Tag Archives: migration

Penguin forensics: Tracking the winter whereabouts of penguins by analyzing tail feathers

Penguin forensics
( Louisiana State University, Physorg 8 >August 2017; Photo M. Polito)

While a postdoctoral researcher at Woods Hole Oceanographic Institution, Polito and his colleagues conducted high-resolution forensic analyses of the chemical composition of the feathers using a technique called compound-specific stable isotope analysis of amino acids.

The scientists were able to identify the unique chemical signatures of penguin’s wintering areas in the ocean based on the coordinates from the tags and the data from the feather analyses. From this understanding, they were able to deduce where the other penguins that had not been tagged went over the winter based solely on the analyses of their tail feathers.

“This novel approach could be applied to different tissues from a wide variety of marine animals that migrate over long distances including seabirds, sea turtles, seals and whales,” Polito said. “Using stable isotope forensics to increase the size and scope of animal tracking studies will help us to better understand these charismatic species and ultimately aid in their conservation.”

Knowing where and how Antarctic penguins, and other seabirds and marine predators, migrate is critical for conservation efforts. Although electronic tracking devices have helped scientists track marine animals’ migration patterns, the devices can be expensive, invasive for the animal and challenging to retrieve. Scientists have discovered a new and potentially better way to track where penguins go over the winter using forensics.

“You can say, penguins ‘are where they eat,’ because a geochemical signature of their wintering area is imprinted into their feathers,” said LSU Department of Oceanography & Coastal Sciences Assistant Professor Michael Polito, the lead author of this study that will be published Aug. 9 in Biology Letters.

Chinstrap and Adélie penguins are part of the family of “brush-tailed” penguins named after their approximately 15-inch long, stiff tail feathers. These birds shed all of their feathers after each breeding season and before they migrate to their oceanic wintering grounds. However, their long tail feathers continue to grow well into the winter when penguins are at sea.

Polito and his collaborators from NOAA Southwest Fisheries Science Center, Oxford University and the Instituto Antártico Argentino attached tags to 52 adult Chinstrap and Adélie penguins at their breeding colonies and retrieved the tags the following breeding season to determine where the birds went over the winter. When they retrieved these tags, the researchers also took a tail feather grown over the winter from each tracked penguin and from 60 other penguins that had not been tagged.

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How migrating birds ‘run a marathon,’ burning muscles and organs in long flights

How migrating birds 'run a marathon,' burning muscles and organs in long flights

(Physorg, University of Massachusetts Amherst 12 July 2017)

Migrating birds complete long non-stop flights of many hours for songbirds and days for some shorebirds to reach breeding or wintering grounds. During such flights a bird’s metabolic rate is very high, fueled by stored fat, but also by burning the protein in musc

les and organs in a process that is not well understood, says eco-physiologist Alexander Gerson at the University of Massachusetts Amherst.

Now he has received a three-year, $756,000 National Science Foundation grant to thoroughly investigate the consequences and mechanisms of this phenomenon, which sometimes leads to dramatic reductions in migrating birds’ muscle mass and organs but may not result in significant loss of function.

As he explains, “There is evidence that some birds see a 20 percent reduction in muscle mass and up to 50 percent mass losses in the liver, intestine, kidneys and other organs except the brain and lungs. In one of the longest flights documented in this hemisphere, the blackpoll warbler during migration flies 22 hours over water, where they absolutely cannot stop. When you run a marathon like that, you either run out of fuel or water, but these birds can produce both by metabolizing their muscle and organ tissues.”

He adds, “We’re interested in what happens during flight, where the energy comes from, and how they maintain water balance. Water is produced from metabolism, and breaking down protein yields the most. But what happens when you lose 20 percent of your pectoralis muscles? Do you lose function or just size? These are a few of our questions.”

Gerson says this study will use two ultra-specialized tools not available to most researchers: a field-portable quantitative magnetic resonance imaging (QMRI) machine, and a wind tunnel specifically designed to study long duration flight in birds, one of just three in world, located at the Advanced Facility for Avian Research at Western University in London, Ontario.

