Research library

Can giraffes add but not subtract? In earlier experiments, captive giraffes chose larger food portions, with their choices also influenced by the size and spacing of the pieces. That showed they could judge food amounts, but tracking a portion as it changes requires more than comparing what is in view. The new study investigated whether giraffes could choose the larger portion after watching food being added, removed or moved between containers, with the final amounts hidden.

Iker Loidi and his team tested four giraffes at Barcelona Zoo, showing them starting portions of carrot and letting them watch the changes before choosing a container. In one addition condition, a container began with one piece and another with two. Adding two pieces to the first made the final choice three versus two, so remembering which container had started with more would give the wrong answer. The researchers compared choices after additions with those after removals and transfers.

All four giraffes chose the larger final portion more often than chance after additions, averaging 68% success. None performed significantly above chance after removals or transfers, which does not establish that they were unable to track those changes. Because the experiment did not separate the number of pieces from the bulk amount of food, success does not demonstrate arithmetic. The findings suggest that these four giraffes could update a remembered food amount when they saw more being added.

Skin disease does not seem to kill giraffes, but it slows their walk. In a three-year study in Tarangire, Tanzania, researchers followed 382 adult giraffes through photographs and detected no increase in mortality associated with skin disease. That finding does not establish harmlessness, and it concerns a different population from the walking study. In Ruaha National Park, crusted skin patches often surround the front leg joints, prompting researchers to investigate whether affected giraffes walk differently.

Noah T. Dunham and colleagues reported filming 40 adult Masai giraffes in Ruaha National Park, Tanzania. They compared videos of animals walking on flat ground, looking at how their movements differed with the severity of the skin patches and whether one or both front legs were affected. Comparing affected animals with those without visible disease, they examined whether slower walking involved shorter strides or more time to complete each stride, allowing for differences in body size.

Affected giraffes walked more slowly because each stride took longer; the researchers found no significant difference in stride length. This was an observational comparison, so it links skin disease with slower walking without proving that the lesions caused the change. The slower rhythm appeared even in animals with mild patches or only one affected front leg: the difference in walking was already apparent before visible disease became extensive.

For giraffes, how food is eaten may matter beyond how much. Stripping leaves from branches or extracting food from a feeder keeps the tongue working in ways that swallowing easily available food does not. Across a large zoo study, those different kinds of eating were associated with different patterns of repetitive tongue movements and licking.

Jason Wark and Katherine Cronin analysed 66 giraffes at 18 US zoos, building on their earlier account of the animals’ behaviour. More than 8,000 short observation sessions covered roughly a year. Their models compared feeding, movement and repetitive behaviours with housing, herd size, public feeding, weather, time of day, age and sex.

Giraffes that spent more time browsing or extracting food showed fewer repetitive oral behaviours. Time spent in other feeding activities did not show that same relationship across individuals. At zoos offering visitor feeding, giraffes browsed less and spent more time on other feeding. These were associations between existing zoo conditions, not an experiment proving that changing a feeder or closing a programme would improve welfare. Still, the distinction is useful: an animal can spend time eating without performing the searching, grasping and manipulation that make feeding a richer part of a giraffe’s day.

Some Luangwa giraffes were living beyond the edge of their mapped range. This isolated form of Masai giraffe lives only in Zambia’s Luangwa Valley, so overlooking part of its distribution means overlooking part of the entire population. Earlier surveys concentrated on its better-known core, while sightings farther south suggested that the published map was incomplete.

Catherine Sun, Frederike Otten and colleagues drove photographic surveys between August and November 2023, extending their search 120 kilometres south of that mapped boundary. They identified giraffes from their individual coat patterns and analysed 439 encounters with 277 adults and subadults. Repeated sightings fed a model that accounted for uneven search effort and animals missed by observers; calves were excluded because their movements were not independent of adults.

The team identified 55 giraffes beyond the old southern boundary. Across the study area, the model estimated 760 adults and subadults, with a credible range of 651–890. That larger total does not demonstrate population growth: the survey covered more ground and used different methods. Giraffes were concentrated near permanent rivers, including in moderately human-modified areas. The discovery changes where conservation needs to look, not simply how many giraffes it should expect to find.

