Characterisation of limb development and locomotion in the brown kiwi (Apteryx mantelli) : a thesis presented in partial fulfillment of the requirements for the degree of Master of Science in Zoology at Massey University, Palmerston North, New Zealand
This thesis covers broad topics concerning limb growth and development and their
effects on locomotion in the brown kiwi (Apteryx mantelli).
I begin by describing the morphological features of a collection of unknown-age wild
kiwi embryos from early development to point of hatch. Using these features, I assign
developmental stages to each embryo and compare the progress of development to the
same-staged ostrich and chicken embryos. Measurements of the hindlimb, bill and
crown-rump length are used to develop an aging scheme based on comparisons with the
ostrich and the chicken. The ostrich model and chicken model create age predictions for
the unknown aged kiwi embryos. One kiwi embryo was of known age and both models
gave identical predictions for this marker embryo, but gave differing predictions for all
other kiwi embryos.
Using captive-reared kiwi chicks, I characterise hindlimb, bill and bodyweight growth
from the time of hatch to 3 months of age. Growth patterns are very linear within this
time period for all measurements but bodyweight. Female kiwi hatch with longer bills
than males, but the growth of both sexes converges by the end of the 3-month period.
Growth of bodyweight in the males slows earlier than in females. Bodyweight and bill
length were then compared to a wild population of kiwi. Captive-reared chicks were
found to hatch with shorter bills than the wild birds and to increase in bodyweight at a
faster rate than wild birds. Rapid weight gain has been implicated in developmental
limb deformities in other precocial and long-legged birds and has the potential to
produce similar results in captive kiwi.
I further studied the movement of the hindlimb during locomotion in two adults and one
juvenile kiwi by filming them while they were walking on a treadmill. Kinematic
parameters were measured from the video recordings and compared to overground
parameters from another study. Similarity between the treadmill and overground
locomotor parameters validates the use of a treadmill in studying kiwi locomotion.
None of the birds achieved the theoretical transition from a walk to a run at a duty factor
of 0.5. After normalising for size, the juvenile showed a longer stride length and lower stride frequency with increasing speed than the adults. Lateral head oscillations were
observed during the stride cycle, which I propose having a sensory function as well as a