Sandra:
Unfortunately, there is a lot of unconfirmed information circulated in the
lay literature. Although I am not an expert on the Noisy Miner, I am
familar with the species and somewhat knowledgeable within the topic of
animal communication. I offer the following summary comments:
1) As a rule, most social species (including birds) emit between 15 to
30 different vocalizations - sounds that can be identified as belonging to
a particular acoustical and/or functional category.
2) However, many species may also use what is called graded signalling.
If they do, then they will varying one or more aspects (acoustical
features) of their voice - such as repetition rate, frequency, cadance,
etc.. For example, as a bird gets more excited the pitch of its voice may
rise and the rate of calling may also increase. At any point along such a
continuum would you classify any particular sound as a distinct call? I
would not unless it can be shown that the listener partitions the sounds
into meaningful categories. With this said, it is also true that changes
in volume, frequency, etc, can convey information (e.g. when you are angry
you may scream and this sudden increase in volume will draw the attention
of people around you regardless of your words, etc.). I would not,
however, classify the word "help" as necessarily having a different
meaning because it is scream louder or softer. Would you?
3) I have heard people say that Noisy Miners have two or three
different alarm calls (acoustically distinct calls) that are associated
with different types of predators (hawk, ground predator, and snake).
This is possible, but I have not been able to confirm this. It is also
possible that the miner's alarm calls fit along a continuum - if so you
could argue that they have an infinite number of alarm calls. Few people
would agree to this interpretation. You must also keep in mind that in
many species, young birds learn to give particular alarm calls
under different circumstances by observving the behaviour of
other birds.
4) Birds that can mimic sounds are capable of producing a large number of
distinct "calls", but in most species it is unlikely if any of these
"copied" or "invented" sounds convey a unique message. I don't believe
that the Noisy Miner mimics sounds, but I am open to the possibility.
5) Doug Dow's 1975 paper (published in the Emu) lists a
number of different calls and behaviours of the Noisy Miner.
I hope this helps.
Dr. Wm. James Davis, Editor
Interpretive Birding Bulletin
On Tue, 11 Aug 1998, Sandra Wilson wrote:
> In her latest "Bird Talk" column in a Sunshine Coast newspaper, Valda McLean
> comments that a keen raptor observer once told her that the noisy miner has
> fifty (50) different calls and he had learnt what each one meant.
> I am interested in this. Does anyone know of any scientific studies into
> the calls of the noisy miner? I know it's not one of our favourite birds!!
> Regards.
> Andrew Thelander
>
|
