LifeLife HistoryHistory && EcologyEcology ofof thethe WoodWood StorkStork ((MycteriaMycteria americana)americana)
Dr. Shawn Liston Research Manager, SW Region
Hart Rufe, St. Lucie Audubon
WoodWood StorkStork MycteriaMycteria americanaamericana
“Wood Ibis”
• Only stork species currently breeding in the U.S. • Largest breeding colony in the northern hemisphere @ Corkscrew Swamp Sanctuary • LENGTH: 33 ½ - 45 ½ inches • WINGSPAN: 59 – 69 inches • WEIGHT: 72 – 93 ounces (4 ½ - 5 ¾ lbs)
HOW TO ID DISTRIBUTION MIGRATION NESTING FEEDING DIET ECOLOGY IMPACTS Wood Stork Mycteria americana • Often take advantage of atmospheric thermals – conserves energy (16.0 J/m flapping vs. 1.9 J/m soaring) • Heights over 1,000 m; travel over 40 km to feeding sites • When thermal updrafts are strong, WOST can glide 16-24 km (10-15 mi) with wings motionless
HOW TO ID DISTRIBUTION MIGRATION NESTING FEEDING DIET ECOLOGY IMPACTS WoodWood StorkStork MycteriaMycteria americanaamericana
Milky Stork Painted Stork Yellow-billed Stork (M. cinerea) (M. leucocephala) (M. ibis)
HOW TO ID DISTRIBUTION MIGRATION NESTING FEEDING DIET ECOLOGY IMPACTS Historically,Historically, USUS populationpopulation summerssummers inin GAGA && SCSC andand winterswinters inin FLFL
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HOW TO ID DISTRIBUTION MIGRATION NESTING FEEDING DIET ECOLOGY IMPACTS HOW TO ID DISTRIBUTION MIGRATION NESTING FEEDING DIET ECOLOGY IMPACTS HOW TO ID DISTRIBUTION MIGRATION NESTING FEEDING DIET ECOLOGY IMPACTS HOW TO ID DISTRIBUTION MIGRATION NESTING FEEDING DIET ECOLOGY IMPACTS HOW TO ID DISTRIBUTION MIGRATION NESTING FEEDING DIET ECOLOGY IMPACTS HOW TO ID DISTRIBUTION MIGRATION NESTING FEEDING DIET ECOLOGY IMPACTS HOW TO ID DISTRIBUTION MIGRATION NESTING FEEDING DIET ECOLOGY IMPACTS HOW TO ID DISTRIBUTION MIGRATION NESTING FEEDING DIET ECOLOGY IMPACTS HOW TO ID DISTRIBUTION MIGRATION NESTING FEEDING DIET ECOLOGY IMPACTS COLONYCOLONY SITESSITES FreshwaterFreshwater && marine-estuarinemarine-estuarine forestedforested habitatshabitats InundationInundation ofof treestrees detersdeters nestnest predationpredation
HOW TO ID DISTRIBUTION MIGRATION NESTING FEEDING DIET ECOLOGY IMPACTS MonogomousMonogomous PairPair bondsbonds likelylikely dodo notnot endureendure forfor moremore thanthan aa singlesingle seasonseason NoNo apparentapparent sitesite fidelityfidelity fromfrom yearyear toto yearyear MaleMale establishesestablishes nestnest sitesite andand courtscourts femalesfemales CourtshipCourtship lastslasts hourshours toto daysdays MaleMale usuallyusually initiatesinitiates nestnest constructionconstruction
HOW TO ID DISTRIBUTION MIGRATION NESTING FEEDING DIET ECOLOGY IMPACTS MostMost oftenoften nestnest inin mixed-speciesmixed-species coloniescolonies (esp.(esp. ANH,ANH, GREG,GREG, GBH)GBH)
