Cardita caliculaeformis

Early days of the COVID-19 <a href="https://www.earth.com/news/pandemic-restrictions-had-a-lasting-effect-on-behavior-patterns/">pandemic</a> were a stressful time marked by fear, isolation, and uncertainty. But for birds, the reduction in noise and commotion created a wider range of habitat in cities.



A new study from the <a href="https://www.washington.edu/">University of Washington</a> reports that many birds were just as likely to be found in highly developed urban areas as they were in less-developed green spaces during COVID-19 lockdowns in the Pacific Northwest.



“Our findings suggest that some birds may have been able to use more spaces in cities because our human footprint was a little lighter,” said Olivia Sanderfoot, who completed the study as a doctoral researcher and is now a postdoctoral scholar in the Department of Ecology and Evolutionary Biology at the University of California, Los Angeles.&nbsp;



“For about half of the species we observed, neither land use nor canopy cover had an effect on their site use. That’s very interesting, because we would expect that whether a habitat was mostly covered in concrete or vegetation would tell you something about what birds would be there,” said Sanderfoot.



In the spring of 2020, more than 900 community scientists were recruited to participate in the study. The volunteers chose their own monitoring sites such as backyards and parks, and recorded the birds they observed at least once a week. This allowed researchers to gather data despite the lockdowns and gave many volunteers a welcomed distraction from the stresses of the pandemic.



Among the 35 species that showed the strongest changes in behavior were some of the Pacific Northwest’s most iconic, including chickadees, great blue herons, downy woodpeckers and Wilson’s warblers. The researchers focused on 46 bird species overall and completed more than 6,000 individual surveys.



To compare bird observations to human activity, the team used data from Google’s Community Mobility Reports, which track the relative amount that people moved around at various points during the pandemic.



As people returned to public spaces and human activity increased, volunteers recorded an increase in sightings of several bird species in green spaces. While the birds may have been elsewhere during lockdowns enjoying the absence of human disturbance, they returned to green spaces when activity picked up again.&nbsp;&nbsp;



“This could tell us how important it is to build green spaces into our cities. That’s the biggest takeaway for me.” said Sanderfoot.



The study is published in the journal <a href="https://www.nature.com/srep/">Scientific Reports</a>.



Image Credit: Holly Hauser



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By <a href="mailto:katherinebucko@gmail.com">Katherine Bucko</a>, <a href="https://www.earth.com/staff/">Earth.com</a> Staff Writer

Birds expanded into quieter cities during Covid lockdowns

Early days of the COVID-19 pandemic were a stressful time...

Every year, trillions of <a href="https://www.earth.com/news/pitcher-plants-harness-rain-energy-to-capture-insects/">insects</a> in Western Europe undertake seasonal migrations; usually they move southward towards the Mediterranean and North Africa at the end of the northern summer, and return northward during the spring or early summer. The same pathway is followed by many species of moths, butterflies and hoverflies; vast numbers of these insects cross the Alps in order to fly as directly as possible to their overwintering destinations.&nbsp;



Although these enormous migrations are understood on a population level, very little is known about how individual insects manage to navigate their way through the considerable obstacles, or what methods they use to locate their destinations. This gap in understanding is due, mostly, to the challenge of tracking these small animals as they fly, surprisingly rapidly and often at night.&nbsp;



A new study on migrating death’s-head hawkmoths (Acherontia atropos) has now used miniscule tracking devices and a light aircraft to track seven individual moths as they migrated across the Alps at night. The study, published by the <a href="https://www.aaas.org/">American Association for the Advancement of Science</a> (AAAS), reveals that these hawkmoths make use of complex migratory strategies to stay on track.&nbsp;



The death’s-head hawkmoth, known for the sinister skull-shaped marking on its thorax, is the largest lepidopteran in Europe, weighing in at up to 3.5g. It is a long-distance Afro-Palearctic migrant that arrives to breed in Europe, north of the Alps, in spring each year. The subsequent generation returns south the following autumn to winter-breeding regions in the Mediterranean Basin and sub-Saharan Africa, covering a distance of up to 4,000km.&nbsp;



The researchers fitted tiny, very high frequency radio transmitters to the backs of 14 hawkmoths and recorded their precise GPS locations from a light aircraft at regular intervals (every 5 to 15 min, when possible) throughout their migration. They obtained detailed tracks for seven of the moths. The moths all started their migratory flights shortly after sunset, and were followed by the researchers for between 1 and 3.7 hours. During this time, the moths flew a mean distance of 63.7km, with the longest distance being 89.6km. This represents the longest distance over which any insect has been continuously tracked in the field.



