The Ardeid Newsletter, 2007 ~ Audubon Canyon Ranch

8/9/2019 The Ardeid Newsletter, 2007 ~ Audubon Canyon Ranch

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Conservation Science and

Habitat Protection at

Audubon Canyon Ranch

2007

Sonoma Sunshine

vernal pools

energy footprints

Tomales Bay

waterbirds

foraging horizons

herons and egrets

tiny pathogen

sudden oak death

THE

ARDEID


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the Ardeid 2007

In this issue

Saving Sonomas Sunshine: Vernal pool restoration at Bouverie Preserve by Sherry Adams, Jeanne Wirka, and Daniel Gluesenkamp ......................................... page 1

Energy Footprints on Tomales Bay:The importance o ephemeral ood abundance by Wesley W. Weathers and John P. Kelly.................................................................... page 4

Foraging Horizons: How broadly do herons and egrets search the landscape to fnd ood? by John P. Kelly and Mark McCaustland ..................................................................... page 7

Tiny Pathogen with Tremendous Impact: Landscape perspectives in conservation by Emiko Condeso .................................................................................................. page 10

Cover: Surf Scoter on cresting wavelet. Photo by R. Crossley /VIREO

Audubon Canyon RanchConservation Science andHabitat Protection

Executive StafSkip Schwartz, Executive DirectorJohn Petersen,Associate DirectorYvonne Pierce,Administrative Director and

Bolinas Lagoon Preserve Manager

Science StafJohn Kelly, PhD, Director, Conservation Science

and Habitat ProtectionEmiko Condeso, Research CoordinatorDaniel Gluesenkamp, PhD, Habitat Protection

and Restoration SpecialistGwen Heistand, Bolinas Lagoon Preserve

BiologistJeanne Wirka, Bouverie Preserve BiologistSherry Adams, HPR Projects Leader (Bouverie

Preserve)Denise Della Santina, HPR Projects Leader

(Marin)Mark McCaustland, Helen Pratt FellowEric Richardson, HPR Field echnician

Land StewardsBill Arthur, Bolinas Lagoon PreserveDavid Greene, omales Bay propertiesJohn Martin, Bouverie Preserve

Research AssociatesJules EvensHelen PrattRich Stallcup

Habitat Protection and RestorationAssociates

Len BluminRoberta Downey

The Watch

Nancy Abreu (H); Ken Ackerman (S,W);Sarah Allen (S); Peter Ashley (R); ShirleyAustin-Peeke (R,C); Bob Baez (S,W);

Norah Bain (H); Bruce Bajema (H,S,R);Justin Baker (R); Katy Baty (W); omBaty (W); Gordon Bennett (S,W); LoisBielelt (R); Sherm Bielelt (R); Gay Bishop(S); Giselle Block (H); Greg Block (H);Len Blumin (S); Patti Blumin (H); EllenBlustein (H,S); Noelle Bon (H); JanetBosshard (H); Melissa Brockman (H);Phil Burton (H); Denise Cadman (H);Alexa Carlson (R,C); Melissa Carlson(RC); Kate Carolan (W); Ann Cassidy(H); Saul Chaikin (F); Brian Cluer (H);George Clyde (W); Miles Dakin (R); SamDakin (R); Karen Davis (H); MelissaDavis (H,W); John Dineen (H); PabloDoce (R); Roberta Downey (R); Bob Dyer(H); Gladys Ellis (H); Jules Evens (S,W);Binny Fischer (H,W); Jobina Forder (R);Carol Fraker (H); Dillon Franklin (R);

Dennis Fujita (R); Amanda Gardner (H);Jennier Garrison (H); Daniel George(S); ony Gilbert (H,S,W); Beryl Glitz(H); Dohn Glitz (H); Johanna Good (R);Philip Greene (H); David Greene (W);John Grennitteer (R); Pamalah Grennitteer(R); Erik Grijalva (R); Elana Gureny (R);Madelon Halpern (H); Fred Hanson (S,W);Christian Hellwig (H); Andrea Hernandez(R); Logan Heyerly (R); Diane Hichwa (H);Pat Hildreth (H); om Hildreth (H); KimHobson (H); Joan Hofman (H); IngridHogle (R); Roger Hothem (H); Lisa Hug(S,W,H); Shelly Hughes (H); Jared Jacobs(R,C); Jeri Jacobson (H); Rick Johnson(H,S,W); Gail Kabat (W); Jerry Karr (H);Guy Kay (H); Drew Kerr (R); Ellen Krebs(H); Carol Kuelper (S); Eva Laevastu (H);Joan Lamphier (H,S,W); Charlotte Lee

(H); Mike Lennox (H); Stephanie Lennox

(H); Robin Leong (H); Eileen Libby (H);Joan Lippman (H); Wayne Little (H);Sawyer Lloydd (R); Steve Lombardi (H);

Carolyn Longstreth (H); John Longstreth(H); Arthur Lyons (W); Nancy MacDonald(R); Art Magill (R); Lyn Magill (R);Sandy Martensen (R); Jen McBroom (R);ripp McCandlish (R); Diane Merrill(H); Jean Miller (H); Stephen Moore(H); Ian Morrison (S); Joan Murphy (S);Dan Murphy (S); Kim Neal (H); AllisonNelson (R); Len Nelson (H); DexterNelson (R); Wally Neville (H); erryNordbye (S,W); Alina Nuebel (R,C); PatOBrien (R); Precious Peoples (H); KatePeterlein (S); Ryan Phelan (H); Bob Pitts(H); Richard Plant (W); Maris Purvins(R,C); Jef Reichel (H); Linda Reichel(H); Don Reinberg (S); Rudi Richardson(W); Arthur Robinson (H); Jane Rodgers(R); Glenda Ross (R); Ellen Sabine (H);Marilyn Sanders (H); Sharon Savage (R);

Phyllis Schmitt (H,R,C); Gordon Schremp(H); Alice Schultz (H); Harold Schulz (H);Steve Shafer (H); Elliot Smeds (R,C); PatSmith (H); Joe Smith (W); Marjorie Smith(W); Ben Snead (W,F); John Somers (H,S);Bill Stanley (H); Jean Starkweather (H); LizSterns (R); ina Styles (H); Lowell Sykes(H,S,R); Judy emko (H,S); Janet Tiessen(H,W); Melissa Tompson (W); Mikeracy (R); Tomas ucker (H); MariamUpshaw (H); Gerrit Van Sickle (R,C);Varia Walle (H); anis Walters (S); RichardWassen (R,C); Wesley Weathers (H); GraceWellington (R,C); Jim White (S,W); AdeleWikner (H); Ken Wilson (S); Will Wilson(S,W); Brandon Witwicki (R); DylanWitwicki (R); Wendy Wood (H); PatrickWoodworth (H,S,W)

Volunteers or ACR research or habitat restoration projects since TeArdeid2006. Please call (415) 663-8203 i your name should have beenincluded in this list.

Project ClassifcationsC = Bouverie Preserve Craysh ResearchH = Heron and Egret ProjectR = Habitat Restoration and Protection S = omales Bay ShorebirdCensus W = omales Bay Waterbird Census


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Sonoma sunshine (Blennosperma bakeri)may yet thrive in the Valley o theMoon. Tis small yellow daisy-like annual,a ederally listed endangered species, isrestricted to the vernal pools and swaleson the Santa Rosa Plain and in the SonomaValley. Indeed, the last remaining viableSonoma Valley population o this specialplant occurs very close to Audubon CanyonRanchs Bouverie Preserve. Along with theproximity o this population at the Preserve,another rare vernal pool plant is present,dwar downingia (Downingia pusilla). Tisofers the Audubon Canyon Ranch scienceprogram an opportunity to take a leadershiprole in the preservation o both o these rareplants, as well as the local vernal pool land-scapes that support them. Here we reporton the exciting new directions o this work,recently boosted by additional unding,sta ng, and strong local partnerships.

A plant species can be rare or manyreasons. Some have always been rare, whileothers have become rare with anthropogenicchanges to the landscape. A plant that is ahabitat specialist, ound in a narrow rangeo conditions, is particularly vulnerable tobecoming rare. Another characteristic thatcan make a plant vulnerable is dependenceon another species or some part o its liecycle. In the case o some owering plants,

a decline in the population o aspecialized pollinator, or example,may result in lower seed produc-tion. Tat combination o habitatspecicity and specialist pollinatorshas caused a decline in many ver-nal pool plants (see box below).

As with vernal pools statewide,the majority o vernal pools inSonoma County have been elimi-nated, a casualty o being locatedon private land that is consideredprime real estate or agricultureor development. Tree plantsound in Sonoma County vernalpools are currently recognized byboth state and ederal agencies asendangered. Some animal special-ists, such as the Caliornia tigersalamander, are also impacted bythis loss o habitat.

Te Bouverie Preserve contains a net-work o interconnected vernal pools andswales in the 30-acre grassland on the west-ern boundary o the Preserve. Like mostvernal pools in Caliornia, the Bouveriepools ace a host o challenges that threatento impair the system. Te typical vernal poolhydrological cycle o complete inundationin winter ollowed by complete desiccationin summer protects the small-stature native

plants rom being replaced by the inva-

sive plants that dominate the surroundinggrassland. Where this hydrologic regime hasbeen compromised by silt deposition, thepools have been invaded and their speciescomposition altered. Furthermore, Bouver-ies pools are located immediately adjacentto a busy highway rom which nitrogen-laden vehicle exhaust can ertilize invasiveplants, making them even more competitivewith the diminutive native owers.

Vernal pool restoration at Bouverie Preserve

Saving Sonomas Sunshine

by Sherry Adams, Jeanne Wirka, and Daniel Gluesenkamp

2007 THE ARDEID page 1

Figure 1. Native plants like the colorul calicofower (Downingia

concolor) characterize intact vernal pools.

California Vernal Pools: Precarious Islands of Nativeness

Vernal pools are spots where rainwater collects because o bedrock or clay soils, creating a seasonal wetland. Caliornias winter rainsll the small pools or interconnected swales, and with the onset o the dry season in spring they become completely desiccated. Vernalpools have a suite o specialist speciesstunning plants and animals specially adapted to this challenging environment. Approximately90% o all vernal pools have been destroyed, as they are oen located in areas which are deemed ideal or agriculture or development.Vernal pool destruction is generally mitigated with the creation o substitute pools, with varying success in sustaining populations o thehighly specialized plants and animals that are adapted to this unique habitat. Te remaining natural pools are a crucial reservoir o thenative, and requently endemic, biota.

Most Caliornia vernal pools are located in grasslands with microtopographic relie. Tese grasslands are among the most invadedhabitats anywhere. In a typical Caliornia grassland over 90% o the biomass is rom grasses o European origin, introduced by people.However, the hydrologic regime in the vernal poolscomplete inundation in winter ollowed by complete desiccation in summerisone that ew species are able to invade. As a result, these depressions are islands o native species surrounded by an ocean o invasivegrasses. Where the hydrologic regime is compromised, pools can quickly become invaded, with an associated decline in native diversity.Adding to the vulnerability o vernal pool ora, many species only thrive when visited by specialist pollinators: solitary ground-nestingnative bees that only visit owers o a particular genus.


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Given these threats, in 2005 AudubonCanyon Ranch initiated a vernal poolmanagement program that began withprescribed grazing to remove some o thebiomass rom European annual grasses.Funding rom the Community Foundationo Sonoma County has been crucial, and has

allowed us to study the efects o nitrogendeposition rom highway vehicles and toully characterize the oristic and physicalcharacteristics o the pools (Gluesenkampand Wirka,Ardeid2006). New undingrom the U.S. Fish and Wildlie Service en-ables us to take the next step toward actualrestoration o our target species.

Our target species: Sonoma sunshineand dwarf downingia

Sonoma sunshine is a Caliornia endem-ic in the sunower amily (Asteraceae) that

blooms rom February through April. Atleast 30% o the documented occurrences oSonoma sunshine have been eliminated orseriously damaged, and most o the remain-ing sites are threatened with urbanization,irrigation with wastewater e uent, andconversion o habitat to agricultural lands(CNPS 2007). Tere are ewer than tenlocations in the Santa Rosa Plain where thespecies remains. O the ve occurrencesdocumented in Sonoma Valley in 2000,only one remains.

Tis Sonoma Valley population o Sonomasunshine is located just a short walk rom

ACRs Bouverie Preserve. Historical photossuggest that the pools on either side othe highway were once interconnected,indicating that they once shared the samegroup o species. Preliminary data romwork currently underway by the Laguna deSanta Rosa Foundation (Christina Sloop,personal communication) suggests that thispatch o Sonoma sunshine may be geneti-cally distinct rom occurrences on the SantaRosa Plain, underscoring the importanceo its protection. While the population is

currently protected rom development, it iswithin 2 m o an annually disked re break.Tere is no ence separating it rom a busyrural highway that conveys 15,000 vehiclesa day. Recently, the last wild population oDelphinium bakeri was eliminated by roadcrews in Marin County. Te elimination o

this other endangered roadside plant rein-orces our concern that Sonoma sunshinemay be just one errant driver away romdestruction.

Our other rare plant, dwar downingia,is a diminutive annual belly plant in thebellower amily (Campanulaceae) withtiny white or blue owers that bloom romMarch to May. It grows in vernal poolsand on margins o vernal lakes and othermoderately wet areas in oothill and valleygrassland. Dwar downingia is consideredrare in the nine Caliornia counties in which

it occurs. Sonoma County is the only coastalcounty where the species persists, yet threeo the 14 Sonoma County occurrences listedin State Natural Diversity Data Base havebeen extirpated (Dittes and Guardino 2003).Because the majority o extant occurrenceso this species are located on private land,its conservation trajectory in Caliornia willmost likely parallel the declines o othervernal pool taxa in the state. Fortunately,the Bouverie Preserve supports a persistentpatch o dwar downingia in a long-aban-doned quarry near the vernal pools (Glue-senkamp,Ardeid2005).

Restoration work at BouverieTe challenge o restoring habitat or

these two species, as well as the myriadother native vernal pool plants at the Bouv-erie Preserve, is signicant. Restoration aimsto provide or maintain the necessary habitatcharacteristics (hydrology, soil type, vegeta-tion), while adding su cient propagules(seeds or baby plants) to enhance the targetspecies. Because we are not starting rom aclean slate, we must be careul to balancehabitat requirements and practical manage-

ment considerations to yield optimal results.Several pools at Bouverie do not cur-

rently have su cient water depths to main-tain a native species composition and havebeen invaded by non-native species such asvelvetgrass (Holcus lanatus) and pennyroyal(Mentha pulegium). Shallow water depthslikely resulted rom historic management,especially irrigation and tilling which canlead to siltation. Tere are intact vernalpools as well at Bouverie, which are domi-nated by native species and host a variety overnal pool specialist plants, although in low

numbers.

Restoration Takes TeamworkAudubon Canyon Ranch is working with a number o partners to advance the sci-

ence and practice o vernal pool conservation in Sonoma County. Tis work benetsrom leadership by the Laguna de Santa Rosa Foundation, the Milo Baker chapter o theCaliornia Native Plant Society, the Sonoma Valley Regional Park District, representa-tives o ederal and state agencies, and consultants who specialize in vernal pool work.Tis vernal pool working group is putting together a network o volunteer botanistseach o whom adopts a vernal pool to revisit yearly. Te goals are to set standards orhow vernal pools should be monitored and to provide the baseline data needed to ad-equately protect the natural resource.

At Bouverie Preserve, the coordinated eforts o staf scientists, volunteers, universityresearchers, and private consultants make restoration work possible. Dan Gluesenkamp

leads the Habitat Protection program at ACRs preserves and, as president o the Calior-nia Invasive Plant Council, is a statewide leader in invasive species management and edu-cation. Jeanne Wirka is the resident biologist at Bouverie and brings extensive experiencein native grasses and restoration projects. Sherry Adams has recently joined the AudubonCanyon Ranch science staf and has taken the lead on the vernal pool restoration project.Sherry gained experience in vernal pool monitoring in the Central Valley.

