Not only are pronghorn the fastest land animals in North America—they can run at speeds close to 60 miles per hour—they have the longest land migration in the continental United States. They make an annual, 150-mile journey (each way) between Wyoming’s Upper Green River Basin and Grand Teton National Park. The only other land animal to travel farther in North America is the caribou.
We human beings have certain basic needs. We must have air, food, water and shelter to survive, according to NASA. If any one of these basic needs is not met, then humans cannot persist. I think the same applies to more-than-human animals, as well.
Personally, I like to think of that fourth need as “a safe home” or “uncontaminated homeland” rather than “shelter.” All of us, I believe, need our natural habitats. For example, Wyoming is the grounds for some of North America’s most abundant populations of pronghorn. While they have largely been stable in recent years, a new analysis shows that many herds are experiencing long-term declines in fawn production due to advancing trees and gas and oil development. And, in Greenland, areas with more essential minerals in the ground lead to higher reproductive success in musk oxen. What’s in our homes is certainly important for our survival.
It also turns out that keeping our respective homes—or our natural habitats—intact keeps us safer from diseases.
Although to make their migrations, Wyoming pronghorn must cross highways, the roads proved not to be a prominent driver of long-term declines in pronghorn productivity.
Gas and oil development: unprolific pronghorn
Wyoming is home to about half of North America’s pronghorn population. But gas and oil development in the state and the encroachment of trees are causing long-term declines in the numbers of pronghorn fawns, says a research team from the University of Wyoming, the University of Arkansas, the University of Florida, the University of Nebraska-Lincoln and the Northern Plains Agricultural Research Laboratory.
For their study, published in the journal Global Ecology and Conservation in April 2024, the researchers looked at data collected by the Wyoming Game and Fish Department for 40 pronghorn herds over a 35-year period from 1984 to 2019. In addition to analyzing the Wyoming Game and Fish Department’s extensive information from annual pronghorn population surveys, the researchers examined region-specific data regarding gas and oil development, fire, invasive plants, precipitation patterns, roads and tree encroachment.
They found that both tree cover and gas and oil development have increased substantially across most herd units in Wyoming over the last 40 years. The other threats to pronghorn—which include wildfires; annual, non-native grass invasions; increased winter precipitation; and roads—were not prominent drivers of long-term declines in pronghorn productivity.
Wyoming’s sagebrush ecosystems are threatened by tree encroachment. For the state’s pronghorn, that means a loss of forage areas.
Interestingly, while gas and oil development already is widely recognized as having a huge influence on Wyoming’s rangelands and the species on those lands, the researchers noted that tree encroachment is not generally viewed as a threat to the state’s sagebrush ecosystems. That’s likely because average tree cover ranged from less than 1% to 18% across the 40 pronghorn herd unit areas. But even low levels of invading trees have been shown to have drastic effects on sagebrush-dependent wildlife, the scientists wrote. For Wyoming’s pronghorn, the increase in trees could be providing cover for predators, driving loss of forage associated with grassland and sagebrush cover, and thus causing pronghorn to avoid those areas.
These results contribute to the growing amount of evidence that early management of invading trees—such as controlled burning and manual removal—within sagebrush habitat will help maintain the numbers of iconic rangeland species, such as pronghorn. Protecting their habitats is the most cost-effective and impactful approach, the researchers conclude.
Copper and selenium ground: multiplying musk oxen
When women get pregnant, they can go to a pharmacy and buy supplements, such as vitamin D, folic acid and iron. But wild animals can’t do that. Instead, they tend to go to areas where plants and the ground contain more of the essential minerals that they need.
Greenland’s largest land mammal is the musk ox. The Greenlandic name for musk ox is “Umimmak,” meaning “the long-bearded one.” Remnants of the last Ice Age, musk oxen once lived widely across the Arctic but are now confined to smaller territories in Arctic Canada and Greenland.
In a new study that appeared in the journal Science of the Total Environment on December 10, 2023, it was reported that when Greenland musk oxen go to areas with more copper and selenium in the ground, they have more calves. These animals were the ones that stayed in the valleys and ate grass, versus those who migrated into the mountains to forage on heathlands.
This study marks the first time that the chemical composition of the ground has been coupled with reproductive success in wildlife. Usually, say the scientists, studies tend to focus on pollutants or major elements, such as carbon and nitrogen. However, thanks to technological improvements, scientists were able to examine the essential, smaller components—trace elements, such as copper and selenium—as well.
To show how the chemistry of the ground affects the reproductive success of the musk oxen, researchers needed four sets of data: 1) the location of the musk oxen at different times, 2) the number of animals and how the population expanded or decreased over time, 3) which plants were abundant in the different areas, and 4) the chemical composition of the plants and the ground.
Normally, Greenland musk oxen prefer to stay in the valleys to forage on dwarf willow (center) rather than go to the heathlands farther up the mountains.
Luckily, musk oxen in Greenland have been studied closely for the past 25 years. Some of the animals have GPS-trackers on them, allowing the researchers to know where the animals go to forage. And every summer, a field crew of researchers perform visual counts of all the musk oxen they find in an area and make a note of how many adults, females, males and calves they see. The data from a quarter century of studying musk oxen was then paired with maps created from the chemical composition of vegetation and soil samples gathered at 50 different spots.
