Research and Protection of Masai Giraffes
Our giraffe research is discovering where Masai giraffes are doing well, where they are not, and why. Our research supports communities working to protect and connect areas important to Masai giraffe conservation.
The gentle, iconic giraffe indicates the health of African savanna ecosystems, home to the most spectacular displays of wildlife in the world.
But savanna ecosystems are in serious trouble. Habitat loss, illegal hunting, and disease are decimating savanna wildlife. Giraffe numbers have declined drastically to only 97,000.
Despite the popularity of giraffes, scientists know surprisingly little about them.
Wild Nature Institute scientists are studying wild Masai giraffes in the Tarangire and Serengeti Ecosystems of Tanzania using a computer program that recognizes each animal’s unique fur pattern from photographs. We are monitoring more than 3500 individual giraffes throughout their lifetimes in an area over 25,000 sq. km. This is the biggest giraffe study in the world, and one of the biggest large-mammal demography studies in history.
The gentle, iconic giraffe indicates the health of African savanna ecosystems, home to the most spectacular displays of wildlife in the world.
But savanna ecosystems are in serious trouble. Habitat loss, illegal hunting, and disease are decimating savanna wildlife. Giraffe numbers have declined drastically to only 97,000.
Despite the popularity of giraffes, scientists know surprisingly little about them.
Wild Nature Institute scientists are studying wild Masai giraffes in the Tarangire and Serengeti Ecosystems of Tanzania using a computer program that recognizes each animal’s unique fur pattern from photographs. We are monitoring more than 3500 individual giraffes throughout their lifetimes in an area over 25,000 sq. km. This is the biggest giraffe study in the world, and one of the biggest large-mammal demography studies in history.
In The Masai Giraffe Project, we are learning how natural and human factors affect giraffe demography and behavior in a landscape where wildlife habitat is increasingly fragmented by humans. Demography is survival, births, and movements, and these processes determine whether a population is growing or shrinking.
Our giraffe research is urgently needed so we can provide effective conservation actions in an ever more fragmented world, and ensure the future of wild giraffes and all creatures of the savanna.
We participated in the global status assessment of giraffes through the IUCN, and our research documented the effectiveness of community conservation and anti-poaching efforts. Wild Nature Institute scientists are affiliated with Pennsylvania State University, University of Zurich, and the Nelson Mandela African Institute for Science and Technology. We collaborate with scientists from the USA, South Africa, Tanzania, Spain, Germany, the United Kingdom, and Switzerland.
We believe animal welfare must be a priority for scientists working to protect wildlife. All our methods are completely non-invasive. We collect photographs and DNA samples without capturing and traumatizing the giraffes. The life of a wild animal is very difficult naturally, and because of the global spread of humans and our influences, wild animals are facing ever more challenges as they lose habitat and are forced to interact with people and human-dominated landscapes more often. We strive to make sure our research has no negative effects on the giraffes we study.
Learn more about our Giraffe-Themed Conservation Education, and Children's Books, and Fun Giraffe Facts.
Our giraffe research is urgently needed so we can provide effective conservation actions in an ever more fragmented world, and ensure the future of wild giraffes and all creatures of the savanna.
We participated in the global status assessment of giraffes through the IUCN, and our research documented the effectiveness of community conservation and anti-poaching efforts. Wild Nature Institute scientists are affiliated with Pennsylvania State University, University of Zurich, and the Nelson Mandela African Institute for Science and Technology. We collaborate with scientists from the USA, South Africa, Tanzania, Spain, Germany, the United Kingdom, and Switzerland.
We believe animal welfare must be a priority for scientists working to protect wildlife. All our methods are completely non-invasive. We collect photographs and DNA samples without capturing and traumatizing the giraffes. The life of a wild animal is very difficult naturally, and because of the global spread of humans and our influences, wild animals are facing ever more challenges as they lose habitat and are forced to interact with people and human-dominated landscapes more often. We strive to make sure our research has no negative effects on the giraffes we study.
Learn more about our Giraffe-Themed Conservation Education, and Children's Books, and Fun Giraffe Facts.
What you can do to help save giraffes.
- Donate Money or Time. Giving money and/or donating time to conservation groups like Wild Nature Institute is a great action to help giraffes. People can use their skills by providing advice, services, or goods in their personal area of expertise that can help the cause.
- Raise Awareness about the Silent Extinction of Giraffes. Speak up within your social circles, and encourage others to donate money or time to saving giraffes. You can raise awareness in your home communities by writing, speaking, and contributing to the global conversation about our planet’s climate and biodiversity crises.
- Plant Native Trees. Giraffes and many other species need native trees, but deforestation continues worldwide. Planting native trees helps fight the global climate crisis and helps biodiversity too!
- Support Legal Protections for Wildlife. Laws like the Endangered Species Act and other environmental laws make the world safer for wildlife and people. Call and write to your congressperson, senator, governor, and president telling them you support strong law enforcement to protect wildlife.
- Volunteer online to help measure giraffes at our Zooniverse project.
- We can craft a personal plan for you to become a giraffe hero. Email us at [email protected].
Your tax-deductible donation or adoption of a baby giraffe will help to conserve giraffes for future generations.
View A Video About Our Masai Giraffe Conservation Work
Journal Covers Featuring Our Giraffe Research
Summary of Our Giraffe Scientific Research Results
Precision, accuracy, and costs of survey methods for giraffe Giraffa camelopardalis was one of our first publications from the project. We estimated giraffe density and abundance in the Tarangire Ecosystem in northern Tanzania using two ground survey methods—distance sampling and capture-mark-recapture—and compared our ground-based estimates with those from the most recent aerial survey. We found aerial survey estimates were biased low, while ground-based surveys were more precise and cost less. However, aerial surveys are useful over large regions of Tanzania and thus can provide landscape-scale population estimates. We computed correction factors to improve the accuracy of aerial surveys and suggested ways to further improve aerial survey methods.
Our two papers about Giraffe Skin Disease (GSD), The occurrence and prevalence of giraffe skin disease in protected areas of northern Tanzania, and Soil correlates and mortality from giraffe skin disease in Tanzania described the disorder in the Journal of Wildlife Diseases. We documented that GSD prevalence was best explained by soil fertility, with less disease prevalence on more fertile soils. We found no mortality effect of GSD on adult giraffe in Tarangire National Park. Based on our findings, GSD is unlikely to warrant immediate veterinary intervention, but continued monitoring is recommended to ensure early detection if GSD-afflicted animals begin to show signs of increased mortality or other adverse effects.
In Spatial variation in giraffe demography: a test of 2 paradigms, we examined whether spatial variation in demography of a tropical mega-herbivore (the giraffe) followed the “temporal paradigm” or the “adult survival paradigm” of ungulate population dynamics that were formed from temperate-zone studies. We quantified how giraffe demographic rates of survival and reproduction varied across space at regional (northern Tanzania) and continental (Africa-wide) scales. Spatial variability of demographic rates at the continental scale supported the temporal paradigm of low variability in adult survival and more highly variable reproduction and calf survival. In contrast, at the regional scale, adult female survival had higher spatial variation, which supported the adult survival paradigm. At both scales, variation in adult female survival made the greatest contribution to variation in local population growth rates. We also found human-caused reductions in adult female giraffe survival are the most likely reasons of population declines.
In Giraffe demography and population ecology, we summarized current knowledge of demography and population ecology of giraffes and provided a framework for using population models when developing and evaluating conservation and management efforts for giraffes (or other large herbivore species).