The experimental series will look at body fat, lean mass and water content in one larger species, Swainson’s thrush, and one smaller, the yellow-rumped warbler, in the field and in wild birds flying in the climate-controlled wind tunnel. There, researchers can manipulate such factors as humidity and temperature to study the amount of water lost to respiration. This is relevant to climate change, Gerson notes, because flying in warmer air means more protein and water loss.

His research team will also look at water-loss rates in non-flight conditions, at rest, and look for differences among migrants and non-migrants. Further, Gerson and colleagues will conduct metabolic phenotyping and use transcriptomics to explore molecular mechanisms of protein breakdown and regeneration with UMass Amherst molecular biologists Courtney Babbitt and Larry Schwartz.

Gerson intends to engage many undergraduate and graduate students from diverse backgrounds in the research, training them in a range of cutting-edge techniques applicable to many science, technology, engineering and mathematics (STEM) fields. They will in turn develop and implement science communication and outreach programs for middle school students in a local low-income school district yet to be determined.

At the end of three years, Gerson says, “We hope to better understand the influence of climate on flight metabolism and have a better understanding of functional consequences of protein breakdown, which has the potential to be exciting because they burn a lot of muscles and don’t seem to show any dramatic functional loss. It may shed some really new light on questions that have been around for quite some time.”

Birds’ migration genes are conditioned by geography

(Lund University 6 July 2017; Photo Max Lundberg)

The genetic make-up of a willow warbler determines where it will migrate when winter comes. Studies of willow warblers in Sweden, Finland and the Baltic States show that “migration genes” differ — depending on where the birds breed in the summer. The willow warblers that breed in southern Sweden migrate to West Africa, while those in northern Sweden, Finland and the Baltic States fly to southern or eastern Africa.

According to a new study led by biologists at Lund University, the key to the willow warblers’ differing migration patterns probably lies in their genes.

The researchers studied the entire genetic make-up of willow warblers that breed in southern and northern Sweden, Finland and the Baltic States. The comparison shows that the genomes are almost completely identical, but there are significant differences between the birds that breed in southern Sweden and those that breed in the northern parts of the country and east of the Baltic.

The differences are restricted to two regions in the genome, where the comparison shows extensive differences in over 200 genes.

“Of these 200 or so genes, there are several that can be considered to be important for migration-related physiological adaptations and others that, according to our present knowledge, have a poorly characterized or unknown function,” says Max Lundberg, researcher at Lund University.

According to him and his colleagues, the genetic differences are probably decisive in determining that willow warblers in southern Sweden migrate to West Africa, whereas the more northerly willow warblers head for the south-east of Africa.

Researchers have previously known that the migration behaviour of many birds is strongly determined by genetics. Inherited information in the genes determines the direction of migration and a schedule that contains information about when and how far the birds are to migrate. The migration over thousands of kilometres also requires inherited physiological adaptations, for example to store and use fat and energy as efficiently as possible. Up to now, however, very little has been known about the specific changes in the genetic make-up that underlie where birds, in this case willow warblers, migrate.

“Our results represent an important addition to the understanding of migration-related genetics and will guide future studies in the subject,” says Staffan Bensch, a professor at Lund University.

 

Birds’ feathers reveal their winter diet

(AOS 21 June 2017; Photo RM Jensen)
Influences outside the breeding season can matter a lot for the population health of migratory birds, but it’s tough to track what happens once species scatter across South America for the winter months. A study from The Condor: Ornithological Applications tries a new approach for determining what declining migratory grassland birds called Bobolinks eat after they head south for the winter—analyzing the carbon compounds in their plumage, which are determined by the types of plants the birds consume while growing their feathers during their winter molt.

