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Tag Archive: birds

  1. Declining baby songbirds need forests to survive drought

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    • Birds in larger mature forest areas, on the other hand, were better able to withstand the dry conditions since these areas offer more shade and resources. Forest cover helps maintain climatic conditions, including moist soil, which is an important factor for wood thrush food availability

    October 19, 2017 Virginia Tech  read full ScienceDaily article here

    According to a new study by biologists at Virginia Tech and the Smithsonian Migratory Bird Center, the offspring of a certain songbird, the wood thrush, are more likely to survive drought in larger forest plots that offer plenty of shade and resources…

    Wood thrush are common to the United States, but populations have declined by more than 60 percent since the 1960s. In addition, many species of songbirds, such as blue jays, robins, and cardinals, as well as wood thrush, face the highest risk of dying within the first five days of leaving their nests.

    …Birds in larger mature forest areas, on the other hand, were better able to withstand the dry conditions since these areas offer more shade and resources. Forest cover helps maintain climatic conditions, including moist soil, which is an important factor for wood thrush food availability. These conditions ultimately make areas more resilient to drought.

    The research highlights the role that forest cover can play in buffering animals from stressful environmental conditions — in this case, promoting survival of young birds during drought conditions,” said Amanda Rodewald, professor and director of conservation science at the Cornell Lab of Ornithology, who was not involved with the research. “This finding is yet another that underscores the importance of maintaining forested landscape mosaics in strategies to conserve biodiversity.”….

    For ideal survival, then, Vernasco says fledglings do well with a “mosaic” of habitats made up of forests that differ in age and thus vegetation structure.

    Ben J. Vernasco, T. Scott Sillett, Peter P. Marra, T. Brandt Ryder. Environmental predictors of nestling condition, postfledging movement, and postfledging survival in a migratory songbird, the Wood Thrush (Hylocichla mustelina). The Auk, 2017; 135 (1): 15 DOI: 10.1642/AUK-17-105.1

  2. Even modest oil exposure can harm coastal and marine birds

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    • “Even birds with relatively limited exposure to oil from the Deepwater Horizon spill sustained damage to circulating red blood cells and had evidence of anemia, which can adversely affect reproduction and reduce survival.”

    October 12, 2017 Wiley read full ScienceDaily article here

    Many birds and other wildlife die following an oil spill, but there are also other potential long-terms effects of oil exposure on animals. study that examined blood samples from birds present in the Gulf of Mexico in 2010 and 2011 following the Deepwater Horizon oil spill, even birds with small amounts of oil present on their feathers experienced problems related to their red blood cells.

    The findings show that even modest oil exposure can cause problems for individual birds and bird populations.

    Jesse A. Fallon, Eric P. Smith, Nina Schoch, James D. Paruk, Evan A. Adams, David C. Evers, Patrick G.R. Jodice, Christopher Perkins, Shiloh Schulte, William A. Hopkins. Hematological indices of injury to lightly oiled birds from the deepwater horizon oil spill. Environmental Toxicology and Chemistry, 2017; DOI: 10.1002/etc.3983

  3. House sparrow decline linked to air pollution and poor diet

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    • City sparrows suffer from more stress than their country cousins, find Spanish researchers, especially during breeding season

    October 3, 2017 Frontiers  read full ScienceDaily article here

    House sparrows are well-adapted to living in urban areas, so it is surprising their numbers have fallen significantly over the past decades. An investigation into this worrying trend finds that sparrows living in urban areas are adversely affected by pollution and poor nutrition. The study also finds the birds suffer more during the breeding season, when resources are needed to produce healthy eggs….

    …if our cities are unhealthy for birds, which is what our study is suggesting, then as their neighbors we should be concerned because we are exposed to the same environmental stressors as house sparrows.”

    …”We took a small blood sample from each bird, according to its weight and physical condition, and released them unharmed,” she explains. The samples were analyzed for signs of oxidative stress, which can be used to measure how much an environmental stressor, such as pollution, is weakening the bird’s natural defenses….