Swallowing water may help pump blood through a giraffe's neck. A giraffe bending towards an empty pond provided an unexpected clue: its blood pressure fell and stayed low. In giraffes actually drinking, pressure initially fell too, but then climbed again despite their heads remaining down.

Christian Aalkjær and colleagues recorded pressures in neck arteries and veins as instrumented giraffes moved and drank voluntarily in managed enclosures. Drinking-pressure measurements came from seven animals, with blood-flow measurements in two. Separate experiments on anaesthetised giraffes and isolated blood vessels examined how blood volume, fluid around the brain and small arteries respond to the enormous height changes between standing and drinking.

During drinking, pressure in neck veins oscillated at a rhythm that generally differed from the heartbeat. The authors propose that water moving down the food pipe squeezed neighbouring veins, helping return blood to the heart and restore arterial pressure. That pumping mechanism remains an interpretation of the measurements, not a directly isolated effect. Meanwhile, increased resistance in vessels supplying the head helped keep measured carotid flow steady despite rising pressure there. Drinking thus appears to involve two opposing processes at once: blood collecting in neck veins as the head drops, and swallowing helping move it back.

Shorter legs could make a giraffe's heart work harder. Keeping the animal equally tall would mean a longer neck and a heart closer to the ground. Blood would then have farther to climb before reaching the brain, increasing the pressure—and energy—the heart must supply.

Roger Seymour and Edward Snelling built a numerical model from published giraffe measurements and mammalian estimates of cardiac efficiency. They compared a model giraffe with an imaginary animal of the same mass and height but shorter, eland-like legs. Its extra-long neck compensated for the lower body. This allowed them to vary heart height while holding the animal's overall height and resting energy requirements constant.

The model estimated that the giraffe's main pumping chamber used about 16% of its resting energy expenditure. With eland-like legs and the correspondingly longer neck, that share rose to about 21%. Those percentages depend on uncertain inputs, particularly how much blood the giraffe heart pumps; they were not measured directly in living animals. The geometric advantage is simpler: long legs raise the heart as well as the head. Their contribution to giraffe height therefore reduces the circulatory burden of reaching high foliage, although the calculation does not establish why long legs originally evolved.

Worms related to an eyeworm turned up inside diseased giraffe skin. Researchers examining lesions in Tanzania's Ruaha National Park found tiny larvae embedded in the tissue, then recovered DNA closely resembling a parasite usually associated with eyes. It was an unexpected lead in a skin condition whose cause remains unresolved.

J. Wanda, E. Mjingo, E. Mwega and J. Malago examined biopsies from ten Masai giraffes with skin lesions, sampled during a tagging operation in October–November 2022. They studied thin tissue sections under a microscope, looking for parasites and inflammation. They then tested the six samples containing visible worms for a genetic marker and compared recovered sequences with known roundworms.

Larvae occurred in six biopsies, alongside inflammatory cells and damaged tissue. Three samples yielded the targeted DNA, and the reported sequence was more than 99% similar to reference sequences of Thelazia callipaeda, commonly called an eyeworm. That close match supports a relationship, but does not establish that this worm causes giraffe skin disease: the study lacked unaffected animals for comparison and did not determine how the parasites reached the skin. The finding narrows the investigation to a tangible organism within lesions, while leaving infection route and responsibility for the disease open.

Giraffes living with lions stayed alert ten times longer after hearing their roars. Both populations in a South African experiment noticed the sound, but the resemblance ended with that first response. Giraffes from a lion-free reserve soon returned to feeding, while those sharing their landscape with lions continued watching.

Anton Baotic and Georgine Szipl played recordings of lion roars and grunts, and harmless dove calls, to 51 adult southern giraffes in July–September 2024. Twenty-four lived where lions had been reintroduced about five years earlier; 27 lived in a reserve without lions. Each giraffe heard both sound types, with the order varied, while video captured how quickly it reacted and how long its vigilance lasted.

After lion calls, average vigilance lasted about eight and a half minutes in the lion-inhabited reserve, against less than a minute in the lion-free reserve. Responses to doves did not differ between sites. This supports a role for ecological experience in sustained attention, but comparing two reserves cannot prove individual learning or separate it completely from other site differences. Nor does a quick initial reaction establish an inherited fear of lions. The revealing distinction is between noticing a sound and continuing to treat it as a threat.

