Endangered species

There are more than 500 species of sharks in the world’s oceans, from the 7-inch dwarf lantern shark to whale sharks that can grow to over 35 feet long. They’re found from polar waters to the equator, at the water’s surface and miles deep, in the open ocean, along coasts and even in some coastal rivers. With such diversity, it’s no surprise that sharks serve many ecological functions. For example, the largest individuals of some big predatory species, such as tiger and white sharks, can have an oversized role in maintaining balances among species. They do this by feeding on prey and sometimes by just being present and scary enough that prey species change their habits and locations. In a newly published study, colleagues and I surveyed decades of research on sharks’ ecological roles and considered their future in oceans dominated by people. We found that because sharks play such diverse and sometimes important functions in maintaining healthy ocean...

Activities associated with cocaine trafficking threaten two-thirds of the most important landscapes in Central America for 196 forest bird species, including 67 migratory species. This is the key takeaway from a study that colleagues and I published in June 2024 in the journal Nature Sustainability. Our findings suggest that there is real potential for drug-related deforestation to negatively affect populations of migratory birds. Many of these species are unusually concentrated in winter in Central America, which has a comparatively smaller area than their summer breeding regions in North America. For 1 in 5 migratory species that travel to Central American forests annually, including familiar birds like the Baltimore oriole, more than 50% of their global population winters in areas that are becoming more attractive to traffickers. For half of migratory species, at least 25% of their populations winter in these areas. Baltimore orioles...

Fatal attractions are a standard movie plotline, but they also occur in nature, with much more serious consequences. As a conservation biologist, I’ve seen them play out in some of Earth’s most remote locations, from the Gobi Desert to the Himalayan Highlands. In these locales, pastoralist communities graze camels, yaks and other livestock across wide ranges of land. The problem is that often these animals’ wild relatives live nearby, and huge, testosterone-driven wild males may try to mate with domestic or tamed relatives. Both animals and people lose in these encounters. Herders who try to protect their domestic stock risk injuries, emotional trauma, economic loss and sometimes death. Wild intruders can be displaced, harassed or killed. These clashes threaten iconic and endangered species, including Tibetan wild yaks, wild two-humped camels and Asia’s forest elephants. If the wild species are protected, herders may be forbidden from chasing or harmin...

Rats thrive around humans, for good reason: They feed off crops and garbage and readily adapt to many settings, from farms to the world’s largest cities. To control them, people often resort to poisons. But chemicals that kill rats can also harm other animals. The most commonly used poisons are called anticoagulant rodenticides. They work by interfering with blood clotting in animals that consume them. These enticingly flavored bait blocks are placed outside of buildings, in small black boxes that only rats and mice can enter. But the poison remains in the rodents’ bodies, threatening larger animals that prey on them. My colleagues and I recently reviewed studies from around the world that sought to document wild mammal carnivores’ exposure to anticoagulant rodenticides. Many animals tested in these studies were already dead; others were alive and a part of other studies. Researchers detected rodenticides in about one-third of the animals in these analyses, i...

Fishermen across the Gulf of Mexico are reporting that something is eating fish off their lines. What’s to blame? Many recreational anglers point a finger at sharks. This conflict has caught politicians’ attention. Congress has directed the National Oceanic and Atmospheric Administration, which regulates fishing in U.S. waters, to review shark and dolphin interactions with fisheries, and the U.S. House of Representatives recently passed the SHARKED Act, which would create a task force to address the problem. I’ve studied this conflict, which is formally called depredation, for the past decade. While some shark populations in the Gulf of Mexico, such as bull sharks, are increasing, my colleagues and I have found evidence that human perceptions are also an important factor. A Gulf angler races to land a fish before sharks take it. Sharky waters The Gulf of Mexico is home to more than 70 species of sharks – and those...