    …”We need to work hard to improve the quality of the urban environment, for example, air quality and the design of green areas. Even the leftovers that we throw in the bin at the park should encourage us to reflect on ourselves: more nuts and fruit and fewer chips and cookies would be better for humans as well as for birds,” Herrera-Dueñas advises.

    Amparo Herrera-Dueñas, Javier Pineda-Pampliega, María T. Antonio-García, José I. Aguirre. The Influence of Urban Environments on Oxidative Stress Balance: A Case Study on the House Sparrow in the Iberian Peninsula. Frontiers in Ecology and Evolution, 2017; 5 DOI: 10.3389/fevo.2017.00106

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

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    August 29, 2017 University of Oxford  read full ScienceDaily article here

    …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….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……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….’To the best of our knowledge, this is the first study that follows free-ranging foraging trips in sensorily manipulated birds. ..

    Cory’s Shearwater, Calonectris borealis, in flight.
    Credit: © hstiver / Fotolia

    O. Padget, G. Dell’Ariccia, A. Gagliardo, J. González-Solís, T. Guilford. Anosmia impairs homing orientation but not foraging behaviour in free-ranging shearwaters. Scientific Reports, 2017; 7 (1) DOI: 10.1038/s41598-017-09738-5

  5. For Birds & People — Water, Carbon, and Education, Point Blue E-News July 28 2017

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    July 2017 Point Blue E-News

    Data-Driven Water Management
    It takes science and partnership to figure out the best way to manage limited supplies of fresh water in California’s Central Valley for humans and wildlife. A recent paper co-authored by Point Blue scientists shows a worrisome mismatch in flooded habitat and shorebird spring migration. This has important implications for how government agencies and NGO partners manage water on refuges and in agricultural fields.

    Coming soon, thanks to further funding from NASA, we’ll be analyzing more satellite data with our newly hired Quantitative Ecologist, Dr. Erin Conlisk. Our goal is to figure out when and where to put water to achieve the greatest benefit for wetland-dependent wildlife while also recharging groundwater and providing recreational opportunities. Stay tuned for results!

    Meadows & Climate Change
    Our science is helping to determine if restored Sierra meadows can store enough carbon to help slow climate change while also benefitting birds and other wildlife. The outcome could help direct more funds from California’s cap-and-trade program toward meadow restoration, and it looks promising! Read this wonderful Audubon article highlighting Point Blue’s collaborative work.

    Climate Science Education: New Tools!
    Today’s young people need climate science knowledge to help build a better future for themselves and the next generations. That’s why we’ve created and disseminated a climate-smart riparian restoration curriculum, which you can find here. We’ve also added a number of our science resources to the Bay Area Climate Literacy and Impact Collaborative database for Bay Area educators here. We invite you to use these resources and share them with others. Together we are educating and inspiring the next wave of climate-smart conservation leaders!

    Thanks for your continued, generous support of Point Blue’s science.

  6. Greatest threat to forest birds of eastern US is habitat loss on wintering grounds; magnified by climate change in future

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    • the first study to measure the combined impact of climate change and land-use change over a bird’s full annual cycle
    • The study finds loss of wintering habitat in the near future will likely be magnified by the long-term effects of climate change.

    July 24 2017 Cornell University read full ScienceDaily article here

    Within the next few decades, human-caused habitat loss looms as the greatest threat to some North American breeding birds. The problem will be most severe on their wintering grounds, according to a new study published today in the journal Global Change Biology. By the end of this century, the study’s authors say predicted changes in rainfall and temperature will compound the problem for birds that breed in eastern North America and winter in Central America.

    “This is really the first study to measure the combined impact of climate change and land-use change over a bird’s full annual cycle,” says lead author Frank La Sorte at the Cornell Lab of Ornithology. “Typically, studies tend to focus on the breeding season. If you do that, you’re missing the real story which is inherently dynamic and complex.”

