Horn growth patterns of Nubian ibex from the Sinai, Egypt

Abstract Documenting patterns of horn growth and horn-age relationships of Nubian ibex (Capra nubiana) can contribute to a more comprehensive understanding of their natural history, horn development in ibex in general, and future conservation of the species. Our specific objectives included (1) documenting age-horn growth patterns; (2) contrasting horn growth patterns of Nubian ibex with other ibex species; and (3) determining whether horn development accurately reflects age of Nubian ibex in Sinai, Egypt. As expected, all male and female horn measurements had significant relationships with age. Horn growth in males started plateauing at ca. age 7–8, whereas female horn growth started plateauing at ca. age 4–6. The extremely arid environment of Nubian ibex in the Sinai may account for the slowing of horn growth at a younger age than seen in populations of some other ibex species. We found a significant relationship between the number of horn ridges and age, indicating that counting horn ridges provides a viable method of aging males to within ±1 y. Thus counting horn ridges may be a useful and non-invasive method to determine age or age class, which can further our understanding of age structure, the natural history, and management of Nubian ibex populations.