Within the next century, rising ocean temperatures around the Galápagos Islands are expected to make the water too warm for a key prey species, sardines, to tolerate. A new study by Wake Forest University biologists, published in PLOS ONE Aug. 23, uses decades of data on the diet and breeding of a tropical seabird, the Nazca booby, to understand how the future absence of sardines may affect the booby population.
Researchers have studied diet, breeding and survival of Nazca boobies as part of a long-term study at Isla Española in the Galápagos Islands for more than 30 years. In 1997, midway through the study, sardines disappeared from Nazca booby diet samples and were replaced by the less-nutritious flying fish.
As flying fish replaced sardines in the birds' diet, "reproductive success was halved," said Emily Tompkins, a Ph.D. student at Wake Forest and lead author of the study. "If the current links between diet and reproduction persist in the future, and rising ocean temperatures exclude sardines from the Galápagos, we forecast the Nazca booby population will decline," Tompkins said.
David Anderson, Wake Forest professor of biology and co-author of the study, said: "Few connections have been made between ocean warming and population effects in the tropics, making this study significant."
The study increases understanding of one species' response to climate change in tropical oceans, but also suggests that other Galapagos predators that do well when sardines are available must adjust to a new menu within the next 100 years.
PNNL's ThermalTracker software can aid responsible wind farm siting and operations.
Pacific Northwest National Laboratory's (PNNL) ThermalTracker software analyzes thermal video to help birds and bats near offshore wind farms. PNNL engineer Shari Matzner is shown here with a thermal video camera she's using for this research. Credit: PNNL.
The same technology that enables soldiers to see in the dark can also help protect birds and bats near offshore wind turbines.
Night vision goggles use thermal imaging, which captures infrared light that's invisible to the human eye. Now, researchers at the Department of Energy's Pacific Northwest National Laboratory are using thermal imaging to help birds and bats near offshore wind farms. PNNL is developing software called ThermalTracker to automatically categorize birds and bats in thermal video. Birds and bats fly over offshore waters, but they're difficult to track in such remote locations.
"ThermalTracker can help developers and regulators make informed decisions about siting and operating offshore wind projects," said PNNL engineer Shari Matzner, who leads ThermalTracker's development. "We need scientific tools like this to better understand how offshore wind turbines can coexist with birds and bats."
The software can help determine if there are many birds or bats near an offshore wind project and if they could be affected by the project. If that's the case, officials can consider adjusting the location of a proposed project or modifying an existing project's operations.
Biologists at the non-profit Biodiversity Research Institute are testing the system this summer to determine how well it identifies birds compared to their field observations in Maine, one of the states considering offshore wind power.
"This is an extraordinary collaboration between technology developers, engineers and wildlife biologists who are working together on cutting-edge technology," said Wing Goodale, deputy director of Biodiversity Research Institute. "Developing technology to detect bird and bat avoidance at terrestrial and offshore wind farms will promote a better understanding of the nature of wildlife risks -- or lack thereof -- at any type of wind farm, and reduce uncertainty about the potential for unintended impacts during operation. These cameras could provide a reliable method of detecting bird and bat response to offshore wind projects, where it is not possible to conduct traditional wildlife monitoring."
Offshore potential
Winds are stronger over the ocean than on land, and DOE estimates the U.S. could potentially generate nearly twice the amount of electricity it currently uses if we captured the energy in winds that blow off our shores.
Offshore wind power is starting to take off in the U.S. The nation's first commercial offshore wind project is spinning off of Rhode Island and another proposed project near New York recently received early approval. Offshore wind is further along in Europe, where nearly 3,600 offshore turbines have a total generation capacity of about 12,000 megawatts.
For the birds
American officials are aiming to make U.S. offshore wind environmentally responsible, including limiting its impact on birds and bats near American shores. Today, most wind power sites are evaluated for birds and bats by biologists who stand in a field and take notes on what they see. For offshore wind power sites, scientists board a boat, but can only observe in daylight and when the weather cooperates. Remote sensing technologies could enable longer-term bird and bat monitoring that is also less expensive and labor-intensive.
Scientists have long used thermal imaging to observe bats, which are nocturnal and can't be seen with traditional video at night. But while thermal cameras see general animal shapes when visibility is low, they don't provide clear images or color, which makes identifying animals difficult.