In Migratory herds of wildebeests and zebras indirectly affect calf survival of giraffes, we utilized our data about a large-mammal predator–prey savanna food web to evaluate support for 2 hypotheses relating to the indirect effects of “apparent competition” and “apparent mutualism.” We examined how the presence of migratory herds of wildebeests (Connochaetes taurinus) and zebras (Equus quagga) affected survival of resident giraffe calves, as mediated by their shared predator, African lions (Panthera leo). African lions are generalist predators whose primary, preferred prey are wildebeests and zebras, but lion predation on secondary prey such as giraffes may change according to the relative abundance of the primary prey species. We found that local lion predation pressure on giraffes was reduced by local density of wildebeests and zebras, making giraffe neonatal and calf survival probabilities higher when the migratory herds were present. This supported the apparent mutualism hypothesis. Natural predation had a significant effect on giraffe calf and neonate survival, and could significantly affect giraffe population dynamics, thus if wildebeest and zebra populations in this ecosystem continue to decline as a result of increasingly disrupted migrations and poaching, then giraffe calves will face increased predation pressure as the predator–prey ratio increases. Our results suggest that the widespread population declines observed in many migratory systems are likely to trigger demographic impacts in other species due to indirect effects like those shown here.
We were proud to contribute to the IUCN Red List Assessment for giraffes, which reclassified giraffes as Vulnerable due to an observed population decline of 36–40% over three generations (30 years, 1985–2015). The factors causing this decline (direct killing and habitat loss) have not ceased throughout the species’ range. The best available estimates indicate a total population in 1985 of 151,702–163,452 giraffes (106,191–114,416 mature individuals), and in 2015 a total population of 97,562 giraffes (68,293 mature individuals). Some giraffe populations are stable or increasing, while others are declining, and each population is subject to pressure by threats specific to their local country or region. The populations of giraffes are scattered and fragmented with different growth trajectories and threats, but the species trend reveals an overall large decline in numbers across its range in Africa.
We documented for the first time that Season of birth affects juvenile survival of giraffe. Variation in timing of reproduction and subsequent juvenile survival often plays an important role in population dynamics of ungulates in temperate and boreal regions. Tropical ungulates often give birth year round, but survival effects of birth season for tropical ungulate species were previously unknown. We found significant differences in juvenile survival according to season of birth, with calves born during the dry season experiencing the highest survival probability. Phenological match (matching birth season with vegetation growth) may explain the juvenile survival advantage to offspring born during the dry season from 1) greater accumulated maternal energy reserves in mothers who conceived in the long rainy season, 2) high-protein browse in the late dry-early short rainy seasons supplementing maternal and calf resources, 3) reduced predation due to decreased stalking cover, or some combination of these. Asynchrony is believed to be the ancestral state of all ungulates, and this investigation illustrated how seasonal variation in vegetation can affect juvenile survival and may have played a role in the evolution of synchronous births.
We contributed to a lively discussion about How many species of giraffe are there? Giraffes are presently classified as one species, with nine subspecies. A paper in Current Biology presented DNA data and a taxonomy with four species of giraffe. The present consensus of one species divided into nine subspecies had previously been questioned several times over the past few decades. We presented the various taxonomic schemes and offered that the fundamental reason for different taxonomic interpretations is that they are based upon different datasets that adopt different statistical techniques and follow different criteria. These different taxonomies create a basis for future taxonomy discussions and conservation efforts.
Movements and source–sink dynamics of a Masai giraffe metapopulation provided a regional metapopulation analysis of the Tarangire ecosystem to inform conservation management for Masai giraffes in five subpopulations defined by land management designations. We assessed the source–sink structure of the study population, and we created a matrix metapopulation model to examine how variation in demographic components of survival, reproduction, and movement affected metapopulation growth rate. Movement data indicated no subpopulation was completely isolated, but movement probabilities varied among subpopulations. Source–sink statistics and flow of individuals indicated three subpopulations were sources, while two subpopulations were sinks. We found areas with higher wildlife protection efforts and fewer human impacts were sources, and less-protected areas were identified as sinks. Our results highlight the importance of identifying source–sink dynamics among subpopulations for effective conservation planning and emphasize how protected areas can play an important role in sustaining metapopulations.
Our study Seeing spots: Quantifying mother-offspring similarity and assessing fitness consequences of coat pattern traits in a wild population of giraffes revealed wild giraffe spot patterns are heritable, with elements of the pattern passed down from mother to offspring, and certain spot traits improved survival for newborns. Coats with complex patterns are found on many mammal species from anteaters to zebras, and these pelage traits are hypothesized to improve survival and reproduction by affecting predator and parasite evasion, temperature regulation, and social communication. This study was the first to examine complex mammal coat markings as individual traits that might have fitness consequences.
Together with computer engineers from Microsoft, we published An automated program to find animals and crop photographs for individual recognition. This paper describes a new image processing service using machine learning technology deployed on the Microsoft Azure cloud. Using a computer vision object detection algorithm, the Microsoft team trained a program to recognize giraffe torsos using some existing annotated giraffe photos. The program was iteratively improved using an efficient Active Learning process, where the system identified new images and showed its predicted cropping squares on these images to a human who could quickly verify or correct the results. These new images were then fed back into training algorithm to further update and improve the program. The resulting system identifies the location of giraffe torsos in images with a very high accuracy.
Correlates of home range sizes of giraffes, Giraffa camelopardalis examined what affects the size of giraffe home ranges. We found that giraffes living closer to towns had larger home ranges than giraffes living far from towns, suggesting a need to range longer distances—and expend more energy—to obtain critical resources in human-impacted areas. No such relationship was evident with bomas, which are homesteads built by indigenous livestock-keeping Maasai people, suggesting that giraffes are tolerant of more traditional, lower-impact land uses.
In Simultaneous multiple-calf allonursing by a wild Masai giraffe, we provide the first documentation of three calves nursing at the same time from one adult female in the wild. This unusual sighting suggests that for animals that live in social groups and share in caring of young, the benefits of sometimes allowing other females' calves to nurse might be greater than the costs.
In Fission-fusion dynamics of a megaherbivore are driven by ecological, anthropogenic, temporal, and social factors, we found food availability was more important than predation risk in mediating grouping dynamics of adult giraffes. Predation risk, on the other hand, was a significant predictor of where groups with calves congregated. Where natural predation risk was high, adult females with dependent calves tended to form smaller groups, and to seek cover in thicker vegetation. Calf groups also tended to be found closer to traditional pastoralist homesteads (bomas) where behaviours of predators are disrupted, but avoided towns which had high human populations, agriculture, and poaching risk.
Translocations to re-introduce giraffes to previously occupied areas or to establish new populations could be a useful conservation tool, but before now guidelines to ensure success did not exist. Two papers, Giraffe translocations: A review and discussion of considerations and Giraffe translocation population viability analysis provide strong guidance to biologists planning any conservation translocations of giraffe.
Using one of the largest-scale metapopulation networks ever studied in a wild mammal, in Proximity to humans affects local social structure in a giraffe metapopulation we reveal that social communities of giraffes living closer to human settlements exhibit weaker relationship strengths and more exclusive social associations—a signature of a disrupted social environment based upon previous experimental research.
In Sociability increases survival in adult female giraffes, we found that females grouping with more other females leads to higher survival. Benefits of female grouping may include cooperative care of young, more efficient foraging, and reduced stress in general. Effect of sociability on survival was more than that of the natural surrounding or proximity to people, although living closer to towns also lowered survival. Forming groups with other females and living in areas with fewer human impacts help adult female giraffe thrive.
Female Masai giraffes live in distinct social communities of up to 90 other friends, and although areas used by these communities often overlap, they have very different rates of reproduction and calf survival, we showed in Socially defined subpopulations reveal demographic variation in a giraffe metapopulation. This means that population structure can arise from social behavior rather than discrete space use. Giraffe calf survival was higher in social communities that had less area of dense bushlands in their ranges, and calf survival and reproductive rates were higher in the social communities that spent more time outside of the national parks.
We developed and validated a body condition scoring system for giraffes using photographs in Development of an image-based body condition score for giraffes Giraffa camelopardalis and a comparison of zoo-housed and free-ranging individuals. Body condition scoring based on the hip was the most precise reflection of body mass index. We found that zoo-housed and free-ranging juveniles had the highest body condition scores. Wild adult males had higher scores than wild adult females, likely reflecting the energetic strain on females due to reproduction, and overall zoo-housed giraffes had higher scores than free-ranging animals. Using photographs to score giraffes will enable monitoring of health at a population level.
Dispersal, the process where animals reaching sexual maturity move away from family, is important for maintaining genetic diversity and is key to the long-term persistence of natural populations. For most animals, this involves having to make risky journeys into the unknown in the hope of finding new communities in which to settle and reproduce. However, many animal societies—including those of humans—have structured social communities that overlap in space with one-another. These potentially provide opportunities for maturing individuals to disperse socially without having to make large physical displacements. Leaving by staying: Social dispersal in giraffes shows that this strategy is employed by young dispersing giraffes.
We studied social relationships of more than 1000 giraffes in the Tarangire Ecosystem over 5 years. In Social connectedness and movements among communities of giraffes vary by sex and age class, we found that males were more socially connected than females to all the other giraffes. Adult males wander long distances looking for mating opportunities. Young males visit many different groups as they explore their social environment before moving permanently away from their mothers and sisters. Females had stronger and enduring social relationships over the years than males. In the end, female giraffes have closer ‘friends’ than male giraffes, while males have more ‘acquaintances’ than females. This information is important for understanding population dynamics, spread of information, and even how diseases move through a population and is therefore important for conservation.
A native bush-encroaching shrub species called Sickle Bush (Dichrostachys cinerea) is disliked by livestock keepers and rangeland managers, but loved as forage by wild giraffes, according to Forage selection by Masai giraffes (Giraffa camelopardalis tippelskirchi) at multiple spatial scales. The findings showed that giraffe significantly preferred foraging on bush-encroaching species such as the native Sickle Bush at local and landscape spatial scales and in both the wet and dry seasons. The results of this study suggest that browsing wildlife such as giraffes could be adversely affected by the removal of Sickle Bush from rangelands.
The Tarangire region, where WNI has been studying giraffes and other ungulates for the past 10 years, hosts hundreds of thousands of people, millions of livestock, large mines, booming towns, two major tarmac roads, and a patchwork of agricultural fields—and yet still supports one of the most significant long-distance migrations of wildlife remaining in the world, much of it taking place on community land. It also is home to one of the most important populations of giraffes in Tanzania, and therefore in the world. Our book Tarangire: Human-Wildlife Coexistence in a Fragmented Landscape summarizes multidisciplinary work on wildlife conservation in the Tarangire Ecosystem and highlights practicable and locally adapted solutions for shaping human-wildlife interactions towards coexistence.
In Trophic processes constrain seasonal ungulate distributions at two scales in an East African savanna, we found giraffe distribution in the Tarangire Ecosystem was less constrained by water (they were not closer to rivers and waterholes during the dry season than the wet seasons) but more constrained by the seasonal presence of preferred food such as Vachellia drepanolobium in the long rains. Mixed feeders and smaller-bodied species had different habitat needs. These results provide important information for effective conservation strategies for giraffes and other ungulates in the Tarangire Ecosystem.
Animal coat patterns may have several functions, one of which might be to help individuals to recognize each other. In Phenotypic matching by spot pattern potentially mediates female giraffe social associations, we revealed that spot traits were individually variable among adult female giraffes in the Tarangire Ecosystem, and that females showed stronger associations with other females that had similar spot shapes. Our previous study found that spot shape was also similar between mother giraffes and their offspring, suggesting an effect of relatedness on both pattern similarities and female social relationships. Spot patterns of giraffes could be a visual cue for communicating and for recognizing related family members.
Giraffes are the perfect animal to study population dynamics and behavior of a large mammal using spot-pattern recognition, where natural born spot patterns provide every animal with a unique identifier scientists can use. Spot-pattern recognition is superior to tagging because it is non-invasive, the animals are never captured and affixed with a tag; the spots are permanent whereas tags are often lost; and we can identify and get data from every animal in our population, rather than just a few tagged animals. In Using spot pattern recognition to examine population biology, evolutionary ecology, sociality, and movements of giraffes: a 70-year retrospective we reviewed 70 years of research on giraffes based on identifying individuals by their unique spot patterns. We describe our Masai Giraffe Project in the Tarangire Ecosystem of Tanzania, and explain how recognizing individuals by the patterns allows scientists to learn about births and deaths, movements, social structure, and health. We also provide recommendations for conservation actions based on what we have learned from the past 7 decades of research, so that we can safeguard a future for this magnificent mega-herbivore.
Urban development of Arusha city and agricultural expansion have caused Arusha National Park to be increasingly isolated from other protected areas in northern Tanzania, but the current status of giraffes in the park was not known. In Masai giraffe population change over 40 years in Arusha National Park, we enumerated individual giraffes to see how well they were doing compared to 40 years ago and collected DNA from dung samples to assess the genetic connectivity of the park’s giraffes with other giraffe populations in the region. We documented a 49% population decline and changes in the age distribution, adult sex ratio, reproductive rate, and movement patterns relative to the previous study. Mitochondrial DNA analysis revealed genetic connectivity between Arusha National Park and other Masai giraffe populations east of the Gregory Rift Escarpment in northern Tanzania and south-eastern Kenya, providing evidence that Masai giraffe once moved widely across the landscape.
Climate change is predicted to cause widespread declines in wildlife populations in the coming decades. Climate anomalies interacting with human pressures can place additional stress on already declining populations, but little is known about the interactions between climate and anthropogenic effects on large African herbivore species despite the growing importance of these pressures. In Effects of local climate anomalies on giraffe survival, we found that in an East African savanna, higher temperatures positively affected adult giraffe survival, indicating this mega-herbivore is adapted to hot conditions, but adult and juvenile giraffe survival was reduced during rainier wet seasons, possibly due to parasites and disease and/or increased stalking cover for predators. Higher vegetation greenness also reduced adult giraffe survival, potentially because faster leaf growth reduces nutrient quality. Climate effects were most pronounced for giraffes living closer to the edge of the protected areas during the short rains, possibly because of higher livestock-mediated disease risk and/or muddier conditions that prevent effective anti-poaching patrols. Projected climate changes in East Africa, including heavier rainfall during the short rains, will likely threaten persistence of giraffes in one of Earth’s most important landscapes for large terrestrial mammals, pointing to the need for effective land-use planning and law enforcement to provide giraffes more resilience to the coming changes.
In Genetic evidence of population subdivision among Masai giraffes separated by the Gregory Rift Valley in Tanzania, we showed that populations of Masai giraffes separated geographically by the Great Rift Escarpment have not interbred — or exchanged genetic material — in more than a thousand years, and in some cases hundreds of thousands of years. We recommend that the two populations be considered separately for conservation purposes, with separate but coordinated conservation efforts to manage each population.
IMegaherbivores play “outsized” roles in ecosystem functioning but are vulnerable to human impacts such as overhunting, land-use changes, and climate extremes. However, such impacts—and combinations of these impacts—on population dynamics and extinction risk are rarely examined using empirical data. In Extinction risks and mititgation for a megaherbivoe, the giraffe, in a human-influenced landscape under climate change, we combined the information learned from previous studies of giraffes to create an individual-based model that simulated realistic population dynamics and extinction risk under different scenarios of environmental change over 50 years. Results showed that the greatest risk of population declines and extinction for giraffes is caused by a reduction in wildlife law enforcement leading to more poaching. The study highlights the great utility of law enforcement as a nature conservation tool.