Bouveries dedicated volunteers make labor-intensive projects like this possible.Young volunteers returned week aer week to careully collect the seeds rom the low-to-the-ground vernal pool plants (Figure 2). Te dedicated Bouverie Stewards volunteercrew, led by long-time Audubon Canyon Ranch volunteer Ken Ackerman, installed anextensive encing system in the vernal pool grasslands, which made the grazing pro-gram at Bouverie possible. I you are interested in volunteering or this project or othernatural areas restoration work, please contact Sherry Adams at [email protected].

page 2 THE ARDEID 2007

Figure 2. Seventh-graders Sawyer Lloyd and Miles Dakin

collect seeds or reintroduction in Bouverie vernal pools.

ACRPHOTO


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An important part o the restorationwork began in 2005, when cattle grazing wasreinstituted on the grasslands that contain

Bouveries vernal pools. Research has shownthat vernal pool native diversity increaseswith some grazing (Marty 2005). Te cattlepreerentially consume the ast-growing Eu-ropean grasses that, le ungrazed, degradevernal pools by competing with nativeplants or soil and light resources and leave athick layer o thatch at the end o the grow-ing season. Importantly, European grassesmay have a negative impact on nativeplants by changing the hydrologic regime,as ground water evaporates into the airthrough the extensive surace area o these

grasses, resulting in less water in ungrazedpools. Te Bouverie Stewards volunteercrew dramatically improved grazing atBouverie by installing proessional-qualityences in the grassland.

Te next phase in vernal pool restorationat Bouverie involves removing accumu-lated invasive-grass biomass and possiblyeven removing silt, which has accumulatedin some pools. Tis work will restore thehydrologic regime that avors the vernalpool species adapted to it. With the help oBouverie volunteers, invasive species will beremoved rom pools where they dominate.

Tis phase o the restoration is slated tobegin in all o 2007.

Audubon Canyon Ranch has recently

received approval by the State o Caliorniato collect Sonoma sunshine seeds usingmethods that do not negatively impactthe species. Trough careul hydrologicmeasurements, locations at Bouverie havebeen identied that are very similar to theconditions in which the plant currentlythrives. Both rare plant species will begrown to the seedling stage in the Bouveriegreenhouse and careully outplanted in therestored vernal pools. In addition, we havebeen collecting seeds o other vernal poolspecies that are currently present only in

one or two pools, or sowing into restoredpools. Te reintroduction work will beginin early 2008.

Taking measure of our workA crucial component o the vernal pool

restoration work at Bouverie is the monitor-ing program. By evaluating the outcomeo our restoration eforts, we can adaptmethods as necessary and share lessons withother vernal pool practitioners.

In our monitoring eforts at Bouverie,we observe hydrology by measuring waterdepths at permanently marked locations

through the season. In addition, we will sur-vey vernal pool vegetation each year to ol-low the status o the two species o concern.We have already started to notice an increasein vernal pool plants in areas grazed lastyear, and we expect that long-lived nativeseeds will continue to benet rom grazing

and the other restoration eforts.When Audubon Canyon Ranch was

granted the necessary permits to collectseeds o the endangered Sonoma sunshine,we agreed to protect the plant in perpetu-ity where it becomes established and tomaintain long-term monitoring o both theestablished and parent occurrences.

Audubon Canyon Ranchs ability topreserve these plants in perpetuity is one othe most important ways in which we cancontribute to the long-term conservationand restoration science o vernal pools in

Sonoma County. All too oen in conserva-tion eforts, interest or unding dries up aeran initial project, resulting in little inorma-tion about what methods yielded long-termsuccess. With the Bouverie Preserve locatedin the heart o the Valley o the Moon, ourstaf, volunteers, and collaborators cancontinue to use it as a living laboratory tourther conservation eforts in the region.

AcknowledgementsTis work has been supported by gener-

ous unding rom the Community Founda-tion o Sonoma County, the U.S. Fish andWildlie Services Private Stewardship GrantProgram, and rom private donors.

ReferencesCNPS (Caliornia Native Plant Society). 2007. Inventory

o Rare and Endangered Plants (online edition, v7-07a).Caliornia Native Plant Society, Sacramento, CA. [online:http://www.cnps.org/inventory].

Dittes, J. and J. Guardino. 2003. Dwar DowningiaDowningia pusilla (G. Don) orr. Species account andconservation strategies, rst dra (November 2003).Prepared or Sacramento County, Dittes and GuardinoConsulting, Sacramento, CA.

Gluesenkamp, D. 2005. Protecting the rare and uncommonplants o Audubon Canyon Ranch lands: stewardshipethic. Ardeid 2005, Audubon Canyon Ranch.

Gluesenkamp, D. and J. Wirka. 2006. Is nitrogen pollutionrom vehicles harming ragile ecosystems? Sonoma Valleyvernal pools. Ardeid 2006, Audubon Canyon Ranch

Marty, J. . 2005. Efects o cattle grazing on diversity inephemeral wetlands. Conservation Biology 19: 1626-1632.

Callitriche marginata winged water-starwort

Crassula aquatica water pygmyweed

Deschampsia danthonioides annual hairgrass

Downingia concolor downingia or calicofower

Downingia pusilla dwar downingia

Eleocharis macrostachya pale spike-rush

Eryngium aristulatum coyote thistle

Gratiola ebracteata bractless hedge-hyssop

Isoetes howellii Howells quillwort

Juncus xiphioides iris-leaved rush

Lilaea scilloides fowering quillwort

Limnanthes douglasii meadowoam

Mimulus guttatus seep monkey-fower

Montia ontana water montia

Navarretia intertexta needle-leaved navarretia

Plagiobothrys stipitatus popcorn fower

Pleuropogon caliornicus Caliornia semaphore grass

Psilocarphus brevissimus dwar wooly marbles

Ranunculus aquatilis broad-leaved water buttercup

Triphysaria eriantha butter-and-eggs


Table 1. Native plants in the Bouverie Preserve vernal pools.


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How important are water-birds to omales Baysecology? rying to answerthis question is like simul-taneously putting togethernumerous jigsaw puzzles. Forecologists, one o natures mostimportant puzzles is energy.Understanding energy use bywaterbirds on omales Bayis a puzzle with as many as25,000 bird piecesone oreach loon, grebe, cormorant,duck, or other bird on theopen waterplus countlessother pieces accounting or thebirds sources o ood energy.In addition, several thousandshorebirds and gulls dependeach winter on ood producedin omales Bay. But with jigsaw puzzles,

some pieces are more important than oth-ers, and all the pieces do not have to be inplace beore an image appears. All animalsrequire a continual supply o energy, whichthey obtain rom ood, to uel everythingrom oraging and reproduction to juststaying alive. Knowing how much energy agiven species needs, and whatraction o the total availableenergy that need represents,provides a key indication o aspecies ecological importance.

During winter, omales

Bay plays host to over 57 spe-cies o waterbirds and providesspawning habitat or Pacicherring (Clupea harengus pal-lasi), which move into thebay between late Novemberand early March to lay theireggs on eelgrass. Spawningherring provide ood or avariety o animals includinginvertebrates, sh, birds, andmammals. Spawning eventsprecipitate huge eeding ren-zies at the waters surace that

The importance o ephemeral ood abundance to wintering waterbirds

Energy Footprints on Tomales Bay

by Wesley W. Weathers and John P. Kelly

Figure 1. Gill net harvest o Pacic herring in Tomales Bay.

Sur Scoter running to take fight.


PHOTOBYJOHNP.KELLY

PHOTOBYJ.JANTUNEN/VIREO

can last or days. Large numbers o ducks,

gulls, cormorants, pelicans, and other ma-rine birds, as well as Caliornia sea lions andharbor seals, can be seen easting on herringor herring eggs (roe).

In this article, we assess how impor-tant herring eggs might be to omales Baywaterbirds by calculating the birds energy

requirement and estimatinghow much o that requirementcould be met by consumingherring roe. We exclude gullsrom our calculations becauseomales Bay gulls typicallycommute to regional landllsto eed on garbage. Althoughgulls may at times orm cloudsabove active spawns, they canonly reach the herring eggsduring very low tides and onlyi the eggs are laid in certainareas that become exposed.Gulls harvest little roe ontheir own, instead piratingeggs rom diving birds andpicking up eggs driing in thewater (Bayer 1980). Resultso stomach samples reveal the

maximum number o eggs ound in gulls

is variable but mostly much smaller thanthe number ound in scoters and scaup(Haegele 1993).

