14 Reasons Why You're Always Hungry
When you're hungry, your stomach may "growl" and feel empty, or you may get a headache, feel irritable, or be unable to concentrate.
Most people can go several hours between meals before feeling hungry again, though this isn't the case for everyone.
There are several possible explanations for this, including a diet that lacks protein, fat, or fiber, as well as excessive stress or dehydration.
This article discusses 14 reasons for excessive hunger.
1. You’re Not Eating Enough Protein
Consuming enough protein is important for appetite control.
Protein has hunger-reducing properties that may help you automatically consume fewer calories during the day. It works by increasing the production of hormones that signal fullness and reducing the levels of hormones that stimulate hunger (1Trusted Source, 2Trusted Source, 3Trusted Source, 4Trusted Source).
Due to these effects, you may feel hungry frequently if you're not eating enough protein.
In one study, 14 men with excess weight who consumed 25% of their calories from protein for 12 weeks experienced a 50% reduction in their desire for late-night snacking, compared with a group that consumed less protein (5Trusted Source).
Additionally, those with a higher protein intake reported greater fullness throughout the day and fewer obsessive thoughts about food (5Trusted Source).
Many different foods are high in protein, so it's not difficult to get enough of it through your diet. Including a source of protein in every meal can help prevent excessive hunger.
Animal products, such as meat, poultry, fish, and eggs, contain high amounts of protein.
This nutrient is also found in some dairy products, including milk and yogurt, as well as a few plant-based foods like legumes, nuts, seeds, and whole grains.
Protein plays an important role in appetite control by regulating your hunger hormones. For this reason, you may feel hungry frequently if you don't eat enough of it.
2. You’re Not Sleeping Enough
Getting adequate sleep is extremely important for your health.
Sleep is required for the proper functioning of your brain and immune system, and getting enough of it is associated with a lower risk of several chronic illnesses, including heart disease and cancer (6Trusted Source).
Additionally, sleeping enough is a factor in appetite control, as it helps regulate ghrelin, the appetite-stimulating hormone. Lack of sleep leads to higher ghrelin levels, which is why you may feel hungrier when you are sleep deprived (7Trusted Source, 8Trusted Source).
In one study, 15 people who were sleep deprived for only 1 night reported being significantly more hungry and chose 14% larger portion sizes, compared with a group that slept for 8 hours (9Trusted Source).
To keep your hunger levels under control, it's generally recommended to get at least 8 hours of uninterrupted sleep each night.
Sleep deprivation is known to cause fluctuations in your hunger hormone levels and may leave you feeling hungry more frequently.
3. You’re Eating Too Many Refined Carbs
Refined carbs have been processed and stripped of their fiber, vitamins, and minerals.
One of the most popular sources of refined carbs is white flour, which is found in many grain-based foods like bread and pasta. Foods like soda, candy, and baked goods, which are made with processed sugars, are also considered to be refined carbs.
Since refined carbs lack filling fiber, your body digests them very quickly. This is a major reason why you may be hungry frequently if you eat a lot of refined carbs, as they do not promote significant feelings of fullness (10Trusted Source).
Furthermore, eating refined carbs may lead to rapid spikes in your blood sugar. This leads to increased levels of insulin, a hormone responsible for transporting sugar into your cells (10Trusted Source, 11Trusted Source).
When a lot of insulin is released at once in response to high blood sugar, it quickly removes sugar from your blood, which may lead to a sudden drop in blood sugar levels, a condition known as hypoglycemia (10Trusted Source, 11Trusted Source).
Low blood sugar levels signal your body that it needs more food, which is another reason why you may feel hungry often if refined carbs are a regular part of your diet (10Trusted Source).
To reduce your refined carb intake, simply replace them with healthier, whole foods like vegetables, fruit, legumes, and whole grains. These foods are still high in carbs, but they are rich in fiber, which helps keep hunger under control (12Trusted Source).
Refined carbs lack fiber and cause blood sugar fluctuations, which are the primary reasons why eating too many of them may leave you feeling hungry.
