B I R D I N G • M A Y 2 0 1 132

Patches of snow still linger in the cooler hollows, and

streams are running high from the snow melt. Spring is

barely discernable on the chilly air, yet we are out check-

ing the rocks on Powdermill Run. It is late March, and we are

looking for the first signs of the season’s earliest neotropical mi-

grant, the Louisiana Waterthrush. Each year male Louisiana Wa-

terthrushes home in early on Powdermill Run, a mixed

hemlock-and-broadleaf ravine in the Appalachian foothills of

southwestern Pennsylvania. Surprisingly elusive and quiet for

the first few days, males are most reliably located by the telltale

droppings left behind on the rocks (affectionately known as

“splay”), where they forage for in-stream macroinvertebrates.

Maybe an occasional sharp metallic chip note will be heard.

Then, suddenly, one day a song breaks the silence of the win-

ter woods, still leafless and brown: a resounding see-up see-up

see-up followed by a variable jumble of notes—the opening

reveille of a wondrous invasion of color and song powering

northward through eastern North America.

Felicity L. Newell • Ashland, Oregon • felicity.newell@gmail.com

W W W . A B A . O R G 33

Less than two miles away, Laurel Run is still silent. The rocks remain bare. Soon thesqueaky-wheel weesa weesa weesa of a Black-and-white Warbler will be heard among theleafless trees. Buds are opening, and yet more birds fill in the silence. The melodic, flute-like ee-o-lay of the Wood Thrush and the emphatic teacher teacher teacher of the Oven-bird echo across the land. But it is not until late April that waterthrushes are finallydetected along Laurel Run, the first signs visible on the rocks. In the end, only a fewpairs breed here. Compared to all the waterthrush activity along Powdermill Run, Lau-rel Run is clearly different.Why?

Powdermill Nature ReserveBoth Powdermill Run and Laurel Run flow through Powdermill Nature Reserve, the bio-logical field research station of the Pittsburgh-based Carnegie Museum of Natural History.Created in 1956 through the vision of the late M. Graham Netting, director of the mu-seum for more than two decades, the reserve was named for the healthy, productive streamrunning through its center. The idea for the reserve was to protect a place for the long-termstudy of how natural ecosystems change over time. “The forest grows. The forest alsochanges,” wrote John Guilday, a former museum scientist summing up the essence andvalue of Powdermill. “This is the unparalleled offering of the reserve—the gift of time.”

An obligate riparian songbird,

the Louisiana Waterthrush depends

on forested headwater streams.

In this article, we learn that various

measures of population health in

waterthrushes can be predicted by

stream quality—a result that points

to the Louisiana Waterthrush as a

valuable “bio-indicator” for riparian

forested ecosystems throughout

the species’ range. Bernardsville,

New Jersey; April 2009. Photo by

© Jim Gilbert.

L O U I S I A N A W A T E R T H R U S H

Today the reserve encompasses more than 2,200 acres atthe edge of Forbes State Forest in southwestern Pennsylva-nia and supports a variety of long-term ecological researchprojects. Birders likely know the reserve best for the Pow-dermill Avian Research Center (PARC), which operates oneof the longest-running year-round bird-banding stations inNorth America. Since its founding in 1961 by Robert Leber-man, who recently retired after more than 40 years of band-ing, more than half a million birds of some 200 species havebeen banded. Amassing an internationally recognizeddataset, the bird-banding program at Powdermill continuesto contribute to our understanding of migration, molt strate-gies, effects of climate change, population dynamics, andother aspects of avian life cycles for many North Americanlandbird species. The banding operation also provides avaluable opportunity for training, learning, and collabora-tion among students, interns, and visiting researchers.Robert Mulvihill, who coordinated field work and data

analysis for the recently completed second PennsylvaniaBreeding Bird Atlas, first came to Powdermill in 1978 as anundergraduate eager to learn about bird banding. Workingfull time on the banding program alongside Leberman (thetwo together are knownas the “The Bobs”) be-ginning in 1983, Mulvi-

B I R D I N G • M A Y 2 0 1 134

At the beginning of the breeding season, male LouisianaWaterthrushes fight with neighbors to obtain the best

territories. Among the earliest spring migrants from theneotropics, the Louisiana Waterthrush starts arriving in

southern Florida by mid-February and hasreached the northern part of its range

by mid-April. Cook County, Illinois;May 2009. Photo by © Brian Tang.

