--- How Energetic Demands and Habitat Utilisation Can Make or Break Giraffes
Understanding how large herbivores balance energy intake and expenditure is critical for effective rangeland management and conservation. Giraffes (Giraffa camelopardalis), as selective browsers, depend on high-quality forage resources that vary seasonally, influencing their movement patterns, home range and habitat selection. However, the extent to which nutritional constraints drive giraffe spatial ecology in arid savanna ecosystems remains poorly understood. This study aims to examine the relationship between giraffe movement patterns, habitat selection and the nutritional properties of preferred vegetation communities within the Rooipoort Nature Reserve, South Africa. We fitted seven male and eleven female giraffes with GPS collars to track their spatial movements over 12 months. Habitat selection was analysed using ArcGIS to identify high-use areas and preferred vegetation types. Nutritional analyses of dominant forage species, including Senegalia erioloba, Ziziphus mucronata and Vachellia tortilis, were integrated with movement data. Statistical analyses included t-tests for sex-based movement differences, linear regression for home range overlap vs. rainfall, and ANOVA for seasonal habitat use. Males exhibited significantly larger home ranges (utilising ~63% of the study area) and travelled greater distances than females (p = 0.005), primarily due to reproductive roaming strategies. Habitat selection varied seasonally, with dry-season nutritional stress leading both sexes to expand their ranging. High-protein browse species (approximately 10%–20% crude protein) were preferentially selected, indicating that nutritional constraints shape spatial distributions. Giraffes rely on specific high-energy forage species and concentrated resource areas, making them vulnerable to habitat degradation and seasonal resource shortages. Conservation management should prioritise the protection of Senegalia erioloba woodlands and Ziziphus mucronata shrublands—critical dry-season refuges of high-quality forage—to support sustainable giraffe populations.
--- Faecal Analysis as an Indicator of the Dietary Quality Utilised by Free-Roaming Giraffe in the Free State Province, South Africa
Accurate monitoring of wildlife diets and nutrient requirements is needed for effective biodiversity conservation. This also rings true for the world's tallest ruminant, the giraffe (Giraffa camelopardalis). The complexity of its anatomy is also reflected in its intricate ruminant, digestive properties. Being selective browsers, giraffes have evolved unique ways to effectively maximise the absorption of dietary nutrients and thereby maintain their critical energy balance. Using non-invasive faecal collections, the current study analysed 10 chemical parameters (dry matter, organic matter, ash, crude protein [CP f ], crude fat, gross energy, neutral-detergent fibre, acid-detergent fibre [ADFfOM ], acid-detergent lignin [ADLfOM ], and phosphorous) by chemical analyses, commonly used in domestic livestock health and nutrition monitoring. Fresh giraffe faecal samples were collected from six different locations, with different feeding practices, across different seasons from 2021 to 2023 in the Free State Province, South Africa. Results indicate that % CPf , % ADFfOM , and % ADL fOM may successfully and significantly differentiate between different feeding practices and between seasons from faeces collected from giraffe populations in the Free State Province and could be used conjunctive with each other to determine diet quality and nutrient value.
--- Nutrient Composition of Natural Diet Items and Faeces in Free-Ranging Southern Giraffes: A Pilot Study
Food preference and selection of free-ranging giraffes have been well recorded, but limited data concerning the chemical composition of their diet and faeces are currently available. This pilot study added information on natural diet, nutritional quality and a description of faecal chemical composition of free-ranging giraffe in the Free State Province, South Africa. Measured crude protein levels in leaves were lower compared to previous reports. The leaf calcium (Ca) content was higher than the phosphorus (P) content in all samples, supporting concepts that giraffe may be P but not Ca limited. In the faecal samples of the present study, nitrogen and P concentrations were above the thresholds considered indicative of nutritional deficiency.