4. Your Diet is Low in Fat
Fat plays a key role in keeping you full.
This is partly due to its slow gastrointestinal transit time, meaning that it takes longer for you to digest and remains in your stomach for a long period. Additionally, eating fat may lead to the release of various fullness-promoting hormones (13Trusted Source, 14, 15Trusted Source).
For these reasons, you may feel frequent hunger if your diet is low in fat.
One study including 270 adults with obesity found that those who followed a low-fat diet had significant increases in cravings for carbs and preferences for high-sugar foods, compared with a group that consumed a low-carb diet (16Trusted Source).
Furthermore, those in the low-fat group reported more feelings of hunger than the group that followed a low-carb eating pattern (16Trusted Source).
There are many healthy, high-fat foods that you can include in your diet to increase your fat intake. Certain types of fats, such as medium-chain triglycerides (MCTs) and omega-3 fatty acids, have been studied the most for their ability to reduce appetite (17Trusted Source, 18Trusted Source, 19Trusted Source, 20Trusted Source).
The richest food source of MCT is coconut oil, while omega-3 fatty acids are found in fatty fish like salmon, tuna, and mackerel. You can also get omega-3s from plant-based foods, such as walnuts and flaxseeds.
Other sources of healthy, high-fat foods include avocados, olive oil, eggs, and full-fat yogurt.
You may feel hungry often if you don't eat enough fat. That's because fat plays a role in slowing digestion and increasing the production of fullness-promoting hormones.
5. You’re Not Drinking Enough Water
Proper hydration is incredibly important for your overall health.
Drinking enough water has several health benefits, including promoting brain and heart health and optimizing exercise performance. Additionally, water keeps your skin and digestive system healthy (21Trusted Source).
In one study, 14 people who drank 2 cups of water before a meal ate almost 600 fewer calories than those who didn't drink any water (24Trusted Source).
Due to water's role in keeping you full, you may find that you feel hungry frequently if you're not drinking enough of it.
Feelings of thirst can be mistaken for feelings of hunger. If you're always hungry, it may help to drink a glass or two of water to find out if you are just thirsty (23Trusted Source).
To ensure you're properly hydrated, simply drink water when you feel thirsty. Eating lots of water-rich foods, including fruits and vegetables, will also contribute to your hydration needs (25Trusted Source).
You may always be hungry if you're not drinking enough water. That's because it has appetite-reducing properties. Additionally, you may be mistaking feelings of thirst for feelings of hunger.
6. Your Diet Lacks Fiber
If your diet lacks fiber, you may feel hungry frequently.
Additionally, a high fiber intake influences the release of appetite-reducing hormones and the production of short-chain fatty acids, which have been shown to have fullness-promoting effects (12Trusted Source).
It's important to note that there are different types of fiber, and some are better than others at keeping you full and preventing hunger. Several studies have found soluble fiber, or fiber that dissolves in water, is more filling than insoluble fiber (27Trusted Source, 28Trusted Source, 29).
Many different foods, such as oatmeal, flax seeds, sweet potatoes, oranges, and Brussels sprouts, are excellent sources of soluble fiber.
Not only does a high-fiber diet help reduce hunger, but it's also associated with several other health benefits, such as a reduced risk of heart disease, diabetes, and obesity (30Trusted Source).
To ensure you're getting enough fiber, opt for a diet that's rich in whole, plant-based foods, such as fruits, vegetables, nuts, seeds, legumes, and whole grains.
If your diet lacks fiber, you may find that you are always hungry. This is because fiber plays a role in reducing your appetite and keeping you full.
7. You Eat While You’re Distracted
If you live a busy lifestyle, you may often eat while you are distracted.
Although it may save you time, distracted eating can be detrimental to your health. It's associated with greater appetite, increased calorie intake, and weight gain (31Trusted Source).
The primary reason for this is because distracted eating reduces your awareness of how much you're consuming. It prevents you from recognizing your body's fullness signals as efficiently as when you're not distracted (31Trusted Source).
