Wild Nature Institute
Wild Nature Institute
News Article | May 31, 2017
Eastern White-bearded Wildebeest migrate with their calves in northern Tanzania from the Gelai Plains calving grounds to Tarangire National Park. A new study described in detail for the first this endangered long-distance wildebeest migration in the Tarangire ecosystem of northern Tanzania. Credit: Wild Nature Institute A new study was published this week describing an endangered long-distance wildebeest migration in the Tarangire ecosystem of northern Tanzania. In the study, wildlife scientists used machine learning and connectivity algorithms to delineate a previously undefined migratory corridor in order to save this vanishing natural phenomenon. Dr. Derek Lee, principal scientist at the Wild Nature Institute and co-author of the paper in Landscape Ecology said, "From a practical standpoint, we need better tools to understand how animals get from one place to another. Our work shows how data from multiple sources and the latest analytical techniques can be integrated to identify, connect, and protect an ecologically and economically important migratory corridor." A variety of different animal species undertake seasonal long-distance migrations, defined as round-trip movements between distinct areas not used at other times of the year. These journeys are made to avoid predators and severe weather, and to access resources in the place and time of highest quality. Consequently, migrations enable animal populations to grow far more numerous than non-migratory populations, with important effects on landscape structure and function. For example, in the famous Serengeti ecosystem in Tanzania, migratory wildebeest outnumber non-migratory wildebeest by nearly two orders of magnitude. Human hunter-gatherer societies around the world relied upon the superabundance of protein present in migratory species to support human population persistence for tens of thousands of years, and animal migrations likely played an important role in spreading people around the world after our emergence in Africa. Long-distance migrations also provide ecological benefits and services to the systems where they occur by transferring nutrients, fertilizing soil, and dispersing seeds. Until the 1800s, grassland ecosystems around the world continued to support vast herds of migratory hoofed mammals numbering in the millions of individuals, and these moving herds structured entire ecosystems. Unfortunately, migrations are now mostly lost, and the remaining few are in precipitous decline globally because of rapid, human-caused changes in the landscapes where they occur. Human population growth and agricultural expansion have led to the loss of most historical migratory routes, including the elimination of all but three migrations of wildebeest. East Africa still supports a high diversity and abundance of migratory ungulates, but most of the remaining populations are threatened. Migratory populations often respond suddenly and severely to the disruption of migratory routes. At the end of the 19th century the Tarangire ecosystem's wildebeest population likely numbered in the hundreds of thousands and connected with populations in southern Kenya. More recently, the Tarangire ecosystem's wildebeest population decreased from an estimated 40,000 animals in 1988 to approximately 11,000 today. The Tarangire ecosystem's eastern white-bearded wildebeest is genetically distinct from the much larger population of western white-bearded wildebeest in the Serengeti ecosystem, thus the loss of wildebeest in Tarangire would mean the loss of an evolutionarily significant population. The sustainability of the Tarangire wildebeest population is important to the ecological function and economic value of Tarangire National Park, one of the most popular and profitable parks in a country where ecotourism is the largest sector of the economy. "Given the growing demands on grazing lands in these migratory landscapes, there is an important need to accurately document core habitat used by migratory wildlife, and then provide this information to the policy makers who decide how land will be managed," said Dr. Tom Morrison, of the University of Glasgow and co-author of the study. "Conserving migratory habitat for wildebeest will have the added benefits of protecting connectivity of rangelands used by Masai pastoralists and their livestock, and will benefit other wildlife species in this ecosystem, as they all use these habitats to move and graze." Explore further: How does the loss of a wildebeest migration also harm giraffes? More information: Bond ML, Bradley CM, Kiffner C, Morrison TA, & Lee DE. (2017) A multi-method approach to delineate and validate migratory corridors. Landscape Ecology, DOI: 10.1007/s10980-017-0537-4
News Article | June 21, 2017
