On February 21st, 2018 we learned about

The sounds of snapping shrimp used by scientists, and whales, to estimate the abundance of coastal wildlife

Your alarm clock may play soft, soothing sounds of distant waves to help you nod off to sleep, but you’re only getting a tiny portion of the cacophony of noise echoing through the ocean. From whale greetings to acoustic gravity waves, there are a lot of vibrations moving through the water. Researchers are learning to listen in more carefully, as these sounds are a great way to monitor what’s happening in underwater ecosystems, although they may be a bit late to the party. Some studies are finding that the residents of the ocean, like Pacific gray whales, may regularly be tuning into specific sounds as indirect indicators of where to find a bite to eat.

Popping as a population proxy

One of the louder sea creatures capturing human and cetacean ears is the snapping shrimp. Like its infamous cousin, the mantis shrimp, this crustacean can snap its claw shut so quickly that it causes a tiny, temporary vacuum in the water, called a cavitation bubble. That bubble then collapses, releasing a lot of energy in the process, hopefully stunning the shrimp’s prey so it can capture its dinner. Like less dramatic bubbles, the bubbles also make a loud popping noise that can be heard from a considerable distance away.

When enough snapping shrimps are hunting at once, these pops start to sound like a bit like something sizzling and splattering in hot oil. Because it’s coming from groups of shrimp hunting at once, researchers have started using the sound to estimate shrimp populations and activity levels. For instance, summer waters off the coast of North Carolina see a 15 decibel increase, as shrimp crackle and pop up to 2,000 times a minute. In the winter, they calm down considerably, with no more than 100 pops being recorded in a minute.

Signaling snack time

Snapping shrimp surprised researchers off the coast of Oregon when they dipped a hydrophone into the water. The shrimp were previously unknown in the area, and yet they were clearly turning up in sizable numbers in researchers’ recordings. What’s more, the researchers apparently weren’t the only one’s listening for snapping shrimp, as Pacific gray whales often turned up when the shrimp started hunting.

The whales weren’t following the popping sounds to eat the shrimp though, as the noisy crustaceans just aren’t part of their diet. The best guess at this point is that the whales understood that the shrimp’s activity meant there was other food nearby. Since so much of the ocean is essentially devoid of food, following the sound of the popping bubbles saves the whales a lot of trouble. They’ve learned that when the shrimp are hunting, there’s probably something for whales to eat in the same location. With whales’ keen sense of hearing, the noisy bubbles must be hard to ignore.

Like those whales, ecologists are looking to figure out just how reliable a signal the snapping shrimp can be. If they’re consistent enough, listening for the sound of shrimp bubbles may be a relatively quick and inexpensive way to assess the health of coastal ecosystems, and maybe find some hungry whales at the same time.

Source: Snapping Shrimp May Act as 'Dinner Bell' For Gray Whales Off Oregon Coast, AGU.org

On February 19th, 2018 we learned about

Bat feces is a crucial fertilizer for Cambodian farmers

Even though nobody can grow or eat it, bat poop has become one of the most lucrative markets in Cambodian agriculture. Farmers have long encouraged bats to roost in the palm trees near their fields so that they could ‘harvest’ the guano that accumulates on the ground to use as fertilizer. In many cases, they will even tie extra palm fronds to trees in order to make them denser and more accommodating to the flying mammals. The effort is worth it, as bat poop is in such demand that guano-cultivators don’t even need to haul it to markets- clients will come to them, then buy the poop for around 38 cents a pound. That may not seem like much, but earning up to $10 a day for maintaining a bat latrine is attractive enough for some farmers to drop their other crops and focus on guano exclusively.

Fantastic feces for farmers

The idea that poop makes a good fertilizer isn’t new. Horse manure, bird poop and bat poop have all been used as a source of nutrients for plants around the world. In Cambodia, part of particular attraction to bat guano is just how well it performs. Controlled experiments have found that crops like eggplant, jackfruit and longan fare better with bat poo than commercial fertilizers, even though the feces has less nitrogen, phosphorus and potassium per pound. The magic of the bat droppings hasn’t been conclusively proven, but it’s thought that the other materials commonly found in bat poop, right down to beneficial bacteria, likely plays a role. The fact that the guano also helps with things like water retention in the soil makes it even more attractive, as farmers feel like the poo just makes for higher quality crops and soil.