Several studies have shown that those who engage in distracted eating are hungrier than those who avoid distractions during mealtimes (31Trusted Source).
In one study, 88 women were instructed to eat either while distracted or sitting in silence. Those who were distracted were less full and had a significantly greater desire to eat more throughout the day, compared with the non-distracted eaters (32Trusted Source).
Another study found that people who distracted themselves with a computer game during lunch were less full than those who did not play the game. Additionally, the distracted eaters consumed 48% more food in a test that occurred later that day (33Trusted Source).
To avoid distracted eating, you can try practicing mindfulness, minimizing screen time, and silencing your electronic devices. This will allow you to sit down and taste your food, helping you better recognize your body's fullness signals.
Distracted eating may be a reason why you are always hungry, as it makes it difficult for you to recognize feelings of fullness.
8. You Exercise a Lot
Individuals who exercise frequently burn a lot of calories.
This is especially true if you regularly participate in high-intensity exercise or engage in physical activity for long durations, such as in marathon training.
Research has shown that those who exercise vigorously on a regular basis tend to have a faster metabolism, which means that they burn more calories at rest than those who exercise moderately or live sedentary lifestyles (34Trusted Source, 35Trusted Source, 36Trusted Source).
In one study, 10 men who engaged in a vigorous 45-minute workout increased their overall metabolic rate by 37% for the day, compared with another day when they did not exercise (37Trusted Source).
Another study found that women who exercised at a high intensity every day for 16 days burned 33% more calories throughout the day than a group that did not exercise and 15% more calories than moderate exercisers. The results were similar for men (38Trusted Source).
Although several studies have shown exercise to be beneficial for suppressing appetite, there is some evidence that vigorous, long-term exercisers tend to have greater appetites than those who do not exercise (39Trusted Source, 40Trusted Source, 41Trusted Source, 42Trusted Source).
You can prevent excessive hunger from exercise simply by eating more to fuel your workouts. It is most helpful to increase your intake of filling foods that are high in fiber, protein, and healthy fats.
Another solution is to cut back on the time you spend exercising or reduce the intensity of your workouts.
It's important to note that this mostly applies to those who are avid athletes and work out frequently at a high intensity or for long periods. If you exercise moderately, you probably don't need to increase your calorie intake.
Individuals who regularly exercise at a high intensity or for long durations tend to have greater appetites and faster metabolisms. Thus, they may experience frequent hunger.
9. You’re Drinking Too Much Alcohol
Studies have shown that alcohol may inhibit hormones that reduce appetite, such as leptin, especially when it is consumed before or with meals. For this reason, you may feel hungry often if you drink too much alcohol (43Trusted Source, 44Trusted Source, 45Trusted Source).
In one study, 12 men who drank 1.5 ounces (40 ml) of alcohol before lunch ended up consuming 300 more calories at the meal than a group that drank only 0.3 ounces (10 ml) (46Trusted Source).
Additionally, those who drank more alcohol ate 10% more calories throughout the entire day, compared with the group that drank less. They were also more likely to consume high amounts of high-fat and salty foods (46Trusted Source).
Another study found that 26 people who drank one ounce (30 ml) of alcohol with a meal consumed 30% more calories, compared with a group that avoided alcohol (47Trusted Source).
Alcohol may not only make you hungrier but also impair the part of your brain that controls judgment and self-control. This may lead you to eat more, regardless of how hungry you are (44Trusted Source).
To reduce the hunger-inducing effects of alcohol, it's best to consume it moderately or avoid it completely (48Trusted Source).
Drinking too much alcohol may cause you to feel hungry frequently due to its role in decreasing the production of hormones that promote fullness.
10. You Drink Your Calories
Liquid and solid foods affect your appetite in different ways.
If you consume a lot of liquid foods, such as smoothies, meal replacement shakes, and soups, you may be hungrier more often than you would be if you ate more solid foods.