PNNL's solution involves algorithms that can identify birds and bats based on their flight behaviors. The ThermalTracker software specifically evaluates two characteristics: the shape of the path that birds or bats take to fly from point A to B, and how frequently their wings beat up and down. The software evaluates thermal video for these behaviors and then determines whether the observed animals are bats or belong to bird families such as gulls, terns or swallows.
Upping the game
Two previously published papers describe how an early version of ThermalTracker detected 81 percent of all animals recorded in thermal video and correctly classified 82 percent of those observed animals. And it took humans an average of five times longer to arrive at the same conclusions as the software.
Now, Matzner and her PNNL colleagues are improving their software. They've already updated its algorithms so it can detect animals as video is being recorded, instead of processing video after the fact. Live data processing means the software only saves video when a bird or bat is detected. With less data to store, the system can be used for long-term observation and provide more complete information about birds and bats near offshore wind power sites.
The team is also creating a system that has "stereo vision," or 3D video by using two thermal cameras instead of the just one. Having 3D video provides depth perception, which helps determine if birds are flying at the heights where turbines spin and if birds are avoiding existing turbines. Stereo vision will also reveal how far a bird is from a camera, which can determine bird size and, in turn, more accurately identify a bird.
Testing it out
BRI field researchers are testing the new stereo camera system this summer. While the two-camera system records, the Institute's scientists are documenting which birds they observe, how far away birds are, and how well the camera system works.
Next, Matzner and her colleagues will use the field biologists' notes to refine ThermalTracker algorithms so the software can better identify birds and bats from 3D video.
Interdisciplinary teams at Pacific Northwest National Laboratory address many of America's most pressing issues in energy, the environment and national security through advances in basic and applied science. Founded in 1965, PNNL employs 4,400 staff and has an annual budget of nearly $1 billion. It is managed by Battelle for the U.S. Department of Energy's Office of Science. As the single largest supporter of basic research in the physical sciences in the United States, the Office of Science is working to address some of the most pressing challenges of our time.
Biodiversity Research Institute's mission is to assess emerging threats to wildlife and ecosystems through collaborative research, and to use scientific findings to advance environmental awareness and inform decision makers. BRI has been researching topics related to wildlife and renewable energy since 2009.
Adaptations for flight may have driven egg-shape variety in birds.
This is page 352b, as numbered of 1028, in Volume 5 of the German illustrated encyclopedia Meyers Konversationslexikon, 4th edition (1885-1890), titled "Eggs of European birds. Plate I" showing 78 bird eggs as numbered 1-78, c. 1888. Published 1885-1890 in Leipzig, Germany.
The evolution of the amniotic egg -- complete with membrane and shell -- was key to vertebrates leaving the oceans and colonizing the land and air. Now, 360 million years later, bird eggs come in all shapes and sizes, from the almost perfectly spherical eggs of brown hawk- owls to the tear-drop shape of sandpipers' eggs. The question is, how and why did this diversity in shape evolve?
The answer to that question may help explain how birds evolved and solve an old mystery in natural history.
An international team of scientists led by researchers at Harvard and Princeton universities, with colleagues in the UK, Israel and Singapore, took a quantitative approach to this question. Using methods and ideas from mathematics, physics and biology, they characterized the shape of eggs from about 1,400 species of birds and developed a model that explains how an egg's membrane determines its shape. Using an evolutionary framework, the researchers found that the shape of an egg correlates with flight ability, suggesting that adaptations for flight may have been critical drivers of egg-shape variation in birds. The research is published in Science.
"Our study took a unified approach to understanding egg shape by asking three questions: how to quantify egg shape and provide a basis for comparison of shapes across species, what are the biophysical mechanisms that determine egg shape, and what are the implications of egg shape in an evolutionary and ecological setting," said senior author, L. Mahadevan, the Lola England de Valpine Professor of Applied Mathematics at the John A. Paulson School of Engineering and Applied Sciences (SEAS); Professor of Organismic and Evolutionary Biology, and of Physics at Harvard; and a Core Faculty Member of the Wyss Institute of Bioinspired Engineering at Harvard University. " We showed that egg shapes vary smoothly across species, that it is determined by the membrane properties rather than the shell, and finally that there is a strong correlation linking birds that have eggs that are elliptical and asymmetric with a strong flight ability, the last a real surprise."
The researchers began by plotting the shape -- as defined by the pole-to-pole asymmetry and the ellipticity -- of some 50,000 eggs, representing 14 percent of species in 35 orders, including two extinct orders. The researchers found that egg shape was a continuum -- with many species overlapping. The shapes ranged from almost perfectly spherical eggs to conical-shaped eggs.
