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Re: Long, long last gasp. (fwd)



Phil Bigelow (bigelowp@juno.com) asked:

> Don't the brains of most birds have small olfactory lobes?
> Exceptions being carrion feeders like vultures and maybe
> crows/ravens.

That does generally appear to be the case, but whether or not birds'
olfactory capabilities are adequately characterized by that one fact
can be reasonably debated.  See:

http://instruct1.cit.cornell.edu/courses/psych396/student2002/hcs7

It was written by an undergraduate, but it seems to capture the
essence of the field.  If you're interested, you might also want to
look at:

McKeegan, D.E.F. (2002). "Spontaneous and odour evoked activity in
     single avian olfactory bulb neurones", _Brain Research_,
     929(1):48-58.

>From the introduction of that paper:

     Historically, the existence of an olfactory sense in birds has
     been treated with scepticism [27]. Although it is no longer
     disputed that many avian species have a functional olfactory
     system (primarily as a result of evidence generated by numerous
     behavioural studies, see Ref. [27] for review), the physiology of
     avian olfaction has received little attention. Anatomical studies
     have shown a high degree of similarity between the olfactory bulb
     structure of birds and other vertebrate groups, with the avian
     bulb following the basic vertebrate structure of concentric cell
     layers surrounding a ventricle [1, 10, 33 and 35]. However, there
     is much variation between species in the size of the olfactory
     bulbs in relation to the rest of the brain, as indicated in the
     `relative olfactory bulb' size index described by Bang and Cobb
     [2]. The precise extent to which relative olfactory bulb size
     relates to olfactory capabilities is still not clear [27].

References 2 and 27 are:

B.G. Bang and S. Cobb , The size of the olfactory bulb in 108 species
     of birds. Auk 85 (1968), pp. 55-61.

T.J. Roper , Olfaction in birds, Adv. Stud. Behav. 28 (1999),
     pp. 247-332.

McKeegan's article has been cited twice, both times by articles on
which she was the lead author.

Roper's article cites 291 references, but most of them are about
either pigeons or chickens (McKeegan also recorded from chickens).
>From Roper's reference list, I can tell you that at least as early as
1905, people were asking:

    Hill, A. (1905). Can birds smell?  Nature 71, 318-319

And in case you think fireworks are a hallmark only of modern
scientific debates:

    Audubon, J. J. (1826). Account of the habits of the turkey buzzard
        (Vultur aura), particularly with a view of exploding the
        opinion generally entertained of its extraordinary power of
        smelling.  Edinb. New Philos. J. 2, 172-184

Catchy title, eh?  It appears that a *lot* of work needs to be done in
this field before we should be comfortable with the conventional
wisdom about avian olfactory capabilities.

-- 
Mickey Rowe     (rowe@psych.ucsb.edu)