ClutchClutch size:size: 2-52-5 eggseggs MaleMale && femalefemale tendtend nestsnests (equally)(equally) IfIf 11 adultadult isis lostlost oror abandons,abandons, otherother adultadult maymay incubateincubate 2-32-3 daysdays beforebefore abandoningabandoning IncubationIncubation lastslasts 27-3227-32 daysdays NestsNests attendedattended byby atat leastleast 11 parentparent full-full- timetime untiluntil chickschicks areare ~20~20 dd oldold YoungYoung 50-6050-60 dd oldold beginbegin toto leaveleave nestnest FledgeFledge raterate varies:varies: averageaverage 1.2-2.91.2-2.9 fl/nestfl/nest
HOW TO ID DISTRIBUTION MIGRATION NESTING FEEDING DIET ECOLOGY IMPACTS 2 WKS
HOW TO ID DISTRIBUTION MIGRATION NESTING FEEDING DIET ECOLOGY IMPACTS 4 WKS
HOW TO ID DISTRIBUTION MIGRATION NESTING FEEDING DIET ECOLOGY IMPACTS 6 WKS
HOW TO ID DISTRIBUTION MIGRATION NESTING FEEDING DIET ECOLOGY IMPACTS FLEDGED
HOW TO ID DISTRIBUTION MIGRATION NESTING FEEDING DIET ECOLOGY IMPACTS TheseThese littlelittle guysguys growgrow quicklyquickly andand needneed lotslots ofof food…food…
HOW TO ID DISTRIBUTION MIGRATION NESTING FEEDING DIET ECOLOGY IMPACTS FEEDINGFEEDING SITESSITES NaturalNatural && artificialartificial wetlandswetlands (water(water depthdepth 10-3010-30 cm)cm)
HOW TO ID DISTRIBUTION MIGRATION NESTING FEEDING DIET ECOLOGY IMPACTS Feed using TACTILOCATION (sim. to WHIB, GLIB, ROSP)
WOST bill snap is one of the fastest reflex actions among vertebrates (~25 milliseconds)
OftenOften useuse foot-stirringfoot-stirring and/orand/or wing-flickingwing-flicking
FeedFeed singly,singly, inin groups,groups, inin single-filesingle-file lines,lines, inin mixedmixed speciesspecies aggregationsaggregations
HOW TO ID DISTRIBUTION MIGRATION NESTING FEEDING DIET ECOLOGY IMPACTS ENERGYENERGY REQUIREMENTSREQUIREMENTS Chicks require ~16.5 kg food from hatching to fledging Adults require ~0.52 kg/bird/d (courtship, nest building, incubation, caring for chicks) x 120 d
Small colony (100 pairs): 2 adults/nest fledging 1.5 fledglings/nest requires ~15,000 kg of food
1961 & 1966 CSS colony (6,000 pairs) required 440 lbs food/nest = ~2.6 million kg of food
(estimates probably low- do not consider many factors)
HOW TO ID DISTRIBUTION MIGRATION NESTING FEEDING DIET ECOLOGY IMPACTS Quite particular about water depth & prey density
(Gawlik 2002)
HOW TO ID DISTRIBUTION MIGRATION NESTING FEEDING DIET ECOLOGY IMPACTS Appear to remove larger prey first
Frequency distributions of fish length (SL, mm) collected in 1-m2 throw trap on successive days of heavy wading bird foraging Not true prey
“Day 1” = 3/13/09, “Day 4” = 3/16/2009 (bars represent 1 mm size classes) preference (tactile feeders cannot be 200 120 selective) 100 Likely an artifact of 150
F 1
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q a
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Fish Length (SL, mm)
HOW TO ID DISTRIBUTION MIGRATION NESTING FEEDING DIET ECOLOGY IMPACTS Literature suggests diet is primarily fish Ideally: fish 2-10 cm
OpportunisticOpportunistic:: alsoalso consumeconsume plantplant material,material, insects,insects, snails,snails, crayfish,crayfish, grassgrass shrimp,shrimp, amphibians,amphibians, reptiles,reptiles, smallsmall mammals,mammals, mammalmammal dungdung