So, how is this diverse spectrum of shapes formed?
Researchers have long known that egg membranes play an important role in egg shape -- after all, if an egg shell is dissolved in a mild acid, like vinegar, the egg actually maintains its shape. But how do the properties of the membrane contribute to shape?
Think of a balloon, said Mahadevan. If a balloon is uniformly thick and made of one material, it will be spherical when inflated. But if it is not uniform, all manner of shapes can be obtained.
"Guided by observations that show that the membrane thickness varies from pole to pole, we constructed a mathematical model that considers the egg to be a pressurized elastic shell that grows and showed that we can capture the entire range of egg shapes observed in nature," said Mahadevan.
The variations of shape come from the variation in the membrane's thickness and material properties and the ratio of the differential pressure to the stretchiness of the membrane.
The next question is, how are these forms related to the function of the bird?
The researchers looked at correlations between egg shape and traits associated with the species of bird, including nest type and location, clutch size (the number of eggs laid at a time), diet and flight ability.
"We discovered that flight may influence egg shape," said lead author Mary Caswell Stoddard, Assistant Professor of Ecology and Evolutionary Biology at Princeton University and former Junior Fellow in the Harvard Society of Fellows. "To maintain sleek and streamlined bodies for flight, birds appear to lay eggs that are more asymmetric or elliptical. With these egg shapes, birds can maximize egg volume without increasing the egg's width -- this is an advantage in narrow oviducts."
So an albatross and a hummingbird, while two very different birds, may have evolved similarly shaped eggs because both are high-powered fliers.
"It's clear from our study that variation in the size and shape of bird eggs is not simply random but is instead related to differences in ecology, including the amount of calcium in the diet, and particularly the extent to which each species is designed for powerful flight" says coauthor Dr. Joseph Tobias from Imperial College, UK.
Next, the researchers hope to observe the egg laying process in real time, to compare it to and refine their model.
Funding sources for this work include Princeton University, the L'Oreal USA For Women in Science Fellowship, the Harvard Society of Fellows, the Milton Fund, Nanyang Technological University, the Oxford Clarendon Fund, the Fulbright Commission, the Natural Environment Research Council, the MacArthur Foundation and the Radcliffe Institution.
Researchers studied the survival and breeding behavior of the Snowy Plover, which are male-biased populations. Credit: Luke Eberhart-Phillips
Extinction risk for some species could be drastically underestimated because most demographic models of animal populations only analyse the number and fertility of females, dismissing male data as 'noise'.
An international team of researchers, including a PhD student and a professor from the Milner Centre for Evolution at the University of Bath, found that population growth in birds was very sensitive to the ratio of males to females in a population, called the adult sex ratio (ASR), which has previously been shown to affect mating behaviour. The researchers have published their findings in the prestigious science journal, Proceedings of the National Academy of Sciences.
Species with a high number of males in a population tend to be polygamous: the females typically breed with several partners in one season, leaving the males to do most of the care for their offspring. However, with a large number of males competing for fewer females, a male biased population can also lead to increased aggression and harassment of females which can reduce survival rates.
Conversely, species with a higher number of females to males have lower parental investment by fathers which can also adversely affect survival of offspring. Where numbers of each sex were evenly balanced, parents cooperated more in care of their young and breeding pairs tended to be monogamous.
The researchers looked at why an unbalanced sex ratio should develop in some birds. They studied the survival and breeding behaviour of 1,259 wild Snowy Plovers in north-western Mexico over a seven year period, a species that is typically male biased. The team found that whilst a similar number of males and females hatched, males had higher survival rates at all stages of life, but particularly at the juvenile stage, when individuals are independent of their parents but not fully grown.
These findings could impact the conservation of endangered species, since ignoring the sex ratio of a population could miscalculate the survival rates and therefore underestimate the vulnerability of species to extinction.
Luke Eberhart-Phillips with a Kittlitz’s plover. Credit: Luke Eberhart-Phillips.
Professor Tamás Székely, from the Milner Centre for Evolution at the University of Bath, said: "Our research has shown that population growth is very sensitive to changes in the survival of the limiting sex. A biased sex ratio either way can compromise population stability - too many males increases violence, whereas too many females leads to less cooperation between parents which reduces the survival of offspring.