A team led by Dr. Myles Menz&nbsp;from the Max Planck Institute of Animal Behavior discovered that the moths did not just fly in a direction with favorable tailwinds, as had been proposed by other scientists in the past. Instead, the moths flew in the most direct straight line to their destination, but were able to correct their specific flight headings constantly, as they came across disruptive winds and specific features of the terrain.&nbsp;



The hawkmoths traveled at a mean ground speed of 33.8km/hour, and they all travelled in straight lines along their entire flight paths, which lasted tens of kilometers. This direct line was maintained, despite the presence of winds of varying strengths and directions throughout their course.&nbsp;&nbsp;



According to the researchers, maintaining a consistently straight flight trajectory and flight speed throughout the night under variable wind conditions strongly suggests that the moths have an internal compass mechanism. This, along with the insect’s exceptional night vision, indicates that the hawkmoths likely use a combination of visual landmarks and Earth’s magnetic field to navigate considerable distances during migration.



Interestingly enough, the moths chose pathways through the mountains that had topographical features (such as high-altitude passes) which allowed them to avoid the very highest altitudes when crossing the Alps. One of these pathways involved using a wide valley running west-southwest that enabled the moths to circumvent the Alps altogether.



The research, published in the journal <a href="https://www.science.org/">Science</a>, sheds new light on the complex and sophisticated behavior of hawkmoths while on seasonal migrations. "To maintain such straight trajectories over long periods of time, as seen here, the moths must regularly update their positions relative to whichever navigational cues they rely on," wrote the study authors. The results show that complex migratory strategies are not the preserve of vertebrates alone, but can be found in these remarkable insects as well.&nbsp;



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By <a href="mailto:bosman@truewan.co.za">Alison Bosman</a>, <a href="https://www.earth.com/staff/">Earth.com</a> Staff Writer

How death’s-head hawkmoths navigate the Alps at night

Every year, trillions of insects in Western Europe undertake seasonal...

Scientists have long known that, just like humans, many species of mammals and birds experience REM (rapid eye movement) sleep – a type of deep sleep during which most dreaming occurs. However, until recently, not much attention has been given to the sleeping patterns of spiders.&nbsp;



Now, a research team led by the <a href="https://www.uni-konstanz.de/en">University of Konstanz</a> in Germany has recorded over 30 baby <a href="https://www.earth.com/news/jumping-spiders-know-the-difference-between-animals-and-objects/">jumping spiders</a> (Evarcha arcuata) during their resting states, and found that they displayed periodical bouts of retinal movements coupled with limb twitching and leg curling, suggesting that they might experience REM sleep too.



While many species similar to spiders do not have movable eyes, which makes it difficult to investigate their sleep cycles, jumping spiders are fierce predators that move their retinal tubes around constantly to redirect their gaze when they hunt.&nbsp;



Moreover, baby jumping spiders have a see-through outer layer which gives scientists a clear window into their bodies. “Sometimes as a biologist, you just get really, really lucky,” said study co-author Paul Shamble, an evolutionary biologist at <a href="https://www.harvard.edu/">Harvard University</a>.&nbsp;



By filming the baby spiders while they were resting, the researchers were surprised to find that they exhibited similar movements and behaviors as other species known to experience REM sleep.&nbsp;



“Here, we report evidence for an REM sleep-like state in a terrestrial invertebrate – periodic bouts of retinal movements coupled with limb twitching and stereotyped leg curling behaviors during nocturnal resting in a jumping spider,” the study authors reported.&nbsp;



“Observed retinal movement bouts were consistent, including regular durations and intervals, with both increasing over the course of the night.&nbsp;This report provides direct evidence for an REM sleep-like state in a terrestrial invertebrate – an arthropod – with clear parallels to REM sleep in terrestrial vertebrates.”



