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
Influences outside the breeding season matter a lot for the population health of migratory birds, but it’s tough to track what happens once species scatter for the winter. A study now tries a new approach for determining what …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 during their winter molt….
Rosalind B. Renfrew, Jason M. Hill, Daniel H. Kim, Christopher Romanek, and Noah G.
Phil. Trans. R. Soc. B 2017 372 20160134; DOI: 10.1098/rstb.2016.0134. 8 May 2017
Compiled and edited by Martijn van de Pol, Stéphanie Jenouvrier and Marcel E. Visser 19 June 2017; volume 372, issue 1723
Cover image: The saltmarsh sparrow nests near the edge of estuaries, where their nests often flood during extreme high tides, which occur around the new and full moons. The flooding events are becoming more frequent as climate change causes sea levels to rise. (Photo credit: Jeanna Mielcarek.)
2 bird species – Oystercatchers and Fairy Wrens- responded very differently
In the special June issue of Philosophical Transactions of the Royal Society B researchers of the Netherlands Institute of Ecology (NIOO-KNAW) launch a new approach to these ‘extreme’ studies.
May 16 2017 Netherlands Institute of Ecology (NIOO-KNAW) from ScienceDaily
…Extremes, outliers, cataclysms. As a field of biological research it’s still in its infancy, but interest in the impact of extreme weather and climate events on nature is growing rapidly. That’s partly because it is now increasingly clear that the impact of extreme events on animal behaviour, ecology and evolution could well be greater than that of the ‘normal’ periods in between. And partly because the frequency of such events is likely to increase, due to climate change….
…But how do we define extreme events in the first place? That’s problematic, explain NIOO researchers Marcel Visser and Martijn van de Pol. “For climatologists, weather has to be warmer, colder or more extreme in another way than it is 95% of the time. But that doesn’t necessarily make it extreme in terms of its impact on nature. There isn’t a 1 to 1 correspondence.”..
….The researchers were keen to find out if the birds would learn from experience and build their nests on higher ground — safer but further from their favourite sea food, “but they don’t.” This could result in natural selection based on nest elevation, with only breeders who build their nest on high ground likely to survive. But this could affect the future viability of the population.
…Less cataclysmic events, too, can have major consequences. Two examples from Phil. Trans. B are oystercatchers that build their nests close to the coast despite rising sea levels, and fairy-wrens — Australian passerine birds — that are increasingly exposed to heatwaves and high temperatures, with sometimes fatal consequences…So how do they respond over time? Do they change their body size to mediate the impact of the extreme temperatures? Van de Pol: “Data over nearly 40 years shows that the two species, although quite similar, respond in completely different ways.”
Martijn van de Pol, Stéphanie Jenouvrier, Johannes H. C. Cornelissen, Marcel E. Visser. Behavioural, ecological and evolutionary responses to extreme climatic events: challenges and directions. Philosophical Transactions of the Royal Society B: Biological Sciences, 2017; 372 (1723): 20160134 DOI: 10.1098/rstb.2016.0134
From Abstract: By summarizing the contributions to this theme issue we draw parallels between behavioural, ecological and evolutionary ECE studies, and suggest that an overarching challenge is that most empirical and theoretical evidence points towards responses being highly idiosyncratic, and thus predictability being low. Finally, we suggest a roadmap based on the proposition that an increased focus on the mechanisms behind the biological response function will be crucial for increased understanding and predictability of the impacts of ECE.
New research shows climate change is altering the delicate seasonal clock that North American migratory songbirds rely on to successfully mate and raise healthy offspring, setting in motion a domino effect that could threaten the survival of many familiar backyard bird species.
A growing shift in the onset of spring has left 9 of 48 species of songbirds studied unable to reach their northern breeding grounds at the calendar marks critical for producing the next generation of fledglings, according to a paper published in Scientific Reports. That’s because in many regions, warming temperatures are triggering plants to begin their growth earlier or later than normal, skewing biological cycles that have long been in sync.
The result, researchers say, could be a future much like the one Rachel Carson hinted at more than 50 years ago. “It’s like ‘Silent Spring,’ …”We’re seeing spring-like conditions well before birds arrive. The growing mismatch means fewer birds are likely to survive, reproduce and return the following year. …”
…The study is the first to investigate the increasing mismatch between songbirds’ springtime arrival and plant growth at the continental scale and across dozens of species, said Mayor, who led the project chiefly at Memorial University of Newfoundland.
Many songbirds migrate hundreds or thousands of miles every year, but their exact routes and flight patterns are something of a mystery. Traditional animal tracking devices based on radio transmitters are too heavy to use on such small birds, so instead researchers have turned to “geolocators”—tiny, lightweight devices that record patterns of light and darkness to estimate the birds’ latitude and longitude—to try to learn more about their migrations.New work published in the journal The Condor indicates that even those lightweight tags may have ill effects on the birds, however. While cerulean warblers tagged with geolocators seemed to fare as well as control birds during the breeding season, fewer of the tagged birds returned the following year in the next migration cycle. Bridget Stutchbury, a researcher who uses geolocator tags but who wasn’t involved in the study, describes the possible good and bad of the tracking technology….
Knowing where migrating birds came from and where they’re headed is essential for their conservation and management. A new study tackles this challenge using stable isotope ratios, which reflect where birds were living while growing their feathers, and reveals that the northern reaches of Canada may have underappreciated importance for North America’s waterfowl.
Rising temperatures and heatwaves are putting songbirds at greater risk for death by dehydration and mass die-offs, report scientists. Projected increases in the frequency, intensity and duration of heatwaves in the desert of the southwestern United States are putting songbirds at greater risk for death by dehydration and mass die-offs, according to a new study.
Researchers used hourly temperature maps and other data produced by the North American Land Data Assimilation System (NLDAS) — a land-surface modeling effort maintained by NASA and other organizations — a long with physiological data to investigate how rates of evaporative water loss in response to high temperatures varied among five bird species with differing body masses. Using this data, they were able to map the potential effects of current and future heat waves on lethal dehydration risk for songbirds in the Southwest and how rapidly dehydration can occur in each species. Researchers homed in on five songbird species commonly found in the desert southwest: lesser goldfinch, house finch, cactus wren, Abert’s towhee and the curve-billed thrasher…
Thomas P. Albright, Denis Mutiibwa, Alexander. R. Gerson, Eric Krabbe Smith, William A. Talbot, Jacqueline J. O’Neill, Andrew E. McKechnie, Blair O. Wolf. Mapping evaporative water loss in desert passerines reveals an expanding threat of lethal dehydration. Proceedings of the National Academy of Sciences, 2017; 114 (9): 2283 DOI: 10.1073/pnas.1613625114
Forget delivering packages or taking aerial photographs — drones can even count small birds. A new study tests this new approach to wildlife monitoring and concludes that despite some drawbacks, the method has the potential to become an important tool for ecologists and land managers….
Andrew M. Wilson, Janine Barr, and Megan Zagorski. The feasibility of counting songbirds using unmanned aerial vehicles. The Auk: Ornithological Advances, February 2017 DOI: 10.1642/AUK-16-216.1
Suburban development is forcing some songbirds to divorce, pack up and leave and miss their best chances for successful reproduction.
… for one group of songbirds — called “avoiders” — urban sprawl is kicking them out of their territory, forcing divorce and stunting their ability to find new mates and reproduce successfully, even after relocating…
John M. Marzluff, Jack H. Delap, M. David Oleyar, Kara A. Whittaker, Beth Gardner. Breeding Dispersal by Birds in a Dynamic Urban Ecosystem. PLOS, December 28, 2016 DOI: 10.1371/journal.pone.0167829