"Current extinction models only take numbers of females into account - our research shows this approach could drastically underestimate extinction risk and states that males should also be part of the equation."
Luke Eberhart-Phillips, PhD student at Bielefeld University (Germany) and first author of the paper, said: "Our research shows that in Snowy Plovers the population is male-biased due to sex differences in survival of young individuals, rather than at birth or during adulthood.
"Therefore, the evolution of different mating systems - whether polygamous or monogamous - could be a consequence of innate sex differences in survival. In mammals, population sex ratios are typically female biased, whereas in birds, these sex ratios are usually male biased. "Based on our results, one could speculate that sex differences in survival during early life are driving these large-scale patterns and the evolution of breeding behaviours."
Golden Eagle at Seedskadee National Wildlife Refuge. Credit: Tom Koerner, USFWS Mountain-Prairie.
New research from Oregon State University will aim to make eagles less likely to collide with wind-turbine blades. The U.S. Department of Energy Wind Technology Office has awarded Roberto Albertani of the OSU College of Engineering a 27-month, $625,000 grant to develop technology for detecting and deterring approaching eagles and for determining if a blade strike has occurred.
A growing energy source in the U.S., wind power uses towers up to 300 feet tall typically equipped with three blades with wingspans double that of a Boeing 747. At their tips, the blades are moving close to 200 miles per hour. Wind power is generally regarded as green energy, but danger to birds - particularly bald eagles and golden eagles - is a concern. Albertani's team, which includes OSU computer scientist Sinisa Todorovic and electrical and computer engineer Matthew Johnston, will work on a three-part system for protecting the eagles. "We're the only team in the world doing this kind of work," said Albertani, an associate professor of mechanical engineering. If successful, he said, the system will be a major breakthrough in a safer-for-wildlife expansion of wind energy worldwide.
The system will feature a tower-mounted, computer-connected camera able to determine if an approaching bird is an eagle and whether it's flying toward the blades. If both those answers are yes, the computer triggers a ground-level deterrent: randomly moving, brightly colored facsimiles of people, designed to play into eagles' apparent aversion to humans.
"There's no research available, but hopefully those will deter the eagles from coming closer to the turbines," Albertani said. "We want the deterrent to be simple and affordable."
At the root of each turbine blade will be a vibration sensor able to detect the kind of thump produced by a bird hitting a blade. Whenever such a thump is detected, recorded video data from a blade-mounted micro-camera can be examined to tell if the impact was caused by an eagle or something else.
"If we strike a generic bird, sad as that is, it's not as critical as striking a protected golden eagle, which would cause the shutdown of a wind farm for a period of time, a fine to the operator, big losses in revenue, and most important the loss of a member of a protected species," Albertani said.
Albertani's team includes two collaborators from the U.S. Geological Survey, biological statistician Manuela Huso and wildlife biologist and eagle expert Todd Katzner. An external advisory board includes Siemens Wind Power and Avangrid Renewables.
Primary field testing will take place at the North American Wind Research and Training Center in Tucumcari, N.M., and the NREL National Wind Technology Center in Boulder, Colo. Field work will also be done in Oregon and California.
The U.S. Fish and Wildlife Service estimates there are roughly 143,000 bald eagles and 40,000 golden eagles in the United States.
An international team of citizen scientists and researchers has identified a major contributor to the dramatic decline of migratory shorebird populations in Australia.
University of Queensland School of Biological Sciences researcher Associate Professor Richard Fuller said Australian shorebirds were under threat due to the degradation and destruction of mudflats thousands of kilometres away in north-east Asia. Associate Professor Fuller was part of a team of researchers who worked on a shorebird study led by the University of Maryland's Assistant Professor Dr Colin Studds. Dr Studds said a critical factor in the decline of migratory shorebirds was their dependence on mudflats in the Yellow Sea, between China and South Korea. "The more a species relies on the disappearing Yellow Sea mudflats, the faster they are declining," Dr Studds said. He said birds including species of godwit, curlew and sandpiper were under threat. Many birds follow the East Asian Australasian Flyway migratory path from their non-breeding grounds in Australia to breeding sites in the Arctic, resting and refueling in the Yellow Sea. "Scientists have long believed that loss of these rest stops could be related to the declines, but there was no smoking gun," Dr Studds said.
