About bird mimicry. I wish I had the energy to do hours of retyping of an
pivotal article on the subject, because it really is important in an Australian
context where we have so many good bird "mimics" apart from that it is
interesting. Most vocal mimicry by birds is certainly fun and entertaining to
observe and ponder about but really it is not mimicry within the usual
biological sense (as in the way that insects mimic the appearance of other
species for example. In that most vocal mimicry by birds it is NOT directed at
the model species, it does not benefit the copier by association with the model
species and it has no relevance to the model species. Most is just copying
sounds in order to increase the vocal range of the mimic bird. It is
interesting to speculate about connections between the bowerbird mimicking a
raptor for example but is their any connection? They mimic so many other
species as well.
This was elucidated by the following article: Dobkin, D.S. (1979), 'Functional
and evolutionary relationships of vocal copying phenomena in birds',
Zeitschrift fur Tierpsychologie 50, 348-363.
And the following is the text taken from my (1994) article 'Batesian Acoustic
Mimicry by the Regent Honeyeater Xanthomyza phrygia.' in the Australian Bird
Watcher 15(6):250-259. This summarises why I think the behaviour of the Regent
Honeyeater is of a Batesian type of mimicry or at least it appears to be, more
than any other kind of mimicry. I'm not going to retype all the other
references used, here, they are in the article.
"An analysis with a more useful bearing on mimicry was given by
Dobkin (1979) who subdivided the term 'mimicry' and suggested some new
terms. He clearly differentiated between the common phenomenon 'vocal
appropriation' (the non-deceptive copying of sounds of other species
for intraspecific communication use) and the rarest form, true mimicry,
plus two other categories, vocal imitation and vocal convergence, which
are not directly relevant here. Although Dobkin's literature search was
extensive, he did not provide an example matching his largely
theoretical exposition of 'Competitive Batesian Acoustic Mimicry', one
of his suggested types of true mimicry. Krebs (1977) discussed the
possible advantage of increase of song repertoire to deceive others
into thinking that bird density is higher than it is. Slater (1978),
Krebs (1978) and especially Rechten (1978) extended that issue into
mimicry. Rechten (1978), citing one hypothesis that 'The imitations are
directed at individuals of the copied species, serving interspecific
territorial defence'. She pointed out that 'For true mimicry, one would
predict a tendency for mimics to choose predatory, larger or competing
species as models.' Batesian mimicry requires that the mimic exist at a
lower population density than the model species, as applies in this
case. Unlike other 'mimics', for which it is now thought that the
mimicry functions to keep the lines of communication open, the Regent
Honeyeater's behaviour fits exactly into Dobkin's and Rechten's idea of
Competitive Batesian Acoustic Mimicry."
The other really interesting phenomenon is the habit of many small birds of
indulging in mimicry whilst being handled for banding. I can't attest to it too
much myself but I've heard several experienced banders report it.
Philip
==============================www.birding-aus.org
birding-aus.blogspot.com
To unsubscribe from this mailing list,
send the message:
unsubscribe
(in the body of the message, with no Subject line)
to:
=============================
|