Eating liquid foods also tends to take less time than eating solid foods. This may lead you to want to eat more, only because your brain hasn't had enough time to process fullness signals (53Trusted Source).
In one study, people who consumed a liquid snack reported less fullness and more feelings of hunger than those who consumed a solid snack. They also consumed 400 more calories throughout the day than the solid-snack group (52Trusted Source).
To prevent frequent hunger, it may help to focus on incorporating more solid, whole foods into your diet.
Liquid foods do not have the same effects on keeping you full and satisfied as solid foods do. For this reason, you may feel hungry frequently if liquids are a major part of your diet.
11. You’re Overly Stressed
Excess stress is known to increase appetite.
This is mostly due to its effects on increasing levels of cortisol, a hormone that has been shown to promote hunger and food cravings. For this reason, you might find that you are always hungry if you experience frequent stress (54Trusted Source, 55Trusted Source, 56Trusted Source, 57Trusted Source).
In one study, 59 women who were exposed to stress consumed more calories throughout the day and ate significantly sweeter foods than women who were not stressed (57Trusted Source).
Another study compared the eating habits of 350 young girls. Those with higher stress levels were more likely to overeat than those with lower levels of stress. The stressed girls also reported higher intakes of unhealthy snacks like chips and cookies (58Trusted Source).
Excessive stress is a reason why you may be hungry frequently, given its ability to increase cortisol levels in the body.
12. You’re Taking Certain Medications
Several medications may increase your appetite as a side effect.
The most common appetite-inducing medications include antipsychotics, such as clozapine and olanzapine, as well as antidepressants, mood stabilizers, corticosteroids, and anti-seizure drugs (61Trusted Source, 62Trusted Source, 63Trusted Source, 64Trusted Source).
Additionally, some diabetes medications, such as insulin, insulin secretagogues, and thiazolidinediones, are known to increase your hunger and appetite (65Trusted Source).
There is also some anecdotal evidence that birth control pills have appetite-stimulating properties, but this is not supported by strong scientific research.
If you suspect that medications are the cause of your frequent hunger, it may help to talk to your healthcare provider about other treatment options. There may be alternative medications that don't make you hungry.
Certain medications cause increased appetite as a side effect. In turn, they may cause you to experience frequent hunger.
13. You Eat Too Fast
The rate at which you eat may play a role in how hungry you are.
Several studies have shown that fast eaters have greater appetites and a tendency to overeat at meals, compared with slow eaters. They are also more likely to have obesity or excess weight (66Trusted Source, 67Trusted Source, 68Trusted Source, 69Trusted Source).
In one study in 30 women, fast eaters consumed 10% more calories at a meal and reported significantly less fullness, compared with slow eaters (70Trusted Source).
Another study compared the effects of eating rates in those with diabetes. Those who ate a meal slowly became full more quickly and reported less hunger 30 minutes after the meal, compared with fast eaters (71Trusted Source).
These effects are partly due to the lack of chewing and reduced awareness that occur when you eat too fast, both of which are necessary to alleviate feelings of hunger (72Trusted Source, 73Trusted Source, 74Trusted Source).
These techniques are a part of mindful eating.
If you are hungry frequently, it may help to eat more slowly. You can do this by taking a few deep breaths before meals, putting your fork down between bites, and increasing the extent to which you chew your food.
Eating too quickly doesn't allow your body enough time to recognize fullness, which may promote excessive hunger.
14. You Have a Medical Condition
Frequent hunger may be a symptom of disease.
First, frequent hunger is a classic sign of diabetes. It occurs as a result of extremely high blood sugar levels and is typically accompanied by other symptoms, including excessive thirst, weight loss, and fatigue (76Trusted Source).
Hyperthyroidism, a condition characterized by an overactive thyroid, is also associated with increased hunger. This is because it causes excess production of thyroid hormones, which are known to promote appetite (77Trusted Source, 78Trusted Source).