Powdermill Run in southwestern Pennsylvania is prime realestate for Louisiana Waterthrushes. Birds settle early eachspring on this forested headwater stream, which has anabundance of macroinvertebrates. Rector, Pennsylvania;May 2004. Photo by © Valeria Ojeda.

hill initially developed Louisiana Waterthrush research tocomplement the banding program.Since the 1960s, field ornithology had been shifting from

natural history to addressing practical conservation issues. Inthe 1980s, ornithologists began observing disturbing trendsin long-term datasets such as the Breeding Bird Survey (BBS).Populations of many bird species across North America ap-peared to be declining sharply, with neotropical migratorysongbirds showing some of the steepest declines. Powder-mill’s current bander-in-charge, Andrew Vitz, says that inmany cases long-term trends in migration banding data atPowdermill match BBS trends. However, the breeding seasonmay be a different story. Powdermill’s breeding birds seem tobe doing just fine, including many forest-interior speciesknown to be sensitive to habitat fragmentation.Differences at Powdermill may have to do with the large

tracts of forest on the reserve and adjacent Forbes State For-est. “In a place like Powdermill where you have protected in-tact forest, species should be showing source, not sink,populations,” Mulvihill says. According to lingo developedby conservation biologists to describe population dynamics,source areas with high quality habitat produce more youngthan are needed to maintain the population; these young canthen emigrate to areas such as sinks where productivity islow—for example, to areas with high rates of nest predationand cowbird parasitism. Identifying important source habi-tat depends on a detailed knowledge of demography, requir-ing intensive color banding and resighting of individuals toestimate survival, then finding and monitoring their nests toestimate productivity. Given that birds are trying to hide their

nests from predators, this work can be daunting—but alsovery rewarding!Louisiana Waterthrushes nest along the banks of streams

or in upturned tree roots nearby. Few ornithologists had paidmuch attention to waterthrush breeding ecology sinceStephen Eaton’s classic life history study in 1958. Given thatwaterthrush nests, once found, are relatively accessible formonitoring, Mulvihill conjectured that the Louisiana Wa-terthrush might provide a practical model for examining for-est bird populations on the reserve. So at a staff meeting inthe winter of 1996, Mulvihill and Leberman decided to ini-tiate a study of waterthrushes at Powdermill, unaware thatthis nondescript little bird might eventually provide a way tohelp assess the ecological health of streams across the region.

Stream Acidification and LouisianaWaterthrushes at Powdermill“Until I began planning for the waterthrush study, I neverfully appreciated the contrast in water quality between Pow-dermill and Laurel Run,” Mulvihill concedes. A quick litmustest shows that Laurel Run, with a pH around 5, is a hundredtimes more acidic than Powdermill Run, which has a neutralpH around 7. Acidified streams can reach pH levels as lowas 2–3, although relatively few aquatic life forms are able tosurvive below pH levels of 4–5—somewhere between blackcoffee and tomato juice.Acidification in the region generally results from either

point-source pollution, such as acid mine drainage from aban-doned coal mines, or more broadly from nonpoint sourceacidic deposition, which occurs when sulfate and nitrate

W W W . A B A . O R G 35

LouisianaWaterthrush

nests are built inupturned treeroots or in the

banks of a stream.A telltale pathwayof leaves leads up

to the nest cup,which is nestled inrootlets and lined

with fine grass andhair. Louisiana

Waterthrushchicks hatch in May,

when mayflies areabundant. Parents

are often observedfeeding beakfuls

of mayflies totheir young. Rector,Pennsylvania; May2005. Photo by©

Robert Wood.

