Fracking Tied to Reduced Songbird Nesting Success

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A researcher handles a Louisiana Waterthrush chick. Photo credit: M. Frantz

The central Appalachian region is experiencing the country’s most rapid growth in shale gas development, or “fracking,” but we’ve known almost nothing about how this is affecting the region’s songbird populations—until now. A new study from The Condor: Ornithological Applications demonstrates that the nesting success of the Louisiana Waterthrush—a habitat specialist that nests along forested streams, where the potential for habitat degradation is high—is declining at sites impacted by shale gas development in northwestern West Virginia.

West Virginia University’s Mack Frantz and his colleagues mapped waterthrush territories and monitored nests along 14 streams from 2009 to 2011 and again from 2013 to 2015. They also mapped and measured disturbances to streams and to the forest canopy, using aerial photographs and satellite imagery as well as extensive ground-truthing, and classifying them according to whether they were related to shale gas development. Their results show that as shale gas development has expanded in the area, nest survival and productivity and riparian habitat quality have declined. At the same time, the size of individual waterthrush territories has increased, suggesting birds need to range farther to find sufficient resources. This study is one of the first to demonstrate that shale gas development can affect songbird reproductive success and productivity, both directly through the presence of fracking infrastructure and indirectly through effects on habitat quality.

“I hope our findings lead to robust protections of our forested headwater stream ecosystems, which are currently overlooked for regulation despite their critical role in providing nutrients and organic matter downstream, not to mention as an important source for drinking water,” says Frantz. “Waterthrushes are a modern-day ‘canary in the coal mine,’ and there are many more opportunities to study how anthropogenic disturbance affects and entangles food webs at the aquatic–terrestrial interface.”

“After twelve years of research conducted with this species, I have seen the numerous impacts hydraulic fracturing has had on waterthrush survival and the toll that the industry has had on our nation’s wild places and wildlife,” adds Louisiana State University-Alexandria’s Leesia Marshall, a waterthrush expert who was not involved in the Condor study. “This paper should serve as a call for all scientists to redouble efforts across all related disciplines to document the present impacts of shale gas extraction and to develop strategies for mitigation and avoidance of potential impacts in the future.”

Demographic response of Louisiana Waterthrush, a stream obligate songbird of conservation concern, to shale gas development is available at http://www.bioone.org/doi/full/10.1650/CONDOR-17-130.1.

About the journal: The Condor: Ornithological Applications is a peer-reviewed, international journal of ornithology. It began in 1899 as the journal of the Cooper Ornithological Club, a group of ornithologists in California that became the Cooper Ornithological Society, which merged with the American Ornithologists’ Union in 2016 to become the American Ornithological Society. In 2016, The Condor had the number one impact factor among 24 ornithology journals.

Warming Temperatures May Cause Birds to Shrink

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The size of adult House Sparrows is predicted by maximum temperatures during development. Photo credit: P. Deviche

Biologists have known for a long time that animals living in colder climates tend to have larger bodies, supposedly as an adaptation to reduce heat loss. However, understanding how temperature affects animals has gained new importance thanks to climate change. A new study from The Auk: Ornithological Advances uses European House Sparrows, which have spread into a variety of climates in Australia and New Zealand since their introduction in the mid-19th century, to show that this trend in birds might actually be due to the effects of high temperatures during development—raising new alarms about how populations might be affected by global warming.

Macquarie University’s Samuel Andrew and his colleagues captured and measured approximately 40 adult House Sparrows at each of 30 locations across Australia and New Zealand. They found that maximum temperatures during the summer, when the birds breed, were a better predictor of adult body size at each location than winter minimum temperatures. This adds support to the idea that excessive heat during development may affect birds’ growth throughout their lives, raising concerns that increasing summer temperatures due to climate change could drive down the average adult body size, with potential effects on the birds’ fitness.

“If variation in body size is linked directly or indirectly to adapting to different climates, then body size could be useful for monitoring the extent to which bird populations are capable of adapting rapidly to changing climates,” says Andrew. “Our work on this common species helps us to understand the adaptive responses of birds to a changing climate and their constraints, and this fundamental knowledge will help future workers and managers focus their work on other species and potentially identify those species most at risk from climate change.”

