Pl Cunningham

Differences in sexual dimorphism among four gazelle taxa (Gazella spp.) in the Middle East

Sexual selection can lead to sexual dimorphism, where elaborated traits used in mate attraction or weaponry are more expressed in the male sex. The degree of sexual dimorphism, however, is known to vary even among closely related taxa. Here we examined sexual dimorphism in horn length and three measures related to body size (body weight, shoulder height, and neck circumference) in four gazelle taxa, representing at least three species, i.e. Dorcas gazelle (G. dorcas), Sand gazelle (G. subgutturosa marica) and Mountain gazelle (G. gazella). The latter is represented by two distinctive phenotypes maintained and bred at the King Khalid Wildlife Research Centre in Saudi Arabia. We describe marked differences in sexual dimorphism among taxa. For example, the difference in sexually dimorphic horn development was driven primarily by females exhibiting pronounced differences in horn development. We discuss how divergent mating systems, and group sizes affect these differences among the examined taxa, with more competition in larger groups probably promoting the evolution of larger horns in females, thereby leading to less sexual dimorphism.

Twenty years of monitoring of the Vulnerable Farasan gazelle Gazella gazella farasani on the Farasan Islands, Saudi Arabia: an overview

The mountain gazelle Gazella gazella in Saudi Arabia is categorized as Vulnerable on the IUCN Red List. On the mainland the species’ survival depends on a few remnant populations in the western Mountains and coastal plains and on two reintroduced populations. The largest natural population of G. gazella in Saudi Arabia is the Farasan gazelle subspecies G. g. farasani, which inhabits the Farasan Islands in the Red Sea. We review and collate the available literature on this subspecies, mainly unpublished reports presenting wildlife census data, and supplement this with the most recent, 2009, count. The number of free-ranging gazelles has remained approximately constant since the first counts in 1988, with an overall density of 0.64 km -2 and an estimated population of 1,039 on Farasan Kebir in 2009. The populations on two other islands, As Saqid and Zifaf, have not fared as well, possibly because of uncontrolled hunting pressure, competition with domestic stock or poor habitat conditions overall. The population on Qummah Island is extinct. Threats to this subspecies include uncontrolled hunting and uncoordinated development. Continued protection of this apparently stable population of mountain gazelle in Saudi Arabia is imperative to ensure the survival of the species.

Population structure of Farasan gazelle

Abstract Some aspects of population structure (group size, group composition, sex ratio, female/juvenile ratio) of the Farasan gazelle Gazella gazella farasani were studied on the Farasan Islands, Saudi Arabia. The overall mean group size has remained consistent since 1988, indicating a stable population. G. g. farasani are mainly observed as single animals with females usually being solitary or in female groups. The largest group of gazelles comprised eight individuals in a mixed herd. The male/female sex ratio of adult animals during summer is skewed towards females with an extremely low juvenile/female ratio. A higher male mortality due to dispersal and related issues with anthropomorphic reasons is suspected. Results are discussed in the light of published and unpublished data from previous studies on the Farasan Islands and other Mountain gazelle (Gazella gazella) populations from the Arabian mainland and the Levant.

Morphological characteristics and ageing criteria of sand gazelle (Gazella subgutturosa marica Thomas, 1897) and their use for wildlife management

Data on some morphological characteristics of 165 male and 229 female sand gazelles (Gazella subgutturosa marica) collected during routine veterinary activity of a captive population at the King Khalid Wildlife Research Centre in central Saudi Arabia were examined for general baseline information on a little studied species. Measurements compared between the sexes and three age classes—juvenile, sub-adult and adult—included body mass, horn length (straight and curved), horn spread, neck circumference, shoulder height, forehead length, ear length and horn length (curved) to forehead and ear length ratios. All measurements were of known age individuals. The most valuable characteristics to use for age determination in the field are horn length (curved) and neck circumference for males and horn length (straight and/or curved) and shoulder height for females. The value of morphological characteristics correlated to known age animals for in situ management is discussed.

Sex ratios of Arabian Sand Gazelle Gazella marica Thomas, 1897 in the Mahazat as-Sayd Protected Area, Saudi Arabia

Abstract The sex ratio of a population of Arabian Sand Gazelle in Mahazat as-Sayd Protected Area in central western Saudi Arabia was compared to that determined from 296 skulls collected from the same area. Skulls were collected between March 2008 and March 2009 during a period of mass die-off caused by a severe drought. Most abundant were male skulls ageing between 18 and 24 months. The skulls of natural mortalities indicated an imbalanced sex ratio skewed towards males (1.39:1), compared to a sex ratio slightly skewed towards adult females (1:1.07) in the living population. Horn lengths of males and females were significantly shorter in the wild population of Mahazat as-Sayd than compared to an analogous population in captivity (King Khalid Wildlife Research Centre, KKWRC, Saudi Arabia). Possible causes for diverging sex ratio were linked to increased male mortality during the drought. Male mortalities and female biased sex ratio are discussed in the light of territoriality, predation, poor environmental conditions and limited opportunities to migrate.