Hypoglycemia, or low blood sugar levels, may also increase your hunger levels. Your blood sugar levels may fall if you haven't eaten for a while, an effect that may be exacerbated by a diet high in refined carbs and sugar (79Trusted Source).
If you suspect that you may have one of these conditions, it's important to talk with your healthcare provider to receive a proper diagnosis and discuss treatment options.
Excessive hunger is a symptom of a few specific medical conditions, which should be ruled out if you are frequently hungry.
The Bottom Line
Excessive hunger is a sign that your body needs more food.
It's often a result of imbalanced hunger hormones, which may occur for a variety of reasons, including inadequate diet and certain lifestyle habits.
You may feel hungry frequently if your diet lacks protein, fiber, or fat, all of which promote fullness and reduce appetite. Extreme hunger is also a sign of inadequate sleep and chronic stress.
Additionally, certain medications and illnesses are known to cause frequent hunger.
If you feel hungry often, it may be beneficial to assess your diet and lifestyle to determine if there are changes you can make to help you feel more full.
Your hunger could also be a sign that you are not eating enough, which can be solved by simply increasing your food intake.
In case you're eating too quickly or distracted at mealtimes, you can also practice mindful eating, which aims to minimize distractions, increase your focus, and slow your chewing to help you realize when you're full.
Reposted with permission from our media associate Healthline.
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Sharks elicit outsized fear, even though the risk of a shark bite is infinitesimally small. As a marine biologist and director of the Florida Program for Shark Research, I oversee the International Shark Attack File – a global record of reported shark bites that has been maintained continuously since 1958.
A Big, Diverse Family<p>Not all sharks are the same. Only a dozen or so of the roughly 520 shark species pose any risk to people. Even the three species that account for almost all shark bite fatalities – the <a href="https://www.floridamuseum.ufl.edu/discover-fish/species-profiles/carcharodon-carcharias/" target="_blank">white shark</a> (<em>Carcharodon carcharias</em>), <a href="https://www.floridamuseum.ufl.edu/discover-fish/species-profiles/galeocerdo-cuvier/" target="_blank">tiger shark</a> (<em>Galeocerdo cuvier</em>) and <a href="https://www.floridamuseum.ufl.edu/discover-fish/species-profiles/carcharhinus-leucas/" target="_blank">bull shark</a> (<em>Carcharhinus leucas</em>) – are behaviorally and evolutionarily very different from one another.</p><p>The tiger shark and bull shark are genetically as different from each other as a dog is from a rabbit. And both of these species are about as different from a white shark as a dog is from a kangaroo. The evolutionary lineages leading to the two groups split 170 million years ago, during the age of dinosaurs and before the origin of birds, and <a href="https://www.ck12.org/book/CK-12-Human-Biology/section/7.2/" target="_blank">110 million years before the origin of primates</a>.</p>
White, tiger and bull sharks are distinct species that diverged genetically tens of millions of years ago. Gavin Naylor / CC BY-ND<p>Yet many people assume all sharks are alike and equally likely to bite humans. Consider the term "shark attack," which is scientifically equivalent to "mammal attack." Nobody would equate dog bites with hamster bites, but this is exactly what we do when it comes to sharks.</p><p>So, when a reporter calls me about a fatality caused by a white shark off Cape Cod and asks my advice for beachgoers in North Carolina, it's essentially like asking, "A man was killed by a dog on Cape Cod. What precautions should people take when dealing with kangaroos in North Carolina?"</p>
Know Your Species<p>Understanding local species' behavior and life habits is one of the best ways to stay safe. For example, almost all shark bites that occur off Cape Cod are by white sharks, which are a large, primarily cold-water species that spend most of their time in isolation feeding on fishes. But they also aggregate near seal colonies that provide a reliable food source at certain times of the year.</p><p>Shark bites in the Carolinas are by warm-water species like bull sharks, tiger sharks and <a href="https://www.floridamuseum.ufl.edu/discover-fish/species-profiles/carcharhinus-limbatus/" target="_blank">blacktips</a> (<em>Carcharhinus limbatus</em>). Each species is associated with particular habitats and dietary preferences.</p><p>Blacktips, which we suspect are responsible for most relatively minor bites on humans in the southeastern United States, feed on schooling bait fishes like menhaden. In contrast, bull sharks are equally at home in fresh water and salt water, and are often found near estuaries. Their bites are more severe than those of blacktips, as they are larger, more powerful, bolder and more tenacious. Several fatalities have been ascribed to bull sharks.</p><p>Tiger sharks are also large, and are responsible for a significant fraction of fatalities, particularly off the coast of volcanic islands like Hawaii and Reunion. They are tropical animals that often venture into shallow water frequented by swimmers and surfers.</p>