Thanks to a quirk of photosynthesis, rice contains a different ratio of carbon isotopes than most of the native grasses in South America where Bobolinks winter. Rosalind Renfrew of the Vermont Center for Ecostudies and her colleagues took advantage of this, collecting feather samples from wintering Bobolinks in a rice-producing region and a grassland region and from breeding Bobolinks in North America. When they analyzed the feathers’ isotopes ratios, the results from South America confirmed that isotopes in Bobolinks’ feathers reflected the differences in their diets between regions with and without rice production. The samples taken in North America showed that the winter diet of most individuals was weighted more toward non-rice material, but that rice consumption was highest late in the winter, when rice is nearing harvest and the birds are preparing for their northbound migration.

Rice could be beneficial by providing the birds with needed calories as they prepare for their journey north, but it could also increase Bobolinks’ exposure to pesticides and threats from farmers who see them as pests. According to Renfrew and her colleagues, maintaining native grasslands, encouraging integrated pest management programs to reduce toxic pesticide applications, and compensating farmers for crops lost to feeding birds all would be helpful.

“The time spent coordinating the field work for this study may well have been greater than the time spent collecting the data,” says Renfrew. “It was truly a team effort, and the assistance we received from our partners was absolutely essential, especially in South America. Aves Argentinas and the Museo de Historia Natural de Noel Kempff Mercado provided priceless logistical support, and this study could not have happened without them. Some of the same partners have provided input on a Bobolink Conservation Plan that lays out actions to address threats to grassland birds in North and South America, based on results from this and other studies.”

“As Bobolink populations continue to decline, Renfrew and her colleagues use state-of-the-art isotope analysis techniques to assess the Bobolink’s diet on its South American wintering grounds,” according to John McCracken of Bird Studies Canada, an expert on grassland bird conservation who was not involved with the study. “The authors conclude that rice may have negative effects on Bobolinks, owing to its relatively low nutritional quality and from exposure to insecticides.

Fuel loads acquired at a stopover site influence the pace of intercontinental migration in a boreal songbird

(Camila Gómez, Nicholas J. Bayly, D. Ryan Norris, Stuart A. Mackenzie, Kenneth V. Rosenberg, Philip D. Taylor, Keith A. Hobson & Carlos Daniel Cadena 13 June 2017)

 

Although migration is an adaptive behaviour in a wide range of animals1,2,3, it is also thought to impose significant costs on individuals4. Studies on various migratory birds5,6,7, mammals8 and fish9 provide evidence that mortality can be higher during migration than during stationary periods of the annual cycle. In addition, work on birds10, 11 and insects12 indicates that migrating individuals often undergo significant metabolic and behavioural adjustments to fulfil the high energetic demands of migration. Time spent and energy used during migration can also determine subsequent breeding success10, 12,13,14,15, emphasizing the high costs that individuals pay when migrating. Because migration is costly, migratory organisms are expected to maximize their fitness behaviourally via minimizing either the time spent, energy consumed, or the risks incurred during migratory journeys16, 17.

In terms of time, the highest cost of migration is generally thought to be experienced during stopovers rather than during periods of flight18, 19, and birds rely on the time spent at stopover sites to rest and refuel for the next leg of their journeys20. Optimal migration theory provides a framework to study stopover behaviour and its consequences by testing whether migrants are time- or energy-minimizers using data on fuelling rate, stopover duration, fuel loads and potential flight ranges17. Individuals attempting to minimize the overall time spent on migration are expected to maximize the amount of fuel they can acquire at each stopover in the shortest time possible. A key consequence of this strategy is that it maximizes the distance that can be flown between stopovers18, 21. Consequently, the fuel loads (amount of fat carried) of a time-minimizer should be tightly linked to local conditions at stopover sites as well as to the conditions expected ahead because these conditions influence fuelling rates18, 21. Furthermore, stopover durations in time-minimizers are expected to have been shaped by or to respond directly to experienced fuelling conditions17, 18. Larger departure fuel loads should allow for longer flights and a faster overall pace of migration because individuals acquiring sufficient fuel in the shortest time possible will need to make fewer stopovers and be able to take more direct routes to their destination, including being able to fly over physical barriers or large areas of unsuitable habitat such as deserts or oceans rather than circumventing these areas22.