L O U I S I A N A W A T E R T H R U S H

emissions from coal-fired power plants react with moisturein the atmosphere to create so-called “acid rain.” Dependingon the underlying bedrock, hydrogeology of streams can dif-fer from watershed to watershed. If limestone is unavailableto neutralize the input of hydrogen ions, the pH of thestream water declines, either chronically (in the case of acidmine drainage) or episodically (during heavy rainfall orsnowmelt events). This difference in stream pH formed the basis of Mulvihill’s

waterthrush study. On Powdermill Run, limestone lies closerto the surface; dissolved calcium bicarbonate generates sub-stantial base-flow alkalinity, which buffers the stream fromany effects of acidic deposition. In contrast, Laurel Run re-mains susceptible to acidification. Pollution of this streamcomes primarily from a small hand-dug “house coal” mineon a private holding in the area. The mine, which was oper-ated from the 1920s to the 1950s, runs less than 200 meters(600 feet) below the surface. Effluent from the mine still im-pacts the stream more than 50 years later.Concerted attempts to restore Laurel Run began in the fall

of 1997 when the Loyalhanna Watershed Association in-stalled a “Successive Alkalinity Producing System” (SAPS),which filters water through organic material and limestoneinto a settling pond to reduce acidity and remove heavy met-als (see Gangewere 1998). In addition, acidic discharge far-ther up in the watershed was treated by the PennsylvaniaDepartment of Environmental Protection using specialized

bioremediation techniques. The stream showed some im-provement, but despite everyone’s best effort, restorationfailed to solve all the water quality issues. The pervasiveproblem of region-wide acidic deposition remained, and per-haps the stream can never maintain a neutral pH.At about the same time that Mulvihill’s work was getting

under way, two other researchers independently decided tostudy Louisiana Waterthrushes in Pennsylvania. Terry Mas-ter of East Stroudsburg University also chose this species asa practical model to answer broad-scale ecological questions,while Robert Brooks and a student, Diann Prosser, at PennState University were interested in verifying a habitat suit-ability index for the waterthrushes, focusing on the effects offorest fragmentation (Prosser and Brooks 1998). The threeresearchers decided to collaborate on a large-scale joint re-search project, and in 1997 they received a U.S. Environ-mental Protection Agency (EPA) Science to Achieve Results(STAR) grant to conduct a study aimed at incorporating theLouisiana Waterthrush into a regional index of biological in-tegrity for forested headwater ecosystems.Headwater streams comprise two thirds of the linear reach

of major drainages in Pennsylvania and are critically impor-tant to the ecological integrity of watersheds. An EPA studyhas shown that as many as 10% of forested headwaterstreams in the northern Appalachians may be acidic duringspring base flow due to acid mine drainage; on top of that,an additional 6–27% of streams were affected by acidic dep-

B I R D I N G • M A Y 2 0 1 136

Research from Europe in the mid-1980s had shown a causal pathway linking anthropogenic stream acidification to insect prey abun-dance to population health of White-throated Dippers. Based on that result, Pennsylvania ornithologist Robert Mulvihill had the insightthat Louisiana Waterthrushes in eastern North America might be the ecological equivalent of dippers. After more than ten years of in-tensive field research, Mulvihill’s hypothesis has been confirmed. Carroll County, New Hampshire; May 2006. Photo by ©Garth McElroy.

osition. In the entire survey, more than 5,000 miles of acid-ified streams were found (Herlihy et al. 1990, Herlihy et al.1993). Given that the EPA is explicitly interested in effects ofpollution, such as acidification, why would the agency careabout a small brown bird bobbing up and down streams?The answer lies in what the waterthrush eats.Aquatic macroinvertebrates comprise the bulk of the