A giraffe's teeth can preserve the moment it was born. A distinct birth-associated line remained visible in the enamel of a lower molar, separating growth before and after that event. Other microscopic lines recorded much shorter rhythms, giving researchers a way to reconstruct tooth formation long after it happened.

Carmen Nacarino-Meneses, Juan Marcos Jannello and Anusuya Chinsamy examined four lower molars from three giraffes in South African collections. They cut ten thin sections through teeth with different stages of development and wear, then measured growth markings under a microscope. Comparing the spacing and position of lines let them distinguish daily enamel layers from finer markings formed within a day.

The fine markings indicated roughly eight-hour growth rhythms, while broader enamel lines repeated daily and others about every three days. Treating every visible line as a full day would therefore give the wrong developmental timetable. Growth rates also varied between tooth regions and between first and third molars, so this small sample cannot provide a single universal clock for giraffe development. It does provide a guide for reading the right markings in the right places. That matters for extinct giraffe relatives, whose teeth may preserve evidence of growth when observations of living animals are impossible.

A sharp oxpecker call can put lunch on hold, sending the animal's attention from its food to its surroundings. The birds that pick parasites from giraffes also call when disturbed. Their hosts might therefore get something extra from the relationship: a cue to look up.

Anton Baotic and Georgine Szipl played oxpecker alarms through a hidden speaker to 53 southern giraffes across seven South African reserves. Ordinary dove or oriole calls provided the comparison. The giraffes were calmly feeding, with no oxpeckers perched on them: could a bird's voice alone interrupt the meal? The researchers also compared responses in a lion-inhabited area and two lion-free areas.

The alarms did interrupt lunch. Giraffes stopped feeding, turned toward the sound, pointed their ears forward and scanned around them. They reacted sooner and watched more than after ordinary bird calls. Where lions lived, the watching lasted longer, although other differences between sites could explain that pattern. The experiment cannot tell whether giraffes recognise a warning or simply find the harsh sound arresting. What it shows is a familiar bird's call changing how a giraffe spends its next moments: less eating, more checking.

A giraffe's extra feed may leave a bacterial signature in its dung. Free-roaming animals receiving manufactured pellets carried a different mixture of microbes in their droppings from giraffes browsing natural vegetation alone. The comparison suggests that food provision may affect more than the quantity an animal eats.

Andri Grobbelaar, Gernot Osthoff, Francois Deacon and Errol Cason analysed 26 selected faecal samples from 13 giraffes at six locations in South Africa's Free State. Samples came from a two-year collection programme spanning 2021–2023. The team sequenced a bacterial identification marker, then compared microbial profiles between feeding practices. They also explored sex differences and followed seasonal variation in one male.

Several microbial groups differed in relative abundance between the feeding groups, including higher proportions of two groups associated with plant digestion in animals receiving supplements. Seasonal and sex comparisons did not yield statistically clear differences in individual microbial abundances. This small, uneven observational sample could not separate feeding from location or establish which mixture was healthier. Like the team's chemical analysis of giraffe dung, it offers a possible way to monitor animals without capture. The immediate achievement is a description of variation among apparently healthy giraffes, not a validated diagnosis of nutritional trouble.

These giraffes ate a plant considered poisonous to livestock. Sodom apple, a shrub often treated as an unwelcome invader, appeared repeatedly in the diet of Nubian giraffes at Kenya’s Lake Nakuru National Park. That unexpected food choice was part of a closer look at how giraffes use a fenced landscape as seasons change.

Consolata Gitau, Judith Mbau and colleagues observed adult giraffes on twelve survey days in 2019, divided between dry and wet seasons. At regular intervals they recorded each animal’s activity and identified the plant it was eating. This produced 11,280 activity records, including more than 6,000 feeding observations, allowing comparisons between seasons, sexes and habitats.

Fever trees supplied about two-thirds of feeding records, with Sodom apple contributing around 9%. Another shrub, Maytenus senegalensis, rose from 12% of dry-season feeding records to 23% in the wet season. Yet overall time spent feeding, resting and moving did not differ significantly between seasons. The study did not test plant toxicity or nutritional benefits in giraffes. What it revealed was a selective, locally varied menu: even an unwelcome shrub can be food, and a changing diet need not mean a radically different daily routine.

