From Urine Signals to Low-Frequency Roars: Field Observations of Unusual Giraffe Behavior

Giraffes on the African savanna are often perceived as quiet and graceful animals. Yet close observation of their daily activities reveals that these extremely tall and structurally unusual mammals possess a set of distinctive behavioral patterns. Several research teams conducted long-term observations of Angolan giraffes (Giraffa giraffa angolensis) at waterholes in Etosha National Park in Namibia. Their work documented a number of traits associated with reproduction, feeding, and responses to environmental stimuli that differ markedly from those seen in other hoofed mammals.

In many large African artiodactyls, males commonly assess whether a female is approaching estrus by smelling freshly voided urine. In antelopes, for example, males typically investigate urine that has fallen onto the ground. They then draw it into the mouth and perform what is known as the flehmen response, a behavior in which the animal curls its lip and allows odor molecules to enter the vomeronasal organ through openings in the oral vestibule. This mechanism enables the detection of chemical signals, particularly reproductive pheromones. Giraffes employ a very different strategy. Because their heads are extremely elevated and their necks are heavy, bending down to the ground to collect urine would involve considerable risk. Male giraffes therefore do not examine urine deposited on the ground. Instead, they position themselves behind a female and stimulate her to urinate by sniffing, lightly touching, or gently nudging the genital region.

When a female is receptive to this interaction, she typically spreads her hind legs widely and adjusts her posture to stabilize her body before releasing urine. At that moment, the male opens his mouth and extends his tongue directly into the urine stream, collecting the liquid as it is being excreted. Most males immediately raise their heads and perform the flehmen response for roughly three to nine seconds, analyzing the chemical signals contained in the urine.

Male giraffe sniffing a female's urine（圖片來源：Hart LA and Hart BL. (2023)，採用 CC BY 4.0 授權）

Female urination usually lasts for more than five seconds, providing sufficient time for the male to obtain the sample. If a female is not approaching estrus, she may reject the male's attempts at contact and inspection from the outset. In contrast, females that are nearing estrus often delay urination until the male approaches, indicating a coordinated interaction between the two individuals during mate assessment. Among the animals observed, one particularly large male with unusually dark coat coloration was especially active. Within short periods he repeatedly examined multiple females, suggesting both high social status and strong mating advantage.

The anatomical structure of the giraffe vomeronasal organ also differs from that of most ruminants. In many ruminants the vomeronasal organ connects clearly with both the nasal cavity and the oral cavity. In giraffes, however, the oral connection is more developed. Liquids can be directed to the vomeronasal organ through the incisive papilla located on the hard palate and the canal behind it. The nasal opening of the vomeronasal organ is extremely small, making it difficult for giraffes to deliver chemical signals to the organ through nasal sniffing alone. This anatomical arrangement fits well with the behavioral pattern in which males collect urine directly into the mouth.

Incisive papilla of a giraffe（圖片來源：Hart LA and Hart BL. (2023)，採用 CC BY 4.0 授權）

Oral duct opening leading to the vomeronasal organ in a giraffe（圖片來源：Hart LA and Hart BL. (2023)，採用 CC BY 4.0 授權）

Beyond reproductive behavior, the observations also recorded giraffes searching the ground for scattered bones from animal carcasses. When a bone was found, a giraffe might hold it in its mouth and chew repeatedly. In some cases the animal lifted its head while the bone hung partially from its mouth, saliva dripping continuously. This behavior, known as osteophagia, has occasionally been mentioned in earlier literature and is generally interpreted as a means of supplementing calcium or phosphorus. The present observations suggest that the behavior may occur more frequently than previously assumed. Some giraffes even appeared to experience considerable discomfort when bones became lodged in their mouths or against the face, preventing them from eating or drinking. One individual spent more than a day attempting to shake loose a bone stuck in its mouth, while another female refused a male's mating inspection because a bone obstructed her mouth. Such incidents indicate that osteophagia may also involve certain risks for giraffes.

At one waterhole an unusual event was recorded after a giraffe had been killed by lions. A fresh carcass of a dark-colored giraffe lay near the waterhole while lions remained nearby for two days. Several scavengers gathered around the site, including black-backed jackals (Lupulella mesomelas), lappet-faced vultures (Torgos tracheliotos), and white-backed vultures (Gyps africanus). Beginning on the third day, after the lions had departed, groups of giraffes started arriving at the carcass. For several days they approached the remains while circling the waterhole, inspecting the body and occasionally picking up scattered leg bones. This activity gradually diminished and ceased by the eighth day. Although the behavior has not yet been clearly explained, possible factors include curiosity, vigilance, or attraction to skeletal material. Regardless of the cause, the observations documented a previously unrecorded aspect of giraffe behavior.

Lions remaining beside a giraffe carcass（圖片來源：Hart LA and Hart BL. (2023)，採用 CC BY 4.0 授權）

After the lions leave, several giraffes interacting around the carcass（圖片來源：Hart LA and Hart BL. (2023)，採用 CC BY 4.0 授權）

Giraffes have often been considered almost silent animals. However, the study recorded that dark-colored males were capable of producing high-amplitude, pulsed low-frequency roars during social interactions. In one event several males were engaged in vigorous necking contests while another pair was mating. Suddenly a dark male that had not been involved in these activities emitted three low roars lasting about thirty seconds in total. Most of the giraffes around the waterhole immediately fled, leaving only the mating pair behind. On another occasion the same male produced a series of twelve roars lasting more than one hundred seconds, again causing the herd to disperse. Acoustic analysis revealed stable resonance peaks near 209 Hz. These findings suggest that male giraffes may employ vocal signals in social competition and communication more extensively than previously recognized, possibly using such sounds as warning or dispersal signals.

In several contexts, including drinking and mating, giraffes must spread their forelegs and hind legs widely in order to reach the ground or maintain balance. This posture reduces body stability and limits the animal's ability to turn or escape quickly, leaving it relatively vulnerable to predators. Field observations occasionally recorded giraffes nearly slipping or falling while drinking, illustrating the biomechanical constraints imposed by their extraordinary body plan.

These scattered yet valuable field records offer a deeper glimpse into how giraffes successfully reproduce and persist within the ecological landscape of the African savanna, maintaining a lifestyle that appears graceful but is shaped by numerous physiological and behavioral challenges.

Author: Shui Ye-You

Reference:

Hart LA and Hart BL. (2023). Flehmen, Osteophagia, and Other Behaviors of Giraffes (Giraffa giraffa angolensis): Vomeronasal Organ Adaptation. Animals.