Te eeding renzies that orm overspawning events also attract shermen who,since 1973, have made herring one o Cal-iornias most valuable sheries (Figure 1).

Te herring shery providestwo types o roe products thatare traditional delicacies in Ja-pan. Egg sacks or skeins, calledkazunoko, constitute thelargest part o the shery and

are obtained with anchoredgill nets that catch the herringas they move into the bay tospawn, which is when the eggsare at their ripest. Te eggskeins are then removed romthe emales, and the male andemale bodies are subsequentlyprocessed or animal eed orhuman consumption. Oneinteresting yet unansweredquestion is to what extent hu-mans compete with waterbirdsor herring roe.


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Caliornias Department o Fish andGame (CDFG) monitors the states herringpopulation and typically sets the maximalannual shery quota at 1520% o theprevious seasons biomass, a level o harvestthought to be sustainable. Yet omales Bayspawning biomass has ranged widely roma high o 22,163 short tons in 197778 to alow o 345 short tons in 199091, makingquota-setting inexact at best. Superimposedupon the year-to-year variability, therehas been a long-term herring populationdecline, with spawning biomass alling rom6697 tons per season beore 1988 (14-year

average) to 3174 tons per season since then(18-year average; Watanabe 2006), a signi-cant decline o one-hal (t

30= 2.57, P< 0.02).

Might dwindling Pacic herring stocks beadversely afecting marine birds that eed onherring or their roe?

Each year, up to 78% o the Sur Scoterpopulation that winters in the lower PacicFlyway is ound in the San Francisco Estuary(Accurso 1992, rost 2002, U.S. Fish andWildlie 2002). Te breeding population othis sea duck, as well as populations o othersea ducks (scaup, goldeneyes, Long-tailed

Ducks, and Harlequin Ducks), have beendeclining since at least 1978 (Hodges et al.1996, Savard et al. 1998). Winter diets oSur Scoters and White-winged Scoters arecomposed primarily o bivalves, but whenPacic herring spawn, scoters shi their dietto herring eggs (yler et al. 2007).

I all omales Bay waterbirds consumedonly herring roe, they would have toconsume 8132 kg o roe per day (see boxat right). Alternatively, instead o merelyconsuming roe to meet their routine energyrequirement, birds might eat as much roeas possible, exploiting an abundant yetephemeral ood supply to deposit body atas a hedge against periods o reduced orag-ing e ciency. I so, maximal consumptionrates could be 1.65 times those we calculate(Kirkwood 1983), or 13,417 kg per day.

Given these estimates or how muchherring roe omales Bay waterbirds mightconsume per day, the question becomeswhat raction o the total roe spawnedmight waterbirds actually consume? Duringthe 200506 season, there were our majorspawning events in omales Bay which,based on CDFG data (Watanabe 2006),

would have produced a total o 275,278 kgo roe. At 750 eggs per gram o roe, thisrepresents over 206 billion herring eggs!According to the CDFG surveys, 1224 shorttons o herring spawned on January 4th and777 short tons spawned on January 21st.Tese two spawning events accounted or99% o the total roe produced that season.Te January 4th spawning event would haveproduced 167,572 kg o roe. omales Bayherring eggs hatch in 10 days. During the10-day period when eggs are available, thebays waterbirds would consume 8132 kgo roe per day i they met all their energyneeds by eating only herring roe, or up to13,417 kg per day i maximally depositingat. Tus, waterbirds could at a maximum

consume 4980% o the roe spawned onJanuary 4th. Te comparable consumptionvalues or the January 21st spawning eventare 77100%.

Under these scenarios, during the200506 season roe-eeding omales Baywaterbirds might consume 60% o the roe imerely meeting their routine energy needsor 88% o the roe i depositing at maxi-mally. Te actual amount o roe consumedby waterbirds would likely be less, becausesome roe is lost to tidal and wave action andsome is consumed by sh and invertebratessuch as crabs. Nevertheless, these calcula-tions permit us to examine the potentialefect o the long-term decline in herringnumbers on waterbirds.

Estimating Energy ConsumptionWe used results rom seven years o baywide winter waterbird surveys (Kelly and

appen 1998) to calculate the total biomass o birds that eed on Pacic herring roe(able 1). We then used the biomass data to calculate each species total energy require-ment, using equations that predict the energy expenditure o ree-living winteringwaterowl (Miller and Eadie 2006) or marine birds (Nagy et al. 1999). Such predictionsare possible because an organisms energy requirement is proportional to the mass obody tissue it must maintain. Te equation o Nagy et al. (1999) is based on the eldmetabolic rate (FMR) o 36 species o wild marine birds, as determined by the doublylabeled water technique. Te equation o Miller and Eadie (2006) is based on the rest-ing metabolic rates o 24 species o wild northern-hemisphere waterowl and assumesthat FMR is three times resting metabolic rate. Tese predictive equations shouldprovide reasonable energy expenditure estimates or omales Bay birds.

We calculated the amount o roe that omales Bay waterbirds would consume basedon (1) their energy needs, (2) the energy content o roe, and (3) the e ciency withwhich birds convert ingested roe to metabolizable energy. Using Sur Scoters as anexample, the calculations were as ollows.

(1) What are the energy needs o Sur Scoters in omales Bay? Te average winterabundance o Sur Scoters on omales Bay is 6810 individuals (Kelly and appen 1998).

Sur Scoters weigh 950 grams on average (Dunning 1993), yielding a total Sur Scoterbiomass on omales Bay o 6469.8 kg (able 1). Te FMR predicted or a Sur Scotero average mass is 1287 kJ day. Multiplying this value by 6810 Sur Scoters gives a totaldaily energy expenditure o 8767 MJ per day.

(2) What is the energy content o herring roe? According to the USDA National Nu-trient Data Laboratory (http://riley.nal.usda.gov/NDL/index.html) the energy contento herring roe is 3.08 MJ per kg wet weight.

(3) How much roe would the omales Bay Sur Scoter population have to con-sume to satisy their energy needs o 8767 MJ per day? We can calculate this value bymultiplying the energy content o herring roe (3.08 MJ per kg -1) times the assimila-tion e ciency o roe (0.82), which we derived as ollows. O the metabolizable energycontained in Pacic herring eggs, 60% is derived rom protein and 40% is derived romat and carbohydrate. Only 70% o the energy contained in protein is available to birds,

versus 100% o the energy contained in at and carbohydrate. Based on these values,the overall assimilation e ciency o herring roe is 82%. Tus, birds eating herring roeobtain 2.53 MJ o usable energy per kilogram o eggs ingested. o obtain the 8767 MJo energy required each day, omales Bay Sur Scoters would need to ingest 3465 kg oroe (8767 MJ day1 divided by 2.53 MJ kg1).

Repeating these calculations or all o the omales Bay waterbirds known to con-sume herring roe (able 1) yields a total consumption o 8132 kg o roe per day.



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Our calculations suggest that omalesBay waterbirds could theoretically consumeup to 88% o the roe produced in 200506.I they did, the roe would provide 30 dayso energy or 33% o the birds total energyneeds during a 90-day herring season.

We can approximate the maximal energy

that waterbirds might have obtained prior tothe decline in the herring population, basedon the mean pre-1988 spawning biomass(6997 short tons) and assuming our equalspawning events per year. Under this sce-nario, waterbirds could consume 56% o theroe spawned, thereby obtaining an amounto energy su cient to meet their needs or66 days, or approximately two-thirds o theentire herring season. his irst-orderapproximation suggests the potentiallymajor importance o herring roe to omalesBay waterbirds.

Te jigsaw puzzle o energy relationshipsbetween waterbirds and herring is ar romcomplete, however. We are continuing to ex-amine related questions, including whethertrends in waterbird abundance actually

reect changes in the spawning intensityo herring, and the extent to which 2050million herring entering the bay each wintermay provide important ood or sh-eatingbirds.

Wes Weathers is Proessor in Animal Scienceat U.C. Davis and a collaborator in Conser-vation Science at ACR.

References citedAccurso, L. M. 1992. Distribution and abundance o

wintering waterowl on San Francisco Bay, 1988-1990.Unpublished. M.S. thesis. Humboldt State University.Arcata, CA. 252 pp.