However, scientists are still not sure whether the spiders are technically asleep while they are in these resting states. Experts such as Jerry Siegel, a sleep researcher at the <a href="https://www.ucla.edu/">University of California, Los Angeles</a> (UCLA), remain skeptical that spiders are in fact capable of REM sleep. “There may be animals that have activity in quiet states. But are they REM sleep? It’s hard to imagine that they could be the same thing,” he said.



Further research is needed to better understand the sleeping patterns of spiders and other similar animals, and clarify how widespread REM sleep is in the animal kingdom, and what evolutionary purposes it might serve. “Comparisons across such long-diverged lineages likely hold important questions and answers about the visual brain, as well as the origin, evolution, and function of REM sleep,” the authors concluded.



The study is published in the journal <a href="https://doi.org/10.1073/pnas.2204754119">Proceedings of the National Academy of Sciences</a>.



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By <a href="mailto:andrei.ionescu5891@gmail.com">Andrei Ionescu</a>, <a href="https://www.earth.com/staff/">Earth.com</a> Staff Writer&nbsp;&nbsp;

Jumping spiders may experience REM sleep

Scientists have long known that, just like humans, many species...

A new study led by the <a href="https://www.ucla.edu/">University of California, Los Angeles</a> (UCLA) has found that female white-faced <a href="https://www.earth.com/news/age-rated-genes-help-capuchin-monkeys-live-longer/">capuchin monkeys</a> living in the tropical forests of northwestern Costa Rico that are better integrated into social networks with other adult females tend to survive longer.



“As humans, we assume there is some benefit to social interactions, but it is really hard to measure the success of our behavioral strategies,” said study senior author Susan Perry, a field primatologist at UCLA. “Why do we invest so much in our relationships with others? Does it lead to a longer lifespan? Does it lead to more reproductive success? It requires a colossal effort to measure this in humans and other animals.”



Together with her research team, Professor Perry tracked the female capuchin monkeys’ social interactions with other females, males, and companions of any sex and age, based on 18 years of data. Interactions taken into account in the study included giving and receiving grooming, foraging nearby, and taking part in coalitionary conflicts, such as intervening to help one another in conflicts by fighting, chasing, or producing aggressive sounds and facial expressions.



While the analyses revealed no evidence that heterosexual relationships provided any survival-related benefits to females, they clearly shown that social integration into networks with other female adults significantly improved their chance of survival. 



“We found the strongest evidence that social integration into female networks predicts survival. Females who frequently engaged in grooming and foraged in close proximity with other females experienced improved survivorship,” the authors explained.



“We also found marginal support that females who frequently provided and received coalitionary support from other females possibly experienced survival-related benefits. The fact that female interactions with other females across all behavioral domains show at least some evidence of beneficial impact on survival suggests that females cultivate strong relationships with each other.”&nbsp;&nbsp;&nbsp;



Further research is needed to better understand why relationships with other females have the greatest impact on the survival of female capuchin monkeys, and to investigate whether this phenomenon can be found in other species of monkeys.



The study is published in the journal <a href="https://academic.oup.com/beheco/article/33/4/807/6598784">Behavioral Ecology</a>.



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By <a href="mailto:andrei.ionescu5891@gmail.com">Andrei Ionescu</a>, <a href="https://www.earth.com/staff/">Earth.com</a> Staff Writer&nbsp;&nbsp;

Female monkeys with strong friendships survive longer

A new study led by the University of California, Los...

Sponges are ancient filter-feeding animals that rely on maintaining a flow of water through their bodies to obtain suspended food and dissolved <a href="https://www.earth.com/news/oxygen-may-have-come-from-ancient-rocks-of-early-earth/">oxygen</a>. They do not have a nervous, digestive or circulatory system, and remove waste products by releasing them into this same flow of water. However, a new study that analyzed videos of sponges over extended time periods has identified a special technique that they use to get rid of unwanted material from inside their bodies.&nbsp;



As one of the oldest multicellular organisms in existence, a sponge spends most of its life stuck to the substratum and cannot move away when conditions become unpleasant. Under these circumstances it may take in unwanted particles of sediment with its constant inflow of water. These waste particles would soon clog up a sponge’s filtration system and so they need to be removed. And the sponge does this by undergoing an extended contraction, referred to as a “sneeze.”



"Our data suggest that sneezing is an adaptation that sponges evolved to keep themselves clean,” said study senior author Jasper de Goeij, a marine biologist at the <a href="https://www.uva.nl/en">University of Amsterdam</a>.



While biologists have known about the contraction behavior, the authors of this paper show that these sneezes get rid of materials the sponges cannot use. “Let’s be clear: sponges don’t sneeze like humans do. A sponge sneeze takes about half an hour to complete. But both sponge and human sneezes exist as a waste disposal mechanism,” says de Goeij.



The researchers used time-lapse videos of sponges to show that these organisms do not simply dispose of waste and unwanted particles with water that flows away through the outlet pores. They actively secrete mucus, often against the direction of water flow, onto their outer surfaces. They then expel unwanted particles through their pores and these become aggregated in the stringy clumps of mucus. Every now and then, the sponge goes through a contraction (sneeze) that loosens the strings of mucus and accumulated particulate matter, dispatching them into the water column.



What is a sponge’s waste is a fish’s windfall. Fish hang around the sponges waiting for these strings of mucus to be shed so that they may eat them.



“We also observed fish and other animals feeding off of the sponge mucus as food,” explained study first author Niklas Kornder. “Some organic matter exists in the water surrounding the coral reef, but most of it is not concentrated enough for other animals to eat. Sponges transform this material into eatable mucus."



The researchers noted this “sneezing” behavior in two species of sponges, the Caribbean tube sponge&nbsp;Aplysina archeri&nbsp;and another Indo-Pacific species of the genus&nbsp;Chelonaplysilla.&nbsp;



“We actually think that most, if not all, sponges sneeze. I’ve seen mucus accumulate on different sponges while diving and in pictures taken by other scientists for other purposes,” said Kornder. 



“Our findings highlight opportunities to better understand material cycling in some of the most ancient Metazoans,” wrote the study authors.



There are still many aspects about sponge “sneezes” that remain to be investigated. “In the videos, you can see that the mucus moves along defined paths on the surface of the sponge before accumulating. I have some hypotheses, but more analysis is needed to find out what is happening,” said Kornder.



“There are a lot of scientists that think sponges are very simple organisms, but more often than not we are amazed by the flexibility that they show to adapt to their environment,” said de Goeij.



The study is, published in the journal <a href="http://dx.doi.org/10.1016/j.cub.2022.07.017">Current Biology</a>.



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By <a href="mailto:bosman@truewan.co.za">Alison Bosman</a>, <a href="https://www.earth.com/staff/">Earth.com</a> Staff Writer

Sponges “sneeze” to get rid of unwanted waste

Sponges are ancient filter-feeding animals that rely on maintaining a...

How did enormous dinosaurs like Brontosaurus carry so much weight on land? A new study led by the <a href="https://www.uq.edu.au/">University of Queensland</a> has finally solved this mystery. Using 3D modeling, the experts digitally reconstructed the foot bones of various <a href="https://www.earth.com/news/giant-sauropods-walked-more-like-hippos-than-elephants/">sauropods</a> to test their function. 



Dr. Andréas Jannel conducted the research during his PhD studies at UQ’s Dinosaur Lab. He said the team discovered that the hind feet of sauropods had a soft tissue pad beneath the "heel" that added cushioning to absorb their immense weight.



“We’ve finally confirmed a long-suspected idea and we provide, for the first time, biomechanical evidence that a soft tissue pad – particularly in their back feet – would have played a crucial role in reducing locomotor pressures and bone stresses,” said Dr. Jannel. “It is mind-blowing to imagine that these giant creatures could have been able to support their own weight on land.”



It was once assumed that sauropods were semi-aquatic and that water buoyancy took literal tons of weight off their relatively small legs. This theory was contradicted in the mid-twentieth century when scientists analyzed sauropod tracks that were found in deposits on land.



Sauropods were also once believed to have feet similar to a modern-day elephant, noted study co-author Dr. Olga Panagiotopoulou of Monash University.



