Celebrate the fascinating relationship between giraffes and trees and the broader web of life that connects humans, plants, animals, and insects. 

The giraffe, one of Africa’s most iconic animals, is facing a crisis. Despite their worldwide popularity, giraffe populations in the wild are declining due to illegal killing and habitat loss. A new study published in the Journal of Wildlife Management reveals that targeted conservation strategies—particularly those focused on adult survival—are essential to reverse these trends in the Serengeti Ecosystem.

Led by scientists from the Wild Nature Institute, the University of Zurich, and their international partners, the study shows that giraffe numbers in the center of Serengeti’s protected areas have stabilized since the late 2000s, following major declines in previous decades. However, populations near the edges of the protected areas continue to shrink.

“We needed to understand whether protected areas in the Serengeti were effectively conserving giraffes,” said Dr. George Lohay, co-author and Head Scientist at the Grumeti Fund. “Our results clearly show where giraffes are doing well and where urgent action is needed.”

The research team compiled multiple years of photographic data identifying 1,520 individual Masai giraffes across four subpopulations. Using both Bayesian and frequentist modelling approaches, they estimated survival rates, birth rates, population densities, and long-distance movements. Their findings highlight significant differences in adult survival among subpopulations, with lower adult survival rates linked to population declines.

“Adult survival emerged as the strongest demographic driver of giraffe population trends,” said Dr. Dominik Behr, co-lead author and postdoctoral researcher at the University of Zurich. “This means that improving adult survival is key if we want to prevent further declines.”

The study also found extremely limited movement between subpopulations—only one giraffe was observed crossing between them. This suggests strong subpopulation insularity and limited gene flow, which may increase the risk of local extinction due to low genetic diversity.

“Giraffes have unique coat patterns, which we use to identify individuals from photographs,” explained Dr. Monica Bond, co-lead author from the University of Zurich and Wild Nature Institute. “We combined all available giraffe images—taken during road surveys and from camera traps—to track individual fates and estimate demographic trends over time.”

Earlier studies in the 1970s and 2000s had documented dramatic population declines, but recent changes in land use and tourism warranted an updated analysis. The new data show that while central and southern subpopulations in the center of the protected areas are now stable, western and northeastern subpopulations along the borders of the protected areas continue to decline—highlighting the need for subpopulation-specific conservation action.

“The best way to conserve giraffes and other large mammals is by protecting large areas of intact habitat,” said Dr Lohay. “Community conservation efforts have successfully raised adult survival in other parts of Tanzania. Scaling up these initiatives around the Serengeti could make a critical difference.”

“Our work shows how long-term demographic monitoring can guide conservation priorities in complex ecosystems,” said Prof. Arpat Ozgul, senior author and ecologist at the University of Zurich. “Targeted efforts that improve adult survival in key areas could determine the fate of these isolated subpopulations.”

The study was conducted by researchers from the University of Zurich, Wild Nature Institute, Pennsylvania State University, Estación Biológica de Doñana, and the Grumeti Fund’s RISE program.

Bond M.L., Behr D.M., Lee D.E., Strauss M.K.L., Campbell P.E., Cavener D.R., Lohay G.G., Madeli J.M., Paniw M., Ozgul A. (2025). Demographic drivers of population dynamics reveal subpopulation-specific conservation needs for giraffes in the Serengeti Ecosystem. Journal of Wildlife Management. DOI: 10.1002/jwmg.70037

One of Wild Nature Institute’s key activities in our Celebrating Africa’s Giants education program is planting trees. Over the past few years, we have established tree nurseries at two schools in communities next to Tarangire and Lake Manyara national parks, places where we have been doing giraffe conservation research for 14 years. Students collect native seeds from the bush and plant them in the nurseries, nurturing them from seedlings to saplings. Some saplings are planted around school grounds and others are donated to the community, fostering good will with community members while improving habitat for giraffes and other African giants. We have thousands of seedlings currently growing, and have distributed 18,000 saplings to the community since we started this activity!

One of the schools is Losirwa Primary School. Losirwa community recently planted 10,000 of our trees near Lake Manyara, restoring and improving habitat for wildlife and benefiting people, too. The trees are whitethorn (Senegalia polyacantha) and umbrella acacia (Vachellia tortilis).

We are only able to do this thanks to funding from our amazing donors who support our Celebrating Africa’s Giants education program - with a special shout-out to the Anne Innis Dagg Foundation for the tree nursery project.

In our new paper, The contribution of community-based conservation models to conserving large herbivore populations published in the journal Scientific Reports, we demonstrated using long-term distance sampling that community-based conservation areas in the Tarangire Ecosystem have contributed to the stabilization of the population of migratory wildebeests and zebras as well as elephants and giraffes.

On Saturday 21 September, more than 1,400 students and teachers from three secondary schools in the Tarangire region of Tanzania celebrated wildlife and conservation in a ‘Giraffe Bonanza’ event sponsored by Wild Nature Institute. Wearing specially made t-shirts that read “Okoa Twiga” (“Save Giraffes”), students led tours of Wild Nature Institute’s tree nursery, which has distributed more than 17,000 tree seedlings for free to the local community!