Bayer, R.D. 1980. Birds eeding on herring eggs at theYaquina Estuary, Oregon. Condor 82:193-198.Dunning, J. B., Jr. 1993. CRC handbook o avian body

masses. CRC Press, Boca Raton.Haegele, C.W. 1993. Seabird predation o Pacic herring,

Clupea pallasi, spawn in British Columbia. Canadian FieldNaturalist 107:7382.

Hodges, J. I., J. G. King, B. Conant, and H. A. Hanson 1996.Aerial surveys o waterbirds in Alaska 1957-94: populationtrends and observer variability. Inormation and echnol-ogy Report 4. USDOI, National Biological Service.

Kelly, J. P., and S. L. appen. Distribution, abundance, andimplications or conservation o winter waterbirds onomales Bay, Caliornia. Western Birds 29:103-120.

Kirkwood, J.R. 1983. A limit to metabolizable energy intakein mammals and birds. Comparative Biochemistry andPhysiology 75A:1-3.

Miller, M. R., and J. McA. Eadie. 2006. Te allometric rela-tionship between resting metabolic rate and body mass inwild waterowl (Anatidae) and an application to estima-tion o winter habitat requirements. Condor 108:166-177.

Nagy, K. A., I. A. Girard, and . K. Brown. 1999. Energeticso ree-ranging mammals, reptiles, and birds. AnnualReview o Nutrition 19:247B77.

Savard, J. P. L., D. Bordage, and A. Reed. 1998. Sur Scoter(Melanitta perspicillata). in Te Birds o North American,No. 363 (A. Poole and F. Gill, eds.). Te Birds o NorthAmerica, Inc., Philadelphia, PA.

rost, R. E. 2002. Pacic Flyway 2001-2002 all and winterwaterowl survey report. U.S. Fish and Wildlie Service,O ce o Migratory Bird Management, Portland, OR.

yler L. L, D. Esler, and W. S. Boyd. 2007. Foraging behav-iors o sur scoters and White-winged Scoters duringspawning o Pacic herring. Condor 109:216-222.

U.S. Fish and Wildlie Service (USFWS). 2002. Waterowlpopulation status, 2002. U.S. Department o the Interior,Washington, D.C. 51pp.

Watanabe, R. 2006. Summary o the 2005-06 omales Bayherring shery season. Unpublished report, CaliorniaDept. Fish and Game. [online: http://www.dg.ca.gov/mrd/herring/tomales0506.pd]

Table 1. Abundance, biomass, and eld metabolic rate (FMR) o roe-eating waterbirds in Tomales Bay. Sur Scoters account or approximately 43% o the energy con-

sumed by these species. FMR is calculated rom body mass using equations o Nagy et al. (1999) or the American Coot and Miller and Eadie (2006) or waterowl.

Species Average Body Baywide FMR Percent FMR

abundance mass (g) biomass (kg) (MJ day1) of all species

Sur Scoter (Melanitta perspicillata) 6810.3 950 6469.8 8767.0 42.61

Bu ehead (Bucephala albeola) 5524.8 404 2232.0 3468.0 16.86

Greater Scaup (Athya marila) 2239.7 945 2116.5 2870.5 13.95

Black Brant (Branta bemicla nigricans) 1194.3 1300 1552.6 2000.9 9.72

Ruddy Duck(Oxyura jamaicensis) 1317.0 545 717.8 1063.1 5.17

Unidentied scaup (Athya spp.)1 803.4 942 756.8 1027.0 4.99

American Coot (Fulica americana) 401.7 642 257.9 405.4 1.97

American Wigeon (Anas americana) 209.9 756 158.7 223.0 1.08

Northern Pintail (Anas acuta) 139.4 1010 140.8 189.0 0.92

Red-breasted Merganser (Mergus serrator) 99.1 1022 101.3 135.6 0.66

Common Goldeneye (Bucephala clangula) 96.2 900 86.6 118.4 0.58

Black Scoter (Melanitta nigra) 71.1 950 67.5 91.5 0.44

Lesser Scaup (Athya af nis) 63.4 820 52.0 72.1 0.35

White-winged Scoter (Melanitta usca) 30.4 1757 53.4 65.5 0.32

Canvasback(Aythya valisineria) 26.3 1219 32.1 41.8 0.20

Unidentied scoter (Melanitta spp.)1 10.6 943 10.0 13.6 0.07

Mallard (Anas platyrhynchos) 9.7 1082 10.5 13.9 0.07

Redhead (Athya americana) 4.1 1045 4.3 5.7 0.03

Barrows Goldeneye (Bucephala islandica) 1.1 910 1.0 1.4 0.01

Long-tailed Duck(Clangula hyemalis) 0.5 873 0.4 0.6


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How broadly do nesting herons and egrets search the landscape to fnd ood?

Foraging Horizons

by John P. Kelly and Mark T. McCaustland

According to specialists who study ightenergetics, the slow, powerul wingbeatthat lends rhythm and grace to the move-ments o herons and egrets is a relativelyine cient orm o bird ight. Te evolution-ary engineering o these birds has, appar-ently, sacriced uel e ciency to meet otherecological needs, such as skillul landings innest trees or quick take-ofs rom tight spac-es in marshes or along creeks. For extendedtravel, soaring would be ar more e cient.I you know this, the sight o a commutingegret winging steadily along a waterway is adisplay o the costly expenditure o energyrequired to access productive eeding areas.Tis may explain why egrets occasionallyseek thermals or extra li when travelingextended distances. I ight costs challengethe ability o herons and egrets to adequatelyprovision their young, any loss or degrada-tion o habitat that orces them to travel

arther to nd ood might threaten theirability to reproduce.

Te quality o wetland oraging sitesuctuates dynamically over short periodso time, a consequence o changing waterlevels, seasonal growth o wetland vegeta-tion, and the dynamics o various preypopulations. o make the most o wetlandeeding opportunities, herons and egretshave become masters at searching hugelandscapes to nd sites o temporarily highprey abundance (Kushlan and Hancock2005). In spite o this ability, they seem to

concentrate their eeding activities nearthe colony sitea pattern suggesting limitsrelated to the costs o extended travel. In ourinvestigations at Audubon Canyon Ranch,we are asking how this apparent cluster-ing o heron and egret eeding activity nearheronries might afect the spatial patterns oother lie across wetland landscapes, as wellas regional goals or wetland habitat protec-tion and restoration.

We employ two complementary methodsto study the oraging dispersion o heronsand egrets. First, teams o observers atselected colony sites watch and record the

Figure 1. Percent o Great Egret arrival and departure fights (pooled) within 16 compass sectors during low tide

(3.12.1 t above MLLW) at West Marin Island in 2006. Most fights were oriented to the north, toward the Petaluma

and Napa marshes and the western shoreline o San Pablo Bay.

Flying Great Blue Heron.


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ight directions o departing and arriv-ing birds, using panoramic photographsand maps to indicate compass directionsrom the center o a colony to numerousreerence points in the eld (Figure 1). Butbird watching this isnt. Its more likeair tra c control, except that the pilots(birds) maintain complete radio silence withthe observers. Observers ollow departing

birds as ar as possible, and the bearings oarriving birds are recorded as soon as theyare picked up, oen 23 km out. Its not un-usual to track three or our or even six birdsat once, coming and going in all directions.At a large colony site such as West MarinIsland, near San Raael, we can easily recordover 180 ight lines per hour. For the sake ocomparison, the tower at San Francisco In-

ternational Airport coordinates at most 120takeofs and landings per hourwith radar.

Flight lines provide an inexpensiveway to determine the directions o pre-erred eeding areas, but they do not revealdistances or particular locations. A secondmethod o evaluating oraging dispersion

involves using aircra to track the ightso individual birds (Figure 2). Followingherons and egrets around with airplanesis intense, exhilarating, and expensive, butgeneral patterns begin to emerge airlyquickly. Landscapes that are amiliar romthe ground take on a antastical and disori-enting aspect when viewed rom an altitudeo 300350 m down the wing o a tightlycircling Cessna. In Suisun Bay (Figure 2),verdant marshes extend out in all directions,orming a shimmering palette o greensand muted golds laced with meandering,

mud-brown sloughs. Te twin peaks o Mt.Diablo provide a conspicuous southernreerence, and the eastern horizon is markedby the amiliar lines o wind turbines alongthe Montezuma Hills.