“This paper is an important addition to a growing body of work that is changing our understanding of the relationships between climate and body size. The big question generated by these results is the extent to which the observed relationship is the outcome of adaptive evolutionary differences among sites as opposed to direct developmental responses to different temperatures. Interestingly, some of these same authors just published experimental evidence for a direct effect of temperature on growth in another bird species,” adds Whitman College’s Tim Parker, an expert who was not involved with the research. “This is not a new idea, but it has been largely ignored by those who have assumed that most morphological variation in birds is due to evolved adaptive variation. We need more work on the direct effects of temperature variation on development in endotherms.”

Clinal variation in avian body size is better explained by summer maximum temperatures during development than by cold winter temperatures is available at http://www.bioone.org/doi/full/10.1642/AUK-17-129.1.

About the journal: The Auk: Ornithological Advances is a peer-reviewed, international journal of ornithology that began in 1884 as the official publication of the American Ornithologists’ Union, which merged with the Cooper Ornithological Society in 2016 to become the American Ornithological Society. In 2009, The Auk was honored as one of the 100 most influential journals of biology and medicine over the past 100 years.

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Endangered Woodpeckers Persist, but Still Struggle, on Private Land

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Red-cockaded Woodpeckers nesting on private land continue to face challenges. Photo credit: B. Beck

The U.S. Fish and Wildlife Service started the Safe Harbor program in North Carolina in 1995 to reduce conflict between landowners and conservation officials and to encourage private landowners to take steps to benefit endangered Red-cockaded Woodpeckers on their land. The program has successfully reduced conflict over conservation and reduced the abandonment of nest clusters, but a new study from The Condor: Ornithological Applications shows that while the program may have raised landowners’ awareness of and tolerance for their feathered neighbors, it has largely failed to improve breeding success of birds on private lands.

Virginia Polytechnic Institute and State University’s Jennifer Smith and her colleagues compared Red-cockaded Woodpeckers’ breeding success on Safe Harbor properties before and after enrollment with that on control properties, monitoring a total of 55 breeding clusters in the North Carolina Sandhills between 1980 and 2014. Nest cluster abandonment increased on control properties while remaining constant and negligible on Safe Harbor properties, but other measures of breeding success such as clutch size, nest failure rates, and fledging success were unaffected by Safe Harbor habitat management efforts. These results suggest that the Safe Harbor program often failed to maintain or increase high-quality foraging habitat for the birds.

Regular fires are essential for maintaining high-quality Red-cockaded Woodpecker habitat, and prescribed burns are not feasible on a large proportion of Safe Harbor properties in the Sandhills due to their proximity to residential areas. In addition, the researchers believe that inadequate funding may have limited the Safe Harbor program’s impact. However, they believe the program and the monitoring efforts that have accompanied it still have value. “The longevity of the research project combined with the initiation of Safe Harbor has had marked benefits because it has allowed us to build relationships with private landowners,” says Kerry Brust, co-author of the paper. “Exchanges with private landowners have presented an ideal opportunity to draw attention to the listed species and the management needed for the persistence of Red-cockaded Woodpeckers.”

“This study identifies the great value that Safe Harbor has brought to Red-cockaded Woodpecker conservation but also highlights important and daunting limitations of the program,” according to U.S. Forest Service biologist John Kilgo, who works on Red-cockaded Woodpecker conservation and was not involved in the study. “As these are primarily related to funding constraints and less stringent habitat management requirements under the program, new and creative approaches will be required if the effectiveness of Safe Harbor is to be improved.”

How effective is the Safe Harbor program for the conservation of Red-cockaded Woodpeckers? is available at http://www.bioone.org/doi/full/10.1650/CONDOR-17-113.1.

About the journal: The Condor: Ornithological Applications is a peer-reviewed, international journal of ornithology. It began in 1899 as the journal of the Cooper Ornithological Club, a group of ornithologists in California that became the Cooper Ornithological Society, which merged with the American Ornithologists’ Union in 2016 to become the American Ornithological Society. In 2016, The Condor had the number one impact factor among 24 ornithology journals.

