Sense of smell is key factor in bird navigation, new study shows

Cory's Shearwater, Calonectris borealis, in flight.

How do birds navigate over long distances? This complex question has been the subject of debate and controversy among scientists for decades, with Earth's magnetic field and the bird's own sense of smell among the factors said to play a part.

Now, researchers from the universities of Oxford, Barcelona and Pisa have shown in a new experiment that olfaction -- or sense of smell -- is almost certainly a key factor in long-distance oceanic navigation, eliminating previous misgivings about this hypothesis.

The research is published in the journal Scientific Reports.

Study leader Oliver Padget, a doctoral candidate in Oxford University's Department of Zoology, said: 'Navigation over the ocean is probably the extreme challenge for birds, given the long distances covered, the changing environment, and the lack of stable landmarks. Previous experiments have focused on the physical displacement of birds, combined with some form of sensory manipulation such as magnetic or olfactory deprivation. Evidence from these experiments has suggested that removing a bird's sense of smell impairs homing, whereas disruption of the magnetic sense has yielded inconclusive results.

'However, critics have questioned whether birds would behave in the same way had they not been artificially displaced, as well as arguing that rather than affecting a bird's ability to navigate, sensory deprivation may in fact impair a related function, such as its motivation to return home or its ability to forage.

'Our new study eliminates these objections, meaning it will be very difficult in future to argue that olfaction is not involved in long-distance oceanic navigation in birds.'

In this new experiment, the researchers closely followed the movements and behaviour of 32 free-ranging Scopoli's shearwaters off the coast of Menorca. The birds were split into three groups: one made temporarily anosmic (unable to smell) through nasal irrigation with zinc sulphate; another carrying small magnets; and a control group. Miniature GPS loggers were attached to the birds as they nested and incubated eggs in crevices and caves on the rocky Menorcan coast. But rather than being displaced, they were then tracked as they engaged in natural foraging trips.

All birds went out on foraging trips as normal, gained weight through successful foraging, and returned to exchange incubation periods with their partners. Thus, removing a bird's sense of smell does not appear to impair either its motivation to return home or its ability to forage effectively.

However, although the anosmic birds made successful trips to the Catalan coast and other distant foraging grounds, they showed significantly different orientation behaviour from the controls during the at-sea stage of their return journeys. Instead of being well-oriented towards home when they were out of sight of land, they embarked on curiously straight but poorly oriented flights across the ocean, as if following a compass bearing away from the foraging grounds without being able to update their position.

Their orientation then improved when approaching land, suggesting that birds must consult an olfactory map when out of sight of land but are subsequently able to find home using familiar landscape features.

Senior author Tim Guilford, Professor of Animal Behaviour and leader of the Oxford Navigation Group in Oxford's Department of Zoology, said: 'To the best of our knowledge, this is the first study that follows free-ranging foraging trips in sensorily manipulated birds. The displacement experiment has -- rightly -- been at the heart of bird navigation studies and has produced powerful findings on what birds are able to do in the absence of information collected on their outward journey.

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Woolly rhino neck ribs provide clues about their decline and eventual extinction

Arrows indicate large articulation facets of cervical ribs on a fossil cervical vertebra of a woolly rhino of Naturalis, Leiden.

Researchers from the Naturalis Biodiversity Center in Leiden examined woolly rhino and modern rhino neck vertebrae from several European and American museum collections and noticed that the remains of woolly rhinos from the North Sea often possess a 'cervical' (neck) rib -- in contrast to modern rhinos.

The study, published in the open access journal PeerJ today, reports on the incidence of abnormal cervical vertebrae in woolly rhinos, which strongly suggests a vulnerable condition in the species. Given the considerable birth defects that are associated with this condition, the researchers argue it is very possible that developmental abnormalities contributed towards the eventual extinction of these late Pleistocene rhinos.

In modern animals, the presence of a 'cervical rib' (a rib attached to a cervical vertebra) is an unusual event, and is cause for further investigation. Though the rib itself is relatively harmless, this condition is often associated with inbreeding and adverse environmental conditions during pregnancy.