The researchers analysed citizen science data collected between 1993 and 2012 on 10 key species, and what they found was dramatic. Even though the birds only spend one or two months of the year at the mudflats, it was the most important factor in determining the population trend. Associate Professor Fuller said the study was founded on decades of bird counting effort by volunteers across Australia and New Zealand. "Without this effort, the study would have been impossible," he said.
Australia has signed agreements with China, Korea and Japan to protect migratory birds, yet the birds have continued to decline. "Every country along the migration route of these birds must protect habitat and reduce hunting to prevent the birds declining further or even going extinct," Associate Professor Fuller said. "We are particularly excited that China and Korea have recently begun the process of listing parts of the Yellow Sea as World Heritage Sites."
Puffin pairs that follow similar migration routes breed more successfully the following season, a new Oxford University study has found.
Many long-lived birds, such as swans, albatrosses or indeed, puffins, are known for their long-lived monogamous, 'soulmate' pairings. Scientists have long understood that in these species, reproductive performance is influenced by pair bond strength and longevity, with long-established pairs usually better at rearing offspring. However, in species like puffins which have to migrate to distant wintering grounds during the non-breeding season, very little is known about how mates maintain their pair-bond and behave. Do they keep in contact to maintain their relationship? Or do they go their own way and abandon their mate until the following spring?
The new study which features in the April 7th 2017 edition of Marine Ecology Progress Series, focused on whether puffin pairs stayed in contact during the winter months or instead headed off and migrated independently, prioritising their individual health and wellbeing, and whether this had any effect on the pairs' subsequent breeding success.
Over the course of six years, the team from Oxford's Department of Zoology, in collaboration with the London Institute of Zoology, used miniature tracking devices called geolocators to track the migratory movements and behaviour of 12 pairs of Atlantic Puffins, breeding on Skomer Island, Pembrokeshire. They assessed if and how much pairs' migratory strategies were related to their future breeding performance and fitness.
While pair members migrated separately, their routes were notably similar during the first part of the winter. Partners would then follow separate paths at the later end of the season, but synchronised their timings of return to the colony in spring.
A key finding of the study is that pairs which followed more similar migration routes bred earlier and more successfully the following spring, showing that there is a clear benefit for puffins to migrate close to their mates. This proximity may make it easier for pairs to synchronise their return to the colony in spring.
The findings also reveal that while migrating close to its partner is key to a puffin's reproductive success, there are other factors at play. Female puffins were found to forage more than males, proving critical to their breeding success the following season. Female puffins that foraged more over winter were able to lay eggs earlier and rear pufflings more successfully, most likely because they were in a better pre-breeding condition.
Dr Annette Fayet, a Junior Research Fellow of Queen's College, Oxford and of the Department of Zoology at Oxford University, who is lead author of the study, said: 'While migrating close to one's partner leads to more successful breeding in puffins, female winter foraging effort seems to be even more critical to ensure high reproductive success. A likely explanation for this finding is that female puffins which spend more time fuelling up over winter return to the colony in better condition and are able to lay higher quality eggs, rearing stronger chicks. Overall it seems that prioritising individual condition is more important for seabirds' breeding success than maintaining contact with their partner outside of the breeding season. However, following similar migration routes to one another may help synchronise returns to the breeding colony, which is known to be important for pair bond and breeding success in many migratory birds.'
Moving forward the team hopes to build on the findings and recent technological developments, investigating the movements and behaviour of seabirds when they are at sea. Dr Fayet said: 'At the end of the breeding season puffins disappear at sea for over eight months before returning the following spring, and scientists have long had questions about where they go during that time. However, until recently tracking devices were too big to use on small birds like puffins. The recent miniaturisation of tracking technology mean we can now study the at-sea movements of puffins and other small migratory seabirds remotely over months and even years. Complex analytical techniques like machine learning can also be used to identify behaviours in tracking data, allowing us to know not only where birds go, but also what they do at sea (e.g. flying, foraging). This will help us study seabirds' at-sea ecology and behaviour, which is currently poorly understood, but the results will also be invaluable for the conservation of seabirds, which are currently threatened by ocean pollution and overfishing, making them the most endangered group of birds on the planet. This includes puffins, which have been dramatically declining in the last few decades. '
If little auk parent-birds are stressed, they ignore the begging of their offspring and start searching food mainly for themselves. (Photo: Dorota Kidawa)
Stress is a factor not only in the best human families; it also appears among animals. To see how bird family members interact with each other in stressful situations, researchers from Vetmeduni Vienna and the University of Gdansk, Poland, studied parent-offspring interactions in a long-lived seabird, the little auk (Alle alle). The scientists gave parent and offspring birds a hormone pellet to increase their "stress levels", with the result that stressed offspring not only intensified their begging but also received more food than "relaxed" chicks. Nevertheless, increased begging was not the determining factor of the parent-offspring interaction. When parent birds were stressed, they automatically reduced offspring feeding and spent more time searching for food for themselves. The parent-offspring interaction among little auks therefore clearly depended on the state of the adult bird, even though little auks usually raise only a single chick. The results have been published in the Journal of Ornithology.