Louisiana Waterthrush’s diet. In the 1980s, Robert Craig ex-amined foraging ecology of both waterthrush species, show-ing that mayflies and caddisflies are important prey (Craig1984, Craig 1987). Immature larval and nymphal stages ofmacroinvertebrates crawl around in sand and decayingleaves, clinging to the underside of rocks and logs along the

stream bottom before emerging as winged adults, often inlarge synchronous hatches. In early spring, waterthrushescan most often be found foraging in the stream channel it-self, but later in May—after a big emergence—birds can alsobe seen taking short flights to pull insects from the sur-rounding vegetation; they do so with a sally-glean maneuvertypical of various other wood-warbler species.In Pennsylvania, waterthrushes seem to hatch young just

as mayflies are becoming abundant, with adults often ob-served feeding them to their chicks. But mayflies are one ofthe groups most sensitive to acidification, with many taxaunable to survive or reproduce at lower pH levels; that’s duein part to ion imbalances which disrupt cell osmosis in

mayflies. EPT indexes (for “Ephemeroptera, Ple-coptera, Trichoptera”—the scientific names of themayfly, stonefly and caddisfly orders, respectively)are used by researchers around the world to assessstream water quality. And those three insect groupsare prime food for waterthrushes.In Great Britain, Steve Ormerod and colleagues at

Cardiff University had already shown that the dis-tribution and density of the White-throated Dipper(Cinclus cinclus) is strongly affected by stream acidi-fication (Ormerod et al. 1986, Buckton et al. 1998).The world’s five species of dippers—unique amongpasserines with their ability to dive and swim underwater—all depend on fast-flowing streams. On acid-ified streams, several aspects of dipper breedingwere affected: Birds nested later, they laid smallerclutches, and both adults and young were found inpoor condition (Ormerod et al. 1991, Vickery

W W W . A B A . O R G 37

Opportunistswhen food is

short, LouisianaWaterthrushes

on acidifiedstreams have beenobserved to bring

large but probablyunpalatable prey toyoung, such as thissalamander foundalong Laurel Run.

Rector, Pennsylvania;May 2006. Photo

by © Robert Wood.

During more than ten years of monitoring, Louisiana Waterthrush numbersalong Powdermill Run have remained relatively stable. Birds breed at muchlower density along acidified Laurel Run, however, with numbers decliningthere. Figure by © Kei Sochi; based on data from Mulvihill et al. (2008).

L O U I S I A N A W A T E R T H R U S H

1992). White-throated Dippers feed their chicksmayflies and caddisflies (Ormerod et al. 1987). Andin western North America, the abundance of Ameri-can Dippers tracks favored mayfly prey (Feck andHall 2004). Although unrelated taxonomically to the White-

throated Dipper, the Louisiana Waterthrush fills a sim-ilar ecological niche in eastern North America, wheredippers are absent. Does the waterthrush, like the dip-per, track stream quality? In such a scenario, acidifica-tion from the surrounding landscape would affectstream water quality, which would affect the aquaticmacroinvertebrate community, which would affect thewaterthrushes that depend on aquatic macroinverte-brates.Mulvihill set out to test this hypothesis. Multiple

broods of field assistants—including Andrew Vitz in1999 and the author in 2004—came to Powdermill, eagerto jump rocks and splash around after birds. Field assistantswaded up and down streams in rubber boots, mist nets wereset up, birds were captured and color banded, nests werefound and monitored, habitat was evaluated, and macroin-vertebrates were collected. After several years of intensive

work and monitoring on the reserve and surroundingstreams, Mulvihill’s hypothesis was confirmed: Stream acid-ification was correlated with waterthrush population health.Compared to birds breeding along unpolluted streams,breeders along acidified streams fledged only half the num-ber of young—not because breeding was unsuccessful, butbecause acidified streams contained half the number ofbreeding pairs (Mulvihill et al. 2008).There is plenty of evidence that Louisiana Waterthrushes

just don’t like acidified streams. Overall, birds started nest-ing more than a week later. Inexperienced birds tended to berelegated to polluted streams with many unpaired males un-able to find mates, singing and singing until either giving upor leaving. Birds were less likely to return year after year, ap-parently moving to unpolluted streams as soon as they couldobtain a territory. During more than ten years of monitoring,waterthrush numbers along Powdermill Run remained rel-atively constant; however, the small population along LaurelRun continued to decline until 2009, when no wa-terthrushes were detected breeding in the study area (seegraph, p. 33). Despite the addition of extensive water treat-ment systems, Laurel Run has never fully recovered. Mulvi-hill says, “there was no measurable gain in base-flowalkalinity, and the waterthrushes basically told us that.”Reasons for the Louisiana Waterthrush’s dislike of acidi-

fied streams seem to be all about food. In the Powdermill

B I R D I N G • M A Y 2 0 1 138

Louisiana Waterthrushes migrate thousands of milesfrom wintering grounds in the Caribbean, Mexico, Cen-tral America, and northern South America to breedinggrounds in eastern North America. Steven Latta of the

Pittsburgh-based National Aviary is trying to under-stand links between waterthrushes’ breeding and win-

tering habitat—with the ultimate goal of protectingmigratory bird populations. Map by © Kei Sochi.

