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Avian News

Posted on 2. March, 2018.

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2018: Year of the Bird
2018 marks the centennial of the Migratory Bird Treaty Act. To honour this milestone, National Geographic, the National Audubon Society, the Cornell Lab of Ornithology and BirdLife International are joining forces with more than 100 other organisations to celebrate 2018 as the Year of the Bird.
This effort aims to heighten public awareness of birds because of their wonder and beauty, and because they symbolise nature’s interconnectedness and the importance of caring for our shared planet.
To get started, visitors to BirdYourWorld.org will discover simple but meaningful steps that anyone can take to help birds each month and join a pledge to participate. These steps include participating in the worldwide Great Backyard Bird Count in February, putting in native plants in the spring, and cutting back on the use of plastic materials.
Through 12 months of storytelling, science research, and conservation efforts, Year of the Bird will examine how our changing environment is driving dramatic losses among bird species around the globe and highlight what we can do to help bring birds back.
Participating organisations include nonprofit and conservation groups, state and federal agencies, zoos, nature centres, and ornithological societies that are working together to raise the visibility of birds and inspire action through #BirdYourWorld throughout 2018. The campaign will also utilise National Geographic’s portfolio of media platforms reaching millions of people around the world with engaging bird content that will educate, inspire, and raise awareness about the challenges that birds are facing and what people can do to help.

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Noise pollution causes chronic stress in birds
Birds exposed to the persistent noise of natural gas compressors show symptoms remarkably similar to those in humans
suffering from post-traumatic stress disorder, according to an article published in the Proceedings of the National Academy of Sciences.
Researchers found that adults and nestlings of three species showed multiple signs of chronic stress caused by noise
pollution, including skewed stress hormone levels, possibly due to increased anxiety, distraction and hypervigilance. The study is the first to test the relationships between noise, stress hormones and fitness in animals that breed in natural areas with unrelenting, human-made noise.
Constant noise could be acting as an ‘acoustic blanket’, muffling the audio cues birds rely on to detect predators, competitors and their own species, said study co-author Rob Guralnick of the Florida Museum of Natural History. Unable to discern whether their environment is safe, mother birds must choose between staying on guard at the nest and finding food for their young.
Nestlings in the noisiest environments had smaller body sizes and reduced feather development, potentially diminishing their odds of survival. Hatching rates in Western Bluebirds – the most noise-tolerant species studied – dropped in response to noise.
‘These birds can’t escape this noise’, said Guralnick. ‘They’re perpetually stressed because they can’t figure out what’s going on. Just as constant stress tends to degrade many aspects of a person’s health, this ultimately has a whole cascade of effects on their physiological health and fitness.’
The research team set up 240 nesting boxes staggered at precise distances from gas compressors. This allowed them to examine stress responses of nesting birds across a measurable gradient of noise. The team tested levels of the stress
hormone corticosterone in three species – Western Bluebirds, Mountain Bluebirds and Ash-throated Flycatchers. Expecting
corticosterone levels to be high, the researchers found the opposite: the louder the noise from gas compressors, the lower the birds’ baseline corticosterone levels. These results were consistent in adults and chicks across all three species.
While initially surprising, the findings came into focus when compared with lab studies of chronic stress. Low corticosterone can be a sign that stress is so intense, the body has dialled down the baseline levels of the hormone as a means of self-protection. 
When testing chicks’ response to a sudden threat, researchers found that the birds’ corticosterone skyrocketed compared
with typical high-stress levels and was slow to return to baseline levels. The link between low baseline corticosterone levels and abnormal spikes in acute stressortriggered corticosterone also parallels previous chronic stress studies on humans and rodents, Guralnick said.
Noise levels at natural gas fields are not unusually loud compared with human-made noise, which has important implications for protecting wildlife and possibly human health, the researchers said.
The article, ‘Chronic anthropogenic noise disrupts glucocorticoid signaling and has multiple effects on fitness in an avian community’ by Nathan J. Kleist, Robert P. Guralnickc, Alexander Cruz, Christopher A. Lowry and Clinton D. Francis, was published in the Proceedings of the National Academy of Sciences, https://doi.org/10.1073/pnas.1709200115.