Little auks (Alle alle) breed in large colonies on rocky cliffsides in arctic regions. These seabirds live in a harsh environment and often face stress in the form of food shortages and poor weather conditions. But this isn't the only thing that makes them so suitable to study stress-induced behavioural mechanisms. They also are of interest for their long lifespan and because little auks raise only a single chick during the year, which excludes sibling rivalry as a factor in stress studies. A team of researchers from Vetmeduni Vienna and the University of Gdansk in Poland thus attained informative insights into the interaction between long-lived birds and their offspring.
Stressed little auk chicks intensify begging for and also recive more food as long as their parents are relaxed. (Photo: Dorota Kidawa)
Stress behaviour in birds controlled by hormones
"Birds respond to stressful situations by releasing the hormone corticosterone," explains senior author Rupert Palme from the Department of Physiology, Pathophysiology and Experimental Endocrinology at Vetmeduni Vienna. This makes corticosterone an important stress indicator in behavioural studies. Hormone pellets can be used to artificially release corticosterone into the birds' bloodstream in order to observe the animals' behaviour under stress. The pellets have the advantage that corticosterone is released in a controlled fashion continuously over a certain period of time. An analysis of faecal samples can be used to show that the additional hormone was metabolised by the body. The internationally recognised method of measuring faecal hormone metabolites was developed by senior author Palme.
To analyse the mechanisms controlling familiar interactions among little auks, the researchers first implanted offspring birds, then parents with hormone-releasing pellets. Chick behaviour was analysed using acoustic recordings, that of the parents by looking at feeding intervals and time spent away from the nest or colony.
Little auk offspring come in second place
Nestlings responded to the artificially heightened stress levels by increasing their begging performance. "More food means more reserves, better fitness and, therefore, a higher chance of survival," says first author Dorota Kidawa from the University of Gdansk, Poland. "The intensified begging behaviour was a cry for help directed at the parent birds that was clearly successful." The stressed offspring weighed more than the control chicks, which indicates that they had been fed more frequently by the parent birds. "Our study shows that adult little auks usually go to their limit, to their caring maximum, in order to give their offspring enough to eat," says Palme.
The second test, however, in which the researchers implanted a hormone pellet into one of the parent birds, showed that this limit depends on the stress level of the parent bird and not on the begging behaviour of the young little auks. Under stress, parent birds alter their behaviour to their own benefit. They left the nest for longer periods of time to provide more food for themselves. As a result, they fed their young less frequently and the physical state of the offspring worsened considerably compared to the control group.
Little auks are longliving seabirds and breed in harsh environmental conditions. Their "selfish" response to stress is thus a normal occurence. (Photo: Dorota Kidawa)
Despite egoistic survival instinct, the birds are not bad parents
"The begging behaviour elicited a care response among the adult little auks. But this response, and its extent, depend on how fit the parent birds feel," says Palme. If their own chance of survival is reduced because of a food shortage or weather conditions, they will focus more on themselves and spend more time looking for their own food than on the care of their only chick. "But that doesn't make them bad parents," says Palme. "This is a normal occurrence in nature that cannot be compared to our behaviour and sense of responsibility." For the long-lived little auks, it is more important to secure their own existence, to survive another year and to raise another offspring in the future. After all, poor food conditions and environmental factors can also reduce the young birds' chance of survival.
Understanding a seemingly unlikely survival strategy.
This is a father and his offspring contemplating the leap off high cliffs at Saunders, Greenland. Photo by Knud Falk.
Before they have the wing span to actually permit them to fly, young guillemots (also known as murres) leap hundreds of metres off towering cliffs and flutter down towards the sea, guided by their fathers. Scientists have long wondered why these tiny chicks make this remarkable leap, hoping to avoid the rocks below them, in what seems an unlikely survival strategy for a species.