Genetic Drift Caught in Action in Invasive Birds

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Japanese Bush-Warblers have experienced genetic drift as they’ve invaded the Hawaiian islands. Photo credit: S. Price

Studies of island bird populations have taught us a lot about evolution, but it’s hard to catch birds in the act of naturally colonizing new islands. Instead, a new study from The Auk: Ornithological Advances examines what’s happened by looking at the genetics of a species that arrived in Hawaii in the twentieth century through decidedly unnatural means—us.

Japanese Bush-Warblers were introduced to Oahu in 1929 and have since become established on all the main islands of Hawaii, providing a unique opportunity to follow post-invasion evolution on a known, recent timescale. Northern Arizona University’s Jeffrey Foster and his colleagues took blood and muscle samples from 147 bush-warblers living on five islands between 2003 and 2005. Their results indicate genetic drift is occurring—Oahu’s birds have higher genetic diversity than those on other islands, whose populations were founded by smaller groups of individuals, just as population genetic theory predicts. Kauai bush-warblers, however, appear to be on a distinct genetic trajectory from those on other islands. Kauai is three times as far from Oahu as the closest other islands, and appears to have received a unique subset of the overall genetic diversity found elsewhere, but it remains to be seen whether the trend on Kauai will continue in the future or if continued dispersal of birds among islands will blur these differences. “This study nicely showed genetic divergence for a very short period using the artificially introduced Japanese Bush-Warblers,” according to Shoji Hamao of Japan’s National Museum of Nature and Science, an expert on the species.

“I got the idea for bush-warblers as a study system due to the challenges associated with my previous work on native Hawaiian birds,” says Foster. “Most of the native bird species I had worked on were exceedingly rare—several of them were endangered species, in fact—so focusing a new project on species in decline or with low numbers was a risky proposition. However, many of the introduced birds are quite common and one species, the Japanese Bush-Warbler, caught my attention with its loud song.

“Bush-Warblers first arrived on the Big Island when I was living there in the 1990s. The idea that one could study this invasion in progress totally blew my mind. The genetic findings largely followed expectations, such as seeing the most genetic diversity on the island where the birds were introduced and less elsewhere. Birds on Kauai, the island just west of Oahu, appear to be more distinct than those birds on islands east of Oahu, suggesting that over time birds on the respective islands may continue to diverge genetically.” But, Foster adds, many questions remain to be answered. “How much are the birds still flying between islands and potentially mixing any genetic signals of differentiation? Why did it take 50 years for the bush-warblers to colonize other islands after Oahu? How have their vocalizations changed after colonization due to new environments or random chance? We still don’t know.”

Population genetics of an island invasion by Japanese Bush-Warblers in Hawaii, USA is available at http://www.bioone.org/doi/full/10.1642/AUK-17-120.1.

About the journal: The Auk: Ornithological Advances is a peer-reviewed, international journal of ornithology that began in 1884 as the official publication of the American Ornithologists’ Union, which merged with the Cooper Ornithological Society in 2016 to become the American Ornithological Society. In 2009, The Auk was honored as one of the 100 most influential journals of biology and medicine over the past 100 years.

Timing of Spring Birdsong Provides Climate Insights

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Hermit Warblers are among the species monitored for a new study of the timing of spring birdsong. Photo credit: M. McGrann

Climate change has scientists worried that birds’ annual migration and reproduction will be thrown out of sync with the seasons. Because birds’ songs are correlated with their breeding behavior and are easily identifiable to species, monitoring birdsong can be a good way to keep tabs on this possibility, and a new study from The Condor: Ornithological Applications takes advantage of this approach to provide new baseline data for the birds of northern California.