Frietson Galis, one of the authors of the peer-reviewed study, found a remarkably high percentage of these neck ribs in the woolly mammoth, published in a previous study.

"This aroused our curiosity to also check the woolly rhino, a species that, like the woolly mammoth lived during the late Pleistocene and similarly died out," said Alexandra van der Geer, one of the authors of the study. "The woolly rhino bones were all dredged from the North Sea and river deltas in the Netherlands. We knew these were just about the last rhinos living there, so we suspected something could be wrong here as well. Our work now shows that there was indeed a problem in the woolly rhino population."

The absence of cervical ribs in the modern sample is by no means evidence that rhino populations today are healthy. Museum collections are based on rhino specimens that were collected at least five decades ago. Rhinoceros numbers are dwindling extremely fast, especially the last two decades, resulting in near extinction for some species and the total extinction of the western black rhinoceros.

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An alternative to wolf control to save endangered caribou

Mountain caribou in British Columbia, Canada, observed during a population census.

What happens when invasive and native species are eaten by the same predator? If the invasive species is abundant, the native species can go extinct because predator numbers are propped up by the invading species. This process is called "apparent competition" because on the surface it "appears" that the invading and native prey directly compete with each other, but really the shared predator links the two prey.

Apparent competition is an increasing problem, causing endangerment and extinction of native prey as abundant species colonize new areas in the wake of human-caused change to the environment. This is exactly what is happening to the iconic woodland caribou across North America. Prey like moose and white-tailed deer are expanding in numbers and range because of logging and climate change, which in turn increases predator numbers (e.g. wolves). With all these additional predators on the landscape, more caribou become by-catch, driving some herds to extinction.

A short-term solution would be to kill wolves but this can be seen as just a band aid, and is no longer politically acceptable in many jurisdictions. As a more ultimate solution, Serrouya and colleagues used a new government policy and treated it as an experiment, to maximize learning. The new policy was to reduce moose numbers to levels that existed prior to widescale logging, with an adjacent reference area where moose were not reduced. The results of this research are published in an article titled "Experimental moose reduction lowers wolf density and stops decline of endangered caribou," and is published today in the peer reviewed and open access journal PeerJ.

Following the reduction of moose using sport hunting, wolf number numbers declined, with wolf dispersal rates 2.5 × greater than the reference area, meaning that dispersal was the process leading to fewer wolves. Caribou annual survival increased from 0.78 to 0.88 for the Columbia North herd, located in the moose reduction area, but survival declined in the reference area (Wells Gray). The Columbia North herd probably stabilized as a result of the moose reduction, and has been stable for 14 years (2003 -- 2017). By expanding their comparison across western Canada and the lower 48 states, they found that a separate herd subjected to another moose reduction was also stable, whereas at least 15 other herds not subjected to moose reductions are continuing to decline.

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Algae fortifies coral reefs in past and present

Lead author of the study Anna Weiss, a Ph.D. candidate in The University of Texas at Austin Jackson School of Geosciences, at a fossilized reef in Adnet, Austria.

The Great Barrier Reef, and most other large reefs around the world, owe their bulk in large part to a type of red algae that grows on corals and strengthens them. New research led by Anna Weiss, a Ph.D. candidate at The University of Texas at Austin Jackson School of Geosciences, has found that ancient coral reefs were also bolstered by their bond with red algae, a finding that could help scientists better understand how reefs will respond to climate change.

"Coral reefs as we know them today are a product of that long term coral-coralline algae relationship," Weiss said. "So if we want to preserve our coral reefs, we need to pay attention to the health of coralline algae as well."

Weiss conducted the research with Rowan Martindale, an assistant professor in the Jackson School's Department of Geological Sciences. Their research was published in August in the journal PLOS ONE.

Coralline algae are a type of red algae that helps build coral reef ecosystems in a variety of ways. They encourage reef growth by attracting coral larvae; they serve as a food source for reef animals; and help patch up broken coral skeletons by growing over breaks. The most important role of the algae when it comes to reef long term growth is directly reinforcing the limestone skeletons of corals with calcite, the hard mineral that forms the algae's skeleton. This allows coral reefs to maintain long-term structures that serve as the foundation of reef ecosystems.

