Abstract:
African wild dogs (Lycaon pictus) are endangered and their population continues to decline
throughout their range. Given their conservation status, more research focused on their
population dynamics, population growth and age specific mortality is needed and this
requires reliable estimates of age and age of mortality. Various age determination methods
from teeth and skull measurements have been applied in numerous studies and it is fundamental
to test the validity of these methods and their applicability to different species. In this
study we assessed the accuracy of estimating chronological age and age class of African
wild dogs, from dental age measured by (i) counting cementum annuli (ii) pulp cavity/tooth
width ratio, (iii) tooth wear (measured by tooth crown height) (iv) tooth wear (measured by
tooth crown width/crown height ratio) (v) tooth weight and (vi) skull measurements (length,
width and height). A sample of 29 African wild dog skulls, from opportunistically located carcasses
was analysed. Linear and ordinal regression analysis was done to investigate the
performance of each of the six age determination methods in predicting wild dog chronological
age and age class. Counting cementum annuli was the most accurate method for estimating
chronological age of wild dogs with a 79% predictive capacity, while pulp cavity/
tooth width ratio was also a reliable method with a 68% predictive capacity. Counting
cementum annuli and pulp cavity/tooth width ratio were again the most accurate methods
for separating wild dogs into three age classes (6±24 months; 25±60 months and > 60
months), with a McFadden's Pseudo-R2 of 0.705 and 0.412 respectively. The use of the
cementum annuli method is recommended when estimating age of wild dogs since it is the
most reliable method. However, its use is limited as it requires tooth extraction and shipping,
is time consuming and expensive, and is not applicable to living individuals. Pulp cavity/tooth width ratio is a moderately reliable method for estimating both chronological age
and age class. This method gives a balance between accuracy, cost and practicability,
therefore it is recommended when precise age estimations are not paramount.
