With a lower lion density, a high density of other prey and better visibility, we expected lower lion predation in Kirawira. Giraffes were photographed and later identified using the coat markings unique to each animal (Foster, 1966). Individual identifications, done by eye, were double-checked using Wild ID pattern-matching software for giraffes (Bolger et al., 2012).
No individuals were observed in more than 1 study area during the sampling period. Most giraffes selleck chemicals llc were sighted multiple times. Using a suite of physical characteristics, including body shape, relative length of the neck and legs, ossicone (horn) characteristics and height, giraffes were categorized into 3 age classes: calf (0–1 year), subadult (1–5 years) or adult (>5 years). For a more fine-scale analysis, subadults were aged to ±1 year by comparing each individual with a sample of known-aged giraffes of the same sex. Height measurements were compared against age–height curves for Serengeti giraffes (Pellew, 1983a). We measured height with a Haglöf electronic clinometer (Haglof Company Group, Långsele, Sweden) (accuracy of ±0.1 m), calibrated by the distance from the observer to the giraffe, which, in turn, was measured with a Bushnell range finder (Bushnell Corporation, Overland Park,
KS, USA) (accuracy of ±1 m). beta-catenin inhibitor Height, from the ground to the top of the ossicones, was measured with the giraffe standing in an upright posture. Height measurements were only taken when a giraffe could be approached closely and remained still long enough for an accurate reading. We recorded the size and composition of giraffe herds, defined as individuals feeding, socializing and/or moving together
MCE (solitary individual equals herd size of 1). Herd members could be dispersed over 1 km, but were usually within close proximity. For each giraffe, we calculated that individual’s ‘mean herd size’ – a measure of social behavior. For example, if individual with identification code SF1 was observed in 5 herds of sizes 1, 5, 10, 5 and 2, SF1′s mean herd size would be equal to 4.6. A total of 917 individual giraffes were identified during this study. Photographs of 702 giraffes (132 calves, 187 subadults and 383 adults) were inspected for predation marks. These data were used to calculate predation-mark prevalence. Individuals (n = 215) with unsatisfactory photographs were excluded. Calves were rarely excluded and males were excluded slightly more often than females because some males were seen infrequently or only at a distance. Two classes of predation marks were recorded: unambiguous lion claw marks and ambiguous marks. We defined unambiguous claw marks as sets of parallel incisions/scars, or as long scars extending over multiple, usually adjacent, body regions. Figure 1 illustrates the appearance of lion claw marks on 2 herbivore species, zebra Equus burchelli and eland Taurotragus oryx, and Fig.