Paleontologists think that the algae found in fossilized reefs plays a similar role in reef ecosystems as it does today. Weiss said that her study is the first to test that assumption by quantifying and statistically measuring that the algae has a significant, long term effect on reef diversity and structure.

Weiss research involved analyzing data from 128 fossilized coral reefs with coralline algae present cited in the research literature. She zeroed in specifically on reefs that were fossilized in the late Cretaceous and Cenozoic, a period that spans from 100 million years ago to the present.

She found that reefs with significant algae fortification were strongly associated with having higher structural integrity and more active ecosystems than those with little or no signs of algae -- a correlation that is also found in modern day coral reefs.

"Studying ancient events and ecosystems provide is important information about the modern world," Weiss said. "This work shows that the important interaction between corals and coralline algae isn't new, it goes back millions of years."

Today, climate change is warming ocean water and making it more acidic, putting stress on coral reefs around the world. Weiss said that other research indicates that the algae may be more vulnerable to the effects of climate change than coral, a finding that she said exemplifies the importance of learning more about algae's relationship with corals now and in the past.

"We know how important coralline algae are to reef building, so that could mean that coralline algae actually play a larger part than corals in determining whether a coral reef survives an ocean acidification event," Weiss said. "My research underscores the importance of coralline algae to coral reefs and confirms the antiquity of that importance."

Richard Aronson, an expert on the paleontology and ecology of marine communities and the department head of biological sciences at the Florida Institute of Technology, emphasized the importance of looking to ancient reefs -- and the factors that influenced their life cycles -- to understand reefs in the future.

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New ancient sea reptile found in Germany, the earliest of its kind

Skull reconstruction of Lagenanectes richterae.

A previously unrecognized 132 million-year-old fossilized sea monster from northern Germany has been identified by an international team of researchers. Findings published in the Journal of Vertebrate Paleontology.

The bizarre sea creature was a plesiosaur, an extinct long-necked aquatic reptile resembling the popular image of the Loch Ness monster, which dominated the seas during the Age of Dinosaurs.

The remains of the eight-meter-long skeleton were collected in 1964 by private fossil collectors. The perfectly preserved bones were rescued from heavy machinery excavating a clay-pit at Sarstedt near Hannover.

Despite being discovered nearly half a century ago, a group of international scientists was only recently invited to study the specimen by the Lower Saxony State Museum in Hannover. "It was an honor to be asked to research the mysterious Sarstedt plesiosaur skeleton" says Sven Sachs from the Natural History Museum in Bielefeld, Germany, and lead author on the study. "It has been one of the hidden jewels of the museum, and even more importantly, has turned out to be new to science."

The new plesiosaur was named Lagenanectes richterae, literally meaning 'Lagena swimmer', after the medieval German name for the Leine River near Sarstedt. The species was named for Dr Annette Richter, Chief Curator of Natural Sciences at the Lower Saxony State Museum, who facilitated documentation of the fossil.

The skeleton of Lagenanectes includes most of the skull, which had a meshwork of long fang-like teeth, together with vertebrae, ribs and bones from the four flipper-like limbs.

"The jaws had some especially unusual features." says Dr Jahn Hornung a palaeontologist based in Hamburg and co-author on the paper. "Its broad chin was expanded into a massive jutting crest, and its lower teeth stuck out sideways. These probably served to trap small fish and squid that were then swallowed whole."

Internal channels in the upper jaws might have housed nerves linked to pressure receptors or electroreceptors on the outside of the snout that would have helped Lagenanectes to locate its prey.

The bones also showed evidence of chronic bacterial infection suggesting that the animal had suffered from a long-term disease that perhaps eventually claimed its life.

"The most important aspect of this new plesiosaur is that it is amongst the oldest of its kind" says Dr Benjamin Kear from the Museum of Evolution at Uppsala University in Sweden and senior author on the study. "It is one of the earliest elasmosaurs, an extremely successful group of globally distributed plesiosaurs that seem to have had their evolutionary origins in the seas that once inundated Western Europe."