The California Department of Fish and Wildlife Brett Furnas and William Jessup University’s Michael McGrann analyzed data from two bird survey programs from California’s Klamath Mountains and Southern Cascades, both of which used automated recorders to monitor bird sounds between 2009 and 2011. In addition to providing the first comprehensive assessment of songbird occupancy over a 40,000 square kilometer region of northern California, they were able to identify the precise dates of peak vocal activity for eight songbird species, and their work shows that this will be a feasible method to track advances in the timing of vocal activity over the coming decades. Species characterized by strong single peaks in vocal activity already tended to reach those peaks later than other species, perhaps because birds with tightly constrained timing are less able to adapt to changing climatic conditions.

“Climate change is disrupting songbird populations, distributions, and breeding behaviors in our mountain ecosystems. Mountains are particularly sensitive because temperature and precipitation interact in complex ways on mountains,” says McGrann. “If Neotropical migrants are unable to adjust their breeding behaviors, then there may be a mismatch in the timing of raising their young to the peak availability in food resources, namely insects. Our technique should allow us to track shifts in elevation, changes in the state of the population, and changes in breeding behaviors in response to climate change over the next ten to twenty years.”

“Furnas and McGrann provide a textbook example of how to detect differences in the timing of nesting among bird species using information on the peak date of singing derived from surveys and automated recorders,” according to UC Berkeley’s Steve Beissinger, an expert on avian phenology who was not involved in the study. “Their results support recent findings of a five to twelve day shift forward in the timing of peak singing by California birds in the nearby Sierra Nevada and coastal ranges in response to climate change.”

Using occupancy modeling to monitor dates of peak vocal activity for passerines in California is available at http://www.bioone.org/doi/full/10.1650/CONDOR-17-165.1.

About the journal: The Condor: Ornithological Applications is a peer-reviewed, international journal of ornithology. It began in 1899 as the journal of the Cooper Ornithological Club, a group of ornithologists in California that became the Cooper Ornithological Society, which merged with the American Ornithologists’ Union in 2016 to become the American Ornithological Society. In 2016, The Condor had the number one impact factor among 24 ornithology journals.

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Engineered Sandbars Don’t Measure Up for Nesting Plovers

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Piping Plovers were more successful nesting on natural sandbars than engineered ones. Photo credit: D. Borden

Dams alter rivers in ways that reduce the creation of natural sandbars, which is bad news for threatened Piping Plovers that depend on them for nesting habitat. Between 2004 and 2009, more than 200 hectares of engineered sandbars were built along the Missouri River to address the problem—but how does this engineered habitat compare to the real thing? A new study from The Condor: Ornithological Applications takes advantage of a natural experiment created by the region’s 2011 floods, demonstrating that the engineered habitat doesn’t provide the benefits of sandbars created by nature.

Kelsi Hunt of the Virginia Polytechnic Institute and State University and her colleagues collected data downstream of Gavins Point Dam from 2005 to 2014, monitoring more than 1,000 nests and banding almost 3,000 individual birds both before and after massive floods in 2011 created vast new areas of natural sandbar habitat. Nest success, chick survival, and total reproductive output all increased after the flood and remained high as flood-created sandbars began to age, even without the intensive predator management that had been done on the engineered sandbars. In contrast, Piping Plover populations nesting on engineered sandbars grew in the first year after the habitat’s construction, but there wasn’t enough space to go around—high population densities quickly led to high risk from predators and decreased reproductive rates.

“I realized just how interesting of a natural experiment the flood provided us with when my advisor and I boated the entirety of the Gavins Point Reach prior to the 2012 field season,” says Hunt. “The amount of sandbar habitat that the 2011 flood created was incredible to see. Where before there was just river, huge sandbars replaced it. Some of the sandbars it created were larger than city blocks and took hours to survey.” She hopes that managers can learn from this study to create better engineered habitat for sandbar-nesting birds, building more nesting space at one time and constructing new habitat close to existing sandbars so that young birds will have an easy time finding and colonizing it.

“This paper presents a clear contrast in demographic rates of Piping Plovers in naturally created and human-restored habitats that can be used to compare and refine conservation strategies,” adds Anne Hecht, Piping Plover recovery coordinator for the U.S. Fish and Wildlife Service. “Although it focuses on Missouri River sandbars, it has important implications for conservation of Piping Plover habitat rangewide, as well as for other species experiencing disruption of habitat formation processes.”