In Sexual dimorphisms in body proportions of Masai giraffes and the evolution of the giraffe’s neck, we measured differences in body proportions between male and female giraffes, both captive and wild, and found females have a proportionally longer neck and torso, whereas males have proportionally longer forelegs and more massive necks. We speculate the initial evolution of the long neck and legs was driven by female nutritional demands (reaching deep into bushes and higher into trees) and mating (males with longer legs can mount females) and later the neck mass was increased in males as a result of neck sparring.
Our two papers about Giraffe Skin Disease (GSD), The occurrence and prevalence of giraffe skin disease in protected areas of northern Tanzania, and Soil correlates and mortality from giraffe skin disease in Tanzania described the disorder in the Journal of Wildlife Diseases. We documented that GSD prevalence was best explained by soil fertility, with less disease prevalence on more fertile soils. We found no mortality effect of GSD on adult giraffe in Tarangire National Park. Based on our findings, GSD is unlikely to warrant immediate veterinary intervention, but continued monitoring is recommended to ensure early detection if GSD-afflicted animals begin to show signs of increased mortality or other adverse effects.
In Spatial variation in giraffe demography: a test of 2 paradigms, we examined whether spatial variation in demography of a tropical mega-herbivore (the giraffe) followed the “temporal paradigm” or the “adult survival paradigm” of ungulate population dynamics that were formed from temperate-zone studies. We quantified how giraffe demographic rates of survival and reproduction varied across space at regional (northern Tanzania) and continental (Africa-wide) scales. Spatial variability of demographic rates at the continental scale supported the temporal paradigm of low variability in adult survival and more highly variable reproduction and calf survival. In contrast, at the regional scale, adult female survival had higher spatial variation, which supported the adult survival paradigm. At both scales, variation in adult female survival made the greatest contribution to variation in local population growth rates. We also found human-caused reductions in adult female giraffe survival are the most likely reasons of population declines.
In Giraffe demography and population ecology, we summarized current knowledge of demography and population ecology of giraffes and provided a framework for using population models when developing and evaluating conservation and management efforts for giraffes (or other large herbivore species).
In Migratory herds of wildebeests and zebras indirectly affect calf survival of giraffes, we utilized our data about a large-mammal predator–prey savanna food web to evaluate support for 2 hypotheses relating to the indirect effects of “apparent competition” and “apparent mutualism.” We examined how the presence of migratory herds of wildebeests (Connochaetes taurinus) and zebras (Equus quagga) affected survival of resident giraffe calves, as mediated by their shared predator, African lions (Panthera leo). African lions are generalist predators whose primary, preferred prey are wildebeests and zebras, but lion predation on secondary prey such as giraffes may change according to the relative abundance of the primary prey species. We found that local lion predation pressure on giraffes was reduced by local density of wildebeests and zebras, making giraffe neonatal and calf survival probabilities higher when the migratory herds were present. This supported the apparent mutualism hypothesis. Natural predation had a significant effect on giraffe calf and neonate survival, and could significantly affect giraffe population dynamics, thus if wildebeest and zebra populations in this ecosystem continue to decline as a result of increasingly disrupted migrations and poaching, then giraffe calves will face increased predation pressure as the predator–prey ratio increases. Our results suggest that the widespread population declines observed in many migratory systems are likely to trigger demographic impacts in other species due to indirect effects like those shown here.
We were proud to contribute to the IUCN Red List Assessment for giraffes, which reclassified giraffes as Vulnerable due to an observed population decline of 36–40% over three generations (30 years, 1985–2015). The factors causing this decline (direct killing and habitat loss) have not ceased throughout the species’ range. The best available estimates indicate a total population in 1985 of 151,702–163,452 giraffes (106,191–114,416 mature individuals), and in 2015 a total population of 97,562 giraffes (68,293 mature individuals). Some giraffe populations are stable or increasing, while others are declining, and each population is subject to pressure by threats specific to their local country or region. The populations of giraffes are scattered and fragmented with different growth trajectories and threats, but the species trend reveals an overall large decline in numbers across its range in Africa.
We documented for the first time that Season of birth affects juvenile survival of giraffe. Variation in timing of reproduction and subsequent juvenile survival often plays an important role in population dynamics of ungulates in temperate and boreal regions. Tropical ungulates often give birth year round, but survival effects of birth season for tropical ungulate species were previously unknown. We found significant differences in juvenile survival according to season of birth, with calves born during the dry season experiencing the highest survival probability. Phenological match (matching birth season with vegetation growth) may explain the juvenile survival advantage to offspring born during the dry season from 1) greater accumulated maternal energy reserves in mothers who conceived in the long rainy season, 2) high-protein browse in the late dry-early short rainy seasons supplementing maternal and calf resources, 3) reduced predation due to decreased stalking cover, or some combination of these. Asynchrony is believed to be the ancestral state of all ungulates, and this investigation illustrated how seasonal variation in vegetation can affect juvenile survival and may have played a role in the evolution of synchronous births.
We contributed to a lively discussion about How many species of giraffe are there? Giraffes are presently classified as one species, with nine subspecies. A paper in Current Biology presented DNA data and a taxonomy with four species of giraffe. The present consensus of one species divided into nine subspecies had previously been questioned several times over the past few decades. We presented the various taxonomic schemes and offered that the fundamental reason for different taxonomic interpretations is that they are based upon different datasets that adopt different statistical techniques and follow different criteria. These different taxonomies create a basis for future taxonomy discussions and conservation efforts.
Movements and source–sink dynamics of a Masai giraffe metapopulation provided a regional metapopulation analysis of the Tarangire ecosystem to inform conservation management for Masai giraffes in five subpopulations defined by land management designations. We assessed the source–sink structure of the study population, and we created a matrix metapopulation model to examine how variation in demographic components of survival, reproduction, and movement affected metapopulation growth rate. Movement data indicated no subpopulation was completely isolated, but movement probabilities varied among subpopulations. Source–sink statistics and flow of individuals indicated three subpopulations were sources, while two subpopulations were sinks. We found areas with higher wildlife protection efforts and fewer human impacts were sources, and less-protected areas were identified as sinks. Our results highlight the importance of identifying source–sink dynamics among subpopulations for effective conservation planning and emphasize how protected areas can play an important role in sustaining metapopulations.
Our study Seeing spots: Quantifying mother-offspring similarity and assessing fitness consequences of coat pattern traits in a wild population of giraffes revealed wild giraffe spot patterns are heritable, with elements of the pattern passed down from mother to offspring, and certain spot traits improved survival for newborns. Coats with complex patterns are found on many mammal species from anteaters to zebras, and these pelage traits are hypothesized to improve survival and reproduction by affecting predator and parasite evasion, temperature regulation, and social communication. This study was the first to examine complex mammal coat markings as individual traits that might have fitness consequences.
Together with computer engineers from Microsoft, we published An automated program to find animals and crop photographs for individual recognition. This paper describes a new image processing service using machine learning technology deployed on the Microsoft Azure cloud. Using a computer vision object detection algorithm, the Microsoft team trained a program to recognize giraffe torsos using some existing annotated giraffe photos. The program was iteratively improved using an efficient Active Learning process, where the system identified new images and showed its predicted cropping squares on these images to a human who could quickly verify or correct the results. These new images were then fed back into training algorithm to further update and improve the program. The resulting system identifies the location of giraffe torsos in images with a very high accuracy.