--- The Rostral Epidural Rete Mirabile: Functional Significance in Blood Flow Regulatory Mechanisms in Giraffe
The distinctive long neck of the giraffe (Giraffa camelopardalis) entails functional difficulties brought about by the extended distance between the heart and the head. Blood must be circulated over 2 m from the heart to the brain against gravitational force. The natural movement of the head to ground level would result in a large volume of blood moving toward the brain with the force of gravity. Large blood volumes also rush to the brain during bulls’ fighting (necking), rendering the giraffe susceptible to possible brain damage. The natural movement of the head from ground level to fully erect would result in blood moving away from the brain with gravitational force. The lack of blood perfusing the brain can cause fainting. The giraffe, however, suffers neither brain damage nor fainting. What adaptations do giraffes have to counteract these challenges? The aim of this study was to investigate the functionality of the rostral epidural rete mirabile situated just beneath the brain and its possible contribution to successful circulation in long-necked giraffes. The unique rostral epidural rete mirabile structure significantly contributes to counteract physiological challenges. Turns and bends characterize this structural arterial meshwork and subsequently an increased artery length through which blood flow must proceed before entrance into the brain, exerting resistance to blood racing to the brain when the head is lowered to the ground. The brain is supplied mainly by the maxillary artery through the carotid rete, with a rudimentary basilar artery not contributing to the brain’s blood supply. The resistance to blood flow due to the structure and position of the rostral epidural rete mirabile when the head is in the upright position is counteracted by the unique carotid-vertebral anastomosis allowing immediate cerebral blood supply. The rostral epidural rete mirabile structure in giraffes is an essential feature balancing physiological difficulties arising due to the extensive heart-to-head distance and might fulfill the same function in other long-necked artiodactyls.
--- A Preliminary Study on the Siphon Mechanism in Giraffe
Long-necked animals like giraffes face the challenge of adequately supplying blood to the brain. The heart of such tall animals must work harder to pump blood over a 2 m headto-heart distance against the force of gravity compared to a short-necked animal. Does a mechanism exist to assist tall animals in overcoming this challenge? We found that there is a possibility of a mechanism that can enhance blood flow to the brain and a subsequent increase in oxygen supply, which will reduce the heart’s workload to pump blood over a 2 m distance in a Giraffe. In shortnecked animals, the workload on the heart is less to supply blood to the brain adequately; therefore, no additional mechanism is necessary. We, however, suggest that a similar mechanism might have been functional in dinosaurs with extremely long necks to help with adequate blood supply to the brain by comparing relevant giraffe physiology and anatomy with existing data on paleontology.
--- Drought Impact on Woody Plant Leaf Phenology and Browse Availability in a Semi-Arid Environment
The phenology of plants is influenced by numerous environmental factors such as temperature, day length and rainfall. Droughts are characterised by below average rainfall and above average temperatures and are likely to impact plant phenology. In the semi-arid and arid environments of South Africa, droughts occur frequently but are predicted to become more common because of climate change. The impact of drought and climate change on woody plant phenology can be detrimental to wildlife and livestock that are reliant on woody plants as a food source. To determine the potential impact of drought on woody plant phenology and ultimately leaf biomass available to browsing herbivores, the leaf phenology and leaf biomass of eighteen woody species were determined over a 24-month period during a prolonged drought. It was found that drought affected all species studied as it altered periods of growth and dormancy in plants. Specifically, the drought resulted in deciduous species flushing new leaves later in the season while the dropping of leaves occurred much sooner than normal. In evergreen species total leaf carriage was reduces. Consequently, the drought also resulted in prolonged periods of reduced browse availability. The study also found that reduces rainfall over longer periods (i.e. 6 months) had the greatest effect on leave phenology. It was concluded that intense drought can result in severe food limitations. Increased drought frequencies due to climate change may therefore reduce the productivity of the Kalahari region. It is likely that land managers will have to become even more pragmatic in the management of wildlife populations, specifically focusing on stocking rates and the mix of species maintained.