SAMBURU NATIONAL PARK, KENYA—For conservationists stationed in politically volatile regions, life can be harrowing. Last October, John Doherty had to take refuge under his desk here for nearly 2 hours as armed herders, angry at grazing restrictions, attacked a nearby ranger headquarters. He could hear shouting and frenzied footsteps outside and bullets smacking into his office wall. "I was wondering whether I should call my family to tell them I love them," says the zoologist, of Queen's University Belfast in the United Kingdom. In recent months, drought and overgrazing in northern Kenya have sent thousands of herders and their livestock into national parks and other protected areas, intensifying tensions over land and grazing. Violence has taken the lives of several rangers, and a surge in wildlife killings is devastating populations of one of East Africa's most majestic beasts: giraffes. "This affects all wildlife, but giraffes may be particularly hard hit," says Fred Bercovitch, a zoologist at Kyoto University in Japan and director of Save the Giraffes, a nonprofit in San Antonio, Texas. For hunters, "giraffes are an easy target," he notes. And as scientists have recognized only recently, giraffes have multiple species, and several populations are already in serious decline. In the past 30 years, populations of two East African varieties, the Nubian and reticulated giraffes, have plunged by 97% and 78%, respectively, and the International Union for the Conservation of Nature may soon declare them critically endangered, says Doherty, who is involved in the assessment and leads the Reticulated Giraffe Project, a joint initiative with the Kenya Wildlife Service. In response to the threat, he and other scientists are stepping up research on the animals' birth and survival rates, movements, and interactions with resources and landscapes, hoping to pinpoint risks and focus conservation efforts. The biggest threats to the animals are rapid human population growth and the influx of herders, along with refugees fleeing regional conflicts. In the refugee camps bordering Kenya and Somalia, for instance, bush meat, including giraffes, is an important source of food for half a million destitute people. A traditional predator, the lion, may also be taking a growing toll. A study led by Derek Lee, a zoologist at the Wild Nature Institute, a nonprofit in Concord, New Hampshire, found that giraffe calves in the Tarangire Ecosystem in northern Tanzania are more likely to be eaten by lions, resulting in a 37% drop in reproductive success, when wildebeest and zebra are not around. The finding suggests that because those migratory animals, the cats' preferred prey, are in sharp decline, the lions may be turning to other prey, including giraffes. "This just shows how important it is to study giraffes, or any species, as part of the bigger picture," says Anne Innis-Dagg, a zoologist at the University of Waterloo in Canada, who was not involved in the study, published last year in Ecology and Evolution. Adding to the pressure is exponential growth in mining and infrastructure development—highways, railways, oil pipelines, and industrial compounds—which often encroach on key giraffe habitats, including those in national parks. The newly opened $3.2 billion Mombasa-Nairobi railway, for instance, cuts through Kenya's Tsavo National Park. Such infrastructure projects "are going to have a massive impact on the ecosystems," Lee says. Giraffes are especially vulnerable to population decline because of their life history. After sifting through 40 years of field data, Bercovitch and Philip Berry, a zoologist in Mfuwe, Zambia, came to a disturbing conclusion. An average female gives birth to five calves during her lifetime, and only half of those normally survive, they reported last year in the African Journal of Ecology. "This means that the species has zero population growth," Bercovitch says. Conservation efforts, he says, should aim to maximize calf survival and females' lifetime reproductive success by, for instance, protecting breeding and calving grounds. To identify those areas as well as giraffes' preferred foraging grounds and migratory corridors, conservationists need to map the animals' behavior and movements. Giraffes' unique coat patterns make it possible to follow individuals, both in the field and by analyzing images and video with pattern-recognition software. But scientists would also like to track individual animals more closely, and capturing giraffes to attach a conventional tag or collar isn't easy. "It can be risky, too, because giraffes are uniquely fragile," Doherty says. "Their body shape makes them especially prone to neck and leg injuries." His team is developing a new technique to track a large number of giraffes without having to capture them. "It's trauma-free," says Doherty, who says confidentiality agreements with Kenyan authorities prevent him from disclosing the details. For now, conservationists hope the turmoil in northern Kenya will not worsen—and with it the plight of the giraffes. "I wasn't unaware of the risk when I decided to station here 9 years ago," Doherty says. "But that October morning was one I hope will not repeat."