Correlates of home range sizes of giraffes, Giraffa camelopardalis examined what affects the size of giraffe home ranges. We found that giraffes living closer to towns had larger home ranges than giraffes living far from towns, suggesting a need to range longer distances—and expend more energy—to obtain critical resources in human-impacted areas. No such relationship was evident with bomas, which are homesteads built by indigenous livestock-keeping Maasai people, suggesting that giraffes are tolerant of more traditional, lower-impact land uses.
In Simultaneous multiple-calf allonursing by a wild Masai giraffe, we provide the first documentation of three calves nursing at the same time from one adult female in the wild. This unusual sighting suggests that for animals that live in social groups and share in caring of young, the benefits of sometimes allowing other females' calves to nurse might be greater than the costs.
In Fission-fusion dynamics of a megaherbivore are driven by ecological, anthropogenic, temporal, and social factors, we found food availability was more important than predation risk in mediating grouping dynamics of adult giraffes. Predation risk, on the other hand, was a significant predictor of where groups with calves congregated. Where natural predation risk was high, adult females with dependent calves tended to form smaller groups, and to seek cover in thicker vegetation. Calf groups also tended to be found closer to traditional pastoralist homesteads (bomas) where behaviours of predators are disrupted, but avoided towns which had high human populations, agriculture, and poaching risk.
Translocations to re-introduce giraffes to previously occupied areas or to establish new populations could be a useful conservation tool, but before now guidelines to ensure success did not exist. Two papers, Giraffe translocations: A review and discussion of considerations and Giraffe translocation population viability analysis provide strong guidance to biologists planning any conservation translocations of giraffe.
Using one of the largest-scale metapopulation networks ever studied in a wild mammal, in Proximity to humans affects local social structure in a giraffe metapopulation we reveal that social communities of giraffes living closer to human settlements exhibit weaker relationship strengths and more exclusive social associations—a signature of a disrupted social environment based upon previous experimental research.
In Sociability increases survival in adult female giraffes, we found that females grouping with more other females leads to higher survival. Benefits of female grouping may include cooperative care of young, more efficient foraging, and reduced stress in general. Effect of sociability on survival was more than that of the natural surrounding or proximity to people, although living closer to towns also lowered survival. Forming groups with other females and living in areas with fewer human impacts help adult female giraffe thrive.
Female Masai giraffes live in distinct social communities of up to 90 other friends, and although areas used by these communities often overlap, they have very different rates of reproduction and calf survival, we showed in Socially defined subpopulations reveal demographic variation in a giraffe metapopulation. This means that population structure can arise from social behavior rather than discrete space use. Giraffe calf survival was higher in social communities that had less area of dense bushlands in their ranges, and calf survival and reproductive rates were higher in the social communities that spent more time outside of the national parks.
We developed and validated a body condition scoring system for giraffes using photographs in Development of an image-based body condition score for giraffes Giraffa camelopardalis and a comparison of zoo-housed and free-ranging individuals. Body condition scoring based on the hip was the most precise reflection of body mass index. We found that zoo-housed and free-ranging juveniles had the highest body condition scores. Wild adult males had higher scores than wild adult females, likely reflecting the energetic strain on females due to reproduction, and overall zoo-housed giraffes had higher scores than free-ranging animals. Using photographs to score giraffes will enable monitoring of health at a population level.
Dispersal, the process where animals reaching sexual maturity move away from family, is important for maintaining genetic diversity and is key to the long-term persistence of natural populations. For most animals, this involves having to make risky journeys into the unknown in the hope of finding new communities in which to settle and reproduce. However, many animal societies—including those of humans—have structured social communities that overlap in space with one-another. These potentially provide opportunities for maturing individuals to disperse socially without having to make large physical displacements. Leaving by staying: Social dispersal in giraffes shows that this strategy is employed by young dispersing giraffes.
We studied social relationships of more than 1000 giraffes in the Tarangire Ecosystem over 5 years. In Social connectedness and movements among communities of giraffes vary by sex and age class, we found that males were more socially connected than females to all the other giraffes. Adult males wander long distances looking for mating opportunities. Young males visit many different groups as they explore their social environment before moving permanently away from their mothers and sisters. Females had stronger and enduring social relationships over the years than males. In the end, female giraffes have closer ‘friends’ than male giraffes, while males have more ‘acquaintances’ than females. This information is important for understanding population dynamics, spread of information, and even how diseases move through a population and is therefore important for conservation.
A native bush-encroaching shrub species called Sickle Bush (Dichrostachys cinerea) is disliked by livestock keepers and rangeland managers, but loved as forage by wild giraffes, according to Forage selection by Masai giraffes (Giraffa camelopardalis tippelskirchi) at multiple spatial scales. The findings showed that giraffe significantly preferred foraging on bush-encroaching species such as the native Sickle Bush at local and landscape spatial scales and in both the wet and dry seasons. The results of this study suggest that browsing wildlife such as giraffes could be adversely affected by the removal of Sickle Bush from rangelands.
The Tarangire region, where WNI has been studying giraffes and other ungulates for the past 10 years, hosts hundreds of thousands of people, millions of livestock, large mines, booming towns, two major tarmac roads, and a patchwork of agricultural fields—and yet still supports one of the most significant long-distance migrations of wildlife remaining in the world, much of it taking place on community land. It also is home to one of the most important populations of giraffes in Tanzania, and therefore in the world. Our book Tarangire: Human-Wildlife Coexistence in a Fragmented Landscape summarizes multidisciplinary work on wildlife conservation in the Tarangire Ecosystem and highlights practicable and locally adapted solutions for shaping human-wildlife interactions towards coexistence.
In Trophic processes constrain seasonal ungulate distributions at two scales in an East African savanna, we found giraffe distribution in the Tarangire Ecosystem was less constrained by water (they were not closer to rivers and waterholes during the dry season than the wet seasons) but more constrained by the seasonal presence of preferred food such as Vachellia drepanolobium in the long rains. Mixed feeders and smaller-bodied species had different habitat needs. These results provide important information for effective conservation strategies for giraffes and other ungulates in the Tarangire Ecosystem.
Animal coat patterns may have several functions, one of which might be to help individuals to recognize each other. In Phenotypic matching by spot pattern potentially mediates female giraffe social associations, we revealed that spot traits were individually variable among adult female giraffes in the Tarangire Ecosystem, and that females showed stronger associations with other females that had similar spot shapes. Our previous study found that spot shape was also similar between mother giraffes and their offspring, suggesting an effect of relatedness on both pattern similarities and female social relationships. Spot patterns of giraffes could be a visual cue for communicating and for recognizing related family members.
Giraffes are the perfect animal to study population dynamics and behavior of a large mammal using spot-pattern recognition, where natural born spot patterns provide every animal with a unique identifier scientists can use. Spot-pattern recognition is superior to tagging because it is non-invasive, the animals are never captured and affixed with a tag; the spots are permanent whereas tags are often lost; and we can identify and get data from every animal in our population, rather than just a few tagged animals. In Using spot pattern recognition to examine population biology, evolutionary ecology, sociality, and movements of giraffes: a 70-year retrospective we reviewed 70 years of research on giraffes based on identifying individuals by their unique spot patterns. We describe our Masai Giraffe Project in the Tarangire Ecosystem of Tanzania, and explain how recognizing individuals by the patterns allows scientists to learn about births and deaths, movements, social structure, and health. We also provide recommendations for conservation actions based on what we have learned from the past 7 decades of research, so that we can safeguard a future for this magnificent mega-herbivore.