--- Ecological Exposure History Shapes Giraffe Vigilance Responses to Anthropogenic Noise: A Multisite Playback Experiment
EAnthropogenic noise is an increasingly pervasive environmental stressor for wildlife, yet its behavioral impacts on large mammals remain poorly understood. Across the genus Giraffa, multiple giraffe species face varying degrees of conservation condern under IUCN criteria due to rapid habitat modification and increasing human disturbance, yet the behavioral consequences of anthropogenic noise exposure have not been experimentally tested. Because vigilance is a key anti-predator response in large herbivores and is highly sensitive to disturbance, we used it as a focal metric to assess giraffe reactions to noise. We conducted multisite playback experiments across three reserves in the Free State Province, South Africa, that differed in human-exposure levels. Free-roaming giraffes were presented with three anthropogenic sound stimuli (drone, vehicle, people talking) and a natural control stimulus (ring-necked dove). Vigilance responses were video-recorded, quantified, and analyzed using mixed-effects models. Giraffes at the low-exposure site showed markedly stronger vigilance responses to anthropogenic than to the natural control, whereas responses at high-exposure sites were weaker and less differentiated across stimuli. These site-specific patterns indicate that ecological exposure history modulates giraffe responsiveness to noise. Across the full dataset, anthropogenic sounds consistently elicited stronger vigilance responses than the control stimulus, demonstrating that noise alone, independent of visual cues, can alter natural behavior in free-roaming giraffes. Collectively, these findings highlight the importance of incorporating acoustic disturbance into environmental impact assessments and protected-area management. More broadly, the results contribute to understanding how wildlife perceive and respond to human-generated noise and emphasize the need to integrate soundscape considerations into conservation planning as anthropogenic noise continues to expand across savanna ecosystems.
--- Feasibility of Using Near-Infrared Reflectance Spectroscopy to Predict the Chemical Composition of Giraffe Faeces
To determine the feasibility of near-infrared spectroscopy (NIRS) for the measurement of certain chemical compounds, a collection of both representative spectral data and reference measurements from many samples (training set) should be compared as part of a screening process. Te aim of this study was to investigate the feasibility of developing a rapid prediction of the chemical composition of faeces collected from populations of free-roaming girafe (Girafa camelopardalis), located within the central Free State Province of South Africa. Faecal NIRS and chemical analysis data were compared via regression analyses (r 2 ) to determine the feasibility of each chemical (chemometric) parameter. Acceptable high (r 2 ≥ 0.8) degrees of screening feasibility for crude protein (r 2 � 0.84; RMSE � 1.10) and acid-detergent lignin (r 2 � 0.83; RSME � 2.26) were achieved. Spectral data diferences are also illustrated based on faeces collected from girafes provided with supplemental feed or only natural available vegetation, as well as during the dry and wet seasons. Tis study is the frst to screen for the feasibility of developing a NIRS model to determine nutritional status, health and growth performance of girafes by using faecal droppings. Te application of faecal NIRS would most certainly have numerous benefts for wildlife conservation and management.
--- Non-targeted metabolomics by 1 H nuclear magnetic resonance spectroscopy; an interspecies comparison of milk between dromedary, giraffe and white rhinoceros with observations on blesbok
Various researchers have shown that milk metabolomes differ between domestic species regarding metabolite composition as well as metabolic pathways of milk synthesis. We contribute to this knowledge by presenting data of wild mammals. Inter-species differences were noted; 3-fucosyllactose was only detected in the milk of dromedary, and N-phenylacetylglycine and UDP-N-acetylglucosamine only in giraffe. Hippurate and 2-oxaloacetate were absent from milk of dromedary; creatinine and glutamate from giraffe; nicotinamide from white rhinoceros; and dimethylamine, creatine, valine, acetone, fumarate and 2-oxaloacetate from blesbok. With MetaboAnalyst 6.0, 15 statistically important metabolites of dromedary, giraffe and white rhinoceros were identified for KEGG metabolic pathway enrichment. Twelve metabolic pathways were identified as important with a specialization within species. In the giraffe mammary cells, the amino sugar and nucleotide sugar metabolism was observed as active and the alanine, aspartate and glutamate metabolism as inactive. The glycerophospholipid metabolism seemed highly active in the white rhinoceros and the galactose metabolism active in both the dromedary and white rhinoceros. Milk was available from only two blesbok, but data is presented as observation.