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Genetic mapping shows migratory birds’ vulnerability to climate change
As Earth’s climate changes, species must adapt, shift their geographical ranges or face decline and in some cases extinction.
Using genetics, scientists at the University of California at Los Angeles’ Bird Genoscape Project are racing against time to find out the potential for adaptation and how best to protect vulnerable populations of birds.
The project’s most recent study, published in Science, focuses on the Yellow Warbler. Found across most of North America, the bird spends its winters in Central and South America, and flies as far north as Alaska and the Arctic Circle in the summer.
Using more than 200 blood, tissue and feather samples from across the breeding range, the researchers discovered genes that appear to be responding to climate, and found that bird populations that most need to adapt to climate change are experiencing declines.
‘With this research, we can say “based on these gene-environment correlations, here’s how populations will have to adapt to future climate change. And here are the populations that have to adapt most”’, said Kristen Ruegg, co-director of the Bird Genoscape Project. Whether the Yellow Warbler will be able to adapt is another matter. ‘That’s our next big question’, she said.
By comparing the genetic findings to breeding bird surveys dating back to the 1960s that track changes in bird abundance, the researchers determined that the populations that need to adapt most are already in decline. Using genetic maps, the habitats of the populations most vulnerable to climate change can now be targeted for protection, said Rachael Bay, lead author of the study.
‘Evolution has the potential to matter a lot when it comes to climate change response’, Bay said. ‘It’s a process we should start to integrate more when we make decisions, and it’s shown a lot of promise that hasn’t been realised yet.’
The study sets the stage for two important next steps. First, it means additional studies need to be done to learn how other species adapt to climate change. Second, the findings can be used now to tailor and inform future conservation management.
The article ‘Genomic signals of selection predict climate-driven population declines in a migratory bird’ by Rachael A. Bay, Ryan J. Harrigan, Vinh Le Underwood, H. Lisle Gibbs, Thomas B. Smith and Kristen Ruegg, was published in Science, https://doi.org/10.1126/science.aan4380.

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When birds meet high-speed rail
A new study has examined the impact of high-speed trains on birds such as magpies, pigeons, crows and buzzards in Spain. The research was published in Frontiers in Ecology and Evolution.
Researchers installed a video system in the cabins of locomotives during more than 14,000 km of circulation at speeds of 250–300 km h–1. ‘This has allowed us to obtain the first ever published estimate of bird mortality by high-speed trains and better understand the behaviours that condition the crash’, said Juan Malo, of the Autonomous University of Madrid.
They have calculated that a highspeed train crosses birds in the vicinity approximately every 14.5 km and runs over a bird every 360 km. ‘On the Madrid–Levante line, on which the work has been carried out, some 60 birds per kilometre between Madrid and Motilla del Palancar, and 26 birds per kilometre on the stretch
between Motilla del Palancar and Albacete, can be run over every year’, said Malo.
The researchers recorded 1,090 birds in front of a train cabin to better understand which ones are more at risk and why. Many of the birds were perched on the ground, roads or cables of the infrastructure just before the train passed.
The videos showed that the birds generally reacted at a distance of 60–135 m of the train, so the train´s speed left them little time to escape. ‘As a result, a small fraction of the birds that can be seen from the front of a train end up dying run over’, said Malo.
The team plans to study procedures to prevent birds from using elements of the infrastructure, and systems that decrease the frequency with which animals fly through the risk area in which trains circulate. ‘The published data will serve to inform about the environmental impact assessments that are made in the future on the railway tracks to be built, and to guide the design of corrective measures’, concludes Malo.
The article, ‘On-board video recording unravels bird behavior and mortality produced by high-speed trains’ by E.L. García de la Morena, J.E. Malo, I. Hervás, C. Mata, S.G. Madrigal, R. Morales and J. Herranz, was published in Frontiers in Ecology and Evolution, https://doi.org/10.3389/fevo.2017.00117.
Material for this story was provided by the Spanish Language Information and Scientific News Service (SINC).