These giraffes spent almost a third of the night feeding. Their long nighttime lying periods were repeatedly interrupted by getting up and eating. A zoo visitor watching only during opening hours would miss a substantial part of that routine, along with the chance to see whether changing companions affected days and nights in the same way.

Hanna Mebus, Sebastian Schneider, Paul Dierkes and Anna Lena Burger-Schulz recorded three female reticulated giraffes at Germany's Opel-Zoo over 22 consecutive days and nights. Indoor cameras followed a sequence of group changes: two other females departed, then a male arrived. The male was separated from the females at night. The researchers measured time spent feeding, standing, walking and lying, and recorded nearby companions and social interactions.

Across the observations, feeding occupied about 28% of the defined nighttime period and lying nearly half. Nighttime activity budgets remained fairly similar across the three phases, while daytime feeding decreased and standing increased. This small, sequential study, with no coverage outside the indoor enclosure, cannot isolate a male's effect or establish a general response to introductions. It shows why a giraffe's daytime behaviour is only part of its daily life.

A giraffe can become a three-dimensional model while it eats. A brief scan can capture the outline of its body without anaesthesia or a measuring tape around its belly. That offers a practical way to describe changes that people looking at the same animal every day might find difficult to judge consistently.

Nobuhide Kido, Sohei Tanaka and colleagues scanned seven reticulated giraffes, five okapis and three black rhinoceroses at three Japanese zoos. Handheld devices recorded both sides while feeding helped keep the animals still. Building on their earlier giraffe trial, the team divided each digital body into cross-sections five centimetres apart, comparing width, height, shape and estimated trunk volume.

The models revealed individual differences in how bodies widened and narrowed, and longer animals generally had larger estimated volumes. But a broad belly and a large volume did not always rank animals in the same order. The scans measured external shape, not fat: skeletal differences, food in the digestive system and pregnancy could all affect the outline, and missing scan regions required estimation. The result is a promising way to document a giraffe’s dimensions, rather than a validated substitute for weighing it or diagnosing its nutritional health.

Wild giraffes can rest beside farm animals. In Niger, West African giraffes share their home with people, cattle, sheep and goats. Such company might seem likely to keep a wild animal alert, but a study of their daytime behaviour found a more tolerant relationship.

Pavla Hejcmanová, Kateřina Gašparová and colleagues observed giraffes in the country’s farming and pastoral landscape during the 2020 dry season. Across 143 twenty-minute observation sessions, they recorded feeding, walking, vigilance and rest, and measured distances to other giraffes, livestock, people and houses. They asked whether resting depended on who was nearby, rather than simply how many giraffes were in a herd.

Giraffes spent about a quarter of observed time resting, usually standing rather than lying down. They were more likely to rest when another giraffe was closer; herd size itself made no detectable difference. Livestock proximity showed a similar but statistically uncertain tendency, while distance to people did not significantly predict rest. These short observations cannot prove that livestock make giraffes feel safe. They nevertheless show that living among farms need not mean constant disturbance: here, giraffes rested in a landscape shared with people and domestic animals.

A sick giraffe need not have fewer kinds of gut bacteria. In a Chinese safari park, animals with diarrhoea had a different bacterial mixture in their dung, but the study did not detect a clear drop in overall diversity. Which microbes were present mattered beyond a single measure of variety.

Baisheng Yu and colleagues collected faeces from 18 healthy giraffes and six with diarrhoea at Qingyuan Chimelong Safari Park in April 2023. The healthy animals included calves, younger giraffes and adults. DNA sequencing compared bacterial communities across age and health groups, while blood measurements in the healthy giraffes allowed the researchers to examine whether microbial differences accompanied changes in blood cells and chemistry.

Diarrhoeic animals differed in the relative abundance of several bacterial groups, including lower representation of some linked to plant digestion. Healthy age groups also differed: younger, still-developing giraffes did not share exactly the same microbial profile or blood values as adults. These cross-sectional comparisons cannot show whether microbes caused diarrhoea or changed because of it, and age was accompanied by differences in diet. The study therefore supplies associations rather than a diagnostic test. A giraffe's microbial community needs to be interpreted in the context of the animal carrying it.