In the case of certain crops, the bat poop is actually required. Heritage crops like the Kampot pepper are not allowed to be grown with industrial products like commercial fertilizers, as per the Kampot Pepper Promotion Association. Bat guano, having been a part of Cambodia’s ecosystems long before people were farming there, is allowable, driving those farmers to stock  up on bat droppings every year.

Bats versus bug spray

While bat feces are clearly a winner against other fertilizers, there’s growing conflict with farmers’ use of pesticides. While insect-eating bats are saving rice farmers as much as $300,000 per year in pesticide purchases, enough of the poisons are being used in Cambodia to pose health risks to the bats. While the rapid reproductive rates of insects give them a chance to develop resistances to pesticides, bats aren’t keeping up as well, and their populations are being hurt by the increasingly strong doses of poisons being used around farms. That then leads to fewer bats to hunt the insects and fewer bats to make new fertilizer.

It seems like the bats present a win-win for farmers, but conservationists are still concerned about their well-being. Farmers exposed to advertising for commercial fertilizers and pesticides were less likely to rely on bats, meaning the guano-harvesters may need to start investing in bat guano’s branding to make sure it’s properly appreciated in the public eye.

Source: Bat faeces: how this ‘black gold’ improves the fortunes of Cambodian farmers by Claire Baker-Munton, Southeast Asia Globe

On February 11th, 2018 we learned about

Migrating mallards may be moving a considerable quantity of seeds and spores in their stool

A nearby park has become home to over a growing number of both domesticated and mallard ducks. At busier times, it almost seems like the shores of the two artificial ponds are completely lined with ducks. This naturally means that the plants and paths nearby end up nearly completely covered in poop, to the point where my four-year-old is looks like he’s playing hop-scotch to avoid stepping in it. Soiled shoes aside, the poop from the mallards in particular may be making an important impact on the ecology of the park. Since those birds migrate from other locales, they’re likely bringing seeds and spores with them, although scientists are only just starting to measure how much of an impact their poop might make.

Deposits from digestive tracts

The duck poop at my local park wasn’t tested, but a more extensive study was recently completed that looked specifically at mallard (Anas platyrhynchos) migration in central and eastern Europe. Even ignoring the larger seasonal migrations these ducks make each year, a mallard may fly as far as 12 miles in 30 minutes, giving them ample opportunity to disperse seeds around an ecosystem. Scientists knew that seeds may sometimes get stuck to the birds’ wings or feet, but this was the first serious look at ducks’ endozoochory, or seed and spore dispersal, as a product of their digestive tracts. Basically, the question was how many seeds are these birds eating and indirectly planting in new places?

The 200 fecal samples collected in the wetlands of Hungary showed a fair amount of diversity. 21 species of flowering plants were found, including 13 that were terrestrial enough to grow outside a pond. More unusually, the duck poop was also turned up with spores from the watermoss Salvinia natans. This adds mallards to the short list of animals like deer, mice and fruit bats, that was previously known to help spread ferns across large distances. So while most expectations about seed and spore dispersal point to frugivores, or fruit-eaters, it turns out that the common mallard may also be shaping ecosystems around the world.

How significant are these seeds?

The full extent of the ducks’ poop isn’t known yet. While they clearly carried a number of plants seeds in their stomachs, the most frequently found seed was for the fig Ficus carcica, and none of those seeds seemed to actually germinate in their new Hungarian home. This is probably good news, as some less-welcome seeds were discovered as well. The hackberry tree is normally found in North America, and while only one such seed was found in this sample, it would likely function as an invasive species around the wetlands of Hungary. The combination of both diversity and unpredictable germination suggests that we really need to find out more about what these ducks are depositing around or ponds, parks and paths.

Source: Duck faeces shed light on plant seed dispersal by Sabrina Weiss, British Ecological Society

On January 30th, 2018 we learned about

Foxes and coyotes living in the city avoid the conflicts of their rural counterparts

Few animals evolved among the material excess of modern western society. Their bodies, brains and behavior all developed to keep them alive, or at least reproducing, in a world where one’s safety or nutritional needs were never guaranteed. This understandably breeds a bit of wariness about species that might be interested in competing for resources, such as foxes and coyotes, who both head out in the evenings to eat a similar assortment of mice, rabbits and other prey. The fact that the coyotes are big enough to kill a fox should only add tension to the dynamic, but somehow these species are happily coexisting all around the city of Madison, Wisconsin. They seem to have realized that in that environment, there’s enough food, and maybe even space, for everyone.