Urban development of Arusha city and agricultural expansion have caused Arusha National Park to be increasingly isolated from other protected areas in northern Tanzania, but the current status of giraffes in the park was not known. In Masai giraffe population change over 40 years in Arusha National Park, we enumerated individual giraffes to see how well they were doing compared to 40 years ago and collected DNA from dung samples to assess the genetic connectivity of the park’s giraffes with other giraffe populations in the region. We documented a 49% population decline and changes in the age distribution, adult sex ratio, reproductive rate, and movement patterns relative to the previous study. Mitochondrial DNA analysis revealed genetic connectivity between Arusha National Park and other Masai giraffe populations east of the Gregory Rift Escarpment in northern Tanzania and south-eastern Kenya, providing evidence that Masai giraffe once moved widely across the landscape.
Climate change is predicted to cause widespread declines in wildlife populations in the coming decades. Climate anomalies interacting with human pressures can place additional stress on already declining populations, but little is known about the interactions between climate and anthropogenic effects on large African herbivore species despite the growing importance of these pressures. In Effects of local climate anomalies on giraffe survival, we found that in an East African savanna, higher temperatures positively affected adult giraffe survival, indicating this mega-herbivore is adapted to hot conditions, but adult and juvenile giraffe survival was reduced during rainier wet seasons, possibly due to parasites and disease and/or increased stalking cover for predators. Higher vegetation greenness also reduced adult giraffe survival, potentially because faster leaf growth reduces nutrient quality. Climate effects were most pronounced for giraffes living closer to the edge of the protected areas during the short rains, possibly because of higher livestock-mediated disease risk and/or muddier conditions that prevent effective anti-poaching patrols. Projected climate changes in East Africa, including heavier rainfall during the short rains, will likely threaten persistence of giraffes in one of Earth’s most important landscapes for large terrestrial mammals, pointing to the need for effective land-use planning and law enforcement to provide giraffes more resilience to the coming changes.
In Genetic evidence of population subdivision among Masai giraffes separated by the Gregory Rift Valley in Tanzania, we showed that populations of Masai giraffes separated geographically by the Great Rift Escarpment have not interbred — or exchanged genetic material — in more than a thousand years, and in some cases hundreds of thousands of years. We recommend that the two populations be considered separately for conservation purposes, with separate but coordinated conservation efforts to manage each population.
IMegaherbivores play “outsized” roles in ecosystem functioning but are vulnerable to human impacts such as overhunting, land-use changes, and climate extremes. However, such impacts—and combinations of these impacts—on population dynamics and extinction risk are rarely examined using empirical data. In Extinction risks and mititgation for a megaherbivoe, the giraffe, in a human-influenced landscape under climate change, we combined the information learned from previous studies of giraffes to create an individual-based model that simulated realistic population dynamics and extinction risk under different scenarios of environmental change over 50 years. Results showed that the greatest risk of population declines and extinction for giraffes is caused by a reduction in wildlife law enforcement leading to more poaching. The study highlights the great utility of law enforcement as a nature conservation tool.
In Sexual dimorphisms in body proportions of Masai giraffes and the evolution of the giraffe’s neck, we measured differences in body proportions between male and female giraffes, both captive and wild, and found females have a proportionally longer neck and torso, whereas males have proportionally longer forelegs and more massive necks. We speculate the initial evolution of the long neck and legs was driven by female nutritional demands (reaching deep into bushes and higher into trees) and mating (males with longer legs can mount females) and later the neck mass was increased in males as a result of neck sparring.
Our Scientific Publications on Giraffes (click to download):
D. R. Cavener, M. L. Bond, L. Wu-Cavener, G. G. Lohay, M. W. Cavener, X. Hou, D. Pearce, & D. E. Lee. 2024. "Sexual dimorphisms in body proportions of Masai giraffe and the evolution of the giraffe’s neck." Mammalian Biology DOI:10.1007/s42991-024-00424-4.
M. L. Bond, D. E. Lee, & M. Paniw. 2023. "Extinction risks and mitigation for a megaherbivore, the giraffe, in a human-influenced landscape under climate change." Global Change Biology 29:6693–6712. DOI:10.1111/gcb.16970.
G. G. Lohay, D. E. Lee, L. Wu-Cavener, D. L. Pearce, X. Hou, M. L. Bond, & D. R. Cavener. 2023. "Genetic evidence of population subdivision among Masai giraffes separated by the Gregory Rift Valley in Tanzania." Ecology and Evolution DOI: 10.1002/ece3.10160
M. L. Bond, A. Ozgul, & D. E. Lee. 2023. "Effect of local climate anomalies on giraffe survival." Biodiversity and Conservation 32:3179–3197. DOI:10.1007/s10531-023-02645-4
D.E.Lee, G.G. Lohay, J. Madeli, D.R. Cavener, & M.L. Bond. 2023. "Masai giraffe population change over 40 years in Arusha National Park." African Journal of Ecology 61:345-353. DOI: 10.1111/aje.13115
D.E. Lee, G.G. Lohay, D.R. Cavener, & M.L. Bond. 2022. "Using spot pattern recognition to examine population biology, evolutionary ecology, sociality, and movements of giraffes: a 70-year retrospective." Mammalian Biology 102:1055-1071. DOI:10.1007/s42991-022-00261-3
K. Morandi, A.K. Lindholm, D.E. Lee, & M.L. Bond. 2022. "Phenotypic matching by spot pattern potentially mediates female giraffe social associations." Journal of Zoology 318:147-157. DOI:10.1111/jzo.13009
N.L. James, M.L. Bond, A. Ozgul, & D.E. Lee. 2022. "Trophic processes constrain seasonal ungulate distributions at two scales in an East African savanna." Journal of Mammalogy 103:956-969. DOI:10.1093/jmammal/gyac050
C. Kiffner, M.L .Bond, D.E. Lee. 2022. "Tarangire: Human-Wildlife Coexistence in a Fragmented Ecosystem." Ecological Studies Series Volume 243, Springer Nature.
M. Levi, D. E. Lee, M. L. Bond, A. C. Treydte. 2022. "Forage selection by Masai giraffes (Giraffa camelopardalis tippelskirchi) at multiple spatial scales." Journal of Mammalogy 103:737-744. https://doi.org/10.1093/jmammal/gyac007
J. M. Lavista Ferres, D. E. Lee, Md Nasir, Yu-Chia Chen, A. S. Bijral, F. B. Bercovitch, M. L. Bond. 2021. "Social connectedness and movements among communities of giraffes vary by sex and age class." Animal Behaviour 180:315-328. https://doi.org/10.1016/j.anbehav.2021.08.008
M. L. Bond, D. E. Lee, A. Ozgul, D. R. Farine, B. König. 2021. "Leaving by staying: Social dispersal in giraffes." Journal of Animal Ecology. 90:2755-2766. DOI: 10.1111/1365-2656.13582
I. Clavadetscher, M. L. Bond, L. F. Martin, C. Schiffmann, J-M Hatt, M. Clauss. 2021. "Development of an image-based body condition score for giraffes Giraffa camelopardalis and a comparison of zoo-housed and free-ranging individuals." Journal of Zoo and Aquarium Research. 9:170-185. doi.org/10.19227/jzar.v9i3.615
M. L. Bond, B. König., A. Ozgul, D. R. Farine, D. E. Lee. 2021. "Socially defined subpopulations reveal demographic variation in a giraffe metapopulation." Journal of Wildlife Management 85:920-931. doi.org/10.1002/jwmg.22044
M. L. Bond, D. E. Lee, D. R. Farine, A. Ozgul, B. König. 2021. "Sociability increases survival of adult female giraffes." Proceedings of the Royal Society B 28: 20202770. doi.org/10.1098/rspb.2020.2770
M.L. Bond, B. König, D.E. Lee, A. Ozgul, D.R. Farine. 2021. "Proximity to humans affects local social structure in a giraffe metapopulation." Journal of Animal Ecology 90:212-221. doi.org/10.1111/1365-2656.13247
Z. Muller, D. E. Lee, C. P. J. Scheijen, K. D. Carter, M. Strauss, F. Deacon. 2020. "Giraffe translocations: A review and discussion of considerations." African Journal of Ecology doi.org/10.1111/aje.12727
D. E. Lee, E. Fienieg, C. Van Oosterhout, Z. Muller, M. Strauss, K. D. Carter, C. P. J. Scheijen, F. Deacon. 2020. "Giraffe translocation population viability analysis." Endangered Species Research DOI:10.3354/esr01022
M.L. Bond, D. E. Lee, A. Ozgul, & B. König. 2019. "Fission-fusion dynamics of a megaherbivore are driven by ecological, anthropogenic, temporal, and social factors." Oecologia 19: 335-347. DOI:10.1007/s00442-019-04485-y.