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More to Know<p>There still is much to learn about sharks, especially the 500 or so species that have never been implicated in a bite on humans. One example is the tiny <a href="https://www.newsweek.com/one-worlds-rarest-sharks-also-one-most-adorable-325280" target="_blank">deep sea pocket shark</a>, which has a strange pouch behind its pectoral fins.</p><p>Only two specimens of this type of shark have ever been caught – one off the coast of Chile 30 years ago, and another more recently in the Gulf of Mexico. We're not sure about the function of the pouch, but suspect it stores luminous fluid that is released to distract would-be predators – much as its close relative, the <a href="https://sharkdevocean.wordpress.com/2015/04/23/second-ever-pocket-shark-discovered-in-gulf-of-mexico/" target="_blank">tail light shark</a>, releases luminous fluid from a gland on its underside near its vent.</p>
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By Jenny Morber
Caribbean corals sprout off Texas. Pacific salmon tour the Canadian Arctic. Peruvian lowland birds nest at higher elevations.
Known and anticipated changes in species distribution due to climate change around the world have implications for culture, society ecosystems, governance and climate change. Figure used with permission from Gretta T. Pecl, originally published on 31 Mar 2017 in Science 355(6332).<p>How we define species is critical, because these definitions influence perceptions, policy and management. The U.S. National Invasive Species Council (NISC) defines a biological invasion as "the process by which non-native species breach biogeographical barriers and extend their range" and states that "preventing the introduction of potentially harmful organisms is … the first line of defense." But some say excluding newcomers is myopic.</p><p>"If you were trying to maintain the status quo, so every time a new species comes in, you chuck it out," says Camille Parmesan, director of the French National Centre for Scientific Research, you could gradually "lose so many that that ecosystem will lose its coherence." If climate change is driving native species extinct, she says, "you need to allow new ones coming in to take over those same functions."</p><p>As University of Florida conservation ecologist Brett Scheffers and Pecl warned in a <a href="https://www.nature.com/articles/s41558-019-0526-5" target="_blank">2019 paper in <em>Nature Climate Change</em></a>, "past management of redistributed species … has yielded mixed actions and results." They concluded that "we cannot leave the fate of biodiversity critical to human survival to be randomly persecuted, protected or ignored."</p>
Existing Tools<p>One approach to managing these climate-driven habitat shifts, suggested by University of California, Irvine marine ecologist Piper Wallingford and colleagues in <a href="https://www.nature.com/articles/s41558-020-0768-2" target="_blank">a recent issue of Nature Climate Change</a>, is for scientists to adapt existing tools like the <a href="https://www.iucn.org/theme/species/our-work/invasive-species/eicat" target="_blank">Environmental Impact Classification of Alien Taxa (EICAT)</a> to assess potential risks associated with moving species. Because range-shifting species pose impacts to communities similar to those of species introduced by humans, the authors argue, new management strategies are unnecessary, and each new arrival can be evaluated on a case-by-case basis.</p><p>Karen Lips, a professor of biology at University of Maryland who was not associated with the study, echoes the idea that each case is so varied and nuanced that trying to fit climate shifting species into a single category with broad management goals may be impractical. "Things may be fine today, but add a new mosquito vector or add a new tick or a new disease, and all of a sudden things spiral out of control," she says. "The nuance means that the answer to any particular problem might be pretty different."</p>