News Article | September 16, 2017
A villager in Kenya was herding animals one day recently when he came upon a head-turning sight. A ghostly creature with a mighty long neck was grazing off in the distance. Upon closer inspection, the vision was revealed to be a female reticulated giraffe — tall, majestic and preternaturally white — and she was accompanied by a smaller apparition: a pale baby giraffe. The sightings in June, in Garissa County near the Ishaqbini Hirola Conservancy, sent the villager scurrying off to tell rangers, the founder of the Hirola Conservation Program said on Thursday. The news has been ricocheting across continents and making headlines ever since. Conservationists who hurried to the site managed to capture what is believed to be the first known video footage of white giraffes, said Abdullahi H. Ali, who founded Hirola and has been working to conserve the critically endangered hirola antelope in the eastern part of the country. “We spent almost 20 minutes with the beautiful animals and had the pleasure of getting close-up photos and video of the duo,” he said by email. “To our surprise, one normal color reticulated giraffe also was among the mother and calf. You can actually compare the difference.” Hirola said on its website : “They were so close and extremely calm and seemed not disturbed by our presence. The mother kept pacing back and forth a few yards in front of us while signaling the baby giraffe to hide behind the bushes.” The white giraffes displayed the characteristics of a genetic condition known as leucism, which inhibits pigmentation in skin cells, Dr. Ali said. The condition occurs across the animal kingdom. Birds, lions, fish, peacocks, penguins, eagles, hippos, moose and snakes have all displayed the trait . Leucism is not albinism, however: Animals with albinism produce no melanin throughout their entire bodies. Animals with leucism may have darker pigment in their soft tissue, and their eyes retain a normal color. The eyes of animals with albinism are usually red. The baby giraffe, Hirola said, was not totally white, but its tinges of color seemed to be “fading away, leaving the baby white as it approaches adulthood.” It was unclear if, under the hot African sun, the giraffes’ skin was vulnerable to damage, Dr. Ali said. The rangers did not get close enough to examine the mother and baby, but he added: “I think they will be O.K. They seemed to be in excellent shape.” The communities in the area were “excited” about the rare sightings of leucistic giraffes, Dr. Ali said, and they were banding together to protect them. Giraffes, which can grow to 20 feet and are the world’s tallest land mammals, have been declared “vulnerable” to extinction because of poaching and a loss of habitat, according to the Red List of Threatened Species published in 2016 by the International Union for the Conservation of Nature. The giraffe population had declined by 40 percent over the past three decades and stood at about 97,600 at the time the findings were released. According to the Giraffe Conservation Foundation , the animals are extinct in at least seven countries in Africa and can live up to 25 years in the wild. But more than half of all giraffe calves die before they’re six months old because they’re often the targets of predators like lions, hyenas, wild dogs and crocodiles. Dr. Ali said his team would like to follow and monitor the white giraffes seen in Kenya to document their life spans. He said it was the third such sighting in recent years: “The only two known sightings have been made in Kenya and Tanzania.” A previous sighting was reported in April 2016 in Garissa County. Dr. Ali said a white giraffe was also seen in January 2016 in Tarangire National Park in Tanzania . According to National Geographic, scientists at the Wild Nature Institute , based in New Hampshire, first reported the newborn Masai giraffe calf in 2015 , and a guide named her Omo , after a brand of popular detergent. In many parts of the world, white animals are hunted, revered or protected. There are fewer white lions in the wild compared with the hundreds in captivity, according to the Global White Lion Protection Trust in South Africa. In Cajun lore, seeing a white alligator in the swamp , like the ones with translucent skin and deep blue eyes that have been housed at the Audubon Aquarium of the Americas in New Orleans, is considered good luck. Besides having pale skin because of leucism or albinism, animals can have a third condition, called isabellinism, that leaves them looking grayish-yellow; but they can still produce pigment. Scientists have quibbled over the exact differences in the conditions, but leucism and isabellinism are sometimes used interchangeably. Legend has it — and surely it was just that — that the color isabella (and hence “isabellinism”) is named after the Archduchess Isabella of Austria, who supposedly made a strange vow at the start of the 17th century not to change her underwear until her husband, the Archduke Albert, had conquered the city of Ostend and united the country’s provinces. That campaign took three long years.
