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.

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.

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.

AUTHOR BLOG: Understanding How Management Affects a Flagship Reed Bed Bird Species

Thomas Oliver Mérő

Linked paper: Reed management influences philopatry to reed habitats in the Great Reed-Warbler (Acrocephalus arundinaceus) by T.O. Mérő, A. Žuljević, K. Varga, and S. Lengyel, The Condor: Ornithological Applications 120:1, February 2018.

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A color-banded singing Great Reed Warbler male, April 2015.

Wetlands are inhabited by disproportionately large number of plants and animals and yet are among the most endangered habitats worldwide due to human-caused habitat loss and fragmentation. Ecologists and conservation biologists work hard on saving wetlands by using various techniques such as vegetation management (e.g. breaking up homogeneous reed beds), water regulation (e.g. maintaining a flood/drought cycle), or reintroduction of extinct species (e.g. cranes in the U.K.). Several recent studies have shown that the management of wetlands such as reed beds by controlling the water level and removing the vegetation by mowing, burning, or grazing can increase species richness and diversity; however, we know less about whether such management provides better conditions for survival and reproduction of single species whose presence is important to other species.

The Great Reed Warbler (Acrocephalus arundinaceus) is an Old World, long-distance migrant bird that breeds in reed habitats of the Western Palearctic and winters in sub-Saharan Africa. In central Europe, the Great Reed Warbler is a widespread breeder inhabiting almost all types of reed habitats (ponds, marshes, canals etc.). Great Reed Warblers arrive in mid-April from their wintering grounds and stay until the end of breeding season in late July.

We have studied the breeding ecology of Great Reed Warblers in northern Serbia for eight years. The region hosts a nice array of wetland habitat types, ranging from oxbows of the Danube to small and large canals, and from sand and clay mining ponds to marshes in natural depressions. For our work, we distinguished six types of reed habitats based on our own observations and information from local water management companies. The six types, which differ in their shape, size, vegetation cover, and water regime, are mining ponds, marshes, large canals, and three classes of small canals.

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Although large canals are preferred by large-winged, probably high-quality, males for nesting, this habitat type provides suboptimal conditions for breeding due to high brood parasitism by Cuckoos; therefore, this habitat type likely functions as an ecological trap.

These wetlands are managed by reed mowing and burning, which led us to wonder how reed management influences the birds and other wetland animals. Specifically, we were interested in whether and how management influences the survival and reproduction of Great Reed Warblers, a flagship species of lowland wetlands in central Europe. Reed management by burning and mowing offered a good opportunity to study the responses of Great Reed Warblers in each of the reed habitat types. For example, we recognized early on that larger-winged, presumably higher-quality, males tend to occupy reed habitats with little management and deep, stable water, which are typically found along large canals.

We color-banded all individuals (both adults and hatch-year birds) from the beginning of our study and regularly checked all reed beds every year during the nesting season to explore potential differences in survival and reproduction of birds in the six reed habitats. We were also curious to find out how reed management and water availability influence survival and reproduction. We first analyzed data on survival and encounter probability that were collected over seven breeding seasons (2009-2015).

We found that the encounter probability of birds banded as hatch-year birds was higher in reed habitats with shallower water, while that of those banded as adults was higher in reed habitats with deeper water. These opposite relationships between hatch-year birds and adults may indicate that experienced adults occupy qualitatively better habitats, similarly to large-winged males (mentioned above). When data were analyzed separately for the sexes, we found that the encounter probability of males depended on variation in reed management and in water depth. In contrast, for females, encounter probability depended only on water depth, i.e. encounter probability increased with water depth. Furthermore, most of the adults and hatch-year birds returned to the reed habitat that they had been occupying initially, indicating that Great Reed Warblers display unexpectedly high fidelity to the reed habitat type they hatched in or bred in before.

How do these results translate to management recommendations? We all want the best possible management for the birds we admire and study. Evidence found in our study showed that reed management by mowing and/or burning influences return rates of juveniles and adult males and females in different ways. These results suggest that in practice, spatially variable reed management should be applied and water with varying depths should be maintained to maximize the return rates of Great Reed Warblers. This is often easier said than done. However, the multitude of reed habitats in our study and the good working relationships we developed with water management authorities and other stakeholders will allow more detailed, experimental studies of the influence of management and the allocation of optimal combinations of management for the benefit of wetland birds.