In recent years, northern flying squirrels in Canada have found themselves in the company of new neighbors — southern flying squirrels expanding their range as the climate warms. Public Domain / USFW<p>Laura Meyerson, a professor in the Department of Natural Resources Science at the University of Rhode Island says scientists should use existing tools to identify and address invasive species to deal with climate-shifting species. "I would like to operate under the precautionary principle and then reevaluate as things shift. You're sort of shifting one piece in this machinery; as you insert a new species into a system, everything is going to respond," she says. "Will some of the species that are expanding their ranges because of climate change become problematic? Perhaps they might."</p><p>The reality is that some climate-shifting species may be harmful to some conservation or economic goals while being helpful to others. While sport fisherman are excited about red snapper moving down the East Coast of Australia, for example, if they eat juvenile lobsters in Tasmania they could harm this environmentally and economically important crustacean. "At the end of the day … you're going to have to look at whether that range expansion has some sort of impact and presumably be more concerned about the negative impacts," says NISC executive director Stas Burgiel. "Many of the [risk assessment] tools we have are set up to look at negative impact." As a result, positive effects may be deemphasized or overlooked. "So that notion of cost versus benefit … I don't think it has played out in this particular context."</p>
Location, Location, Location<p>In a <a href="https://www-nature-com.ezp3.lib.umn.edu/articles/s41558-020-0770-8" target="_blank">companion paper</a> to Wallingford's, University of Connecticut ecology and evolutionary biology associate professor Mark Urban stressed key differences between invasive species, which are both non-native and harmful, and what he calls "climate tracking species." Whereas invasive species originate from places very unlike the communities they overtake, he says, climate tracking species expand from largely similar environments, seeking to follow preferred conditions as these environments move. For example, an American pika may relocate to a higher mountain elevation, or a marbled salamander might expand its New England range northward to seek cooler temperatures, but these new locations are not drastically different than the places they had called home before.</p><p>Climate tracking species may move faster than their competitors at first, Urban says, but competing species will likely catch up. "Applying perspectives from invasion biology to climate-tracking species … arbitrarily chooses local winners over colonizing losers," he writes.</p>
The marbled salamander, a native of the eastern U.S., is among species whose range could expand northward to accommodate rising temperatures. Seánín Óg / Flickr / CC BY-NC-ND 2.0<p>Urban stresses that if people prevent range shifts, some climate-tracking species may have nowhere to go. He suggests that humans should even <a href="https://ensia.com/features/time-for-trees-to-pack-their-trunks/" target="_blank">facilitate movement</a> as the planet warms. "The goal in this crazy warming world is to keep everything alive. But it may not be in the same place," Urban says.</p><p>Parmesan echoes Urban, emphasizing it's the distance that makes the difference. "[Invasives] come from a different continent or a different ocean. You're having these enormous trans-global movements and that's what ends up causing the species that's exotic to be invasive," she says. "Things moving around with climate change is a few hundred miles. Invasive species are moving a few thousand miles."</p><p>In 2019 University of Vienna conservation biology associate professor Franz Essl published a similar argument for species classification beyond the native/non-native dichotomy. Essl uses "neonatives" to refer to species that have expanded outside their native areas and established populations because of climate change but not direct human agency. He argues that these species should be considered as native in their new range.</p>
They Never Come Alone<p>Meyerson calls for caution. "I don't think we should be introducing species" into ecosystems, she says. "I mean, they never come alone. They bring all their friends, their microflora, and maybe parasites and things clinging to their roots or their leaves. … It's like bringing some mattress off the street into your house."</p><p>Burgiel warns that labeling can have unintended consequences. We in the invasive species field … focus on non-native species that cause harm," he says. "Some people think that anything that's not native is invasive, which isn't necessarily the case." Because resources are limited and land management and conservation are publicly funded, Burgiel says, it is critical that the public understands how the decisions are being made.