Lee D.E.,Dartmouth College |
Lee D.E.,Wild Nature Institute |
Bolger D.T.,Dartmouth College
Population Ecology | Year: 2017
Spatial variation in habitat quality and anthropogenic factors, as well as social structure, can lead to spatially structured populations of animals. Demographic approaches can be used to improve our understanding of the dynamics of spatially structured populations and help identify subpopulations critical for the long-term persistence of regional metapopulations. We provide a regional metapopulation analysis to inform conservation management for Masai giraffes (Giraffa camelopardalis tippelskirchi) in five subpopulations defined by land management designations. We used data from an individual-based mark–recapture study to estimate subpopulation sizes, subpopulation growth rates, and movement probabilities among subpopulations. We assessed the source–sink structure of the study population by calculating source–sink statistics, and we created a female-based matrix metapopulation model composed of all subpopulations 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 net flow of individuals indicated three subpopulations were sources, while two subpopulations were sinks. We found areas with higher wildlife protection efforts and fewer anthropogenic 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. © 2017 The Society of Population Ecology and Springer Japan
Lee D.E.,Institute for Bird Populations |
Lee D.E.,Wild Nature Institute |
Bond M.L.,Institute for Bird Populations |
Siegel R.B.,Institute for Bird Populations
Condor | Year: 2012
Understanding how habitat disturbances such as forest fire affect local extinction and probability of colonization-the processes that determine site occupancy-is critical for developing forest management appropriate to conserving the California Spotted Owl (Strix occidentalis occidentalis), a subspecies of management concern. We used 11 years of breeding-season survey data from 41 California Spotted Owl sites burned in six forest fires and 145 sites in unburned areas throughout the Sierra Nevada, California, to compare probabilities of local extinction and colonization at burned and unburned sites while accounting for annual and site-specific variation in detectability. We found no significant effects of fre on these probabilities, suggesting that fire, even fire that burns on average 32% of suitable habitat at high severity within a California Spotted Owl site, does not threaten the persistence of the subspecies on the landscape. We used simulations to examine how different allocations of survey effort over 3 years affect estimability and bias of parameters and power to detect differences in colonization and local extinction between groups of sites. Simulations suggest that to determine whether and how habitat disturbance affects California Spotted Owl occupancy within 3 years, managers should strive to annually survey ≥200 affected and ≥200 unaffected historical owl sites throughout the Sierra Nevada 5 times per year. Given the low probability of detection in one year, we recommend more than one year of surveys be used to determine site occupancy before management that could be detrimental to the Spotted Owl is undertaken in potentially occupied habitat. © The Cooper Ornithological Society 2012.
Lee D.E.,Wild Nature Institute |
Bond M.L.,Wild Nature Institute |
Borchert M.I.,U.S. Department of Agriculture |
Tanner R.,Tanner Environmental Services
Journal of Wildlife Management | Year: 2013
Fire over the past decade has affected forests in the San Bernardino Mountains of southern California, providing an excellent opportunity to examine how this disturbance, and subsequent post-fire salvage logging, influenced California spotted owl (Strix occidentalis occidentalis) breeding-season site occupancy dynamics there and in the nearby San Jacinto Mountains. Using occupancy survey data from 2003 to 2011 for all-detections and pairs-only data, we estimated annual extinction and colonization probabilities at 71 burned and 97 unburned breeding-season sites before and after fire, while controlling for confounding effects of non-fire-related temporal variation and among-site differences in habitat characteristics. We found no statistically significant effects of fire or salvage logging on occupancy dynamics of spotted owls of southern California. However, we found some evidence that fire and logging effects could be biologically meaningful. For pairs data, the model-averaged mean of fire-related effects on colonization and extinction probabilities resulted in a 0.062 lesser site-occupancy probability in burned sites 1-year post-fire relative to unburned sites. Post-fire salvage logging reduced occupancy an additional 0.046 relative to sites that only burned. We documented a threshold-type relationship between extinction and colonization probabilities and the amount of forested habitat (conifer or hardwood tree cover types) that burned at high severity within a 203-ha core area around spotted owl nests and roost centroids. Sites where approximately 0-50 ha of forested habitat within the core area burned at high severity had extinction probabilities similar to unburned sites, but where more than approximately 50 ha of forested habitat burned severely, extinction probability increased approximately 0.003 for every additional hectare severely burned. The majority (75%) of sites burned below this threshold. Sites where high-severity fire affected >50 ha of forested habitat could still support spotted owls, so all burned sites should be monitored for occupancy before management actions such as salvage logging are undertaken that could be detrimental to the subspecies. We also recommend that managers strive to reduce human-caused ignitions along the wildland-urban interface, particularly at lower elevations where owl sites are at higher risk of extinction from fire. © 2013 The Wildlife Society. Copyright © The Wildlife Society, 2013.