After the nursery tour, students staffed information booths about water filtration, birds, snakes, giraffes, elephants, zebras and Wild Nature Institute’s Celebrating Africa’s Giants storybooks (Juma the Giraffe, Our Elephant Neighbours, and Helping Brother Rhinoceros).

After the tours and demonstrations came more fun – the big bonanza! The students were entertained by professional and student dancers, two professional comedians, professional singer Shubert (who created the song and video Okoa Twiga that Wild Nature Institute produced several years ago, click here to watch), and their fellow students participating in creative games and receiving prizes. The entertainment also included useful lessons such as how to escape a charging buffalo. Throughout it all, the students echoed the refrain of Okoa Twiga, cheerfully answering “Twiga” when the emcees called out “Okoa”!

Once again, Wild Nature Institute's education power team of Veila Makundi and Glory Mbuya have delivered extraordinary and memorable conservation-focused activities. Their deep, ongoing, long-term relationships with these schools ensure that our programs are successful.

Of course, none of this would be possible without the financial support of our partners and donors. Thank you so very much for making Wild Nature Institute’s community conservation and education programs possible. The children in Tanzania are benefiting greatly.

Yesterday (31 July) was World Ranger Day! Wild Nature Institute celebrates and supports wildlife law enforcement rangers who dedicate their time and energy to safeguarding giraffes and other wildlife from poaching. Yesterday, our education program staff, Veila, James, and Glory, took 35 Tanzanian children and 3 teachers from St. Jude's Primary School in Mtowambu to Tarangire National Park to meet the rangers and say 'thank you' to them. The visit was a surprise for the rangers (although planned ahead with the Chief Park Warden).

The kids carried a big sign that said "Happy Rangers' Day. Thank you so much rangers for guarding wild animals and making our national parks attractive to the world." The kids all wore special t-shirts we made that said "Happy Ranger's Day" with a picture of giraffes. They delivered hand-written thank-you notes attached to a big giraffe poster. They met many park rangers, including the head of rangers at the Tarangire National Park headquarters. Lots of park visitors from countries around the world were interested and took photos. This helped raise global awareness about the important role that park rangers play in maintaining biodiversity.

The verdict: the rangers were very surprised and really happy!

Afterwards, the kids went for a fun safari to enjoy the wild animals that the rangers help to keep safe.

Of course, all of this is made possible thanks to the financial support and partnership of our donors. Many many thanks for being a part of Wild Nature Institute's "Team Twiga" (team giraffe) and helping with giraffe conservation and education in Tanzania!

World Giraffe Week 2024 in Tanzania was a resounding success, thanks to our fantastic education coordinator Veila Makundi and our entire Wild Nature Institute team. We welcomed our newest member of the education team, Glory Mbuya, and James Madeli helped out and took lots of great photos and videos of the activities.

The kick-off to World Giraffe Week was interviews by Wild Nature Institute's Veila Makundi  on 2 Arusha-based radio stations reaching thousands of Tanzanias about giraffes and what everyone can do to protect them. Then it was off to the schools for activities! More than 540 kids and teachers from 5 schools participated, with a highlight being a 'ngongoti', a man on stilts dressed like a giraffe, which delighted the children. The children made giraffe posters with unique spots (to be delivered to park rangers on World Ranger Day, 31 July), danced and sang, and had a great time celebrating Tanzania's national animal and learning how they can help save them.

Of course, absolutely none of this would have been possible without the amazing support from our donors around the world. Thank you so very much, from all of us at Wild Nature Institute.

This year's theme is GIRAFFE SPOTS! Visit www.worldgiraffeweek.org to learn more about their spots and to try some fun activities to celebrate our tall friends!

Food, then sex, drove the evolution of the giraffe's long neck, according to a new study by Penn State and Wild Nature Institute published in the journal Mammalian Biology.