As part of long-term research to understand bird populationdynamics, Louisiana Waterthrushes are captured with mist-nets,then color banded to identify individuals on territory each year.Prior to fledging, nestlings are weighed, measured, and color-banded. Rector, Pennsylvania; June 2005. © Jessica Bruland.

study, breeding density was predicted by the EPT index, andbirds nested earlier where prey was abundant. Whenmayflies and other acid-intolerant macroinvertebrates dis-appear from acidified streams, waterthrushes have to feedtheir young whatever they can find, including salamandersand other novel prey. To obtain enough food from acidifiedstreams, birds were found to occupy larger territories—sometimes more than 700 meters in length (almost half amile), often with gaps between territories. On pH-neutralstreams, in contrast, territories averaged about 350 meters(less than a quarter mile). On polluted streams, parents haveto work extra hard, dashing up and down large territories orsearching unpolluted seeps and wetlands adjacent to thestream to find prey. A six-egg clutch was never found alongacidified streams in this study, suggesting that the resourcesnecessary to raise so many young, and perhaps the calciumneeded for egg formation, may be limiting. In a nutshell, wa-terthrushes are monitoring stream health.In addition to direct environmental and conservation ap-

plications, this research has provided new natural history in-formation about Louisiana Waterthrushes. Intensivelong-term monitoring has revealed atypical behaviors in thespecies, a normally single-brooded monogamous passerine.Four color-banded males were documented to be pairedwith two females at the same time—a situation referred to asopportunistic polygyny (Mulvihill et al. 2002). In particu-lar, a male waterthrush originally banded as a nestling alongPowdermill Run and polygynous in two successive years ap-peared to be actively pursuing this mating strategy, althoughyoung of his second female tended to be neglected. On eightdifferent occasions throughout the years, waterthrush pairsrenested after successfully fledging young from a previousnest, a life history strategy known as double brooding (Mul-vihill et al. 2009). Interestingly, waterthrushes were neverobserved to attempt a second brood along acidified streams,suggesting that use of this strategy may depend, at least inpart, on food availability. Although most pairs were unableto fledge young from a second nest, the instance of doublebrooding remained at 6% within the population. The rela-tively low occurrence of atypical behaviors may offer clues tohow different life history strategies evolve given suitable en-vironmental conditions.The waterthrush study has also documented the life span

of these small passerines and what individuals do from yearto year. The first male banded by Master’s lab on 5 May 1995was recaptured for the last time on 1 May 2006, when itwas at least 12 years old! This individual—affectionatelyknown as “Old Guy”—returned annually to the same 300-meter length of stream at Van Campens Glen on the NewJersey side of the Delaware Water Gap National RecreationArea. Such strong site fidelity may be typical of male wa-

terthrushes, but some females were found to be more mo-bile. A female was banded as a young bird with white, black,and silver bands at Powdermill Run 9 July 1997. She nestedalong Laurel Run in 1999, jumped streams to PowdermillRun several hundred meters below the study area in 2000,was caught with fledglings around the banding lab in 2002,and then moved back to Powdermill Run in 2004, whereshe fledged five young from a nest in an upturned tree root.She came back the following year to the same territory. Liv-ing for at least eight years, she left acidified Laurel Run afterthe first breeding season.Original impressions that waterthrushes breed success-

fully on the reserve and surrounding forests were supportedby the result that more than half the nests fledged young.Females on average were able to fledge three young per year,likely more than enough to replace the breeding pair. At leasthalf the adults survived each year, returning with the highsite fidelity typical of many passerine species. The researchsuggests that, without stream acidification, waterthrushes inthe region are doing well, with streams likely supporting oneof those all-important source populations for the species.Protecting intact forests—such as those at Powdermill andsurrounding areas—may be one of the best ways of main-taining forest songbird populations.Today, Steven Latta, Director of Conservation and Field