Lee D.E.,Wild Nature Institute |
Bond M.L.,Wild Nature Institute
Condor | Year: 2015
High-severity forest fire often is presumed to adversely affect the occupancy of territories by California Spotted Owls (Strix occidentalis occidentalis) because these owls are associated with mature and old-growth forests. We used single-season, multi-state occupancy statistics to estimate site occupancy probability for Spotted Owls at 45 historically occupied sites during the breeding season immediately following the 2013 Rim Fire, which was one of the largest forest fires on record in California. We quantified how occupancy probability was influenced by the amount of high-severity fire occurring in mature forested habitat within Protected Activity Centers (PACs). The model-averaged estimate of site-occupancy probability for at least a single owl was 0.922 (±SE=0.073), which was higher than other published occupancy probability estimates for this subspecies in either burned or long-unburned sites in the Sierra Nevada. Mean site-occupancy probability for pairs was 0.866 (±0.093), and most sites (33) were occupied by pairs. The amount of high-severity fire in the PAC did not affect pair occupancy. Occupancy probability by at least a single bird was negatively correlated with the amount of high severity fire in the PAC but remained >0.89 in 100% high-severity burned PACs. These data add to observations that California Spotted Owls continue to use post-fire landscapes, even when the fires were large and where large areas burned at high severity, suggesting that owls are not generally negatively impacted by high-severity fire. Based on this and other studies of Spotted Owls, fire, and logging, we suggest land managers consider burned forest within and surrounding PACs as potentially suitable California Spotted Owl foraging habitat when planning and implementing management activities, and we recommend against logging burned forest within at least 1.5 km of nests or roosts for the conservation and recovery of this declining subspecies.
Lee D.E.,Wild Nature Institute |
Bond M.L.,Wild Nature Institute
Journal of Mammalogy | Year: 2016
Giraffes Giraffa camelopardalis are megafaunal browsers and keystone species in African savanna ecosystems. Range-wide population declines are suspected, but robust data are lacking. Tanzania holds the largest population of giraffe of any range state, and aerial surveys constitute most of Tanzania's giraffe population monitoring data, but their accuracy has not yet been assessed. An IUCN status assessment for giraffe is currently underway, and calibrating aerial surveys with ground-based surveys can quantify accuracy of the aerial surveys to ensure more reliable estimates of populations nationwide. We estimated giraffe density and abundance in the Tarangire Ecosystem in northern Tanzania using 2 ground survey methods, distance sampling and capture-mark-recapture, and compared our ground-based estimates with those from the most recent aerial survey in 4 sites. We found aerial survey estimates were biased low, while ground-based surveys were more precise and cost less. We computed correction factors to improve the accuracy of aerial surveys and suggested ways to further improve aerial survey methods. © 2016 American Society of Mammalogists.
Lee D.E.,Wild Nature Institute |
Bond M.L.,Wild Nature Institute
Journal of Wildlife Diseases | Year: 2016
Giraffe skin disease (GSD) is a disorder of undetermined etiology that causes lesions on the forelimbs of Masai giraffe (Giraffa camelopardalis tippelskirchi). We estimated occurrence and prevalence of GSD in six wildlife conservation areas of Tanzania. The disjunct spatial pattern of occurrence implies that environmental factors may influence GSD. © Wildlife Disease Association 2016.
News Article | January 27, 2016
Wildlife animals are usually fierce-looking that it is impossible for anyone to not take notice. In Tanzania, an extremely rare white giraffe is attracting attention, but it is not because of usual reasons. North Carolina-based Wild Nature Institute (WNI) spotted the 15-month-old giraffe at the Tarangire National Park. The animal had a pale white skin color and a reddish mane. Fortunately, the group was able to capture photos. The giraffe was named Omo, after the name of a local detergent brand. The recent sighting is not the first time that scientists were able to spot the rare animal. Around the same time in 2015, Omo made its first appearance. "We are thrilled that she is still alive and well," the WNI blog post reads. Tarangire is the sixth biggest national park in Tanzania and has over 3,000 giraffe species. The white giraffe sighting is very rare that it has only been seen twice in Tarangire within the past two decades. People may think that the giraffe got its white color from albinism, which is characterized by lack of melanin in the skin. WNI's principal scientist Dr Derek Lee says that is not the case for Omo. Instead, he explained that the white giraffe has leucism, which involves the partial loss of pigmentation in all bodily cells, including the eyes. As a result, the Omo's eyes are red from the underlying blood vessels. Giraffe is the national animal of Tanzania, hence, it is unlawful to kill the creatures. Despite the rules, Lee says about 50 percent of giraffe populations are killed during its first year of life due to predators such as lions, leopards and hyenas. Bush meat poaching is also a problem, not only for the likes of Omo, but for all giraffe species as well. Luckily, Omo lives in a national park, where there are anti-poaching measures, giving the rare giraffe a better chance at survival. Lee and his wife are currently studying how humans can live with giraffes by going to places where both species frequently have contact. They hope to heighten the survival of Omo and its relatives through their conservation project. Other giraffes accepting Omo despite its unique appearance speaks volumes to humans, Lee suggests. Humans have this yearning for acceptance and tolerance amid differences, and the situation of the giraffes right now is good example of that.