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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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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