To understand what these contented canids were up to, researchers from the University of Wisconsin-Madison put radio collars on 11 coyotes (Canis latrans) and 12 red foxes (Vulpes vulpes). After two years, the data was mapped to see how each species was handling living in an urban environment, hopefully helping wildlife managers plan for the animals’ welfare in the future. What they found was a surprising amount of tolerance between two creatures that normally avoid each other in the wild; A fox and coyote were found to be foraging just yards away from each other, with no sign of conflict. For a few weeks, a coyote made visits to a fox den, but the foxes didn’t consider that to be much of a threat, as they never relocated to a new location.

The benefits of boundaries

This doesn’t mean that Madison is some kind of feral canine-commune. The two species may forage for food near each other, but they don’t bed down side-by-side. Coyotes seem to favor natural terrain, living in wooded areas. Even if the foxes wanted some woodland real estate, they probably couldn’t risk challenging their larger cousins directly. With that said, there’s a chance that the foxes don’t mind living closer to human activity, as they’ve been known to make dens in urban areas, such as London, even without pressure from a larger predator.

In areas where the animals have less room to move around, it turns out they can still make things work. While coyotes in Madison’s Arboretum can be exclusive with their territory, packs on the west side of the city are less picky. With less open space in general, they’ve ended up crossing into areas already occupied by foxes, apparently without a problem.

An abundance of food is certainly contributing to the placid relationship between foxes and coyotes, but researchers suspect that the diverse and divided spaces of an urban landscape are helping too. By breaking the land and food sources into block-sized chunks, human activity may have made these animals feel like they aren’t directly competing for the same resources. To find out more about this, the next phase of tracking will involve more human help. Volunteers are being asked to report sightings of foxes and coyotes around Madison, providing a new stream of data on their furry neighbors’ behavior.

Source: Urban foxes and coyotes learn to set aside their differences and coexist by University of Wisconsin-Madison, Phys.org

On January 28th, 2018 we learned about

Slow prey present special challenges to big predatory cats

Cheetahs probably wish their favorite food was faster. This isn’t because they want to burn more calories during every hunt, or necessarily have some deep enjoyment of speed. It’s because the hardest impalas (Aepyceros melampus) to catch aren’t the fastest runners, but the individuals who move slower and less predictably. Rather than race the fastest runners on Earth past their 60 mile-an-hour speeds, evolution has taken prey species in a different direction, or rather, as many different directions as they can manage, in order to out-maneuver the cats that want to eat them.

To test the dynamics between predators and prey, lions, cheetahs, zebras and impalas were outfitted with motion-sensing collars. While none of the test subject directly interacted, researchers were able to use the compiled speed, acceleration and directional data to build a model about how each species interacts. What became clear was that a zebra or impala that tried to simply outrun a lion or cheetah respectively was doing the cat a favor— an animal running at top speed can’t change directions very well, nor can it adjust its speed to avoid the final lunge of a chase. Instead, the most successful targets moved at slower speeds, enabling them to dodge and surprise their pursuer. Outmaneuvering the cats effectively put the prey in the driver’s seat, greatly increasing their chances of survival.

The roles of size, speed and strength

This isn’t to discount the physicality of these encounters. A zebra couldn’t hope to outrun or out-maneuver a cheetah, but their relative size allows them to scare those cats away. An impala could simply out-run a lion, but is an attractive size for a cheetah to tackle. Even when properly matched up in these ways, the cats still hold an athletic edge over their targets, as they were on average 38 percent faster, 37 better accelerators, and pound-for-pound were simply more powerful, with 20 percent stronger muscles. This would be a hard evolutionary race for prey to catch up with, so it makes sense that they’ve come to survive by learning to swerve at just the right moments.

As much as an impala running at full-speed would help a cheetah out, there’s an upside for predators here too. Big cats catch around one-third of the prey they chase, which is apparently just enough to keep them healthy if hungry. This balancing point then helps avoid over-hunting a herd, which may fill a cat’s belly in the short-term, but could lead to a food shortage if the herd’s population is stressed too far. Even if they can’t see every facet of the relationship, it’s probably good that these big cats can’t catch everything they chase after.

Source: Big cats in evolutionary arms race with prey: study by Marlowe Hood, Phys.org

On January 14th, 2018 we learned about

Differing degrees of intervention needed to protect endangered birds’ nests

One of the jobs of many bird nests is to keep the eggs, and later chicks, safe from harm. Different species have come up with a huge range of nest designs, although none are so perfect that they couldn’t use a helping hand in certain situations. In some cases, help means keeping people away from nests, while in others it means adding light sensors and mechanization to deal with threats that birds just haven’t had time to adapt to. Granted, those threats can often be traced back to human activity, but that shouldn’t preclude people from doing what we can to help keep these endangered birds as safe as possible.