Although male and female giraffes have the same body proportions at birth, they are significantly different as they reach sexual maturity. Females have proportionally longer necks and longer bodies than males, which might help with foraging and child rearing, while males have wider necks and longer front legs, which might help win fights against other males and with mating. Credit: Penn StateWhy do giraffes have such long necks? A study led by Penn State biologists explores how this trait might have evolved and lends new insight into this iconic question. The reigning hypothesis is that competition among males influenced neck length, but the research team found that female giraffes have proportionally longer necks than males—suggesting that high nutritional needs of females may have driven the evolution of this trait.
The study, which explored body proportions of both wild and captive giraffes, is described in a paper that appeared today, June 3, in the journal Mammalian Biology. The findings, the team said, indicate that neck length may be the result of females foraging deeply into trees for otherwise difficult-to-reach leaves.
In their classic theories of evolution, both Jean Baptiste Lamarck and Charles Darwin suggested that giraffes' long necks evolved to help them reach leaves high up in a tree, avoiding competition with other herbivores.
However, a more recent hypothesis called "necks-for-sex" suggests that the evolution of long necks was driven by competition among males, who swing their necks into each other to assert dominance, called neck sparring. That is, males with longer necks might have been more successful in the competition, leading to reproducing and passing their genes to offspring.
"The necks-for-sex hypothesis predicted that males would have longer necks than females," said Doug Cavener, Dorothy Foehr Huck and J. Lloyd Huck Distinguished Chair in Evolutionary Genetics and professor of biology at Penn State and lead author of the study.
"And technically they do have longer necks, but everything about males is longer; they are 30% to 40% bigger than females. In this study, we analyzed photos of hundreds of wild and captive Masai giraffes to investigate the relative body proportions of each species and how they might change as giraffes grow and mature."
The researchers gathered thousands of photos of captive Masai giraffes from the publicly accessible photo repositories Flickr and SmugMug as well as photos of wild adult animals that they have taken over the past decade.
Because absolute measurements like overall height are difficult to determine from a photograph without a point of reference of known length, the researchers instead focused on measurements relative to one another, or body proportions—for example, the length of the neck relative to the entire height of the animal. They restricted their analysis to images that met strict criteria, such as only using images of giraffes perpendicular to the camera, so they could consistently take a variety of measurements.
"We can identify individual giraffes by their unique spot pattern," Cavener said. "Thanks to the Association of Zoos and Aquariums, we also have the full pedigree, or family tree, of all Masai giraffes in North America in zoos and wildlife parks, as well as their birthdates and transfer history.
"So, by carefully considering this information, when the photo was taken and the approximate age of the animal, we could identify the specific individual in nearly every photo of a captive giraffe. This information was critical to understanding when male and female giraffes start to exhibit size differences and whether they grow differently."
Giraffe body proportion measurement landmarks and definitions. Measurements are performed on images that are perpendicular to the plane of the body trunk and neck. Measurements were performed between landmarks lying along the two-dimensional perimeter of the giraffe. Credit: Mammalian Biology (2024). DOI: 10.1007/s42991-024-00424-4At birth, male and female giraffes have the same body proportions. The researchers found that, although males generally grow faster in the first year, body proportions are not significantly different until they start to research sexual maturity around three years of age. Because body proportions change early in life, the team limited their study of wild animals—whose ages are largely unknown—to fully grown adults.
In adult giraffes, the researchers found that females have proportionally longer necks and trunks—or the main section of their body, which does not include legs or the neck and head. Adult males, on the other hand, have longer forelegs and wider necks. This pattern was the same in both captive and wild giraffes.
"Rather than stretching out to eat leaves on the tallest branches, you often see giraffes—especially females—reaching deep into the trees," Cavener said. "Giraffes are picky eaters—they eat the leaves of only a few tree species, and longer necks allow them to reach deeper into the trees to get the leaves no one else can. Once females reach four or five years of age, they are almost always pregnant and lactating, so we think the increased nutritional demands of females drove the evolution of giraffes' long necks."
The researchers noted that sexual selection—either competition among males or preference among females for larger mates—was likely responsible for the overall size difference between males and females, as is the case in many other large, hoofed mammals that are polygynous—where one male mates with many females.
They suggest that, following the evolution of the long neck, sexual selection—including male body pushing and neck sparring behaviors—may have contributed to males' wider necks. Additionally, the longer forelegs of males may assist in mating, which the researchers said is a brief and challenging affair that is rarely observed.
"Interestingly, giraffes are one of few animals whose height we measure to the top of the head—like humans—rather than to their withers—the highest part of the back, like in horses and other livestock," Cavener said. "The female has a proportionally longer axial skeleton—a longer neck and trunk—and are more sloped in appearance, while the males are more vertical."
The research team is also using genetics to identify relationships in groups of wild giraffes to better understand which males are successful at breeding. The goal is to shed additional light on mate choice and sexual selection, as well as guide conservation efforts for this endangered species.
"If female foraging is driving this iconic trait as we suspect, it really highlights the importance of conserving their dwindling habitat," Cavener said. "Populations of Masai giraffes have declined rapidly in the last 30 years, in part due to habitat loss and poaching, and it is critical that we understand the key aspects of their ecology and genetics in order to devise the most efficacious conservation strategies to save these majestic animals."
In addition to Cavener, the research team at Penn State includes Monica Bond, academic affiliate of biology; Lan Wu-Cavener, academic affiliate of biology; George Lohay, a postdoctoral researcher at the time of the research who is now at the Grumeti Fund; Mia Cavener, a graduate student at the time of the research; Xiaoyi Hou, graduate student in the Molecular, Cellular, and Integrative Biosciences program; David Pearce, an undergraduate student at the time of the research; and Derek Lee, academic affiliate of biology.

Funding from Penn State, the Penn State Huck Institutes of the Life Sciences and the Wild Nature Institute supported this research.