</p><p>Piero Genovesi, chair of the International Union for the Conservation of Nature's Invasive Species Specialist Group, sees the debate about classification — and therefore about management — as a potential distraction from more pressing conservation issues.</p><p>"The real bulk of conservation is that we want to focus on the narrow proportion of alien species that are really harmful," he says. In Hawaii "we don't discuss species that are there [but aren't] causing any problem because we don't even have the energy for dealing with them all. And I can tell you, no one wants to remove [non-native] cypresses from Tuscany. So, I think that some of the discussions are probably not so real in the work that we do in conservation."</p><p>Indigenous frameworks offer another way to look at species searching for a new home in the face of climate change. According to <a href="https://link.springer.com/article/10.1007%2Fs11625-018-0571-4" target="_blank">a study</a> published in Sustainability Science in 2018 by Dartmouth Native American studies and environmental studies associate professor Nicholas Reo, a citizen of the Sault Ste. Marie Tribe of Chippewa Indians, and Dartmouth anthropology associate professor Laura Ogden, some Anishnaabe people view plants as persons and the arrival of new plants as a natural form of migration, which is not inherently good or bad. They may seek to discover the purpose of new species, at times with animals as their teachers. In their paper Reo and Ogden quote Anishnaabe tribal chairman Aaron Payment as saying, "We are an extension of our natural environment; we're not separate from it."</p>
The Need for Collaboration<p>The successful conservation of Earth's species in a way that keeps biodiversity functional and healthy will likely depend on collaboration. Without global agreements, one can envision scenarios in which countries try to impede high-value species from moving beyond their borders, or newly arriving species are quickly overharvested.</p><p>In Nature Climate Change, Sheffers and Pecl call for a Climate Change Redistribution Treaty that would recognize species redistribution beyond political boundaries and establish governance to deal with it. Treaties already in place, such as the Convention on International Trade in Endangered Species of Wild Fauna and Flora, which regulates trade in wild plants and animals; the Migratory Bird Treaty Act; and the Agreed Measures for the Conservation of Antarctic Fauna and Flora, can help guide these new agreements.</p><p>"We are living through the greatest redistribution of life on Earth for … potentially hundreds of thousands of years, so we definitely need to think about how we want to manage that," Pecl says.</p><p>Genovesi agrees that conservationists need a vision for the future. "What we do is more to be reactive [to known threats]. … It's so simple to say that destroying the Amazon is probably not a good idea that you don't need to think of a step ahead of that." But, he adds, "I don't think we have a real answer in terms of okay, this is a threshold of species, or this is the temporal line where we should aim to." Defining a vision for what success would look like, Genovesi says, "is a question that hasn't been addressed enough by science and by decision makers."</p><p>At the heart of these questions are values. "All of these perceptions around what's good and what's bad, all [are based on] some kind of value system," Pecl says. "As a whole society, we haven't talked about what we value and who gets to say what's of value and what isn't."</p><p>This is especially important when it comes to marginalized voices, and Pecl says she is concerned because she doesn't "think we have enough consideration or representation of Indigenous worldviews." Reo and colleagues <a href="https://cpb-us-e1.wpmucdn.com/sites.dartmouth.edu/dist/9/52/files/2012/10/Reo_etal_AIQ_invasive_species_2017.pdf" target="_blank">wrote in American Indian Quarterly in 2017</a> that climate change literature and media coverage tend to portray native people as vulnerable and without agency. Yet, says Pecl, "The regions of the world where [biodiversity and ecosystems] are either not declining or are declining at a much slower rate are Indigenous controlled" — suggesting that Indigenous people have potentially managed species more effectively in the past, and may be able to manage changing species distributions in a way that could be informative to others working on these issues.</p><p>Meanwhile, researchers such as Lips see species classification as native or other as stemming from a perspective that there is a better environmental time and place to return to. "There is no pristine, there's no way to go back," says Lips. "The entire world is always very dynamic and changing. And I think it's a better idea to consider just simply what is it that we do want, and let's work on that."</p>
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