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.

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Abstract. The mouthparts of the Australian semaphore crab HeIoecius cordiformis (H. Milne-Edwards, 1837) are described. Male and female semaphore crabs were observed and collected from mangrove swamps around the south side of Botany Bay, Australia between 1983 and 1987. Semaphore crabs inhabit mangrove mud/sand flats between the midlittoral intertidal zone and the supralittoral fringe of bordering saltflats. Scanning electron micrographs provide detailed pictures of mouthpart morphology and the setae present on the third, second, and first maxillipeds; the second and first maxillae; and the mandibles. Amongst other setal types, "spoon-tipped", "corn", and "bottle-brush" setae are described. While semaphore crabs are primarily deposit feeders (microphagous), they have well developed mandibles and are, therefore, also able to eat larger plant and animal material (macrophagous). A brief comparison is made between the mouthparts of semaphore crabs and fiddler crabs ( Uca spp.), since the two genera are closely related, occupy similar niches, and resemble each other in appearance. This comparison reveals that while the second maxilliped setal morphology differs between the two genera (Heloecius possesses corn setae, Uca possesses spoontipped setae) these setae may have similar functions. The feeding behaviour of H. cordiformis is related to substrate composition, burrow construction and various mouthpart specialisations. It is conlcuded that, within the context of the present study, certain structural e.g. mouthpart modifications allowing both scavenging and deposit feeding, and behavioural modifications e.g. mound building in wet muddy habitats, enable semaphore crabs to occupy a wide range of habitat types within the mangrove.