It is di cult to coordinate the ight oa single-engine aircra, throttled back toits minimum yable threshold o perhaps135 km per hour, to ollow a oraging egretwith an air speed o about 35 km per hour(Custer and Osborne 1978, Pennycuick2001). Such work strongly depends onskilled pilots and copilots who volunteertheir expertise and aircra. Inside thecockpit, it is hot and noisy. Communica-tion is possible only through headsets andhand signals. Sometimes the target bird getslost in the glare or catches a thermal andrapidly spirals above the plane. But heronsand egrets usually y straight and low, asi ollowing a plumb line to their oragingdestination.

We ollowed one Great Egret as it ewrom the Delta Pond colony in the Lagunade Santa Rosa, northward along the Rus-sian River valley. We managed to stay withit or over 20 minutes as it ew with stately,

unwavering precision past several appar-ently suitable marshes and ponds. Te birdnally landed in a water treatment pondwest o Healdsburg, over 15 km rom itsnest. Even determined observers nd thatconcentrating, scanning, and circling overa traveling egret can be exhausting andeven nauseating. Aer a long ight, theymay eel as i they had done all the appingthemselves!

We use these ollowing ights to buildstatistical models that predict the generalpattern o ight distances rom heronries.

Te ight distances we have observed are


Figure 2. Great Egret oraging fight vectors rom two nesting colonies in Suisun Marsh.

Figure 3. Estimated cumulative oraging dispersion o Great Egrets rom heronries in Suisun Marsh, relative to (A)

fight distance and (B) areal extent o estuarine and palustrine emergent wetland accessible within the fight radius

(models based on 1000 bootstrap samples o 36 fights).


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similar to those exhibited by herons andegrets in other regions (Custer and Os-borne 1978, Smith 1995, Custer and Galli2002). We estimated that about 60% o theGreat Egrets oraged within 3 km o theheronry or within a radius that encom-passed approximately 20 km2 o estua-rine/palustrine emergent wetland (Figure3). Tis inormation is then used to createmaps that predict landscape oraging pat-

terns (Figure 4). Te patterns are calculatedby summing, or each point on the map(100-m resolution), the number o birdsexpected to disperse rom each colony sitein the region (Kelly et al. 2006).

Te predictive map or Great Egrets sug-gested that oraging densities were substan-tially concentrated near heronries, evenwhen relatively ewer wetlands were availablenearby (Figure 4). Based on these predic-tions, regional oraging densities should behighest in Suisun Marsh, the lower PetalumaMarsh, and along the western shoreline oSan Pablo Bay southward to the northern

shoreline marshes o Central San FranciscoBay. However, inormation is lacking on theextent to which areas ar rom heronriesmight be subject to oraging by non-breedingindividuals not limited by the need to returnto nest sites. Te map also suggests that therestoration o wetlands in northern SanPablo Bay may result in a limited increasein the number o oraging egrets, whereasrestoration sites in Suisun Bay may be subject

to more intensive egret predation.O course, many inuences on oraging

movements remain unknown, includingthe complex dynamics o prey availabilityand the mysterious habitat cues herons andegrets use to optimize oraging success.Nonetheless, predictions o oraging disper-sion provide a basis or comparing levels oheron and egret predation between marshesand evaluating the extent to which nest-ing herons and egrets might be afected bychanges in the wetland landscape. Ultimate-ly, such inormation could be importantin understanding how wetland restoration

projects are likely to inuenceor be inu-enced bythe oraging activities o thesewide-ranging predators.

Literature CitedCuster, C. M., and J. Galli. 2002. Feeding habitat selection by

Great Blue Herons and Great Egrets nesting in east centralMinnesota. Waterbirds 25: 115-124.

Custer, . W, and R. Osborn. 1978. Feeding habitat use bycolonially breeding herons, egrets and ibises in NorthCarolina. Auk 95: 733-743.

Kelly, J. P., K. Etienne, C. Strong, M. McCaustland, and ML. Parkes. 2006. Annotated atlas and implications or theconservation o heron and egret nesting colonies in theSan Francisco Bay area. ACR echnical Report 90-3-17[online: www.egret.org/atlas]. Audubon Canyon Ranch,Marshall, CA 94940.

Kushlan, J. A., and J. A. Hancock. 2005. Te herons. OxordUniversity Press, New York.

Pennycuick, C. J. Speeds and wingbeat requencies omigrating birds compared with calculated benchmarks.Journal o Experimental Biology 204: 3283-3294.

Smith, J. P. 1995. Foraging ights and habitat use o nestingwading birds at Lake Okeechobee, Florida. ColonialWaterbirds 18: 139-158.

Figure 4. Predicted Great Egret oraging densities in estuarine and palustrine emergent wetlands in northern San Francisco Bay, based on average nesting distribution, 1991

2005, and oraging dispersion rom heronries relative to the extent o wetlands accessible within fight distances.


MAPBYDIANASTRALBERG


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From the view atop Sonoma Mountain,not ar rom the Valley o the Moon, thepattern o the landscape is striking. Patcheso oak woodland are like islands in a seao grasses. Seen rom aar, coast live oaksappear as dark, broccoli-like clusters inter-mixed with lighter, more graceul canopieso Oregon white oak(Quercus garryana)

and big lea maple (Acer macrophyllum).Occasionally I spot a spray o Caliorniabay(Umbellularia caliornica) zigzaggingthrough the woodland as it ollows the patho a drainage. From this vantage point it isnot di cult to imagine how the mosaic pat-

tern o habitat typeswoodland and grass-landmight inuence the creatures thatreside within. My goal as I trekked throughthe woodlands o Sonoma Mountain was tounderstand how spatial pattern might inu-ence the spread o an unwelcome but well-established visitor: Phytophthora ramorum,the pathogen that causes Sudden Oak Death

(Condeso and Meentemeyer 2007).Although landscape pattern is obvious

rom this perspective, the reasons or itsinuence on habitat quality are not. Complexarrangements o vegetation create equallycomplex patterns o abiotic conditions,

such as temperature, humidity, and light.Tese can, in turn, afect ecological pro-cesses that inuence the lives o plants andanimals. Small patches o oak woodland areoen warmer, drier, and brighter than largepatches, as their canopies provide less shadeand create a distinctly diferent environ-ment than large patches. In addition to such

within-patch efects, the surroundings ata larger scale may also impact woodlandspecies. Diferences in the arrangement andtypes o habitat elements can impact manylarge-scale processes, rom the movementrates o individuals, including disease organ-isms, to gene ow within populations, to therequency and intensity o natural distur-bances such as re. As human alteration othe landscape increases, understanding howecological processes are related to spatialpattern has become increasingly important.Tis landscape geometry inuences the

persistence o the native inhabitants o ourwoodlandsand non-native invaders as well.

Te pathogen that causes Sudden OakDeath is just such an invader. Tis orest dis-ease has reached epidemic levels in coastalCaliornia and is also impacting managedlandscapes in Europe. First described in2000, the pathogen has caused extensivemortality o tanoak(Lithocarpus densiforus),coast live oak(Quercus agriolia), Caliorniablack oak(Quercus kelloggii), and ShrevesOak(Quercus parvula v. shrevei). Ratherthan a single disease, Sudden Oak Death canactually be thought o as a suite o diseases

Landscape perspectives in conservation science

Tiny Pathogen with Tremendous Impact

by Emiko Condeso


The patchy oak woodland / grassland landscape o Sonoma County hill country.

Figure 1. Above and at let: Symptoms oPhytophthora ramorum inection on Coast Live

Oak(Quercus agriolia) (photo courtesy o Jennier Davidson, reprinted with permission o

the journal Plant Health Progress, http://www.plantmanagementnetwork.org/php).

Figure 2. At let: Symptoms oPhytophthora

ramorum inection on bay laurel (Umbellularia

caliornica) leaves (photo courtesy o Sonoma

State University).

PHOTOBYEMIKOCONDESO


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caused by a single pathogen. Tesymptoms we see difer amongspecies but can be groupedroughly into two categories: can-ker disease and oliar disease.

