Fracking Tied to Reduced Songbird Nesting Success

CONDOR-17-130 M Frantz

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.

AUTHOR BLOG: Finding the Perfect Spot: Nest-Site Choice and Predator Avoidance in Asian Houbara

João L. Guilherme

Linked paper: Consistent nest-site selection across habitats increases fitness in Asian Houbara by J.L. Guilherme, R.J. Burnside, N.J. Collar, and P.M. Dolman, The Auk: Ornithological Advances 135:2, April 2018.

female_distraction

A female Asian Houbara runs away from the nest area.

For birds that nest on the ground, discretion is everything. As they are especially at risk from predators, choosing where to nest may carry life or death consequences for themselves, their eggs, and their progeny.

We study the ecology of the Asian Houbara (Chlamydotis macqueenii) in the semi-deserts of southern Uzbekistan, as part of a long-term effort to gain insight into the dynamics of this wild population. The landscape has extensive low-density shrub coverage and tends to all look the same on first glance, but a closer look reveals subtly distinct habitats with shrub communities that differ in not just species composition, but also in the size and number of shrubs. The Asian Houbara is a highly cryptic ground-nesting bird inextricably associated with these habitats, breeding throughout. For 23 long days, females have the sole responsibility of laying, incubating, and protecting the eggs, and themselves, from the freezing cold and the strong sun, and from the desert predators such as foxes and monitor lizards.

This behavior of nesting in structurally different habitats made us question if females were choosing similar vegetation structure for nest sites and whether these choices had an impact on their nest success.

Female sitting

A rare glimpse at a female Asian Houbara on her nest.

By following houbara tracks, we succeeded at finding 210 nests. Then we took it upon ourselves to identify and measure the height of the shrubs around all nests and at 194 random locations. Obviously, this was done after the nest was finished and the female and chicks had left the area. In the end, we identified 30 species and measured a total 35,853 shrubs! After running some statistical analysis we found that females were indeed choosing the same nest site features consistently across three structurally different habitats. Their selection was so fine-tuned that the optimal shrub height of about 30 centimeters had the greatest probability of being selected in all habitats. Furthermore, the scrape was consistently in the middle of shrubs that offered some degree of concealment, but enough visibility for the female to anticipate approaching predators.

So, females were choosing similar nest site across habitats, but we wondered if these features were helping them avoid nest predation.

To investigate this, we monitored the nests, placing temperature loggers inside the nest scrape and setting video cameras to collect information through the entire incubation so that we could classify if a nest was successful or if it had failed and, in that case, why (see video here). We found that nests in higher vegetation had a lower probability of being predated, with the likelihood being that the higher vegetation offered more concealment from predators. However, females would not nest in even higher vegetation, as this would eliminate their ability to see around and anticipate approaching predators. In fact, from more than 200 monitored nests, there was not a single time when a female was predated, which normally occurs in other ground nesting birds—females seem to value the old adage “run and hide, live to fight another day.” Nest camera footage showed us that females were eternally vigilant, with their heads extended so they could see just above the vegetation and surreptitiously leave the nest before a predator arrived. In this way, we found the connection between the choice of nest site and the chance of losing the nest to predation.

In a landscape where everything looks the same, there were in reality different habitats where nesting Asian Houbara had to find the “perfect spot” that maximized the chances of hatching while reducing the danger of being depredated. For a species of conservation concern, it is very important to maintain good productivity and minimize changes in vegetation structure away from the optimal choices, as these may lead to abandonment of previously suitable nesting areas, lower nest survival, or increased predation risk for the incubating female.

Warming Temperatures May Cause Birds to Shrink

House Sparrow Male

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.

Read More

Endangered Woodpeckers Persist, but Still Struggle, on Private Land

CONDOR-17-113 B Beck

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.

AUTHOR BLOG: Tracking the Japanese Bush-Warbler Invasion of Hawaii

Jeff Foster

Linked paper: Population genetics of an island invasion by Japanese Bush-Warblers in Hawaii, USA by J.T. Foster, F.M. Walker, B.D. Rannals, and D.E. Sanchez, The Auk: Ornithological Advances 135:2, April 2018.

JABW (c) Jim Denny

A Japanese Bush-Warbler in Hawaii. Photo credit: J. Denny

Over the past several centuries, Hawaii’s native bird populations have been decimated due to an array of factors, including introduced diseases (avian malaria and pox), introduced rats, habitat change, and hunting. As a result, most live near the tops of the mountains and have small populations. Few birds and remote locations make studying many of these native populations incredibly challenging.

In contrast, Hawaii is also home to many introduced birds that can be seen everywhere, from Brazilian Cardinals and Common Mynas on the beaches to Japanese White-eyes and various game birds at the mountaintops. Various organizations in Hawaii introduced these birds from elsewhere in the world to have birdsong fill the air again and occasionally to serve as pest control for crops. Over 170 species have been brought to Hawaii and released into the wild. Of these releases, at least 54 species now have breeding populations, and most seem destined to stay for the long haul. Many species, such as the Japanese White-eye, Northern Cardinal, Zebra Dove, and Common Myna, have robust populations and can be found in a variety of habitats.

One introduced species, the Japanese Bush-Warbler, is perhaps the coolest of them all. However, despite its prominent place as the iconic harbinger of spring in Japan, few people in Hawaii think much of this species—perhaps because it is often heard but rarely seen, or perhaps because when one does finally spy a bush-warbler, it is a drab olive-brown with few prominent markings. Whatever the reason for overlooking it, bush-warblers have successfully colonized most brushy habitats on all of the main Hawaiian Islands. They were released on the island of Oahu in the 1920s, and after decades of population growth on Oahu, they naturally spread to the remaining main Hawaiian Islands by 1997.

Birds on islands have provided some of the best historical examples of the evolutionary process—think Charles Darwin in the Galapagos and Alfred Russel Wallace in the Malay Archipelago. Capturing cases of evolution “in action” is difficult. However, introductions of non-native birds into the Hawaiian Islands provide numerous opportunities for research, particularly in assessing potential evolutionary changes over a relatively short time frame. In this study, we were afforded a unique opportunity to look at the evolution of the Japanese Bush-Warbler within the past several decades by combining population genetic analyses of this species with a detailed invasion timeline on each island. As a result, we were able to see how rapidly genetic changes can occur during an invasion. We found both expected patterns, such as a decline in genetic diversity on the most recently invaded island, and an unexpected pattern, potential assortative mating on each island. These findings suggesting substantial room for future work in a system and setting that is pretty hard to match.

Genetic Drift Caught in Action in Invasive Birds

AUK-17-120 S Price

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

CONDOR-17-165 M McGrann

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.

Read More: