Bird papers

[Tim Williams <twilliams_alpha@hotmail.com>]

Apologies if these have been mentioned on this list...

Pike, A.V.L., Maitland, D.P. (2004).  Scaling of bird claws.  Journal of 
Zoology (London). 262(1): 73-81

ABSTRACT: The claw geometry of birds can be used to predict their mode of 
life. Previous studies, however, have not considered how bird size might 
affect these predictions. Thus, in the present study, the geometric scaling 
relationships of bird claws are examined for a variety of extant birds with 
different modes of life: predatory, climbing, perching or ground-dwelling. 
Measurements of hind-limb claw radius (i.e. claw size) and claw angle (i.e. 
claw 'hookedness') of the third digit claw were made on 120 species of bird 
ranging from 0.0057 kg to 44 kg in body mass. Claw radius was found to be 
proportional to (body mass)0.34 across all species. Claw angle was found to 
increase with body mass for predatory and climbing birds (i.e. bigger birds 
have relatively more hooked claws), and decrease with body mass for 
ground-dwelling birds (i.e. bigger birds have relatively less hooked or 
flatter claws). No significant relationship was found between claw angle and 
body mass for perching birds. Mode of life could not be predicted with any 
certainty using measurements of either claw radius or claw angle, suggesting 
difficulty in assigning fossil species such as Archaeopteryx to a specific 
locomotor category. As claw design should enable the claw to withstand the 
forces placed upon it, further work is needed to establish the stresses 
experienced by the claws of different types of bird.


Nudds, R.L., Dyke, G.J., Rayner, J.M.V. (2004).   Forelimb proportions and 
the evolutionary radiation of neornithes.  Proceedings of the Royal Society 
Biological Sciences Series B.  271 (Suppl. 5): S324-S327.

ABSTRACT: Analysis of a comprehensive dataset demonstrates that the brachial 
index (BI=humerus length/ulna length) of modern birds (Neornithes) varies 
significantly between clades at all taxonomic levels, yet is strongly 
correlated with recent phylogenetic hypotheses. Variance in BI at the 
infraclass level is low, but increases rapidly during the proposed major 
radiation of neornithines in the Palaeocene and Eocene. Although a BI of 
greater than 1 is primitive for Neornithes, more basal groups of Mesozoic 
birds (Confuciusornithidae and some members of the diverse Enantiornithidae) 
had BIs comparable with those of 'higher' modern clades. It is possible that 
occupation of ecological niches by these Mesozoic clades precluded the 
divergence of some groups of neornithines until after the 
Cretaceous-Tertiary boundary. We suggest that with further analysis and data 
collection the relationships between flight behaviour, ecology and BI can be 
determined. Hence, BI may provide a useful tool for characterizing the 
ecology of fossil birds.


On a completely different subject, Dann Pigdon wrote:

> As for cattle: Australian cattle stations are huge (some of them are
> larger than small European countries),

Not a huge feat, per se.  You don't have to be huge to be larger than Monaco 
or San Marino, or even Liechtenstein.  ;-)



Tim

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