Oaks o the genus Quercus(excluding the white oaks), as

well as tanoak, are susceptibleto the canker orm. Tis ormis usually lethal, and inectedindividuals develop bleedinglesions in the lower part o thetrunk (Figure 1). Te appear-ance o bleeding lesions is oenollowed (sometimes years later)by a rather sudden and completebrowning o the crown or cano-py. Other susceptible species de-velop a oliar orm o the disease.Inected plants develop lea le-

sions, which usually occur wherewater can collect on the surace(Figure 2). Tis lea blight isnot atal and is mostly what Iencountered as I walked throughthe woodlands o SonomaMountain. Many Caliornia na-tive species are oliar hosts, andthese hosts play the major role indisease transmission. Dispersalspores are not produced by mostcanker hosts (tanoak being theonly exception), but are produced in volumeby oliar lesions. Caliornia bay, in particu-lar, produces copious amounts o spores andis believed to be the main reservoir host orthis pathogen in coastal Caliornia.

During the winter and spring o 2005, Ispent many hours with many eld assistantscounting these symptomatic bay leaves. Iound that the number o symptomatic ver-sus healthy leaves provided a good index othe severity o Sudden Oak Death disease. Inorder to determine the relationship betweenthe spatial pattern o orested habitat and theseverity o Sudden Oak Death, we assessedthe disease at a number o diferent, random-

ly selected locations (Figure 3). We also kepttrack o which plant species were present ateach site, the abiotic conditions (temperature,relative humidity, and light penetration),and the broad-scale pattern o the surround-ing habitat (densely wooded or sparse andpatchy). All o these data were brought backto the lab and entered into a GIS (Geograph-ic Inormation System) or analysis. GIS hasbecome an important tool in ecology and hasplayed a critical role in many aspects o theresearch and management o Sudden OakDeath (Kelly et al. 2004).

We ound that the amount o orestedarea in a large region surrounding a sampleplot predicted the severity o Sudden OakDeath in our plots better than any othervariable (Figure 4). Plots surrounded bylarge swaths o contiguous orest had higherlevels o disease, while small, isolated patch-es o woodland had lower levels. It was quitesurprising to nd that landscape patternwas a stronger predictor than the number osusceptible hosts within the sample plot. Ananalogous situation would be i the numbero people in your neighborhood was a betterpredictor o the number o amily mem-bers who will get the u than the size your

household.From the perspective oP. ramorum,

our patches o oak woodland did operatesomewhat like islandsalbeit islands with alot o tra c rom one to another. Our datastrongly suggested that the dispersal abilityoP. ramorum ar exceeded the maximumdistance between islands o woodland.Disease severity was high in plots located inlarge, contiguous woodland islands and lowin small ones. Tis trend was most likely dueto the absolute number o trees in the areacapable o supporting P. ramorum reproduc-

tion, and to a lesser degree, to the abiotic

conditions within each sampleplot or the distance betweenorested patches. Our resultswere consistent with ecologi-cal principles that explain thedynamics o isolated subpopula-tions (island biogeography and

metapopulation biology), as wellas with studies o host popula-tion efects on disease incidenceand severity. Large, contiguousswaths o host woodland mayprovide more surace area tointercept incoming spores com-pared to areas with less wood-land cover, increasing coloniza-tion rates and disease severity.A greater number o susceptiblehosts may lead to higher sporeproduction and a lower proba-

bility o disease extinction. Overtime, contiguous woodlandsmay be more efective pathogenreservoirs, maintaining moreresilient levels o disease thantheir smaller neighbors.

Te emergence and rapidspread oP. ramorum hasincreased awareness o theimpact o invasive pathogens onnatural communities. Regula-tory o cials, land managers,

and landowners are in need o inormationthat will help them understand the potentialecological impacts o this disease and guidemanagement decisions. I the probability ooak inection in a given location is propor-tional to the number oP. ramorum sporesbeing produced in that region, as suggestedby our results, it is possible that ragmenta-tion will keep the number o inected oakslow. However, even ragmented areas werenot disease ree on Sonoma Mountain, sothinning or removal o orest would notnecessarily guarantee protectionand anysuch habitat loss could devastate other oakwoodland species.

Intentionally manipulating the habitatmosaic would be risky business, but we maybe able to mimic the efect o ragmenta-tion by means other than outright thinningor clearing. In Sonoma County, a historyo logging and re suppression may haveincreased the overall cover and densityo bays and created conditions that avordisease (Moritz and Odion 2005, Rizzo etal 2005). Tereore, orests could be man-aged or decreased connectivity o reservoirhosts (such as bay laurel) by increasing thediversity and abundance o non-host species

within a orest stand. In addition, restoring


Figure 3. Study area map o Sonoma Mountain based on aerial photography. The land

cover classes (host and non-host) and locations o survey plots are shown.


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historic disturbance regimes such as re, ornding creative ways to reintroduce their e-ects, may result in woodlands that are moreresistant to Sudden Oak Death.

I I had been able to take in a broaderview rom my place atop Sonoma Moun-tain, I would have seen a mosaic not only o

woodland and grassland, but o gol courses,residential areas, and urban developments,all dissected by many roads. Human-drivenlandscape change marches on, with undeni-able and, in some cases, poorly understoodefects on the ecosystem. Studies thatincorporate the larger context o landscapeinuences on ecological process, in conjunc-tion with an understanding o the historicalecology o our region, will help us to bettermanage what is le behind.

Literature Cited

Condeso, . E., and R. K. Meentemeyer. 2007. Efects olandscape heterogeneity on the emerging orest diseasesudden oak death. Journal o Ecology 95: 364-375.

Kelly, M., K. uxin, and F. Kearns. 2004. Geospatial inor-matics or management o a new orest disease: SuddenOak Death. Photogrammetric Engineering and RemoteSensing 70: 1001-1004.

Moritz, M. A., and D. C. Odion. 2005. Examining thestrength and possible causes o the relationship betweenre history and Sudden Oak Death. Oecologia 144:106-114.

Rizzo, D. M., M. Garbelotto, and E. M. Hansen. 2005.Phytophthora ramorum: integrative research and manage-ment o an emerging pathogen in Caliornia and Oregonorests. Annual Review o Phytopathology 43: 309335.


Figure 4. Landscape infuences on lea counts, indicating levels o inection by Phytophthora ramorum. Sudden

Oak Death inection was most strongly dependent on the amount o orested land within 150250 m o the

sample plot (standardized regression coe cients; all predictors were signicant, P < 0.05).

Eects o invasive species on nitrogen retention

and other issues in the ecology and restoration

o coastal prairie. Je Corbin and Carla

dAntonio, UC Berkeley.

Practical restoration tools to increase native

grass establishment in invaded habitats. Je

Corbin, UC Berkeley.

Ecological indicators in West Coast estuaries.

Steven Morgan, Susan Anderson, and

others, UC Davis Bodega Marine Lab, UCSanta Barbara.

Long-term monitoring o the Giacomini

wetland. Lorraine Parsons, Point Reyes

National Seashore.

Analysis o sedimentation in natural and

restored marshes. Lorraine Parsons, Point

Reyes National Seashore.

Factors causing summer mortality in Pacic

oysters. Fred Gri n, UC Davis Bodega Marine

Lab.

A comparison o carbon cycling and material

exchange in grasslands dominated by native

and exotic grasses in northern Caliornia.

Laurie Koteen, UC Berkeley.

Black Brant counts at Drakes Estero, Tomales

Bay, and Bodega Bay. Rod Hug, Santa Rosa,

CA.

Strophariaceae o Caliornia. Peter Werner,

Dennis Desjardin, San Francisco State

University.

Bouverie Preserve amphibian study. David

Cook, Santa Rosa, CA.

Surace water ambient monitoring program:

south coastal Marin and San Francisco surace

water quality study. Karen Taberski, San

Francisco Regional Water Quality Control

Board.

Eects o landscape context and recreational

use on carnivores in northern Caliornia. Sara

Reed, UC Berkeley.

Eects o macroalgal bloom on seagrass

bed productivity in Tomales Bay. Brittany

Hu ngton, San Francisco State University.

Impact o an introduced plant pathogen on

Lyme Disease Ecology. Cheryl Briggs and

Andrew Swei, UC Berkeley.

Caliornia Rapid Assessment Method

wetland assessment calibration. Letitia

Grenier and Sarah Pearce, San Francisco

Estuary Institute.