    Migrant wintering grounds are vitally important because the birds spend a greater proportion of the year in these places…

    Frank A. La Sorte, Daniel Fink, Peter J. Blancher and Steve Kelling. Global change and the distributional dynamics of migratory bird populations wintering in Central America. Global Change Biology · July 2017 DOI: 10.1111/gcb.13794

    Understanding the susceptibility of highly mobile taxa such as migratory birds to global change requires information on geographic patterns of occurrence across the annual cycle. Neotropical migrants that breed in North America and winter in Central America occur in high concentrations on their non-breeding grounds where they spend the majority of the year and where habitat loss has been associated with population declines. Here, we use eBird data to model weekly patterns of abundance and occurrence for 21 forest passerine species that winter in Central America. We estimate species’ distributional dynamics across the annual cycle, which we use to determine how species are currently associated with public protected areas and projected changes in climate and land-use.
    The effects of global change on the non-breeding grounds is characterized by decreasing precipitation, especially during the summer, and the conversion of forest to cropland, grassland, or peri-urban. The effects of global change on the breeding grounds are characterized by increasing winter precipitation, higher temperatures, and the conversion of forest to peri-urban. During spring and autumn migration, species are projected to encounter higher temperatures, forests that have been converted to peri-urban, and increased precipitation during spring migration.
    Based on current distributional dynamics, susceptibility to global change is characterized by the loss of forested habitats on the non-breeding grounds, warming temperatures during migration and on the breeding grounds, and declining summer rainfall on the non-breeding grounds.
    Public protected areas with low and medium protection status are more prevalent on the non-breeding grounds, suggesting that management opportunities currently exist to mitigate near-term non-breeding habitat losses. These efforts would affect more individuals of more species during a longer period of the annual cycle, which may create additional opportunities for species to respond to changes in habitat or phenology that are likely to develop under climate change
  7. Can Restored Meadows Fight Climate Change? California Seeks to Find Out [Sierra Meadows Partnership research]

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    • Franson’s work [with Point Blue] is one of eight studies on carbon storage in Sierra Nevada meadows, all of which are part of California’s pioneering cap-and-trade legislation to reduce carbon emissions.
    • California’s cap-and-trade extension, passed by lawmakers this week, ensures continued study of whether Sierra Nevada meadow restoration can capture carbon pollution and help birds at once.

    …The Sierra Meadows Partnership should help these species, even though its primary goal relates to climate change. Scientists know soils store three times more carbon than vegetation and the atmosphere combined. It’s stored in plants’ deep root systems, and in the accumulation of their dead tissue over time. But changes to the landscape have limited or reversed centuries of carbon storage. Degraded meadows store less carbon, and warmer temperatures from climate change may release carbon back into the atmosphere.

    The Sierra Meadows Partnership is focused on identifying how much carbon meadows are storing, how much they are losing, and whether restoration makes a difference. The group has identified 16 meadows ranging in elevation from 3,045 to nearly 8,700 feet; half are being restored, while the others will serve as control sites that allow scientists to measure the effects of restoration….

    A 2014 study, published by Point Blue Conservation Science, found that restored meadows in the northern Sierra Nevada have the potential to support up to 10 times more breeding bird species and individuals than degraded sites. And preliminary results from a study of meadows restored between 2001 and 2016 found 20 percent more soil carbon, on average, in restored meadows compared to degraded ones….