D. Bolger, J. Ogutu, M. Strauss, D. Lee, A. Muneza, J. Fennessy, & D. Brown. 2019. Giraffa camelopardalis ssp. tippelskirchi. The IUCN Red List of Threatened Species 2019: e.T88421036A88421121.
M. L. Bond & D. E. Lee. 2019. "Simultaneous multiple-calf allonursing by a wild Masai giraffe." African Journal of Ecology 58:126-128. DOI:10.1111/aje.12673.
M. A. Knüsel, D .E. Lee, B. König, M. L. Bond. 2019. "Correlates of home range sizes of giraffes, Giraffa camelopardalis." Animal Behaviour 149:143-151. DOI:10.1016/j.anbehav.2019.01.017.
P. Buehler, B. Carroll, A. Bhatia, V. Gupta, D. E. Lee. 2019. "An automated program to find animals and crop photographs for individual recognition." Ecological Informatics 50:191-196. DOI: 10.1016/j.ecoinf.2019.02.003.
D. E. Lee, D. R. Cavener & M. L. Bond. 2018. "Seeing spots: quantifying mother-offspring similarity and assessing fitness consequences of coat pattern traits in a wild population of giraffes (Giraffa camelopardalis)." PeerJ 6:e5690. https://doi.org/10.7717/peerj.5690.
D. E. Lee. 2018. "Evaluating conservation effectiveness in a Tanzanian Community Wildlife Management Area." Journal of Wildlife Management DOI: 10.1002/jwmg.21549.
D.E. Lee & M.L. Bond. 2018. "Quantifying the ecological success of a community-based wildlife conservation area in Tanzania." Journal of Mammalogy 99:459-464 DOI:10.1093/jmammal/gyy014.
D.E. Lee & D.T. Bolger. 2017. "Movements and source-sink dynamics among subpopulations of giraffe." Population Ecology 59:157-168 DOI 10.1007/s10144-017-0580-7.
F.B. Bercovitch, P.S. Berry, A. Dagg, F. Deacon, J.B. Doherty, D.E. Lee, F. Mineur, Z. Muller, R. Ogden, R. Seymour & B. Shorrocks. 2017. "How many species of giraffe are there?" Current Biology 27:R136-R137.
D.E. Lee, M.L. Bond & D.T. Bolger. 2017. "Season of birth affects juvenile survival of giraffe." Population Ecology 59:45-54 DOI 10.1007/s10144-017-0571-8.
Z. Muller, F. Bercovitch, J. Fennessy, D. Brown, R. Brand, M. Brown, D. Bolger, K. Carter, F. Deacon, J. Doherty, S. Fennessy, A.A. Hussein, D. Lee, A. Marais, M. Strauss, A. Tutchings & T. Wube. 2016. "Giraffa camelopardalis." The IUCN Red List of Threatened Species 2016: e.T9194A51140239.
D.E. Lee, B.M. Kissui, Y.A. Kiwango & M.L. Bond. 2016. "Migratory herds of wildebeest and zebra indirectly affect juvenile survival of giraffes." Ecology and Evolution 6:8402-8411 DOI: 10.1002/ece3.2561.
D.E. Lee & M.K.L. Strauss. 2016. "Giraffe demography and population ecology." Reference Module in Earth Sciences and Environmental Studies. DOI: 10.1016/B978-0-12-409548-9.09721-9.
D.E. Lee, M.L. Bond, B.M. Kissui, Y.A. Kiwango & D.T. Bolger. 2016. "Spatial variation in giraffe demography: a test of 2 paradigms." Journal of Mammalogy 79:1015-1025.
D.E. Lee & M.L. Bond. 2016. "Precision, accuracy, and costs of survey methods for giraffe Giraffa camelopardalis." Journal of Mammalogy 79:940-948.
D.E. Lee & M.L. Bond. 2016. "The occurrence and prevalence of giraffe skin disease in protected areas of northern Tanzania." Journal of Wildlife Diseases 52:753-755.
M.L. Bond, M.K.L. Strauss & D.E. Lee. 2016. "Soil correlates and mortality of giraffe skin disease in northern Tanzania." Journal of Wildlife Diseases DOI:10.7589/2016-02-047.
D.T. Bolger, J.O. Ogutu, M. Strauss, D.E. Lee, J. Fennessy, D. Brown. 2015. “Masai giraffe (Giraffa camelopardalis tippelskirchi) conservation status report.” IUCN/SSC Giraffe and Okapi Specialist Group.
D.E. Lee. 2015. "Demography of giraffe in the fragmented Tarangire ecosystem." PhD Dissertation. Dartmouth College.
D. R. Cavener, M. L. Bond, L. Wu-Cavener, G. G. Lohay, M. W. Cavener, X. Hou, D. Pearce, & D. E. Lee. 2024. "Sexual dimorphisms in body proportions of Masai giraffe and the evolution of the giraffe’s neck." Mammalian Biology DOI:10.1007/s42991-024-00424-4.
M. L. Bond, D. E. Lee, & M. Paniw. 2023. "Extinction risks and mitigation for a megaherbivore, the giraffe, in a human-influenced landscape under climate change." Global Change Biology 29:6693–6712. DOI:10.1111/gcb.16970.
G. G. Lohay, D. E. Lee, L. Wu-Cavener, D. L. Pearce, X. Hou, M. L. Bond, & D. R. Cavener. 2023. "Genetic evidence of population subdivision among Masai giraffes separated by the Gregory Rift Valley in Tanzania." Ecology and Evolution DOI: 10.1002/ece3.10160
M. L. Bond, A. Ozgul, & D. E. Lee. 2023. "Effect of local climate anomalies on giraffe survival." Biodiversity and Conservation 32:3179–3197. DOI:10.1007/s10531-023-02645-4
D.E.Lee, G.G. Lohay, J. Madeli, D.R. Cavener, & M.L. Bond. 2023. "Masai giraffe population change over 40 years in Arusha National Park." African Journal of Ecology 61:345-353. DOI: 10.1111/aje.13115
D.E. Lee, G.G. Lohay, D.R. Cavener, & M.L. Bond. 2022. "Using spot pattern recognition to examine population biology, evolutionary ecology, sociality, and movements of giraffes: a 70-year retrospective." Mammalian Biology 102:1055-1071. DOI:10.1007/s42991-022-00261-3
K. Morandi, A.K. Lindholm, D.E. Lee, & M.L. Bond. 2022. "Phenotypic matching by spot pattern potentially mediates female giraffe social associations." Journal of Zoology 318:147-157. DOI:10.1111/jzo.13009
N.L. James, M.L. Bond, A. Ozgul, & D.E. Lee. 2022. "Trophic processes constrain seasonal ungulate distributions at two scales in an East African savanna." Journal of Mammalogy 103:956-969. DOI:10.1093/jmammal/gyac050
C. Kiffner, M.L .Bond, D.E. Lee. 2022. "Tarangire: Human-Wildlife Coexistence in a Fragmented Ecosystem." Ecological Studies Series Volume 243, Springer Nature.