Impacts o Wild Turkey(Maleagris galpavo) on

native aviauna in northern Caliornia. Angela

Gillingham, Duke University/Caliornia State

Parks.

Lyme disease and western gray squirrels. Dan

Skalkeld and Bob Lane, UC Berkeley.

Eects o planktivorous sh predation on

larvae release patterns o estuarine crabs. Lei

Rasmuson, University o Puget Sound.

Visiting investigators

For more inormation on Sudden Oak Death, see the Caliornia Oak Mortality askForces web site at www.suddenoakdeath.org.


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2007 the Ardeid page 13

The Watch:

project updates

Picher Canyon Heron andEgret ProjectThe ates oall nesting attempts at ACRs

Picher Canyon heronry havebeen monitored annuallysince 1967 to track long-termvariation in nesting behavior andreproduction.

North Bay Counties Heronand Egret Project Annualmonitoring o reproductiveactivities at all known heronand egret nesting colonies in

fve northern Bay Area countiesbegan in 1990. We recentlycompleted theAnnotatedAtlas and Implications for theConservation of Heron and EgretNesting Colonies in the SanFrancisco Bay Area [availableonline: www.egret.org]. The250-page report evaluatesthe regional status, trends,reproductive perormance, andhabitat values o herons andegrets, as well as conservationconcerns, and includes individualaccounts o all known heronriesin the region (over 150 sites). Thework is based on feld studies o

regional heronries by AudubonCanyon Ranch and the SanFrancisco Bay Bird Observatoryover 1537 years.

Tomales Bay ShorebirdProject Since 1989, we haveconducted annual shorebirdcensuses on Tomales Bay. Eachcensus involves six baywidewinter counts and one baywidecount each in August and Aprilmigration periods. A team o1520 volunteer feld observers isneeded to conduct each count.

The data are used to investigate

winter population patterns oshorebirds, local habitat values,and conservation implications.

Tomales Bay Waterbird SurveySince 198990, teams o 1215observers have conducted winter

waterbird censuses rom surveyboats on Tomales Bay. Theresults provide inormation onhabitat values and conservationneeds o more than 50 species,totaling up to 25,000 birds.Future work will ocus on trendsand determinants o waterbirdvariation on Tomales Bay.

Common Ravens in HeronriesBy radio-tracking nestingravens and conducting feldstudies o raven activity in heronand egret nesting colonies, we

have produced scientifc paperson the status o ravens and crowsin the San Francisco Bay area, onhome range use, and on ravenpredatory behaviors.

Impacts o Wild Turkeys onForest Ecosystems Invasive,non-native Wild Turkeys arecommon at Bouverie Preserveand throughout most oSonoma County. The goal othis study is to experimentallymeasure the eects o groundoraging by Wild Turkeys on

vegetation and invertebratesin the orest ecosystem oBouverie Preserve. The resultswill provide inormation that canbe used by agencies to improvemanagement and control oturkey populations.

Monitoring and Control oNon-native Crayfsh JeanneWirka and others are studying thedistribution o non-native signalcrayfsh (Pacifastucus lenisculus) inStuart Creek at Bouverie Preserveand investigating the use obarriers and traps to control thepotential impacts o crayfsh onnative amphibians and otherspecies.

Highway-Generated NitrogenDeposition in Vernal WetlandsDan Gluesenkamp, Stuart Weiss,and Jeanne Wirka are quantiyingthe potential eects o highway-generated nitrogen depositionon Sonoma Valley vernalpools. Enhanced availability onitrogen near highways might

acilitate invasion by non-native

plant species and the loss obiodiversity in sensitive vernalwetlands.

Cypress Point Restoration We are conducting a easibilitystudy or restoring the shoreline

dunes at ACRs Cypress GroveResearch Center on Tomales Bay.The project includes options orreducing the vulnerability o theResearch Center to rising sealevels.

Plant Species Inventory Resident biologists maintaininventories o plant speciesknown to occur on ACRs TomalesBay properties and at Bouverieand Bolinas Lagoon preserves.

Cape Ivy Control, Volunteer

Canyon

Manual removal hasproven to be very successul inreducing non-native cape ivyrom the riparian vegetationin ACRs Volunteer Canyon.Continued vigilance in weededareas has been important, tocombat resprouts o blacknightshade, Vinca, and Japanesehedge parsely.

Annual Surveys and Removalo Non-native Spartina andHybrids In collaboration withthe San Francisco Estuary Invasive

Spartina Project, Emiko Condesoand Gwen Heistand coordinateand conduct comprehensive feldsurveys or invasive, non-nativeSpartina in the shoreline marsheso Tomales Bay and BolinasLagoon.

Saltmarsh Ice Plant RemovalNative vegetation is recruitinginto areas where we have beenremoving non-native ice plantrom marshes and upland edgesat Toms Point on Tomales Bay.

Eradication oElytrigiapontica ssp.pontica Elytrigiais an invasive, non-nativeperennial grass that orms densepopulations in seasonal wetlandsites. At Bouverie Preserve, we areeliminating a patch oElytrigiausing manual removal and lightstarvation/solarization (blackplastic tarps), and using herbicidespot treatments to removeinvasive outlier patches.

Nest Boxes Rich Stallcupmaintains several Wood Ducknest boxes along Bear ValleyCreek in ACRs Olema Marsh.Tony Gilbert maintains WesternBluebird nest boxes in theCypress Grove grasslands.

Restoration o Coastal Dunesby Removal oAmmophilaarenaria Ammophila arenariais a highly invasive, non-nativeplant that alters the topographyand unction o coastal dunes.This project at ACRs Toms Point,on Tomales Bay, is helping toprotect native species thatdepend on mobile duneecosystems.

Grazing o BouverieGrasslands A prescribed

grazing program has beenimplemented to maintain orincrease the abundance o nativegrassland plant species and toprotect the vernal wetlands atBouverie Preserve.

Control and PossibleEradication o PerennialPepperweed in the WalkerCreek Delta We are using avariety o methods to removeand monitor the frst knowninestations oLepidiumlatifolium in Tomales Bay and,

hopeully, prevent urtherinvasion. This non-native weedis known to expand quicklyand establish huge stands thatcover oodplains and estuarinewetlands, compete with nativespecies, and alter habitat values.

Vernal Pool Restoration andReintroduction o ImperiledPlants Dan Gluesenkamp,Jeanne Wirka, and Sherry Adamsare restoring habitat conditionsin the vernal pools at BouveriePreserve. The project includes theremoval o problematic invasiveplants and restablishment o theederally listed Sonoma sunshine(Blennosperma bakeri) andCaliornia species o conservationconcern dwar downingia(Downingia pusilla). The workincludes considerable manualeort by volunteers, propagationand planting o native plants, useo prescribed fre, cattle grazing,and monitoring o changes invegetation and hydrology.


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the

Ardeid

Ardeid (Ar-DEE-id), N., reers to

any member o the amily

Ardeidae, which includes herons,

egrets, and bitterns.

Te Ardeidis published annually by Audubon Canyon Ranch as an ofering to eld

observers, volunteers, and supporters o ACR Conservation Science and Habitat

Protection. To receive Te Ardeid, please call or write to the Cypress Grove Research

Center. Subscriptions are available ree o charge; however, contributions are

grateully accepted. 2007 Audubon Canyon Ranch. Printed on recycled paper.

Managing Editor, John Kelly. Layout design by Claire Peaslee. www.egret.org

AUDUBON CANYON RANCH IS A SYSTEM OF WILDLIFE SANCTUARIES

AND CENTERS FOR NATURE EDUCATION.

BOLINAS LAGOON PRESERVE CYPRESS GROVE RESEARCH CENTER BOUVERIE PRESERVE

Conservation Science

and Habitat Protection

at Audubon Canyon Ranch

Coast live oak tree, a member o woodlands undergoing change.

Landscapes perspectives in conservation sciencesee page 10

Audubon Canyon Ranch4900 State Route One, Stinson Beach, CA 94970

Cypress Grove Research CenterP.O. Box 808

Marshall, CA 94940(415) 663-8203

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Organization

U.S. Postage

PAID

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CLAIREPEASLEE

Documents

The Ardeid Newsletter, 2007 ~ Audubon Canyon Ranch