Elasmosaurs had spectacularly long necks -- the longest of any vertebrate -- including up to 75 individual vertebrae. Not all of the neck vertebrae of Lagenanectes were recovered but it is estimated that around 40 or 50 must have originally been present.

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Largest Ichthyosaurus was pregnant mother

Skeleton of Ichthyosaurus.

Scientists from the UK and Germany have discovered the largest Ichthyosaurus on record and found it was pregnant at the time of death.

The new specimen is estimated to be between 3 and 3.5 m long and is an adult female. Ichthyosaurs were a highly successful group of sea-going reptiles that became extinct about 90 million years ago. Often misidentified as swimming dinosaurs, these reptiles appeared before the first dinosaurs had evolved. The largest species of ichthyosaur grew to over 20 m in length.

The new specimen was originally discovered on the Somerset coast, during the mid-1990s, and is from the Early Jurassic, roughly 200 million years old. However, the specimen remained unstudied until it wound up in the collections of the Lower Saxony State Museum in Hannover, Germany.

Palaeontologist Sven Sachs of the Bielefeld Natural History Museum (Germany) first saw the specimen in August 2016, whilst on a routine visit. He informed University of Manchester palaeontologist and ichthyosaur expert, Dean Lomax, and together, the pair examined the new specimen in early 2017. They identified it as an example of an Ichthyosaurus somersetensis, a new species that Dean and another colleague, Prof. Judy Massare, had previously identified.

Dean said "It amazes me that specimens such as this [the biggest] can still be 'rediscovered' in museum collections. You don't necessarily have to go out in the field to make a new discovery. This specimen provides new insights into the size range of the species, but also records only the third example of an Ichthyosaurus known with an embryo. That's special"

The embryo is incomplete and preserves only a portion of the back bone, a forefin, ribs and a few other bones. The preserved string of vertebrae is less than 7 cm long. The bones of the embryo are not fully ossified, meaning that the embryo was still developing.

Another intriguing discovery the duo made was that the tail of this new specimen did not belong with the rest of the skeleton. A tail from another ichthyosaur had been added to the skeleton to make it appear more complete and visually appealing for display.

Sven added "It is often important to examine fossils with a very critical eye. Sometimes, as in this instance, specimens aren't exactly what they appear to be. However, it was not 'put together' to represent a fake, but simply for a better display specimen. But, if 'fake' portions remain undetected then scientists can fall foul to this, which results in false information presented in the published record.

"Specimens like this provide palaeontologists with important information about when these animals lived. Many examples of Ichthyosaurus are from historical collections and most do not have good geographical or geological records, but this specimen has it all. It may help to date other ichthyosaur fossils that currently have no information."

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Galaxy 5 billion light-years away shows we live in a magnetic universe

Astronomers observed the magnetic field of a galaxy five billion light-years away. The galaxy provides important insight into how magnetism in the universe formed and evolved.

With the help of a gigantic cosmic lens, astronomers have measured the magnetic field of a galaxy nearly five billion light-years away. The achievement is giving them important new clues about a problem at the frontiers of cosmology -- the nature and origin of the magnetic fields that play an important role in how galaxies develop over time.

The scientists used the National Science Foundation's Karl G. Jansky Very Large Array (VLA) to study a star-forming galaxy that lies directly between a more-distant quasar and Earth. The galaxy's gravity serves as a giant lens, splitting the quasar's image into two separate images as seen from Earth. Importantly, the radio waves coming from this quasar, nearly 8 billion light-years away, are preferentially aligned, or polarized.

"The polarization of the waves coming from the background quasar, combined with the fact that the waves producing the two lensed images traveled through different parts of the intervening galaxy, allowed us to learn some important facts about the galaxy's magnetic field," said Sui Ann Mao, Minerva Research Group Leader for the Max Planck Institute for Radio Astronomy in Bonn, Germany.