Avoiding the eagles

Bald eagle (Haliaeetus leucocephalus) populations in the United States have been slowly recovering since the pesticide DDT was banned in 1970, but they’re certainly not in the clear yet. Researchers have been keeping a close eye on breeding pairs, but not in a way that would be obtrusive to the birds themselves. In Minnesota national parks, this respect for the birds’ sanctity also led to the sequestering of around nine eagle nests each year. The goal was to keep people away from any nests that might be home to eggs or eaglets, under the assumption that human interference would reduce the reproductive success of the nesting birds.

The effort to keep humans away from nesting eagles seemed to be moderately successful at first. When the nests were first protected in 1991, nests, eggs and offspring were counted from aerial surveys, and found that protected nests where eight percent more likely to have at least one offspring, and 13 percent more likely to have more offspring than an unprotected nest. These counts were later realized to overlook some variables, like the frequency of egg predation in unprotected nests. Fortunately, a more thorough analysis yielded good news— protected nests were more successful, and were credited with boosting the number of breeding pairs by 37 percent.

Building parrot-protecting boxes

While signs may successfully keep humans from bothering a nest, they’re not as effective at deterring egg-gobbling sugar gliders. Sugar gliders (Petaurus breviceps) are a species of possum that can glide through trees like a flying squirrel, and they have been a growing problem for endangered swift parrots (Lathamus discolor) since they were imported to Tasmania in the mid-19th century. As the parrot population plummets thanks to habitat loss, the nocturnal sugar gliders are making things worse by raiding the remaining 2,000 birds’ nests for food.

Ending deforestation or removing the invasive sugar gliders currently seems like an overwhelming task, but conservationists have made some progress at protecting the swift parrots’ eggs. The Difficult Bird Research Group has designed special nesting boxes for the endangered parrots that take advantage of the birds’ and possums’ different schedules. A light sensor built into the box closes the door at night when it gets dark, keeping the sugar gliders out, then opens the door in the morning when the parrots are ready to start their day.

The so-called “possum keeper-outers” have been working so far, although they can’t save the swift parrots on their own. To really stabilize the species, the logging and agriculture interests need to drastically change course, and stop cutting down the critical habitats the swift parrots normally nest in.

Source: Scouting the eagles: Evidence that protecting nests aids reproduction by David Tenenbaum, University of Wisconsin-Madison News

On January 7th, 2018 we learned about

The future of upcycled surplus food starts with salmon, sushi and smoke

How delicious does “recycled” food sound to you? If that sounds too much like coprophagia to you, maybe you’d prefer to snack on “rescued” produce? Or, like most folks in a study from Drexel Univeristy, you might give some “upcycled” food a chance, even if you do it to benefit society, more than your taste buds. However it ends up being packaged, the world is sure to see more value-added surplus food in the future, hopefully making a dent in the 80 billion pounds of food thrown away in the United States annually. While we still have to wait for our chance at upcycled granola bars, farmed fish are getting a taste of second-hand food right now.

Turning discards into fish dinners

Unlike humans, fish aren’t throwing out billions of pounds of perfectly healthy food because it doesn’t look pretty, was too big a portion, etc. Captive fish do, however, eat a lot of processed meal and pellets, which can be produced so inefficiently it can take 20 pounds of raw fish to bulk up a bluefin tuna by a single pound. Salmon are a bit more efficient to feed, but they’re still being fed fish that could just as easily feed people directly, basically making your dinner use more energy and resources than it should.

Since the fish are already being fed processed pellets instead of fresh prey, various efforts are underway to make those pellets from second-hand energy sources that wouldn’t otherwise be eaten. In Westfield, New York, this strategy has paired the Five & 20 Spirits and Brewing company with TimberFish Technologies. Instead of paying to simply dispose of the used grains and wastewater, the brewery is turning it into compost to feed microbes and invertebrates that then get fed to fish. To complete the loop, the brewery plans to add that same fish to their menu, allowing diners to drink and eat a beer-based meal. Along similar lines, other fisheries are picking up algae and discarded nut and flax seed waste from farms, upcycling components that would otherwise go to waste.

