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

On December 10th, 2017 we learned about

Sorting through the spectrum of what chimpanzees regard as repulsive

You might not want to eat while reading this. According to a recent study that aimed to gross out chimpanzees, text probably isn’t enough to trigger the sense of disgust we’ve inherited from our ancestors. With that said, stories that bring up the issue of coprophagia, or eating feces, probably isn’t great for one’s appetite. At least not a first.

Digging into the details of disgust

Researchers were investigating where chimpanzees, as our closest genetic relative alive today, draw the line with what they’ll put in their mouths to eat. That line certainly wasn’t clear from the outset, as wild chimps will pick seeds out of poop to eat, and captive chimps will go a step further and snack on their poop outright. Researchers learned that there was some nuance to chimps’ consumption of crap, as the animals apparently evaluate feces based on genetic familiarity. A chimpanzee will eat their own poop, or that of closely related family members, but any other chimps’ waste elicits a clear display of disgust.

With that baseline established, researchers set up experiments to further probe chimpanzees’ criteria for when food is too revolting to eat. In one scenario, food was placed in an opaque box, either on top of soft but edible dough, or on top of a piece of rope. Chimps reaching in for the food were obviously repulsed by the soft, moist dough, yanking their hands out of the box as if it bit them. Other tests involved food being placed on what looked like feces, or near the scent of blood, and while no response was apparently quite as disgusting as something soft, wet and squishy, the chimps seemed to have similar guidelines for what was gross that humans do. They didn’t necessarily have the same standards though, as they would sometimes end up eating food from disgusting sources, but overall their criteria was pretty relatable.

Finding the value in what chimps find foul

The fact that these chimpanzees get grossed out like we do may seem obvious, but it wouldn’t have been safe to automatically assume they operated on similar criteria to humans. After all, any degree of coprophagia is probably too disgusting for humans to seriously consider, and researchers wanted to see exactly what our species had in common with our fellow primates. Avoiding substances, like poop or blood, that could easily harbor pathogens makes sense as a survival tactic, and identifying commonalities indicates that chimps and humans likely inherited some of these reference points from a shared ancestor. This work may also help zoos and conservationists manage the health of chimpanzees in their care. Dangerous substances can be presented in a more disgusting manner, and individual chimps that seem too casual about gross sources of food can be given extra attention for exposure to pathogens.

Source: What grosses out a chimpanzee? The origins of disgust by Kyoto University, EurekAlert!

On December 5th, 2017 we learned about

Pigeons parsing time and space suggest that our brains might not be as special as we thought

Thanks to a test of pigeons’ sense of space and time, researchers may be casting doubts on the evolution of human brains. That’s not a knock on the people studying pigeons— these birds are capable of a lot, right down to helping diagnose cancer. The issue is that the birds seem to have a quirk in their perception that has previously only been seen in primates like us. It’s been understood to be tied to the specific structures in our brain that assist with processing spatial and temporal information, but that can’t be the case with these pigeons, because their brains simply don’t have any of the structures in question.

How long is a line, and how long does it last?

The first phase of this test trained pigeons to watch a screen, and then poke a response on a touch screen in order to earn a snack. When looking at a two-inch line and a nine-inch line, they needed to select the longer option. When lines were flashed on the screen for either two or eight seconds, the birds needed to choose the shape shown for the longer duration. This was nothing to sneeze at, but it was only the training for the real testing in phase two.

Once the pigeons seemed comfortable with looking for lengthy lines for longer time periods, researchers complicated their task by mixing in more intermediate choices. Instead of the seven-inch difference between the first sets of lines, the birds now had to consider lines that were only off by one inch. The attribute that was being tested was also less clear, with length and duration both being tested at random. This forced the birds to really pay attention to both space and time, which lead to some interesting blurred lines in their perception.

As the pigeons progressed, a pattern emerged that showed how their brains handled this spatial and temporal information. When the birds saw a longer line, they were also likely to react to it as if it were on screen longer. The reverse was true as well, with lines displayed for longer amounts of time apparently appearing lengthier to the pigeons as well. It may sound strange on paper, but as a primate you’re probably more familiar with this than you might think, as we do this too. The major difference is that we do it thanks to both types of information being processed in the same place in our brains— the parietal cortex in our cerebral cortex. Without such a structure to mash that information together, why does pigeon perception seem to work the same way?

Explaining the overlap in pigeon perception

There are two hypotheses at this point, and both of them reduce the prestige of a primate’s parietal cortex. The first hypothesis is that pigeons, and probably other birds as well, evolved similar cognitive abilities independently of mammals, essentially reproducing what our primate brains do in these tests, right down to the errors. This kind of functional overlap does occur in what’s called convergent evolution, but not usually to this degree of specificity. The strikingly similar overlap in pigeons’ spatial and temporal perception has with primates seems unlikely to have occurred by chance, particularly without any clear evolutionary benefit to promote its growth in two family trees.

The second explanation is that this mental circuitry evolved once, long ago in a common ancestor, and bird and mammal brains have just packed it into different structures in our brains. So instead of using a parietal cortex, those circuits, quirks and all, were packed into birds’ palliums instead. The catch here is that mammals haven’t shared an ancestor with birds for millions of years, meaning this specialized perception has been getting passed down through a lot of different species, well beyond the chimpanzees and pigeons we’ve tested. Since the underlying structure that handles this thinking might not be exclusive to primates, it suggests that some of our amazing cognition just needs to be properly tested in other animals.

Source: Pigeons can discriminate both space and time, Iowa Now

On December 3rd, 2017 we learned about

Like humans, baby bats pick up more speech patterns from their peers than from their mothers

For all the time and energy spent raising offspring, at some point every parent has to come to terms with the fact that they’re not only influence on their children. Whatever manners and language gets used at home, it’s nearly impossible for kids to avoid picking up the sound, style and charming phrasing of their peers’ voices. Apparently this is common not only among human families, but other social mammals as well, as researchers were able to induce the development of a non-native dialect, or group-specific accent, in baby bats.

Bats roost in groups, and spend a lot of that time chatting and bickering with each other. Like humans, baby bats develop their language skills by listening and imitating the sounds they hear in their local environment, which allowed researcher from Tel Aviv University to manipulate some bat pups’ emerging dialects. To do this, they placed some newborn baby bats with their mothers in a lab-controlled colony. When the animals were roosting, researchers played recordings of bats with dialects that contrasted from the pups’ mothers. They then observed and listed to the babies as their voices developed to see if they would sound more like their mother, or more like the artificial group they heard every day.

Gabbing like the larger group

The pups grew up vocalizing in a dialect that sounded more like the recorded chatter than their own mother’s voice. This may sound intuitive to anyone who has heard the children of immigrants speak with the accent of their adopted country, but it’s significant to see it in another species. Songbirds, for instance, are known to learn songs from their elders but seem to be instructed by a single tutor, like their father. This seemingly left humans as the only animal that picked up language instruction from everyone in their local population, aggregating the pronunciation and grammar rules into what we think of as accents.

These bat pups shake those assumptions up, since they’re picking up a dialect from their community like we do. This means that this structure for language acquisition may have been put into a common mammalian ancestor’s brain long ago, or that it has evolved more than once thanks to how useful it may be. To test the utility of sounding like your neighbors, researchers are now planning to see just how much of a difference a dialect can make, studying how bat colonies interact with animals that don’t sound like they grew up in the same group.

Source: Young bats learn bat 'dialects' from their nestmates, Phys.org

On November 21st, 2017 we learned about

Bonobos share food by default, most likely to cement future friendships

Acts of kindness usually don’t feel very costly. The sense of satisfaction from doing the right thing seems to cover whatever effort you may have put in to helping someone out, but that’s not a motivation that’s been widely accepted by science, at least for the animal kingdom. Helping another creature out can demand time, energy, and other resources, which has led to the assumption that there must always be some benefit for being generous. For example, raising another animal’s young may help the nanny’s gene pool if they’re related, or increase the survival rate of one’s own young if they’re not. Bonobo chimps (Pan paniscus) have put their own twist on this, as they’ve been demonstrated to be willing to share their own food with strangers, even if they stand no chance of immediate gain themselves.

Selflessly sharing snacks

Bonobo’s predisposition for sharing has already been established, but a new study looked to define the boundaries of their generosity. A bonobo chimp was placed in an enclosure where they could reach a peg. Pulling the peg would release some food in an adjacent enclosure, but the bonobo had no chance of getting that food themselves. When given the chance to explore this mechanism, the chimps definitely understood its limits, but weren’t compelled to use it on its own.

When a second, unknown bonobo was introduced to the second enclosure, the first bonobo clearly responded. They were four times as likely to take the otherwise unnecessary action of releasing the food if another bonobo was there to receive it. In some trials, the second bonobo’s fencing was open enough that it could reach an arm through to gesture for help with the food, but that apparently wasn’t necessary— the first bonobos seemed just as interested in helping out whether they were asked to or not. Unfortunately, the study didn’t specifically look for expectations that the second bonobo was going to also be generous and share the food, although in many cases the fencing would have prevented that even if the chimps wanted to.

Building new bonds

Weirdly, researchers feel that some of this generosity can be explained by yawning. Like humans, bonobos have contagious yawns, and one individual will often yawn if they see a peer, even one they don’t know, start yawning. It’s thought that this is an expression of social bonding, as it links the two animals through shared activity. Young female bonobos generally leave their families to live with strangers as they grow up, and so building relationships with others is key to their success.

The yawns and shared food may not seem like they provide an immediate benefit, but they may simply be components of a larger set of pro-social behaviors. Giving food to an unknown individual is likely a starting point for these animals to assemble an extended family that will help support them in the future. There’s still a chance that these bonobos feel like they’re doing the right thing on the inside at the time, but they’re probably helping their future self in the process.

Source: Bonobos Help Strangers Without Being Asked by Robin A. Smith, Duke Today

On November 20th, 2017 we learned about

Tracing the origins of turkeys’ supposed stupidity

Nobody wants to be a turkey. Even ignoring the fact that Americans will eat 87 million of these birds on holidays alone, there’s just no glory to be had for these iconic birds. Sure, Benjamin Franklin famously tried to promote their social standing, but today turkeys are solidly associated with incompetence, incoherence, and stupidity. Are they actually a particularly pathetic species, or should we be calling fowl (sorry!) over turkey’s maligned reputation?

To be clear, turkeys are unlikely to really compete with a crow or parrot on an IQ test. They’re not known for being especially cunning birds, but they’re certainly not helpless animals either. Wild turkeys (Meleagris gallopavo) will generally live in social groups of up to 200 individuals, usually composed of hens and their young broods. For protection, they rely on camouflage and the eyes and ears of their flock, like many other social birds. At night, they can overcome their relatively heavy bone structure to fly into trees, staying off the ground where they’d be more easily discovered. To further compensate for their limited flight, they’ve also been known to swim, fanning out their tails to increase buoyancy.

Unwanted associations

The above features were successful enough to see turkeys flourish across North America, but they weren’t enough to really impress humans. Once humans realized that their seed-fed meat was pretty tasty, we started hunting turkeys, taking advantage of their relatively limited mobility. This led to the idea of a “turkey shoot,” as the birds posed little challenge for a well-aimed gun. Limited flight also led to the name “turkey” being used as an insult. In the 1920s, a stage show or movie that performed badly was called a turkey, since sales failed to “take off.” This sense of general failure has probably fed into the idea that turkey’s are stupid, although popular evidence for their poor intelligence is actually a misunderstanding.

Stupidity or neck spasms?

Turkeys are supposedly so stupid that they will stand with their mouth agape, looking up into the sky as it rains, even it it means they drown themselves. Assuming this isn’t evidence of suicidal birds looking for a way out, it does seem fair to criticize animals that can’t be bothered to keep themselves alive. What’s not fair is judging intelligence when the real issue is a genetic condition that causes uncontrollable muscles spasms.

The condition is called tetanic torticollar spasming, and it can be spontaneous, or triggered by external stimuli like loud noises. It can be fatal in hatchlings, as it can interfere with getting food and water, but is more survivable in turkeys with later onset of symptoms. If it seems incompatible with living in the wild, that may be because it’s only associated with domestic turkeys. In manipulating their genomes to maximize muscle growth, humans have helped boost the prevalence of the recessive genes that cause the spasms. These poor birds look stupid because of a disability humans have unknowingly promoted, which for some folks may make eating turkeys a bit easier on their conscience.

None of the above necessarily demands that we completely reevaluate our opinion of turkeys. Domestic turkeys in particular do have a life few would be envious of, but maybe we should start associating them with the pitfalls of being delicious instead of just being dumb. Ok, and maybe a bit weird.

Source: Are turkeys really the dumbest animals? by Valerie Strauss, The Washington Post

On November 19th, 2017 we learned about

Lemurs depend on leaves because their local fruit lacks protein

No matter how delightful a good salad may be, most of us can’t live on leafy greens alone. Primates, including humans, definitely consume plants in our diets, but we eat other items like nuts, fruit or meat to round our our nutritional needs. Lemurs break this pattern though, and skip everything but leaves when they go looking for food. As it turns out, the lemurs might just think that the local produce on in Madagascar just isn’t worth eating in the first place.

To be clear, fruit does grow in Madagascar. Studies have named at least 125 native species, and humans have introduced everything from oranges to avocados. With seemingly a number of choices in their habitat, scientists wondered why more lemurs didn’t follow the model of other primates and make these fruits a bigger part of their diets. Scientists wondered if the fruit supply was historically unstable due to events like cyclones, forcing lemurs to shape their diets around more reliable leaves. After all, even the local fruit bats, Eidolon dupreanum, have to switch to eating nectar for portions of the year when their favorite foods are unavailable.

Not enough nitrogen

When scientists started looking closer at what foods were available to lemurs, they started finding that the quality of the fruit was the real issue. While fruit could be found in the lemurs’ habitat, it didn’t seem to provide much protein per bite. To quickly compare the nutritional content of the fruit available to lemurs and other primates around the world, researchers started measuring nitrogen concentrations, since nitrogen is a key ingredient in many proteins. Fruit eaten by various monkeys from around the world was sampled, and all of it had more valuable nitrogen per bite than the fruit available to lemurs in Madagascar.

To make up for this gap in their diets, it seems that lemurs had to learn to skip the fruit and eat more leaves. Leaves don’t always provide a lot of calories per bite though, and so this required further energy-conserving adaptations, like eating leaves around the clock, or hibernating to use less energy in the first place. Now that the importance of leafy-greens is better understood, conservation efforts can be better designed to ensure that critically endangered lemurs have access to the slightly unintuitive foods they’ve come to depend on.

Source: Lemurs are weird because Madagascar's fruit is weird, Phys.org

On November 15th, 2017 we learned about

Oceanic noise pollution poses serious problems for fish’s reproductive success

When submerged in water, human communication often gets reduced to hand-gestures, like a vague game of slow-motion charades. Without specialized equipment, it’s the best we can do in an environment that doesn’t accommodate our air-based speech. This limitation for our species has led to a lot of ignorance about how other species click, chirp and sing in the water, but new investigations are now discovering the importance of sound to the denizens of the sea. Scientists are now finding that aural communication is much more widespread than headline-grabbing whales and dolphins, extending all the way to the ocean’s floor with mating songs of the humble goby.

Gobies like Pomatoschistus microps are small fish that live usually don’t live more than a year. They live in shallow, coastal areas around Europe, and are mostly preyed up on by larger fish like cod. The sand goby (Pomatoschistus minutus) spends most of its time sitting motionless on the sea floor, waiting to grab passing invertebrates to eat. They perk up a bit in the summer though, when the males will commandeer an empty clam shell, sitting under it while courting local females with song. If the song catches the ear of a female, she’ll spawn her eggs under the male’s shell where he will fertilize and guard them until they hatch.

Sefloor seranade

The goby’s song itself probably won’t sound much like a good Barry White album to a human ear, but experiments have found it to be crucial to reproductive success. To test the role of the male’s song, researchers subjected two female and one male goby to the sound of a motorboat engine, simulating the kind of noise pollution that has become common in today’s oceans. When the humble “purring” (or in case of the common goby, “woodpecker-like”) sounds of the male goby had to compete with sounds of human activity, there was very little interaction between the male and female fish. In the cases where the fish did mate, the eggs seemed to somehow be affected by the noise as well, with half the eggs dying before hatching, and the surviving eggs taking longer to gestate. While slower courtship is likely explained simply by noise drowning out the male’s song, researchers aren’t sure why the eggs also suffered once they’d been fertilized.

This sensitivity to noise is a mounting problem for our oceans, where ships of all sizes, as well as undersea drilling and mining, are making more and more noise each year. However, this study also suggests that noise may be a consideration on small scales as well. The scientists behind this study worry that labs that work with fish need to take greater care to keep noise to a minimum, as fish in aquariums may be reacting to sound and skewing research results more than researchers have commonly been accounting for.

Source: Female fish like males who sing by University of Gothenburg, Science Daily

On November 13th, 2017 we learned about

Isolating the social signals that horses pick up from people’s posture

To communicate with a horse, you might employ reins, bits, lead ropes, halters, bridles, spurs, or riding crops, but you might want to start with your posture. Before getting on to a horse, how you behave on the ground can send signals to the animal, such as if you’re a dominant member of the herd or not. Horse owners have been employing these ideas for a long time, but since horses are known to glean information about people from a variety of sources, researchers wanted to know just how much of a role posture played on its own. When a horse reacts to a human’s presence, is it responding to the human’s posture, stern gaze or the smell of apples coming from a jacket pocket?

To try to isolate the role of human posture, researchers had to come up with an experiment that could account for all the other stimuli a horse looks for. To do this, 30 domestic horses were fed a treat by two women of similar height and build, wearing matching outfits to normalize their appearance as much as possible. The women had never met the horses before, and they they even covered the lower part of their face with a neck warmer to avoid sending unintentional cues with facial expressions. After the initial introduction to the two doppelgangers, the women moved to different parts of the arena to test the horse’s sensitivity to body language.

Looking solely at stature

With all these controls in place, the experimental condition was the posture the women adopted after being “introduced” to the horse. Instead of a matching “neutral” posture, one woman stood up straight, with her arms straight and legs about shoulder-width apart. Her counterpart bent her knees slightly, hunching forward with her hands angled over her abdomen, almost like a person trying to stay warm on a cold day. As expected, over the course of four trials each, the horses were much more likely to approach the woman adopting the submissive posture.

Confirming the importance of posture in human-equine relations may help settle one question, but it naturally raises others. Horses communicate with each other in many ways, such as flattening their ears to show a degree of hostility, which obviously don’t carry over to human anatomy. Likewise, human arm placement isn’t commonly seen in lower-ranked members of a horse herd, so it seems that horses are willing to translate our bodies into a meaningful message. Hopefully further studies, possibly with untamed, or at least unbroken, horses can find out more about when horses learned to read a human’s body language.

Source: Horses can read our body language even when they don't know us by University of Sussex, Science Daily

On November 12th, 2017 we learned about

Birds acting as nannies for other families may be investing in a nest for their own eggs’ future

You might help out your neighbor because you want to be nice, but is there a chance you’re really after their real estate? You might concede that lending a rake or watering a friend’s plants may carry the hope that they’ll reciprocate at some point, but the idea that helping out is a way to position one’s self to inherit land is probably a bridge too far. Even if humans made that kind of transaction, keeping track of those favors for the years until someone was ready to give up their homes seems impractical. Many bird species may disagree though, as they seem to regularly donate time, energy and breeding opportunities to their peers, possibly for the eventual payoff of a better nest and support network for themselves.

Many birds do a good job of co-parenting with their own brood, but the explanations for that are much more straightforward. On some level, they understand that they want to see their own offspring succeed, passing along their own genes in the process. Extended bird families follow this model as well, as older siblings share DNA with younger chicks from the same parents, offering another route to promote a specific gene pool. Helping out with other birds’ offspring gets a bit more confusing when the birds aren’t related, requiring that the birds, and researchers, start looking on a longer timescale for the benefits of these relationships.

Helping out, hatching plans

While helping animals of the same species could thought of as promoting the same gene pool on a much more general scale, some patterns have been observed that point to some more tangible benefits for the helpers. One of the most important trends was that the amount of available territory for each bird seemed to influence their interest in helping out with unrelated chicks. In scenarios where birds couldn’t scoop up prime nesting grounds easily, they were much more keen to help raise other families’ offspring, activity that increased their own chances of eventually inheriting that same nesting site.

So the helper birds do turn out to be acting in their own self-interest in this model, but it’s still a win-win for the larger bird community. A bird that acts as a very attentive nanny helps unrelated chicks grow up, making the nest-owning parents happy. The helper is putting off it’s own chance at reproduction, but it’s getting practice at childcare, and keeping an eye on what it hopes will one day be its own nest. Assuming the helper is successful, it may stand to gain more than a nice nest- the same chicks it helped raise are likely to continue the cycle, helping to raise another generation of birds in hopes of earning the family home back again.

Source: Birds without own brood help other birds with parenting, but not selflessly, EurekAlert!