Not all of the areas in southern Greenland’s tundra where the musk oxen feed is filled with good chemicals. The researchers found places where higher levels of contaminants, such as arsenic and lead, were present—typically in the heathlands farther up the mountains—which can reduce the reproductive success of the musk oxen. Normally, however, the animals preferred to stay in the valleys foraging on dwarf willow and grass.
Even though the results only cover musk oxen in Greenland, the researchers believe that other animals are likely affected by the chemistry of the ground in a similar manner. The next step would be to use the same approach to map other places in the Arctic and Europe.
A new report found that Greenland musk oxen that go to areas with more copper and selenium in the ground have more calves.
Large and intact roosts: decreasing disease
As the studies from Greenland and Wyoming show, conserving and protecting natural habitats is important for the wild animals that live in them. But it also benefits us.
According to two, new companion studies, preserving and restoring natural habitats could prevent pathogens that originate in wildlife from spilling over into domesticated animals and humans. The first study, from researchers at the University of New South Wales in Australia, found that when fruit bats experience food shortages and loss of winter habitats in their natural settings of native forests, their populations splinter; and they excrete more Hendra virus, an often-fatal illness in humans. When those smaller bat communities move closer to humans in agricultural and urban areas, Hendra can then move from fruit bats to horses to people. These results were published in the journal Nature on November 16, 2022.
A second paper published on October 30, 2022, in Ecology Letters, used data from the Nature study to reveal the ecological conditions under which bats excrete less or more virus.
Australia is home to four species of large, fruit-eating bats, also known “flying foxes.” All Australian bats are protected and play a vital role in the country’s natural ecosystems.
While previous research has shown correlations between habitat loss and the occurrence of pathogen spillover, these studies together reveal for the first time a mechanism for such events and provide a method to predict and prevent them.
Hendra, Nipah, SARS-CoV-1, SARS-CoV-2 and possibly Ebola are all examples of viruses that fatally move from bats to humans, sometimes after transmission through an intermediate host. In humans, Hendra virus has a 57% fatality rate, and Nipah virus can be up to 100% fatal, though transmission in humans is inefficient.
For the studies, the researchers developed datasets from 1996 to 2020 in subtropical Australia that described the locations and sizes of fruit bat populations, the landscapes where they foraged, climate and El Nino events (high temperatures in the Pacific Ocean), years when there were food shortages, bat reproductive rates, records of bat intakes into rehabilitation facilities, habitat loss in forests that provide nectar in winter and years when flowering happened in winter in the forests.
Many of Australia’s fruit bats can be seen throughout the Wet Tropics, such as here near Cairns, Queensland, Australia. Their main diet is fruits and nectar, and they play a vital role in the dispersal of rain-forest seeds.
The scientists then created computer models to analyze the data. They discovered two factors driving spillover: habitat loss pushing animals into agricultural areas and climate-induced food shortages. In years following an El Nino event, buds of trees that bats depend on for nectar failed to produce flowers in the subsequent winter, leading to a food shortage. And human destruction of forest habitat for farmlands and urban development has left few forests that produce nectar for bats in winter.
Due to food scarcity, large populations of the bats split into smaller groups and moved to agricultural and urban areas, where weedy species and fig, mango and shade trees offered shelter and reliable but less nutritious food sources than nectar. When stressed from lack of food, few bats successfully reared their young. They also shed virus, possibly because they needed to conserve energy by directing it away from their immune systems. Also, the bats that had moved to novel winter habitats, such as agricultural areas, shed more virus than bats in traditional winter habitats.
In agricultural areas, pathogens may spread when urine and feces drop to the ground where horses are grazing, leading to Hendra virus infections. Horses act as an intermediary and occasionally spread the virus to people.
Australian fruit bats that move to agricultural areas shed more virus than bats in traditional habitats. Pathogens then spread when their feces and urine drop to the ground where horses are grazing, leading to Hendra virus infections that can be transmitted from horses to people.
To their surprise, the researchers discovered that when remaining stands of eucalyptus trees bloomed in winter, large numbers of bats flocked to these areas. During those flowering events, pathogen spillover completely ceased. So, when remaining habitat produces food, spillover stops; and, therefore, a sustainable way to stop these events could be to preserve and restore critical habitat.
Since 2003, researchers have noticed a gradual dwindling of large, nomadic bat roosts in favor of many smaller roosts in agricultural and urban areas; a five-fold increase over the study period. Bats are less frequently returning in large numbers to their shrinking native habitats. This could be because forests that provide nectar in winter have been extensively cleared.
Ecological and homeland integrity: booming biodiversity
It’s true that having our basic needs for air, food, water and shelter met allows us to survive. But making sure that those needs are fulfilled for the more-than-human beings among us is also vital for our own survival.
Every being on Earth needs a healthy and natural habitat—and we all need all of us to have them, too.
Providing that last need may be the most important of the four. Such homelands act as buffers between people and wildlife. There are trillions of microbes in nature, many of them harmful. We rarely get sick, though, because biodiversity acts as a barrier between us and new pathogens.
Every Earth being needs a healthy and natural habitat—and we all need all of us to have them, too.
Here’s to finding your true places and natural habitats,
Candy