Research at the National Aviary in Pittsburgh, continues thewaterthrush research, and has expanded the project’s scope

W W W . A B A . O R G 39

This “Old Guy”—as he came to be known—was at least 12 yearsold when last seen 1 May 2006 with a nest at Van Campens Glenin the Delaware Water Gap near the Pennsylvania–New Jerseyboundary. First banded by Terry Master of East Stroudsburg Uni-versity on 5 May 1995, this male returned to the same 300-meterlength of stream year after year. Delaware Water Gap NationalRecreation Area, New Jersey; May 2004. Photo by© Terry Master.

L O U I S I A N A W A T E R T H R U S H

to include streams in the Dominican Republic during thenon-breeding season. Extending preliminary work by Mas-ter and Mulvihill in Costa Rica (Master et al. 2005), as wellas work by Len Reitsma of Plymouth State University inPuerto Rico (Hallworth et al. 2011), this research increasesknowledge of waterthrush ecology during the non-breedingseason. In the past four years, Latta has been working to un-derstand how stream water quality affects survival and re-turn rates during the winter months. He is also trying tointegrate year-round waterthrush research with the broadgoal of using this species as a model neotropical migrant toachieve better understanding of factors that regulate birdpopulations throughout the annual cycle.

The Future Spring comes and waterthrushes return to Powdermill andLaurel Run, some with color bands on their legs, others un-banded new recruits trying to carve out territories in theworld of rushing streams and tall trees. However, a new en-vironmental hazard threatens streams at Powdermill andmany other places in the northeast. Gas drilling of the Mar-cellus Shale layer is rapidly expanding, even though the en-vironmental impacts of this practice remain unclear andcontroversial. A profitable business in poor economic times,gas extraction occurs through a process called hydraulic frac-

turing (colloquially known as “fracking”), in which thou-sands of gallons of chemically laced water are pumped underextreme pressure a mile or more below the surface to crackthe shale layer and release gas deposits. According to the EPA,which recently initiated further study of hydraulic fractur-ing, some 15–80% percent of fracking fluid is subsequentlyrecovered. Although Marcellus Shale fracturing theoreticallyremains below the water table, cases of water pollution havebeen documented in this and other formations across thecountry. No one really knows what the effects of this type of drilling

are, but some scientists are worried. Petra Wood with theU.S. Geological Survey and West Virginia University beganstudying the effects of gas drilling on Louisiana Water-thrushes in 2008. Greg George and Jim Sheehan, who coor-dinated the project, both initially studied waterthrushes withMaster and Mulvihill. In Pennsylvania, almost half of stateforest land within the Marcellus shale region has been leasedfor drilling, with roads into drill pads potentially fragment-ing ecologically sensitive forests. Scott Stoleson of the U.S.Forest Service says multiple conventional gas wells beingdrilled and fracked at higher densities in some areas couldcreate an even greater footprint. Protecting stream health isalso, of course, important for protecting human health. A re-cent study found associations between stream degradationand cancer rates in the coal mining state of West Virginia(Hitt and Hendrix 2010). From the waterthrushes we al-

ready know how subtle forms of pol-lution can contaminate streamwater for decades.

In 2011, Steven Latta, along with

B I R D I N G • M A Y 2 0 1 140

Much of what we know about Louisiana Waterthrush biologyis based on studies of birds on the breeding grounds. Ongoingresearch on the wintering grounds should provide valuableadditional insights regarding the natural history of thislong-distance migrant. San Francisco de Macoris, Domini-can Republic; January 2010. Photo by© José Panteleón.