Demographic response of Piping Plovers suggests that engineered habitat restoration is no match for natural riverine processes is available at http://www.bioone.org/doi/full/10.1650/CONDOR-17-93.1.

About the journal: The Condor: Ornithological Applications is a peer-reviewed, international journal of ornithology. It began in 1899 as the journal of the Cooper Ornithological Club, a group of ornithologists in California that became the Cooper Ornithological Society, which merged with the American Ornithologists’ Union in 2016 to become the American Ornithological Society. In 2016, The Condor had the number one impact factor among 24 ornithology journals.

Wrens’ Calls Reveal Subtle Differences Between Subspecies

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Biologist Sarah Luttrell records the calls of a Marsh Wren. Photo credit: S. Luttrell

Birds’ songs and the ways they vary between places have been well studied–but what can the simpler vocalizations known as calls tell us about bird biology? A new study from The Auk: Ornithological Advances provides the first detailed description of how Marsh Wren calls vary across eastern North America and hints at the evolutionary processes playing out between wren subspecies.

The University of Maryland Baltimore County’s Sarah Luttrell and Bernard Lohr recorded the calls of five Marsh Wren subspecies at nineteen different sites, encompassing the Gulf Coast, Atlantic Coast, and Great Lakes regions and including migratory, nonmigratory, freshwater marsh, and saltwater marsh populations. Categorizing the recordings into seven different call types, they analyzed how calls differed between subspecies. While some calls were associated with territory patrol, nest building, and courtship, others were used mainly during aggressive encounters with predators or other wrens. Both the acoustic characteristics of some calls and how frequently they were used differed from place to place.

“It was certainly a lot of work to compile data on multiple vocalizations and compare the results, but in the end, it makes for a more nuanced understanding of how various evolutionary processes shape animal behavior as a whole,” says Luttrell. “Twitter” calls differed between migratory and nonmigratory subspecies, for example, while “buzz” and “trill” calls differed between birds that lived in freshwater and saltwater marshes; while differences in habitat can’t directly explain this, all of these call types could be shaped by sexual selection that reinforces the boundaries between subspecies. Atlantic Coast populations produced the “chuck” alarm call more often than others, which suggests they may experience more threats from predators or nest at higher densities that lead to more antagonistic encounters between birds.

Could these differences eventually prompt Marsh Wren populations to diverge into fully separate species? “That’s impossible to say for sure—it all depends on the course that evolution takes!” says Luttrell. “We were excited that the patterns of call variation we observed seemed to coincide with differences ecology and life history, which suggests the possibility that these subspecies are evolving in different directions. In the future, we’re hoping to do some behavioral tests that might help us understand how much the acoustic differences matter to the birds’ behavior in the wild. If we do find that individuals respond less strongly to the vocalizations of another subspecies than to their own, then that would be additional evidence that at least some subspecies are on a trajectory of divergence.”

“This study highlights the diversity of calls that can be found in a single avian repertoire, and nicely illustrates how different elements of those repertoires can evolve independently,” according to the University of Northern Colorado’s Lauryn Benedict, an expert on communication in wrens and other songbirds. “The demonstrated patterns of call use in relation to behavioral context, caller sex, habitat, and migratory behavior raise many future avenues of inquiry. Avian calls are a generally understudied vocalization, and this paper demonstrates how and why we all should pay them more attention.”

Geographic variation in call structure, likelihood, and call-song associations across subspecies boundaries, migratory patterns, and habitat types in the Marsh Wren (Cistothorus palustris) is available at http://americanornithologypubs.org/doi/full/10.1642/AUK-17-110.1.

About the journal: The Auk: Ornithological Advances is a peer-reviewed, international journal of ornithology that began in 1884 as the official publication of the American Ornithologists’ Union, which merged with the Cooper Ornithological Society in 2016 to become the American Ornithological Society. In 2009, The Auk was honored as one of the 100 most influential journals of biology and medicine over the past 100 years.