Giraffes receiving extra feed left a different chemical mixture behind. Their droppings contained amino acids and other small compounds whose abundances differed from those of giraffes browsing vegetation alone. Those traces offered a way to study a complex process involving food, the animal's body and the microbes that help digest a leafy diet.

Andri Grobbelaar, Gernot Osthoff, Ilse du Preez and Francois Deacon analysed 26 selected samples from 13 free-roaming giraffes at six South African locations. Collected during 2021–2023, the samples were examined with instruments that separate and identify many small compounds at once. The team compared feeding groups, sexes, and repeated samples from one male across wet and dry seasons, rather than testing only for a predetermined nutrient.

Several amino-acid-related compounds were more abundant in dung from supplemented giraffes, and chemical profiles also differed between males and females. Seasonal patterns in the repeatedly sampled male were exploratory, without statistically clear differences in individual compounds. The small, unbalanced study cannot separate feed effects from differences among sites and animals, or turn a chemical pattern into a health diagnosis. Its contribution is a starting map of what giraffe dung can reveal without capture: not simply undigested food, but a mixture of dietary and digestive information.

A giraffe’s forehead helps reveal which species it belongs to. The difference lies partly in the bony projection between the eyes, beyond the familiar paired structures on top of the head. Genetic research had supported four species, but the question remained whether their skulls also carried a consistent anatomical signature.

Nikolaos Kargopoulos, Jesús Marugán-Lobón and colleagues assembled 515 skulls from museum collections, African parks and reserves, and taxidermy collections. They made three-dimensional scans, marked corresponding points across each skull and compared shapes among groups. Because male giraffe heads grow larger and develop more prominent bony structures, the analyses also examined sex, growth and the influence of size on shape.

All four species differed statistically in cranial shape. The central forehead projection was particularly informative: it tended to be tall and pointed in northern males, lower and broader in reticulated males, smaller in Masai males, and faint or almost absent in southern males. Females showed subtler differences. Individuals still varied and overlapped, so these are not infallible visual identification rules. Instead, many small measurements revealed a repeated anatomical pattern: the genetic divisions have a counterpart in the shape of giraffes’ heads.

A giraffe's route between national parks may depend on a livestock ranch. In the Tsavo–Mkomazi landscape spanning Kenya and Tanzania, community ranches occupy land between major protected areas. Those spaces could help keep giraffe habitat connected, even where most suitable habitat lies inside park boundaries.

Amos Muthiuru and colleagues combined a June 2021 aerial survey with satellite-based information about rainfall, vegetation, terrain and human modification of the landscape. They used 1,208 occupied map cells to model where Masai giraffes were likely to find suitable habitat. They then treated less suitable land as harder to cross and calculated possible connections between seven major habitat areas, including routes through community ranches.

Human modification was the strongest predictor of suitability, followed by rainfall. About 17% of the habitat classified as suitable lay outside protected areas, mainly on community ranches. The connectivity models highlighted ranchland connections and Tsavo West's position between other major habitat blocks. These were predicted routes built from dry-season presence data, not journeys confirmed by tracking individual giraffes. Their value is to identify places where maintaining usable land could keep protected populations connected. A park can contain good habitat while still depending on decisions made beyond its boundary.

Female giraffes have proportionally longer necks than males. Male Masai giraffes are larger overall, but a study separating size from shape found that females devote more of their potential height to neck and less to foreleg. That distinction matters to the idea that long necks evolved primarily as weapons for competing males.

Douglas Cavener, Monica Bond and colleagues measured body proportions in photographs of captive and wild Masai giraffes. A set of 357 images of 179 known-age captive animals let them examine how proportions changed during growth. They then compared mature zoo giraffes with wild adults from Tanzania to check whether the same differences appeared outside captivity.

Females had relatively longer necks and trunks, while males had relatively longer forelegs and wider neck bases. The photographic area of males’ necks was also proportionally larger, although area is not a direct measurement of mass. These patterns do not establish how necks originally evolved. They challenge the prediction that male competition should produce proportionally longer male necks, while remaining compatible with selection for a heavier fighting neck. A giraffe’s neck length and its bulk tell different parts of the evolutionary story.