Stoleson and Mulvihill, will be ini-tiating further research to studythe potential impacts of hydraulicfracturing and gas production onstream water quality, macroinver-tebrates, and Louisiana Water-thrushes. As Mulvihill says,“anything that impacts the quan-tity and quality of the macroinver-tebrates can affect waterthrushes.”Sampling of environmental con-taminants in waterthrushes acrossPennsylvania may help elucidatesome of the effects of drilling onwildlife and point toward similarpotential impacts on humanhealth. For example, an explo-ratory study by David Evers, Di-rector of the BioDiversity ResearchInstitute, has shown that water-thrushes appear to bioaccumulatehigh blood levels of methylmer-cury from atmospheric deposition.Latta hopes this new research willdocument some of the environ-mental consequences of Marcel-lus Shale fracturing, and suggestways to protect sensitive riparianecosystems.

vvv

Research with waterthrushes tellsa compelling story that birds canprovide essential ecological infor-mation to help guide decisions forthe future. Birders can be a part ofthat story. Walk along any forestedheadwater stream in eastern NorthAmerica. Look and listen for wa-terthrushes while keeping an eyeon the rocks for splay. Pay atten-

W W W . A B A . O R G 41

Do Louisiana Waterthrushes alsofunction as bio-indicators ofstream water quality during thenon-breeding season? That is oneof the questions being addressedby a research team with the Na-tional Aviary. El Yunque NationalForest, Puerto Rico; February 2005.Photo by © Felicity L. Newell.

L O U I S I A N A W A T E R T H R U S H

tion to those first returning birds in early spring; they knowwhere the healthy streams are. Waterthrushes are sure to befound tracking their favored prey of in-stream macroinver-tebrates. Count the birds and be sure to let your local wa-tershed association know what you find. Studies indicatethat at least two territories per kilometer (about four territo-ries per mile) occur on healthy streams.Volunteer birders from local communities can make an im-

portant contribution by conducting bio-assessments ofstream water quality, including waterthrush surveys. BradyMattsson, a research ecologist with the U.S. Geological Sur-vey, says that stream-dependent birds such as the LouisianaWaterthrush can serve as early warning signals for streamdegradation (Mattsson and Cooper 2006). Surveys of stream-side birds, including waterthrushes, have been implementedas part of long-term monitoring of stream health by the U.S.National Park Service’s Eastern Rivers and Mountains Net-work. With the potential for increased water pollution fromgas drilling, it is important to collect baseline data on wa-terthrushes to ensure that these birds do not disappear fromstreams where they are now common. The Louisiana Wa-terthrush’s dependence on unpolluted streams is risky busi-ness. The species is the canary outside the coal mine.

AcknowledgmentsI especially thank Ian Ausprey for help with editing and re-visions, as well as Robert Mulvihill, Steven Latta, Paul Hess,Brady Mattsson, Terry Master, and Pam Ferkett for theircomments. Understanding the role of Louisiana Wa-terthrushes as an indicator of headwater stream health con-tinues to be the result of many people’s combined efforts. Iam pleased to acknowledge the contributions of the indi-viduals mentioned in this article as well as numerous otherswhose past and ongoing work have helped tell this story.

Literature CitedCraig, R. J. 1984. Comparative foraging ecology of the Louisiana and Northern wa-

terthrushes. Wilson Bulletin 96:173–183.

Craig, R. J. 1987. Divergent prey selection in two species of waterthrushes (Seiurus).

Auk 104:180–187.

Eaton, S. W. 1958. A life history study of the Louisiana Waterthrush. Wilson Bulletin

70:210–235.

EPA Volunteer Watershed Monitoring <tinyurl.com/4jcdyvs>.

Feck, J. and R. O. Hall. 2004. Response of American Dippers (Cinclus mexicanus) to

variation in stream water quality. Freshwater Biology 49:1123–1137.

Gangewere, J. R. 1998. Saving our mountain streams. Carnegie Magazine

<tinyurl.com/4rtbdwo>.

Hallworth, M. T., L. R. Reitsma, and K. Parent. 2011. Habitat use of the Louisiana

Waterthrush during the non-breeding season in Puerto Rico. Wilson Journal of

Ornithology in press.

