:
> > > 1. Species (Specific as possible)
> > > 2. Distribution of species (e.g. Cape Parrot Poicephalus robustus
> > > robustus - Afromontane forests of south-eastern South Africa)
> > > 3. Type of defensive call of adult and/or nestling and form of
> > threat
> > > (e.g. mammal like growl when cavity hole approached, snake like
> > hiss,
> > > bee like buzz/hum etc.)
> > > 4. Potential/known nestling predators
> > > 5. Co-operative breeder/Polygynous/Polyandrous/Monogamous/Other
> > > 6. Type of nester: Primary cavity nester (constructs own cavity),
> > > Secondary cavity nester (uses natural cavity or old cavity of
> > primary
> > > cavity nester, or, Constructs enclosed nest (e.g. Ploceus spp.)
> > > 7. Does the species in question supply nest material to the cavity
> > and
> > > what type of material.
> > > 8. Obligate/facultative cavity nester?
> > > 9. Further remarks.
> > >
> > > I hope to accumulate data from various sources in investigating this
> > > issue. Any input will be duly acknowledged should any publications
> > > result.
> > >
> > > If there is anyone on SABirdnet who is connected to any other
> > > "chatgroups", or has any contacts who may be able to help, please
> > > forward this message to them.
> > >
> > > I look forward to a flood of responses.
> > >
> > > Yours sincerely
> > > Craig Symes
> > >
> > > *************************************************
> > > Craig Symes
> > > Research Centre for African Parrot Conservation
> > > Dept. of Zoology and Entomology
> > > University of Natal
> > > P/Bag X01
> > > Scottsville 3209
> > > South Africa
> > >
> > > Phone: (0331) 260-5104/03/27
> > > Fax: (0331) 260-5105
> > > e-mail:
> > > *************************************************
> > >
> > >
> > >
> > >
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> > >
> > >
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> > >
> > >
> > >
> > >
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> > >
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> > >
> > >
> > >
> > >
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> > >
> > >
> > >
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> Re Cavity Predators
> I remember reading an account of a young Philippine Eagle (world's
> largest raptor, once known as Monkey-eating Eagle). This hand-reared
> bird when first making free flights found a hollow in a tree-trunk and
> clung to the edge with one foot while thrusting its other long leg in as
> far as it could and rotating it about, obviously seeking prey. The
> account was in a 'National Geographic' some years ago. Its chief prey is
> the hollow-dwelling mammal the Colugo aka Flying Lemur (it isn't a Lemur
> and it glides, rather than flies).
> I have not heard of any Australian raptor which can extract prey from
> tree-hollows but I have heard of hawks (species nor stated) taking young
> parrots and starlings which had their heads out of the nest hoping for
> food. But Brush-tailed Possums are believed to be partial to eggs and
> small chicks. What other native mammals would be capable of tree-hollow
> predation as well as competing for a des.res.?
> The young of the Speckled Warbler are said to make a most snake-like
> hiss if their enclosed nest at ground-level is disturbed. I've never
> found a nest so I dont speak from experience.
> Anthea Fleming
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Sorry
I only read this after my last reply on Cavity nesters 17/2/99. I think
the recent David Attenborough series on "The Life of Birds" shows a
raptor (Goshawk?????) reaching into a hollow trying to grasp onto cavity
nesters/young. Its worth a look!!
John Harris
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