A new twist on smoked salmon

Most ambitiously, a startup called NovoNutrients is looking to upcycle air pollution into fish food. The company hopes to install equipment on industrial smokestacks to filter and capture carbon dioxide, then feed that to microbes that would produce protein for fish feed. It’s not quite the same loop as feeding fish worms fed on human food waste, but covering 20 percent of a fish’s protein needs while scrubbing air pollution still seems worthy of the “upcycling,” “rescaled” or “reclaimed” monikers.

Source: Waste Not, Want Not: Drink Beer To Feed Fish And Help Save The Planet by Alastair Bland, The Salt

On January 3rd, 2018 we learned about

The crushing, destructive success of signal crayfish

Is it possible to be too good at your job? Looking at the signal crayfish, it seems that the answer is yes, depending on the context. In their native freshwater streams and lakes of northwestern North America, these crustaceans are keystone species, as their daily activities greatly impact their environment. By burrowing into shorelines and eating dead plant material, signal crayfish can alter disperse nutrients, alter water quality and even affect the shape of a stream itself. Equally importantly, these crayfish are notably hardy creatures, which has enabled them to take their environmental engineering skills to no locations that have no way of coping with them.

As signal crayfish (Pacifastacus leniusculus) have increased their range over the last hundred years, the creatures that have suffered the most have been other crayfish. Compared to California’s sooty (Pacifastacus nigrescens) and Shasta crayfish (Pacifastacus fortis), signals grow to a relatively large eight inches long, lay more eggs, mature faster, and spend more time caring for their young. Since signals are happy to eat anything small enough to get their claws on, they’ve been able to make short work of competing species, pushing sooty crayfish to extinction and reducing Shasta crayfish to just a few hundred individuals. The smaller crayfish can barely even hide, as signals are known to walk across land for larger distances, expanding their range at a rate of a half-mile a year.

If signals all of the above weren’t enough to lead signals to total crayfish dominance, humans have pitched in to help. In 1907, a plague decimated European crayfish (Astacus astacus) populations, which were a popular source of food in Sweden and Finland. So in the 1960s, signal crayfish were introduced because they are also tasty, and seemed robust enough to handle being transplanted on the other side of the planet. Ignoring the impact signals had on California ecosystems, people also overlooked the fact that signals are carriers of the same plague that attacked European crayfish in the first place. Being immune to that disease themselves, they’ve had a very easy time spreading across Europe, with Ireland being the last country to to not be overrun.

Crayfish vs. actual fish

At this point, concerns have shifted from native crayfish to salmon. Signals have turned up in Alaska where there are no native species of crayfish to compete with, which means the local fish have no natural defenses against hungry crustaceans with big claws. The fact that signals release sediment into the water as they burrow may prove problematic as well, since the sockeye salmon aren’t used to looking for plankton in murky water.

It may seem like no other crayfish is as powerful as a signal, but other species are invading each other’s territory around the world. Out of the 400 species that live in the United States, many are being threatened by other invasive species, like the rusty crayfish (Orconectes rusticus) and red swamp crayfish (Procambarus clarkii). At this point, these tough critters may be hard to stop, but hopefully humans will at least stop helping them spread.

My third-grader asked: Why are they called “signal” crayfish?

They’re named for the white patch at the joint of the their claw, which maybe looks like a signal light flashing as they open and close their pincers.

Source: The Unassuming Crayfish—and Its Path of Devastation by Jason Bittel, NRDC

On January 2nd, 2018 we learned about

Bugs benefit from birds’ conspicuous displays of disgust

With their bright red bodies and black spots, it’s easy to spot ladybugs crawling among green leaves and stalks. These insects can get away with this eye-catching appearance because they carry toxins that make them unappealing to predators, but that strategy only makes sense if the predators know about it. These so-called “warning colors” can only work if animals like great tits know they represent an unpleasant experience, although scientists have wondered how ladybug populations survive the birds’ dietary education. In an experiment with video screens and artificial bugs, researchers have now confirmed that the birds demonstrate their disgust strongly enough to convince their kin to skip even sampling potentially toxic food.

To test how great tits (Parus major) might teach each other to avoid colorful bugs, researchers needed to present them with a conspicuous snack they’d never encountered before. Their aviary was littered with pieces of paper marked with black crosses as an artificial ground cover. Mixed in with those chits were tiny packages of food, either marked in a matching black cross to represent an insect that camouflages itself, like a green winter moth caterpillar, or a black square, standing out like red ladybug. Accordingly, the black-square “ladybugs” held an almond soaked in bitter flavoring, although the tits had to learn that fact the hard way.