Herlihy, A. T., P. R. Kaufmann, M. E. Mitch, and D. D. Brown. 1990. Regional estimates

of acid mine drainage impact on streams in the Mid-Atlantic and Southeastern

United States. Water, Air, and Soil Pollution 50:91–107.

Herlihy, A. T., P. R. Kaufman, M. R. Church, P. J. Wigington, and J. R. Webb. 1993. The

effect of acidic deposition on streams in the Appalachian Mountain and Pied-

mont Region of the Mid-Atlantic United States. Water Resources Research

29:2687–2703.

Hitt, N. P. and M. Hendrix. 2010. Ecological integrity of streams related to human

cancer mortality rates. EcoHealth 7:91–104.

Latta, S. C. and R. S. Mulvihill. 2010. The Louisiana Waterthrush as an indicator of

headwater stream quality in Pennsylvania, pp. 246–258 in: S. Majumdar, T. Mas-

ter, R. Ross, M. Brittingham, R. Mulvihill, and J. Huffman, eds. Avian Ecology and

Conservation: A Pennsylvania Focus with National Implications. Pennsylvania

Academy of Sciences, Easton.

Master, T. L., R. S. Mulvihill, R. C. Leberman, and J. Sánchez. 2005. A preliminary

study of riparian songbirds in Costa Rica, with emphasis on wintering Louisiana

Waterthrushes, pp. 528–532 in: C. J. Ralph, ed. Bird Conservation, Implementa-

tion, and Integration: Proceedings of the Third International Partners in Flight Con-

ference—20–24 March 2002, Asilomar, California. U.S. Forest Service General

Technical Report PSW-GTR-191.

Mattsson, B. J. and R. C. Cooper. 2006. Louisiana Waterthrushes (Seiurus motacilla)

and habitat assessments as cost-effective indicators of in-stream biotic in-

tegrity. Freshwater Biology 51:1941–1958.

Mattsson, B. J., T. L. Master, R. S. Mulvihill, and W. D. Robinson. 2009. Louisiana Wa-

terthrush (Parkesia motacilla), in: A. Poole and F. Gill, eds. The Birds of North

America, no. 151. Academy of Sciences, Philadelphia, and American Ornithol-

ogists’ Union, Washington.

Mulvihill, R. S., A. Cunkelman, L. Quattrini, T. J. O’Connell, and T. L. Master. 2002.

Opportunistic polygyny in the Louisiana Waterthrush. Wilson Bulletin 114:106–

113.

Mulvihill. R. S., F. L. Newell, and S. C. Latta. 2008. Effects of acidification on the

breeding ecology of a stream-dependent songbird, the Louisiana Waterthrush

(Seiurus motacilla). Freshwater Biology 53:2158–216.

Mulvihill, R. S., S. C. Latta, and F. L. Newell. 2009. Temporal constraints on the inci-

dence of double brooding in the Louisiana Waterthrush. Condor 111:341–348.

Ormerod, S. J., N. Allinson, D. Hutchinson, D. Tyler, and S. J. Tyler. 1986. The distri-

bution of breeding dippers (Cinclus cinclus (L.); Aves) in relation to stream acid-

ity in upland Wales. Freshwater Biology 16:501–507.

Ormerod, S. J., S. V. Efteland, and L. Gabrielson. 1987. The diet of breeding Dippers

C. cinclus cinclus and their nestlings in southwestern Norway. Holarctic Ecology

10:201–205.

Ormerod, S. J., J. O’Halloran, S. D. Gribbin, and S. J. Taylor. 1991. The ecology of dip-

pers Cinclus cinclus in relation to stream acidity in upland Wales: breeding per-

formance, calcium physiology, and nestling growth. Journal of Applied Ecology

28:419–433.

Prosser, D. J. and R. P. Brooks. 1998. A verified habitat suitability index for the

Louisiana Waterthrush. Journal of Field Ornithology 69:288–298.

Vickery, J. 1992. The reproductive success of the dipper Cinclus cinclus in relation

to the acidity of streams in south-west Scotland. Freshwater Biology 28:195–

205.

B I R D I N G • M A Y 2 0 1 142