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The flight speed of birds is more complex than previously thought
Scientists from Lund University in Sweden had previously found that the flight speed of terns is affected by their morphology, weight and the size of their flock – the larger the flock, the faster the speed.
Their new research, published in Animal Behaviour, has found that birds use multiple methods to control their speed in the air to compensate for tailwind, headwind and sidewind.
In their new study, Anders Hedenström and Susanne Åkesson focused on three types of waders: Eurasian Oystercatchers, Red Knots, and Dunlins. They monitored bird flocks on southern Öland with the help of an ornithodolite: a binocular instrument equipped with a laser rangefinder as well as height and side-angle sensors.
By connecting the laser instrument to a computer, they registered a sufficient number of positions to get a clear picture of the birds’ flight paths. They also measured the velocity and direction of the wind at different heights. The wind measurements were subsequently compared to the results obtained using the ornithodolite.
The researchers were able to draw several conclusions. Birds compensate for headwinds by increasing the frequency of their wing strokes and thereby flying faster. They compensate for tailwind through fewer wing strokes compared to when there is no wind. Whenever the birds fly along the coast, the coastline helps them to compensate for sidewind and avoid drifting, which is harder when flying over open water.
Furthermore, the size of the flock affects the speed of the waders the same way it does for terns although the researchers have yet to discover why. ‘We don’t know for sure, but we believe there is a mechanistic explanation; simply, that the largest, heaviest and strongest individuals determine the speed of the flock’, said Hedenström.
The article, ‘Flight speed adjustment by three wader species in relation to winds and flock size’ by Anders Hedenström and Susanne Åkesson, was published in Animal Behaviour, https://doi.org/10.1016/j.anbehav.2017.10.022.

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Crafty crows know how to make a good tool
New Caledonian Crows are the only species besides humans known to manufacture hooked tools in the wild. Birds produce these remarkable tools from the side branches of certain plants, carefully ‘crafting’ a crochetlike hook that can be used for snagging insect prey. A study, published in Current Biology shows how the crows manage to fashion particularly efficient tools, with welldefined ‘deep’ hooks.
The hook is widely regarded as one of humankind’s most important innovations. While our ancestors started making stone tools over 3 million years ago, hooks are a surprisingly recent advance – the oldest known fish hooks are just 23,000 years old.
Scientists from the University of St Andrews have been conducting field research on New Caledonian Crows for over a decade. They recently noticed that the crows’ hooked tools vary considerably in size and shape. While some tools only exhibit a small extension at the tip, others have immaculate hooks.
‘We suspected that tools with pronounced hooks are more efficient, and were able to confirm this in controlled experiments with wild-caught crows. The deeper the hook, the faster birds winkled bait from holes in wooden logs’, said Christian Rutz.
The researchers discovered that the depth of the hook was influenced by both the properties of the plant material, and the technique the crows used for detaching branches. When birds made controlled cuts with their sharp bills, the resulting hooks were significantly deeper than when they used a ‘sloppier’ alternative method of simply pulling off branches. Careful cutting may leave more wooden material at the tip of the stick from which the hook can subsequently be ‘sculpted’.
Surprisingly, the adult crows, which are expected to have considerable tool-making experience, did not produce the deepest hooks and regularly employed the ‘quickand-dirty’ manufacture technique. Rutz notes that making very deep hooks may not be the best strategy in the wild: ‘It probably takes more time and effort to make such tools, and experienced birds may try to avoid these costs. It is also possible that deep hooks break more easily when inserted into narrow holes and crevices.’
The study is the first to examine in a non-human animal what factors determine the morphology of crafted tools, and as a consequence, their foraging efficiency.
The article, ‘Causes and consequences of tool shape variation in New Caledonian Crows’ by Shoko Sugasawa, Barbara C. Klump, James J.H. St Clair and Christian Rutz, was published in Current Biology, https://doi.org/10.1016/j.cub.2017.11.028.