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War-torn Kabul becomes a protected site for migratory birds

(Anne Chaon 13 June 2017)

A rare Afghan marsh that was once a royal hunting ground is set to come under the official protection of the UN environment agency, with the aim of saving hundreds of migratory bird species.

On the long, arid journey to the Caucasus and Siberia, across the Hindu Kush massif, the Kol-e-Hashmat Khan wetlands outside Kabul provide sanctuary for the thousands of storks, egrets, pelicans and flamingos that head north every spring from southern India.

But after 40 years of conflict and neglect, their habitat is being threatened by the growth in new homes, irrigation systems, rubbish and global warming which is gradually changing the local environment.

Now the UN has designated the wetlands a conservation site, the Afghan government said on Sunday, as it also looks to help preserve the water supply of the capital.

“There are probably more than 300 or 400 species that pass through, though without an accurate count it is hard to be sure,” says Andrew Scanlon, head of the United Nations Environment Programme (UNEP) in Afghanistan.

They are migratory birds and “tourists” who stay for a very short period of time to find food, he adds.

At daybreak, the marsh comes alive with the morning chatter of the birds hungry for breakfast.

Binoculars in hand, Scanlon stands atop a tower that dominates the landscape.

In the distance is the silhouette of Bala Hissar, an ancient fortress that defended the city for centuries. Opposite, mud houses and sturdier dwellings made from bricks seem to spring up at random, hurrily erected during wars for tides of refugees and displaced people.

It was once a favoured place for royals to go hunting, though Scanlon stresses any activity would have been carried out “in a sustainable way”.

But with the invasion of the Soviet army in 1979 and the succession of conflicts afterwards, including the civil war in the early 1990s, Afghans were preoccupied by their own survival and the environment suffered.

War saw the marshes more or less abandoned until 2005, Scanlon explains.

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Wind blows young migrant birds to all corners of Africa

(Universiteit van Amsterdam 24 May 2017)

Migrant birds that breed in the same area in Europe spread out across all of Africa during the northern winter. A new satellite-tracking study shows that the destination of individual birds is largely determined by the wind conditions they encounter during their first migration. The results were made available open access in the peer-reviewed journal Proceedings of the Royal Society B.

Until now little was known about how birds learn to migrate. Many young migrant birds die on their way to Africa, due to starvation, exhaustion or predation, or because they fall victim to hunters or collide with power lines and other human-made structures along the way. Wouter Vansteelant, lead author of the study, explains: ´As researchers we take a risk by tracking young birds with expensive tracking devices. Until now most people studied adult birds because they have a higher chance of survival. For this study, however, we decided to place satellite-tracking devices on 31 young honey buzzards that hatched from the egg in southwestern Finland.´

Of the 31 honey buzzards, 27 were able to start their first migration to Sub-Saharan Africa. Vansteelant: ´Twenty-four of these birds survived their first migration, ending up as far west as Mali and as far east as the Congo. The most western bird was located more than 3300km from the most eastern bird.´ The research team found that the location where the birds had ended up further west or east depended on the wind conditions they encountered along the way. ´We also saw that some individuals deviated from their average course to cross barriers. A quarter of the honey buzzards, for example, avoided the Baltic Sea by flying over land through Scandinavia, and therefore ended up further west than other birds, and further west than expected from the wind conditions they encountered alone´.

That young honey buzzards allow themselves to be drifted by the winds shows that their wintering destination is not predetermined genetically and that chance weather events decide where each individual will return to winter for the rest of its life. Vansteelant: ´We suspect this strategy is very common among migrant birds and probably developed at a time when plenty of suitable wintering habitats were available across the whole breadth of tropical Africa.´ It remains to be seen if that strategy will remain viable under ongoing habitat destruction due to intensification of agriculture, deforestation and climate change. ´If we want to conserve European breeding populations of migrant landbirds, we should focus on measures that will ensure preservation of suitable landscapes for these birds across many developing Sub-Saharan countries rather than the creation of a couple of scattered reserves.´