Urban Cooper’s Hawks Outcompete Their Rural Neighbors

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An urban-dwelling Cooper’s Hawk. Photo credit: B. Millsap

Depending on whether a species flourishes in a city environment, urban wildlife populations can be “sources” or “sinks,” either reproducing so quickly that individuals leave to colonize the surrounding area or needing constant immigration from outside to stay viable. A new study from The Condor: Ornithological Applications examines the population dynamics of Cooper’s Hawks in urban Albuquerque, New Mexico, and finds that city-born birds aren’t just thriving—they’re actually forcing their rural neighbors out of their nest sites.

New Mexico State University’s Brian Millsap collected data on Cooper’s Hawks living in a 72 square kilometer area of northeast Albuquerque from 2011 to 2015, monitoring each year’s nests and tracking newly fledged females with radio transmitters. He found that 30 times more hawks emigrated out of the urban area than immigrated into it, suggesting it was a source population for the surrounding region. However, the details didn’t fit neatly with the traditional source–sink model. While the surrounding exurban hawk populations were breeding and surviving well enough to sustain themselves without immigration, females moving out of the urban area were able to beat them to their nesting sites—unlike their exurban neighbors, they didn’t migrate south for the winter.

White-winged Doves, which first became established in the area in the 1980s, provide an abundant food source for city-dwelling hawks. “Individuals living in urban Albuquerque actually have a fitness advantage over their neighbors living in natural habitats. This advantage comes from the higher prey populations in urban areas, which allow urban female Cooper’s Hawks to spend the winter near their eventual breeding sites, as opposed to rural females that migrate south in winter,” explains Millsap. “The urban female hawks begin searching out and claiming nesting territories before the rural hawks return in spring and thus obtain nesting sites without direct competition from migrants. Because of this advantage, the urban Albuquerque Cooper’s Hawk population not only supports itself but also serves as a substantial source of immigrant females for surrounding native habitats.”

Changes in migratory behavior that lead to segregation between different groups can have profound effects on populations, altering how they interact both with each other and with other species in a community. According to the Peregrine Fund’s Chris McClure, an expert on raptor ecology, “This study is a great example of how solid field work and sophisticated modeling can yield new insights in basic and applied ecology.”

Demography and metapopulation dynamics of an urban Cooper’s Hawk subpopulation is available at http://www.bioone.org/doi/full/10.1650/CONDOR-17-124.1.

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.

Timing of Migration Is Changing for Songbirds on the Pacific Coast

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Volunteers collect data on captured songbirds. Photo credit: San Francisco Bay Bird Observatory

Changes in the timing of birds’ migration can have serious negative effects if, for example, they throw the birds out of sync with the food resources they depend on. A new study from The Condor: Ornithological Applications uses a long-term dataset from the Pacific coast and shows that the timing of bird migration in the region has shifted by more than two days in both spring and fall over the past two decades.

Gina Barton and Brett Sandercock of Kansas State University used 22 years of data from the San Francisco Bay Bird Observatory in northern California, where researchers captured and marked migrants as they passed through each year. Examining how migration timing was related to three indices of climate variation, including El Niño, they focused on five species—the Pacific-slope Flycatcher, Orange-crowned Warbler, and Wilson’s Warbler, which are short-distance migrants, and the Swainson’s Thrush and Yellow Warbler, which are long-distance migrants. They found that, over time, birds had been migrating earlier in spring and later in fall. About one third of this change in timing was explained by variation in climate indices, suggesting that some western songbirds can respond flexibly to changing environmental conditions. However, the two long-distance migrants had smaller changes in timing that were not as closely linked to climate indices.

The study of the timing of cyclic natural phenomena such as migration is known as phenology. “Long-term studies are valuable for understanding changes in the seasonal phenology of migratory birds and other organisms,” says Sandercock. “Our results join growing evidence that long-distance migrants may be less able to cope with rapid environmental change. However, the potential impacts of changing phenology on songbird population dynamics are difficult to predict, in part because our understanding of the migratory behavior of western songbirds remains incomplete.”

Sandercock adds that long-term projects like this one wouldn’t be possible without the commitment of many funders, technicians, and volunteers. “Our project was made possible by the dedicated efforts of many volunteers who assisted the staff of the San Francisco Bay Bird Observatory with systematic mist netting at the Coyote Creek Riparian Station. The long-term continuity could not have been maintained without stable financial support from funding by the Santa Clara Valley Water District, and the Pacific Gas and Electric Company.”

Long-term changes in the seasonal timing of songbird migration on the Pacific Flyway is available at http://www.bioone.org/doi/full/10.1650/CONDOR-17-88.1.

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.

Gina is now a Director for Cheesemans’ Ecology Safaris, an ecotourism company in Los Gatos, California. Brett is now a Senior Research Scientist with the Norwegian Institute of Nature Research in Trondheim, Norway.