When a bird tried eating the black-square packets, they rejected the bitter flavor immediately, as bitterness is often the result of toxins in a plant or insect. Instead of simply spitting the bitter almond out, the bird took the extra steps to wipe its beak on its perch, not unlike a small child dramatically rejecting their spinach at the dinner table.

Learning from others’ mistakes

Unbeknownst to the tit, it shared this foul-tasting snack with other birds via a video feed to a second aviary. The viewing audience paid pretty close attention, and apparently modified their own foraging tactics based on their peer’s beak-wiping behavior. When given the chance to browse paper chits on their own, tits that witnessed a grossed-out peer were 32 percent less likely to pick up a bitter, square-marked almond. This saved them from having to sample the bitter “bug” themselves, but in the wild would have saved a brightly colored ladybug as well.

That last fact is one of the significant implications of this study. While we’ve known that insects and other animals are often brightly colored to scare off predators, it wasn’t clear how they could ever arrive at that state. If every predator had to personally eat a red bug in order to learn that they taste bad, so many red insects would need to be eaten the that it would hardly help the bugs’ survival rate. Since predators like great tits can learn from each other, the benefit of being brightly colored has a chance to be multiplied across the species. The tits in this study adjusted their behavior after witnessing just one disgusted peer, so researchers are suggesting that learning curve of predators needs to be more carefully considered when studying the evolution of prey animals.

Source: Birds learn from each other's 'disgust,' enabling insects to evolve bright colors, Science Daily

On December 11th, 2017 we learned about

Florida raptors show surprising resilience in their rapid recovery against invasive snails

The arrival of an invasive species is usually terrible news for an ecosystem. History can offer plenty of examples of plants or animals arriving in a new place, only to out-consume everything that had previously lived there, as no predators are prepared to help keep populations in check. Humans have tried curbing these conflicts by introducing new creatures meant to go after the invaders, but our efforts don’t have the best track record either. All this makes the story of North American snail kites rather surprising, as the native birds have apparently been able to survive, and even take advantage of, snails that would otherwise be wrecking havoc across the Florida Everglades.

Snacking on apple snails

North American snail kites (Rostrhamus sociabilis) live in various locations around the Gulf of Mexico, including parts of Florida. With sharp talons, a long, hooked beak, dark plumage and crimson eyes, these raptors look ready to take on anything. In reality, they’re only interested in one thing, which is the small apple snails they find in wetlands. While they’re capable of feeding on small turtles and rodents in a pinch, the kite’s usual tactic is to hold a snail in one claw while using their long beak to pick flesh out of the mollusk’s shell. As their name implies, snail kites are specialists, which is why ecologists were so worried when their narrow menu options became threatened by…other snails?

Oddly, the invasive species that was encroaching on the apple snails and thus threatening the snail kites was another species of apple snail. However, the South American apple snail grows much larger, making them harder to prey on. This left them more or less unchecked, allowing them to quickly cause billions of dollars worth of damage to the ecosystem, from hurting bird populations to eating plants that normally helped prevent algae blooms. Predictions were grim for the kites and the ecosystem in general.

Getting bigger, faster

Amazingly, the snail kites have found a way to rebound. Their population has grown, as have their bodies and beaks. The birds are now growing eight percent larger than they used to, with some growth spikes reaching as high as 12 percent. They seem to be benefiting from eating the larger snails as prey, but bigger meals alone don’t explain all the changes researchers have witnessed. In less than two generations time, the surviving kites are already showing a bias towards genes that grow larger beaks. It’s easy to see how bigger beaks allows the kites to scoop food out of bigger snail shells, but the rate that these changes are taking place are startling.

Natural selection is continuous process, but it usually operates on longer time-scale in larger animals. It’s easy to witness change in something like bacteria, which can propagate beneficial mutations across multiple generations in 24 hours. The snail kites, on the other hand, live to be eight years old, and so the larger birds with bigger beaks have somehow boosted their real and proportional numbers in less than two life spans. Researchers don’t necessarily think that the snail kites will now reign in Florida’s apple snail problems, but they do feel optimistic for the future of the raptors, which are now estimated to have a population over 2,000 for the first time in ten years.

Source: Things Looked Bleak Until These Birds Rapidly Evolved Bigger Beaks by Douglas Quenqua, New York Times