J. Field Ornithol., 69(4):530-535

NEGATIVE

EFFECTS

OF PATAGIAL ROBERT

TAGS

ON

RUDDY

DUCKS

B. BRUA

Departmentof Biology Universityof Dayton Dayton, Ohio 45469-2320 USA

Abstract.--Patagialtagshave been used in studiesto identify waterfowlindividually.I evaluated the influenceof patagialtagson the behaviorof male and femaleRuddyDucks(Oxyura jamaicensis)in Manitoba,Canada.Patagial-tagged male RuddyDucksdecreasedtheir courtship rate and increasedthe amount of time spentsleepingand preening in comparisonto maleswith leg bandsonly and unmarked males.Comparedwith unmarked females,patagialtaggedfemale Ruddy Ducksincreasedthe amount of time devotedto preening. I suggest that patagialtagsnot be used on Ruddy Ducksor other dbqngducks. EFECTO NEGATIVO EN INDIVIDUOS DE OXYURAJAMAICENSIS DE MARCADORES EN EL PATAGIO

Sinopsis.--Marcadores colocadosen el patagiodel ala, han sido utilizadospara identificar individuosde avesacuaticas.Evaluffla infiuenciade marcadoresen el patagio,en la conducta de individuosde ambossexosde Oxyurajamaicensis.E1trabajose 11ev6a caboen Manitoba, Canada. Los machoscon marcadoresdisminuyeronsu tasade cortejo e incrementaronel periodo de tiempo de acicalarsey para dormir en comparaci6ncon indMduos con anillas en las patas o sin marcar. Pot su parte, las hembras incrementaron el periodo de tiempo que dedicaron a acicalarse.Sugieroque no se utilicen marcadoresen el patagio en aves como la descritay otroszambullidoresdonde las plumasse pueden afectar.Se deben desarrollar y poner apruebanuevastfcnicaspara marcar avesacuaticas.

Often it is necessaryto mark individualsto determine populationdynamics,mating systems, migration routes,or habitat use of a population. Varioustechniques,such as leg bands,dyesor paints,neck collars,radio transmitters,nasal markers, and patagial tags (Kozlik et al. 1959, Anderson 1963, Macinneset al. 1969, Dwyer 1972, Dot3, and Greenwood1974, Korschgenet al. 1984) have been used to identify waterfowlindividually. However, if the marking technique affects the behavior or survivalof individuals,the reliabilityof the data collectedis questionable. In a studyof the mating systemand mate choice of Ruddy Ducks (Oxyura jamaicensis),I needed a permanent marker that waseasyto observe but did not impair the reproductiveperformance of individuals.Prior marking techniquesfor RuddyDucksincludeimping tail feathers(Tome 1987), nasalsaddles(Joyher1975,Koob 1981), and patagialtags(Hughes 1990). However,imping is not permanent, andJoyner (1975) and Koob (1981) warned againstusing a nasal marker for Ruddy Ducks. The apparent successof patagial tagsused by Hughes (1990) on Ruddy Ducks in Great Britain led to their use in my study.However,little information existson the behavior of avian speciescarrying patagial tags.Thus, my objectivewasto determinethe influenceof patagialtagson the behavior of male and female Ruddy Ducks in comparisonto leg-banded-onlyand unmarked

individuals. 530

Vol.69,No.4

Effects ofPatag•al Tags

[53 1

F•ouP, z 1. Site of patagialtag attachmenton a RuddyDuck wing. Note that the wide part of the tag normallyliesover the secondarycoverts,but for illustrativepurposesthe tag hasbeen placed further back on the wing.

METHODS

This study was conducted in the prairie pothole region near Minnedosa,Manitoba, Canada (50ø10'N,99ø47'W)during the summerof 1995. I captured birds using decoy traps (Andersonet at. 1980) and marked malesand femalesindividuallywith standardUnited StatesFish and Wildlife Serviceleg bands and by placing alpha-numericallylabeled patagiat tags,similarto thoseof Maddock (1989), on eachwing.To attachthe tag, I wrappedthe narrow,upper portion of the vinyl cloth tag (30 mm X 20 ram) under the leadingedge of eachwing with the larger (30 mm X 45 ram) portion lying over the wing. I securedeach tag with a size-3monet metal poultry wing band (National Band and Tag, Newport, Kentucky) that pierced the patagiumand locked in place. I locked the tag in place by crimping the piercing, v-shapedend of one arm over the other arm of the band, after the v-shapedend wasplaced through the hole on the other arm at the end of the band (Fig. 1). Each tag weighed approximately 1.2 g and measured60 mm X 45 mm at its widestand longest points,respectively.