    Key organizations in the Sierra Meadows Partnership:

    • California Tahoe Conservancy
    • Trust for Public Lands
    • Sierra Foothills Conservancy
    • USGS
    • National Fish & Wildlife Foundation
    • Occidental Arts and Ecology Center
    • Feather River Land Trust
    • Point Blue Conservation Science
    • Sierra Fund
    • South Yuba River Citizens League
    • CA Dept. of Fish & Wildlife
    • US Forest Service
    • Stillwater Sciences
    • Institute for Bird Populations
    • University of Nevada, Reno
    • UC Davis Center for Watershed Sciences
    • UC Merced
    • American Rivers
    • Plumas Corps
    • Truckee River Watershed Council
    • Trout Unlimited
    • The Nature Conservancy
    • Todd Sloat Biological Consulting
    • Sabra Purdy Consulting
    • National Forest Foundation
  8. Birds avoid crossing roads to prevent predation

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    Why didn’t the bird cross the road? Because it was afraid of predators and venturing into another bird’s territory

    Posted: 19 Jul 2017 07:05 AM PDT  see full ScienceDaily article here

    It was once believed that roads posed no problem to birds because of their ability to fly. A new study finds that they can find these human-made structures problematic, especially small, forest-dwelling species. Their hesitance to cross roads could restrict their positive effects on the natural environment, such as seed dispersal, pollination and insect control….

    …The authors of the study strongly advise that measures are put in place to connect fragments of forest across roads, allowing wildlife to move freely…”There are wildlife-friendly solutions to many of these issues, such as specially-designed overpasses, fauna underpasses and fencing so animals can avoid accessing the road, all of which need to be incorporated into the design of our road systems. Further studies should look at the impacts of man-made breaks in vegetation, such as forest tracks and park walkways on bird movements,” adds Professor Jones. “We are currently using our data to identify the ‘at risk’ bird species within suburban areas, to assist with conservation management.”

    Christopher D. Johnson, Daryl Evans, Darryl Jones. Birds and Roads: Reduced Transit for Smaller Species over Roads within an Urban Environment. Frontiers in Ecology and Evolution, 2017; 5 DOI: 10.3389/fevo.2017.00036

  9. Chillier Winters, Smaller Beaks

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    • researchers found no correlation with summer temperatures but a clear one for winter — the coldest winters were associated with the smallest beaks, whereas warmer winters were associated with larger beaks.

    Posted: 13 Jul 2017 05:20 AM PDT see full ScienceDaily article here

    …in the 1990s, researchers began to explore a new question concerning the relationship between climate and the evolution of beak size…..[before this study]… feeding habits were believed to be the greatest driving force in beak evolution…

    …[comparing] differences between individuals of the same species that are living in wildly different conditions…. the researchers found no correlation with summer temperatures but a clear one for winter — the coldest winters were associated with the smallest beaks, whereas warmer winters were associated with larger beaks.

    …Allen’s Rule, which states that warm-blooded animals living in cold climates will have shorter limbs and appendages than those that live in warmer climates. The biological mechanism behind this rule is thermoregulation — more body surface area helps animals to shed heat better whereas less surface area helps them to conserve it. Since a bird’s beak plays a large role in thermoregulation — it has lots of blood vessels and is not covered in feathers — researchers wondered whether hotter climates beget larger beaks and colder climates beget smaller ones. Indeed, studies revealed that climate has influenced beak size, but not which type of climate had more of an overall impact….

    Nicholas R. Friedman, Lenka Harmáčková, Evan P. Economo, Vladimír Remeš. Smaller beaks for colder winters: Thermoregulation drives beak size evolution in Australasian songbirds. Evolution, 2017; DOI: 10.1111/evo.13274


  10. How eggs got their shapes

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    Posted: 22 Jun 2017 11:30 AM PDT  see full article here

    The evolution of the amniotic egg — complete with membrane and shell — was key to vertebrates leaving the oceans and colonizing the land and air but how bird eggs evolved into so many different shapes and sizes has long been a mystery. Now, an international team of scientists took a quantitative approach to that question and found that adaptations for flight may have been critical drivers of egg-shape variation in birds….

    …”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.

    Mary Caswell Stoddard, Ee Hou Yong, Derya Akkaynak, Catherine Sheard, Joseph A. Tobias, L. Mahadevan. Avian egg shape: Form, function, and evolution. Science, 2017 DOI: 10.1126/science.aaj1945