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Lake Michigan waterfowl botulism deaths linked to warm waters and algae
Since the 1960s, tens of thousands of birds living on the Great Lakes have died during periodic outbreaks of botulism. The outbreaks have only become more common and widespread in recent years, leaving scientists who track the birds puzzled.
To understand the spiking outbreaks, ecologists at the University of Wisconsin Madison and the US Geological Survey turned to citizen scientists. In a USGS programme, volunteers tracked bird deaths along Lake Michigan from 2010 to 2013 to discover what conditions lead to large dieoffs. Their findings were published in the Journal of Applied Ecology.
The researchers found that warm waters and algae – both of which have become more frequent over the years – tended to precede bird deaths, likely because they promoted the growth of botulism toxin producing
bacteria.
Birds can contract botulism in much the same way people can: by eating food infected with the toxin-producing bacteria. The toxin leads to paralysis and death, often in waterfowl by drowning. To keep track of these deaths, the researchers created a citizen-science programme in which volunteers walked along Lake Michigan beaches recording the number of sick and dead birds of different species. Researchers at the centre tested a sample of bird carcasses, and the majority tested positive for botulism.
The citizen scientists were indispensable for the research project, according to Karine Princé, formerly of UW Madison, and now at the National Museum of Natural History in Paris. ‘With citizen-science programmes, we are able to collect a lot of data at multiple spatial and temporal scales, which you can’t necessarily do in a university-led research programme. It’s great that we can have access to this data’, she said.
The team also used satellite data to measure environmental conditions such as temperature, water level and visible algae. This showed that botulism-related die-offs spiked when waters were warmer and algae growth was high. Many lakes have been warming with a changing climate, and clearer water caused by invasive Zebra Mussels provides more sunlight for algae to grow in thicker mats. Those conditions create the low-oxygen environments where the botulism toxin-producing bacteria thrive.
The team also found that die-offs were synchronised within a roughly 40 km radius from one location to another. That kind of spatial co-ordination could help monitor a wider geographic region with fewer people on the ground as data collected in one area could be applicable to a wide geographic region nearby.
The article, ‘Environmental conditions synchronize waterbird mortality events in the Great Lakes’ by Karine Princé, Jennifer G. Chipault, C. Leann White and Benjamin Zuckerberg, was published in the Journal of Applied Ecology, https://doi.org/10.1111/1365-2664.13063.

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As climate warms, more bird nests are destroyed in Finnish farmland
Finnish farmers are adapting to the warming climate by moving the time when they sow their fields in the spring. At the sametime, birds are also advancing their time of breeding as the spring temperatures become milder. A study published in Biological Conservation shows that birds have shifted their time of breeding much faster than the farmers have their sowing times. This means that more birds are laying their eggs on fields that are still to be sown.
Mechanical sowing of large arable areas in spring causes the destruction of many lapwing and curlew nests, since these species make their nests on the ground. The long-term ringing data of breeding curlew and lapwings since the 1970s suggests that as a result of shifts in timing of breeding, the incoming mechanical sowing now destroys most of the nests that are laid on arable land.
‘As the eggs of curlew and lapwings are placed on unsown fields, they are likely to be run over by farming machinery during sowing operations even if farmers were willing to avoid nest destructions’, said Andrea Santangeli of the Finnish Museum of Natural History, which is part of the University of Helsinki.
The link between the responses of humans and wildlife to climate change has so far been largely understudied. This study is among the first to investigate changes in the timing of land management in relation to changes in the timing of key life-stages of wildlife, but the observed pattern is unlikely unique. ‘We believe the types of outcomes uncovered in the Finnish context may be common also in other systems’, said Santangeli.
The article, ‘Stronger response of farmland birds than farmers to climate change leads to the emergence of an ecological trap’ by Andrea Santangeli, Aleksi Lehikoinen, Anna Bock, Pirjo Peltonen-Sainio, Lauri Jauhiainen, Marco Girardello and Jari Valkama, was published in Biological Conservation, https://doi.org/10.1016/j.biocon.2017.11.002.



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