M. Levi, D. E. Lee, M. L. Bond, A. C. Treydte. 2022. "Forage selection by Masai giraffes (Giraffa camelopardalis tippelskirchi) at multiple spatial scales." Journal of Mammalogy 103:737-744. https://doi.org/10.1093/jmammal/gyac007
J. M. Lavista Ferres, D. E. Lee, Md Nasir, Yu-Chia Chen, A. S. Bijral, F. B. Bercovitch, M. L. Bond. 2021. "Social connectedness and movements among communities of giraffes vary by sex and age class." Animal Behaviour 180:315-328. https://doi.org/10.1016/j.anbehav.2021.08.008
M. L. Bond, D. E. Lee, A. Ozgul, D. R. Farine, B. König. 2021. "Leaving by staying: Social dispersal in giraffes." Journal of Animal Ecology. 90:2755-2766. DOI: 10.1111/1365-2656.13582
I. Clavadetscher, M. L. Bond, L. F. Martin, C. Schiffmann, J-M Hatt, M. Clauss. 2021. "Development of an image-based body condition score for giraffes Giraffa camelopardalis and a comparison of zoo-housed and free-ranging individuals." Journal of Zoo and Aquarium Research. 9:170-185. doi.org/10.19227/jzar.v9i3.615
M. L. Bond, B. König., A. Ozgul, D. R. Farine, D. E. Lee. 2021. "Socially defined subpopulations reveal demographic variation in a giraffe metapopulation." Journal of Wildlife Management 85:920-931. doi.org/10.1002/jwmg.22044
M. L. Bond, D. E. Lee, D. R. Farine, A. Ozgul, B. König. 2021. "Sociability increases survival of adult female giraffes." Proceedings of the Royal Society B 28: 20202770. doi.org/10.1098/rspb.2020.2770
M.L. Bond, B. König, D.E. Lee, A. Ozgul, D.R. Farine. 2021. "Proximity to humans affects local social structure in a giraffe metapopulation." Journal of Animal Ecology 90:212-221. doi.org/10.1111/1365-2656.13247
Z. Muller, D. E. Lee, C. P. J. Scheijen, K. D. Carter, M. Strauss, F. Deacon. 2020. "Giraffe translocations: A review and discussion of considerations." African Journal of Ecology doi.org/10.1111/aje.12727
D. E. Lee, E. Fienieg, C. Van Oosterhout, Z. Muller, M. Strauss, K. D. Carter, C. P. J. Scheijen, F. Deacon. 2020. "Giraffe translocation population viability analysis." Endangered Species Research DOI:10.3354/esr01022
M.L. Bond, D. E. Lee, A. Ozgul, & B. König. 2019. "Fission-fusion dynamics of a megaherbivore are driven by ecological, anthropogenic, temporal, and social factors." Oecologia 19: 335-347. DOI:10.1007/s00442-019-04485-y.
D. Bolger, J. Ogutu, M. Strauss, D. Lee, A. Muneza, J. Fennessy, & D. Brown. 2019. Giraffa camelopardalis ssp. tippelskirchi. The IUCN Red List of Threatened Species 2019: e.T88421036A88421121.
M. L. Bond & D. E. Lee. 2019. "Simultaneous multiple-calf allonursing by a wild Masai giraffe." African Journal of Ecology 58:126-128. DOI:10.1111/aje.12673.
M. A. Knüsel, D .E. Lee, B. König, M. L. Bond. 2019. "Correlates of home range sizes of giraffes, Giraffa camelopardalis." Animal Behaviour 149:143-151. DOI:10.1016/j.anbehav.2019.01.017.
P. Buehler, B. Carroll, A. Bhatia, V. Gupta, D. E. Lee. 2019. "An automated program to find animals and crop photographs for individual recognition." Ecological Informatics 50:191-196. DOI: 10.1016/j.ecoinf.2019.02.003.
D. E. Lee, D. R. Cavener & M. L. Bond. 2018. "Seeing spots: quantifying mother-offspring similarity and assessing fitness consequences of coat pattern traits in a wild population of giraffes (Giraffa camelopardalis)." PeerJ 6:e5690. https://doi.org/10.7717/peerj.5690.
D. E. Lee. 2018. "Evaluating conservation effectiveness in a Tanzanian Community Wildlife Management Area." Journal of Wildlife Management DOI: 10.1002/jwmg.21549.
D.E. Lee & M.L. Bond. 2018. "Quantifying the ecological success of a community-based wildlife conservation area in Tanzania." Journal of Mammalogy 99:459-464 DOI:10.1093/jmammal/gyy014.
D.E. Lee & D.T. Bolger. 2017. "Movements and source-sink dynamics among subpopulations of giraffe." Population Ecology 59:157-168 DOI 10.1007/s10144-017-0580-7.
F.B. Bercovitch, P.S. Berry, A. Dagg, F. Deacon, J.B. Doherty, D.E. Lee, F. Mineur, Z. Muller, R. Ogden, R. Seymour & B. Shorrocks. 2017. "How many species of giraffe are there?" Current Biology 27:R136-R137.
D.E. Lee, M.L. Bond & D.T. Bolger. 2017. "Season of birth affects juvenile survival of giraffe." Population Ecology 59:45-54 DOI 10.1007/s10144-017-0571-8.
Z. Muller, F. Bercovitch, J. Fennessy, D. Brown, R. Brand, M. Brown, D. Bolger, K. Carter, F. Deacon, J. Doherty, S. Fennessy, A.A. Hussein, D. Lee, A. Marais, M. Strauss, A. Tutchings & T. Wube. 2016. "Giraffa camelopardalis." The IUCN Red List of Threatened Species 2016: e.T9194A51140239.
D.E. Lee, B.M. Kissui, Y.A. Kiwango & M.L. Bond. 2016. "Migratory herds of wildebeest and zebra indirectly affect juvenile survival of giraffes." Ecology and Evolution 6:8402-8411 DOI: 10.1002/ece3.2561.
D.E. Lee & M.K.L. Strauss. 2016. "Giraffe demography and population ecology." Reference Module in Earth Sciences and Environmental Studies. DOI: 10.1016/B978-0-12-409548-9.09721-9.
D.E. Lee, M.L. Bond, B.M. Kissui, Y.A. Kiwango & D.T. Bolger. 2016. "Spatial variation in giraffe demography: a test of 2 paradigms." Journal of Mammalogy 79:1015-1025.
D.E. Lee & M.L. Bond. 2016. "Precision, accuracy, and costs of survey methods for giraffe Giraffa camelopardalis." Journal of Mammalogy 79:940-948.
D.E. Lee & M.L. Bond. 2016. "The occurrence and prevalence of giraffe skin disease in protected areas of northern Tanzania." Journal of Wildlife Diseases 52:753-755.
M.L. Bond, M.K.L. Strauss & D.E. Lee. 2016. "Soil correlates and mortality of giraffe skin disease in northern Tanzania." Journal of Wildlife Diseases DOI:10.7589/2016-02-047.
D.T. Bolger, J.O. Ogutu, M. Strauss, D.E. Lee, J. Fennessy, D. Brown. 2015. “Masai giraffe (Giraffa camelopardalis tippelskirchi) conservation status report.” IUCN/SSC Giraffe and Okapi Specialist Group.
D.E. Lee. 2015. "Demography of giraffe in the fragmented Tarangire ecosystem." PhD Dissertation. Dartmouth College.
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