HOW TO ID DISTRIBUTION MIGRATION NESTING FEEDING DIET ECOLOGY IMPACTS OurOur datadata suggestsuggest crayfishcrayfish areare likelylikely anan importantimportant dietdiet componentcomponent inin thethe wetwet seasonseason (October-January)(October-January)
HOW TO ID DISTRIBUTION MIGRATION NESTING FEEDING DIET ECOLOGY IMPACTS CONCEPTUAL ECOLOGICAL MODEL
Coastal Salinity Gradients
HOW TO ID DISTRIBUTION MIGRATION NESTING FEEDING DIET ECOLOGY IMPACTS WET SEASON
Most of the landscapelandscape isis inundatedinundated
Aquatic fauna are dispersed throughout the system
HOW TO ID DISTRIBUTION MIGRATION NESTING FEEDING DIET ECOLOGY IMPACTS As water levels recede, fish instinctivelyinstinctively move toward deeper areas
HOW TO ID DISTRIBUTION MIGRATION NESTING FEEDING DIET ECOLOGY IMPACTS DRY SEASON
Fauna become trapped in refuges
Wading birds & other predators take advantage of high prey density
Crayfish burrow underground
HOW TO ID DISTRIBUTION MIGRATION NESTING FEEDING DIET ECOLOGY IMPACTS From flat sheetflow with shallow dimpled pools to a patchwork of ditches, roads, dikes, deep lakes. This systemic alteration has degraded wetland ecology - from primary productivity to top predators
HOW TO ID DISTRIBUTION MIGRATION NESTING FEEDING DIET ECOLOGY IMPACTS Wood Stork Nesting at Corkscrew
18000
16000
14000 s
r 12000 e b 10000 m u N
8000 t s e 6000 N
4000
2000
0 8 6 8 6 4 8 6 0 2 4 8 0 2 4 6 0 2 4 8 0 2 6 0 2 4 8 7 8 9 9 0 5 6 6 6 6 6 7 7 7 7 8 8 8 8 9 9 9 0 0 0 0 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 0 0 0 0 0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 Year
No. of Nesting Pairs No. of Birds Fledged
HOW TO ID DISTRIBUTION MIGRATION NESTING FEEDING DIET ECOLOGY IMPACTS HOW TO ID DISTRIBUTION MIGRATION NESTING FEEDING DIET ECOLOGY IMPACTS Short Hydroperiod Wetlands provide a critical function for Wood Storks and other wading birds
• Wetlands available for foraging in Nov/Dec - short hydroperiod wetlands • Productivity plummeted as a result of loss of Nov/Dec foraging habitat • Major shift in nest initiation from Nov/Dec to Jan/Feb in late 70’s • Preservation/restorationPreservation/restoration ofof Nov/DecNov/Dec wetlandswetlands isis vitalvital toto StorkStork recoveryrecovery
HOW TO ID DISTRIBUTION MIGRATION NESTING FEEDING DIET ECOLOGY IMPACTS FutureFuture WOSTWOST populationpopulation trendstrends inin SouthSouth FloridaFlorida
If they initiate nesting early (Nov-Dec) 28% increase over next 30 years
If they continue to nest late (late Jan-Mar) 38% decrease over next 30 years
(unpublished data, Rena Borkataria, UF)
HOW TO ID DISTRIBUTION MIGRATION NESTING FEEDING DIET ECOLOGY IMPACTS Pressure to develop these few remaining short hydroperiod wetlands increases threat to WOST in SW FL
HOW TO ID DISTRIBUTION MIGRATION NESTING FEEDING DIET ECOLOGY IMPACTS SpecialSpecial thanksthanks toto JasonJason LauritsenLauritsen (Assistant(Assistant Manager,Manager, CorkscrewCorkscrew SwampSwamp Sanctuary)Sanctuary)