It had earlier been suggested that murre offspring headed off to sea once the chicks reached about one-quarter of their adult size and were large enough to defend themselves from potential predators and too large to be fed at the colony. So that this seemingly death-defying behaviour could be better understood as being, in some ways, a tradeoff between the safety offered in the colony and fast growth rates at sea, where more food is available.
But after tracking the behaviour of murre fathers and their offspring for six weeks in murre colonies in some of the most remote locations on the globe, in Nunavut, Greenland, and islands off Newfoundland, scientists have discovered that mortality rates were similar between chicks at sea and in the colonies. Moreover, the team which was made up of researchers from McGill and Memorial Universities in Canada and Aarhus and Lund Universities in Denmark and Sweden discovered that chicks at sea grew at roughly twice the speed of those at the colony, because the murre fathers no longer needed to fly back and forth to the colony to feed them.
Just after the jump -- a father who lost his offspring during the leap off the cliffs followed by another father whose chick survived the descent. Photo by Kyle Elliott
The dads work hard while the mothers stay home and party
Unusually among animals, after three weeks of care by both parents, it is the father who then spends 5 to 7 weeks rearing the offspring by himself on the high seas. Meanwhile, the mother spends her time partying back at the colony, copulating with paramours to choose a potential suitor should her mate not return the next year. The study documented the hard work done by the father. The team recorded males spending up to six hours underwater each day to feed the chick, while the female spent only one to two hours underwater each day.
"The Arctic summer is short", says Elliott, who teaches in McGill University's Department of Natural Resource Sciences. "The mother must produce an egg quickly. Murres have the highest flight costs of any animal, and the female works hard at the front end flying back-and-forth to the colony, leaving her exhausted by mid-summer. Nonetheless, we were astonished to see how hard the father worked through late summer, spending virtually every daylight hour diving to feed the chick."
Making sense of a death-defying leap
"Once you know that there are both higher growth rates for the chicks at sea, and similar survival rates compared with life in the colony, it then makes sense to see this seemingly death-defying leap as a win-win strategy when it comes to survival," says Kyle Elliott, the lead author on a paper on the subject that was published online March 8 in The American Naturalist. Elliott teaches in McGill University's Department of Natural Resource Sciences. "We would never have been able to discover this without using the kind of state-of-the-art recorders that are now available and provide a glimpse into the life of murres on the high seas."
People living in neighborhoods with more birds are less likely to suffer from depression, anxiety and stress.
European Robin in front of Cabot Tower, Bristol, England. Photo: Sam Hobson.
People living in neighbourhoods with more birds, shrubs and trees are less likely to suffer from depression, anxiety and stress, according to research by academics at the University of Exeter, the British Trust for Ornithology and the University of Queensland.
The study, involving hundreds of people, found benefits for mental health of being able to see birds, shrubs and trees around the home, whether people lived in urban or more leafy suburban neighbourhoods.
The study, which surveyed mental health in over 270 people from different ages, incomes and ethnicities, also found that those who spent less time out of doors than usual in the previous week were more likely to report they were anxious or depressed.
After conducting extensive surveys of the number of birds in the morning and afternoon in Milton Keynes, Bedford and Luton, the study found that lower levels of depression, anxiety and stress were associated with the number of birds people could see in the afternoon. The academics studied afternoon bird numbers - which tend to be lower than birds generally seen in the morning - because are more in keeping with the number of birds that people are likely to see in their neighbourhood on a daily basis.
In the study, common types of birds including blackbirds, robins, blue tits and crows were seen. But the study did not find a relationship between the species of birds and mental health, but rather the number of birds they could see from their windows, in the garden or in their neighbourhood.
Previous studies have found that the ability of most people to identify different species is low (e.g. Dallimer et al. 2012), suggesting that for most people it is interacting with birds, not just specific birds, that provides well-being.
University of Exeter research fellow Dr Daniel Cox, who led the study, said: "This study starts to unpick the role that some key components of nature play for our mental well-being".
Birds around the home, and nature in general, show great promise in preventative health care, making cities healthier, happier places to live".
The positive association between birds, shrubs and trees and better mental health applied, even after controlling for variation in neighbourhood deprivation, household income, age and a wide range of other socio-demographic factors.
Recent research by Dr Cox and Professor Kevin Gaston, who are based at the Environmental Sustainability Institute at the Penryn Campus at the University of Exeter, found that watching birds makes people feel relaxed and connected to nature (Cox and Gaston 2016).