532]

R.B. Brua

J.Field Ornithol. Autumn

1998

I observedbehaviorby recordingcontinuouslyall courtship,aggressive, and feeding activitiesof focal birds during 30-min periods (Altmann 1974). Male courtshipactivityincluded Bubble displays,Flight displays, and copulations,whereasaggressive displaysincludedHunched Postures, Hunched Rushes,and fights (Johnsgard1965). Femalecourtshipincluded copulationand Inciting, which consistsof a hunched posturewith neck outstretchedtoward the mate and bill open (Gray 1980). Female aggressionwassimilar to Inciting but included chasingof other birds. I recordedfeeding behavioras the number of divesof focal birds. Lastly,I performed instantaneoussamplingat 1-min intervalsto determine the frequencyof preening and sleepingduring the 30-min observationperiod (Altmann 1974). I ended observationsafter the individualwasout of sight for more

than 5-min.

I identifiedleg-banded-only malesusinga combinationof their unique cheekpatchdesign(Koob 1981) and uniquepatternscut into their tails. Patternscut into the tails were distinguishedeasilyand leg-banded-only malesthat were paired never lost a mate after receivingtheir treatment, nor did leg-banded-onlymales acquire a mate after capture and treatment. Thus, I do not believethe patternscut into the tailsof leg-bandedonly males influenced their behavior. Similarly,I identified unmarked males, which were paired to patagial-taggedfemales,by their unique cheek patch design.I identified unmarked females,paired primarily to leg-banded-only males,by their unique cheekpatch characteristics. I obtained a total of 35.5 bird-hoursof observationon 11 leg-bandedonly, 16 patagial-tagged, and 11 unmarkedmales.The amount of observation time for leg-banded-onlymaleswask = 37.4 --- 6.6 (SE) min/bird; patagial-tagged males,k = 70.4 ___ 10.8 min/bird; and unmarkedbirds,• = 54.1 ___12.2 min/bird.

For females, I obtained a total of 15.2 bird-hours

of observationon eight patagial-taggedand nine unmarked birds. More specifically, I observedpatagial-tagged femalesfor • = 76.5 + 15.8 (SE) min/bird

and unmarked females for • -- 33.4 +__6.4 min/bird.

Becausedatawerenot distributednormally,I comparedaspectsof male behavior using a Kruskal-Wallistest. I used a Mann-Whitney U-testfor statisticalanalysisof female behavior.For each sex, I originally set ot = 0.10, but adjustedthe criticalvalue to ot = 0.02 for the five comparisons. RESULTS

I found no differencein feeding ratesfor the differentlymarked males (Table 1). However,patagial-taggedmales courted lessand spent more time sleepingand preening than either banded or unmarked males (Table 1). I found no difference in these behaviors between banded and

unmarked males.Unmarked malesperformed more aggressive displays than leg-bandedor patagial-taggedbirds (Table 1). I never found a nest on a wetland where I observedcontinuouslya patagial-taggedfemale, even after searchingthe emergentvegetationfor a nest severaltimes. It is unknown how many unmarked or leg-bandedonly femalesthat did not nest, but I did find 125 Ruddy Duck nestson

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t:ffects ofPatagialTags

[533

TABLE1. Resultsof Kruskal-Wallistestscomparingbehaviorsof patagial-tagged(n = 16), leg-banded-only(n = 11), and unmarked (n = 11) male Ruddy Ducks.Valuesreported for each marker type are means _ 1 SE.

Behavior

Patagialtag

Leg band only

Unmarked

Courtshipdisplays/min Aggressive displays/min

0.28 _+0.15Aa 0.02 _+0.02A

1.29 __+ 0.38B 0.03 _+0.01A

1.26 _+0.45B 0.08 __+ 0.0lB

Feeds/min

0.41 _+ 0.12A

0.75 -+ 0.12A

0.36 _+ 0.10A

Sleeping(%) Preening (%)

8.0 _+2.0A 15.0 + 2.0A

3.0 +- 1.0B 5.0 _+3.0B

1.0 _+1.0B 4.0 _+2.0B

X2

P

13.22 0.001 14.04 0.001 4.58

0.101

8.45 0.015 12.83 0.002

a Chi-squarevalue, corrected for ties. Mann-Whitney U-testused for multiple comparison (P < 0.05). Valueswith different letters in the samerow are significantlydifferent.

the studyarea in 1995. Of these nests,I nest-trappedthree femalesthat were leg-banded-only from the previousyear.Also,duringweeklysearches of the studyarea, in which all wetlandson the studyarea were visited,I never observeda patagial-taggedfemale with a brood. However,there were numerous unmarked femaleswith ducklings. I found no difference in courtship,aggression,or feeding rates and percent of time sleeping,betweenpatagial-taggedand unmarked female Ruddy Ducks (Table 2). However, patagial-taggedfemales spent more time preening than unmarked females (Table 2). DISCUSSION

Patagialtagson Ruddy Duckscausesignificantchangesin behaviorand reproductive performance for each sex. Patagial-taggedmale Ruddy Ducksdecreasedtheir courtshiprate and increasedtheir time spentsleeping and preening. Patagial-tagged femalesincreasedthe amount of time spent preening. Although no data were reported, Hughes (1990) found no differencesin behaviorof patagial-taggedand untaggedRuddyDucks in captivity.This result is in contrastto severalother studiesthat have shownnegativeaffectson waterfowland other avian species.Taggedfemale Mallards (Anasplatyrhynchos) experiencedhigher mortality (Szymczak and Ringelman 1986), and female Common Eiders (Somateriamollissima)changed their behavior (Anderson 1963). In other species,patagial-taggedbirds had lower survivaland reproductiveoutput, and reTABLE2. Resultsof Mann-Whitney U-testscomparingaspectsof behaviorof eight patagialtaggedand nine unmarked female Ruddy Ducks.Valuesreported for each marker type are means

+_ 1 SE.

Behavior

Patagialtag

Unmarked

U

P

Courtshipdisplays/min Aggressivedisplays/min

0.04 +_0.02 0.02 _+0.01

0.01 _+0.01 0.01 _+0.01

29 22

0.449 0.093

Feeds/min

0.65 _+ 0.17

0.77 -+ 0.16

29.5

0.531

6.0 _+3.0 9.0 _ 4.0

3.0 _+3.0 1.0 _+0.4

20 5.5

0.071 0.002

Sleeping(%) Preening(%)

534]

R.B. Brua

J.Field Ornithol. Autumn

1998

turned later to their breeding grounds than untaggedbirds (Southern and Southern 1983, 1985; Saunders 1988; Kinkel 1989).

Patagial-tagged female RuddyDuckswere presumablyunable to nest, as I found

no nests and observed

no females

with

broods.

Bustnes

and

Erikstad(1990) reported that patagial-tagged female CommonEidersdelayed nesting and laid smaller eggs.They suggestedthat femaleswere unable to accumulatethe energyreservesnecessaryto initiate nestsearly and lay large eggsdue to interferencefrom patagialtags.This may explain the lack of nestingby patagial-tagged female RuddyDucks,which haveone of the highestenergeticcostsof producinga clutch of eggsfor any waterfowl (Alisauskasand Ankney 1994a,b). Currently,it appearsthat any externalmarker usedcommonlyfor waterfowl,other than leg bands,altersRuddyDuck behavior.With the recent report of the possiblenegativeeffectsof nasal markers on female Mallards (Howerter et al. 1997), more research is needed on the influ-

ence of marking techniqueson waterfowlbehaviorand reproduction. ACKNOWLEDGMENTS

I thankB. LercelandS. Staifor their assistance in decoytrappingandperformingbehavior observations. This studywould not havebeen possiblewithout the financialassistance provided by Delta Waterfowland WetlandsResearchStationand a GraduateStudentFellowship through the Universityof Dayton. This researchwas conductedunder CanadianWildlife Servicepermits and approvedby Animal Care Committeesfrom Delta Waterfowl and Wetlands ResearchStationand the Universityof Dayton.I thank P. Brua Mortensonfor her artistic talent. I thank R. Breitwisch, S. Linville, D. Howerter, C. R. Chandler, and an anon-

ymousreviewerfor their commentson variousdraftsof this manuscript. LITERATURE

CITED

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1994b. Nutrition of breeding female RuddyDucks:the role of nutrient 96:878-897.

ALTMANN, J. 1974. Observationalstudyof behavior:samplingmethods.Behaviour49:227267.

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HOWERTER, D. W., B. L. JOYNT,R. B. EMERY,ANDT. P. SANKOWSKI. 1997. Effectsof nasaldiscs on nesting by Mallards.J. Field Ornithol. 68:1-6.

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Received3 Apr. 1997;accepted10Jul. 1997.