--- The Faecal Microbiome Analysed from Healthy, Free‑Roaming Giraffes
Similar to other herbivores, healthy giraffes (Giraffa camelopardalis) rely on a variety of symbiotic microorganisms in their digestive systems to break down cellulose and hemicellulose. In this study, we investigate the impact that external stimuli might have on the faecal prokaryote composition of healthy, free-roaming giraffes. Faecal samples were collected from six male and seven female giraffe individuals, over a 2-year period, during the wet and dry seasons, from six locations within the Free State Province, South Africa. Giraffe populations were exposed to one of two feeding practices which included provision of supplemental feed or only naturally available vegetation. Seventeen (17) different prokaryotic phyla, consisting of 8370 amplicon sequence variants (ASVs), were identified from the 13 healthy, adult, free-roaming giraffes included in the study. Overall, the bacterial phyla with the largest relative abundance included Fusobacteria (22%), followed by Lentisphaera (17%) and Cyanobacteria (16%), which included 21 dominant prokaryotic ASVs. The relative abundance of Ruminococcaceae UCG 014 and Treponema 2 were found to be significantly (P < 0.05) higher and Escherichia / Shigella, Romboutsia and Ruminococcus 1 significantly lower for giraffes receiving supplemental feed compared to natural available vegetation. This is the first study to investigate the composition of the faecal prokaryotic communities of healthy, free-roaming giraffes. The analysis of faecal prokaryotes contributes to the development of non-invasive methods for assessing the nutritional status and identifying health issues in giraffe populations. Ultimately, such advances are beneficial towards the larger-scale conservation, determining nutritional needs and management of other sensitive wildlife species, as well.
--- Drought impact on plant nutrients in a semi-arid rangeland and its implications for sustaining wild herbivores
Abstract
The impacts of drought on the nutritive value of natural forage and the implications thereof for sustaining herbivores are not well understood. Most studies have shown that drought-induced stress reduces plant nutrient concentrations. The consequential declines in forage quality of rangeland may be an important limiting factor in sustaining wild herbivore populations through periods of drought. In the semi-arid southern Kalahari of South Africa, the 2014-2020 drought resulted in high plant and herbivore mortalities. This study aimed to determine if the drought resulted in nutrient deficient forage, therefore contributing to the declines observed in herbivores. For this, the nutrient content of the most abundant woody and grass species was determined during the drought and the first wet year following the drought. The impact of drought differed markedly between dicot woody species and monocot grasses. In the former, crude protein concentrations were reduced while macro nutrient concentrations were elevated. In the latter, crude protein contents were elevated, and the content of most macro nutrients reduced. Importantly, the drought did not result in nutrient deficient forage. The drought resulted in a prolonged dry season, when forage quantities and nutritive value of plants were naturally at their lowest,. It was concluded that the extension of the dry season was the main cause of herbivore mortalities.
Keywords: plant nutrients, forage, herbivores, nutrient deficiencies
--- First Vasectomy Procedure Successfully Performed on a Southern African Male Giraffe
This study reports the first successful vasectomy on a southern African male giraffe (Giraffa camelopardalis giraffa). The goal of the procedure was to create a teaser male for reproductive studies. Following chemical immobilization using a combination of medetomidine and thiafentanil, the giraffe underwent surgery with local anesthesia. The vas deferens were bilaterally located, dissected, and transected. Histopathological examination confirmed the presence of the vas deferens tissue. Five weeks postvasectomy, the giraffe was immobilized again for semen collection, confirming infertility. The giraffe was then used to confirm oestrus in synchronized females. Pre‐ and post‐vasectomy testosterone levels validated the procedure's effectiveness, confirming no change in the giraffe's normal behavior or attractiveness to females. The outcome was successful, with the giraffe rendered infertile post‐vasectomy.
--- A Fracture in the Proximal Pastern Bone of a Free‐Roaming Giraffe Under Field Conditions
Foot and hoof problems are one of the most common health concerns for giraffes (Giraffa camelopardalis) held in captivity. However, very limited information is available on the foot pathology for free‐roaming giraffes. A free‐roaming giraffe (Giraffa camelopardalis giraffa) situated within a small Free State game reserve presented with limping, and provided a unique opportunity to examine and treat the apparent foot injury. After being sedated and restrained, radiographs were taken in the field. A lateral fracture was diagnosed in the proximal pastern bone of the right front leg of the giraffe. Hoof trimming was used in an attempt to provide treatment and relief to the animal's gait and appearance. The occurrence and treatment of this hoof injury could provide insight on similar pathology in zoo environments.