Magnetic fields affect radio waves that travel through them. Analysis of the VLA images showed a significant difference between the two gravitationally-lensed images in how the waves' polarization was changed. That means, the scientists said, that the different regions in the intervening galaxy affected the waves differently.

"The difference tells us that this galaxy has a large-scale, coherent magnetic field, similar to those we see in nearby galaxies in the present-day universe," Mao said. The similarity is both in the strength of the field and in its arrangement, with magnetic field lines twisted in spirals around the galaxy's rotation axis.

Since this galaxy is seen as it was almost five billion years ago, when the universe was about two-thirds of its current age, this discovery provides an important clue about how galactic magnetic fields are formed and evolve over time.

"The results of our study support the idea that galaxy magnetic fields are generated by a rotating dynamo effect, similar to the process that produces the Sun's magnetic field," Mao said. "However, there are other processes that might be producing the magnetic fields. To determine which process is at work, we need to go still farther back in time -- to more distant galaxies -- and make similar measurements of their magnetic fields," she added.

"This measurement provided the most stringent tests to date of how dynamos operate in galaxies," said Ellen Zweibel from the University of Wisconsin-Madison.

Read more at Science Dialy

Ice age era bones recovered from underwater caves in Mexico

This is a diver with a human skull, found in Hoyo Negro.

When the Panamanian land bridge formed around 3 million years ago, Southern Mexico was in the middle of a great biotic interchange of large animals from North and South America that crossed the continents in both directions. However, fossil animals from this time have been rare for the in-between environments of Central America and southern Mexico. Recently, a team technical cave divers are helping fill in this gap by discovering remains of large animals that once roamed the Yucatán Peninsula, during the end of the last Ice Age (around 13,000 years ago). Lead author, Dr. Blaine Schubert will present the team's findings at this year's annual meeting of the Society of Vertebrate Paleontology held this year in Calgary, Alberta (Canada) on Saturday, Aug. 26th at 9:00am.

The team of divers descended into the flooded passageways to an underground pit known as "Hoyo Negro" (Spanish for "Black Hole"), reaching down 180 ft (55 m) into the darkness. During the last Ice Age, sea level was much lower, and the prehistoric animals were able to walk to Hoyo Negro through horizontal passageways, only to fall into the inescapable pit within the cave. Divers have been photo-documenting the material before extraction, using re-breathing SCUBA equipment to prevent bubbles from disturbing the site. Dr. Blaine Schubert of East Tennessee State University, one of the lead researchers on the project says, "preservation of the fossil material is extraordinary, and will allow us to reconstruct various aspects of anatomy, evolutionary relationships, and behavior. The diversity of the fauna gives us an exciting new picture of this region in the midst of rapid climatic and environmental change."

Thus far the crew has recovered remains of three different giant ground sloths (including an entirely new species), short-faced bears, mountain lions, sabertooth cats, a bizarre relative of elephants called a gomphothere, tapirs, and even a human. "This represents the oldest and most complete early human skeleton in the Americas, and she co-existed with a variety of megafauna" says Schubert. "The remains of the short-faced bear Arctotherium are particularly significant, representing not only the most complete and abundant material from one location, but also the first evidence that they crossed from South America into North America." This fossil fauna is fleshing out a larger ecosystem for southern North America, which has typically been thought of as more of a bridge between landmasses than its own thriving community of local inhabitants. As the international collaboration of U.S. and Mexican researchers continues its work, the scientists hope to better understand the nature of this bridge and its own ecological complexities.

From Science Daily

Plant 'smells' insect foe, initiates defense

Goldenrod can detect a compound produced by gall-inducing flies, according to researchers.

It cannot run away from the fly that does it so much damage, but tall goldenrod can protect itself by first "smelling" its attacker and then initiating its defenses, according to an international team of researchers.

"We found another weapon in the arsenal of defenses that plants might employ against their herbivore attackers, in this case eavesdropping on a very specific chemical signal from an herbivore to detect its presence and prepare for future attack," said Anjel Helms, postdoctoral fellow in entomology, Penn State.

According to Helms, the gall-inducing flies (Eurosta solidaginis) are specialists that, in Pennsylvania, feed only on tall goldenrod (Solidago altissima). The male flies emit a blend of chemicals that is attractive to females. Once the females arrive and the eggs are fertilized, the females deposit their eggs within the stem of a goldenrod plant. After the eggs hatch, the larvae begin feeding on the tissue inside the stem. Chemicals in the saliva of the larvae are thought to cause the plant to grow abnormally and form a gall, or protective casing of plant tissue, around the larvae.

"The flies strongly reduce the plant's fitness by decreasing the number of seeds it produces, as well as the sizes of those seeds," said John Tooker, associate professor of entomology, Penn State. "That's because when the plant's tissues are damaged by the insect, it diverts its energy away from seed production and instead toward production of the gall."

Helms and her colleagues previously found that goldenrod plants exposed to chemicals from the male flies produced greater amounts of a defense chemical known as jasmonic acid when they were damaged by herbivores.

In their current study, the scientists aimed to identify the specific chemical compounds goldenrod plants are detecting and to determine how sensitive the plants are to the compounds. The researchers, including those at the U.S. Department of Agriculture, the University of Hamburg, Germany, and ETH Zurich, first identified the chemical compounds that make up the male fly's chemical emission. After identifying and quantifying the compounds in the male fly emission, the researchers exposed goldenrod plants to the individual compounds and examined their defense responses. They found that the plants responded most strongly to a compound in the blend called E,S-conophthorin.

"E,S-conophthorin is the most abundant compound emitted by the flies," said Helms. "The compound appears to provide a strong and reliable cue for the plants to detect."

Next, the team examined goldenrod's sensitivity to E,S-conophthorin by exposing plants to different concentrations of the compound and measuring their defense responses.

"We found that goldenrod plants are sensitive to even small concentrations of this compound," said Tooker. "This is significant because it likely means that the plant has a dedicated mechanism to perceive this compound. The results provide evidence that goldenrod can detect a single compound from the fly, supporting the idea that there is a tight co-evolutionary relationship between these two species.

In other words, over time, as the fly has adapted to take advantage of the plant, the plant has adapted to protect itself from the fly."

The findings appear in Nature Communications.

According to Tooker, the team's previous work was the first to demonstrate a plant "smelling" its herbivore, and its current work is the first to document exactly what compound the plants are detecting.

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Endangered sharks, rays further threatened by global food markets

Shark fin soup.

A majority of shark fins and manta ray gills sold around the globe for traditional medicines come from endangered species, a University of Guelph study has revealed.

Using cutting-edge DNA barcoding technology, researchers found 71 per cent of dried fins and gills collected from markets and stores came from species listed as at-risk and therefore banned from international trade.

"Despite the controversy around shark fin soup and the fact that many of these species are threatened there is still a large market for shark fins and a growing demand for ray gill plates," said Dirk Steinke, integrative biology professor and member of the Centre for Biodiversity Genomics. "It's an area that until now has been hard to enforce because shark fins are dried and processed before they are sold making it difficult to identify the species."

Shark finning, or removing fins from live sharks, is illegal in Canada. Importing shark fins for sale is also illegal for species at-risk.

Published in Scientific Reports, the study was conducted with researchers from the Guy Harvey Research Institute and Save Our Seas Shark Research Centre at Nova Southeastern University in Florida.

Researchers collected 129 market samples in Canada, China and Sri Lanka representing 20 shark and ray species. Twelve of those species, including whale sharks, are listed as protected and illegal to trade under the Convention on International Trade in Endangered Species (CITES).

"We were surprised to find whale shark fins and gills were being sold," said Steinke. "This magnificent animal has been on the CITES Appendices since 2003."

Developed at U of G, DNA barcoding allows scientists to identify species of organisms using genetic material.

"DNA barcoding is an ideal tool when identifying dried samples or samples that have been processed," said Steinke. "It provides enforcement agencies with a method for detecting whether the fins and gills that are being sold are legal or illegal imported species."

About half of the world's 1,200 species of sharks and rays are listed as threatened by the International Union for Conservation of Nature including 20 that may not be traded internationally.

Read more at Science Daily