“Popular culture - think Jurassic Park or Walking with Dinosaurs - often depicts these behemoths with almost-cylindrical, thick, elephant-like feet,” said Dr. Panagiotopoulou. “But when it comes to their skeletal structure, elephants are actually ‘tip-toed’ on all four feet, whereas sauropods have different foot configurations in their front and back feet."



“Sauropod’s front feet are more columnar-like, while they present more ‘wedge high heels’ at the back supported by a large soft tissue pad.”



This was because sauropods and elephants had different evolutionary origins, explained study co-author Professor Steve Salisbury.&nbsp;



“Elephants belong to an ancient order of mammals called proboscideans, which first appeared in Africa roughly 60 million years ago as small, nondescript herbivores. In contrast, sauropods – whose ancestors first appeared 230 million years ago – are more closely related to birds," said Professor Salisbury.



“They were agile, two-legged herbivores and it was only later in their evolution that they walked on all fours. Crucially, the transition to becoming the largest land animals to walk the earth seems to have involved the adaptation of a heel pad.”



The study is published in the journal <a href="https://www.science.org/journal/sciadv">Science Advances</a>.



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By <a href="http://csexton@earth.com">Chrissy Sexton</a>, <a href="https://www.earth.com/staff/">Earth.com</a> Staff Writer

Mystery solved: how massive dinosaurs carried their weight

How did enormous dinosaurs like Brontosaurus carry so much weight...

Many <a href="https://www.earth.com/news/dinosaurs-self-regulated-their-body-temperature/">dinosaurs</a> replaced their teeth as they fell out - a trait that is shared with modern crocodilians and sharks. Tooth replacement is useful for predatory animals whose teeth are used to hold struggling prey animals and are often broken off.&nbsp;



Now, new research shows that spinosaurids (a group that includes spinosaurus) replaced their teeth even faster than many other dinosaurs. This helps explain why so many spinosaurid teeth have been found littering dinosaur digs.&nbsp;&nbsp;&nbsp;



A team of scientists led by the <a href="https://www.ehu.eus/en">University of the Basque Country</a> assessed a partial spinosaurid jaw from the Late Cretaceous found in La Rioja, Spain. The jaw contained eight alveoli or tooth sockets and tooth remains. Indeed, the researchers found up to three teeth in a single alveolus.&nbsp;



“We recognized up to three generations of teeth in the same alveolus: the functional tooth of the animal, another tooth being formed and which would replace the first, and the germ of the one that would end up replacing the second,” explained Pablo Navarro, co-author of the research published in the journal <a href="https://www.tandfonline.com/doi/full/10.1080/08912963.2022.2069019">Historical Biology</a>.



“This suggests very rapid tooth replacement and is probably one of the reasons why so many spinosaurid teeth can be&nbsp; found on the Iberian Peninsula during the Lower Cretaceous."



Previous research showed that some species of spinosaurids were able to quickly replace their conical teeth, with an estimated time of 60 to 68 days. This research not only verifies the trait for the entire group, but also explains the mechanism of how this regeneration is possible.&nbsp;&nbsp;&nbsp;



“Throughout their lives these animals grew new teeth that gradually replaced the original ones and caused them to fall out. This means that the same animal could generate multiple teeth,” said Navarro.



“These teeth, more or less conical in shape and a centimetre in size, were transported by rivers, accumulated in lake areas and, over time, became fossilised,” said the researcher. They are one of the most common vertebrate remains in Iberian sites of the Lower Cretaceous (between 145 and 113 million years ago)”.



Although scientists aren’t entirely sure why spinosaurid teeth were replaced so quickly, it’s likely this ability gave them an edge over other predators.&nbsp;



The study is published in the journal <a href="https://dx.doi.org/10.1080/08912963.2022.2069019">Historical Biology&nbsp;</a>



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By <a href="mailto:nire518@gmail.com">Erin Moody </a>, <a href="https://www.earth.com/staff/">Earth.com</a> Staff Writer

Spinosaurids rapidly replaced their teeth

Many dinosaurs replaced their teeth as they fell out -...

Cardita caliculaeformis

Taxonomic tree: