The Auk 112(4):904-919, 1995

MOLT OF BLACK BRANT ( BERNICLA NIGRICANS) ON THE ARCTIC COASTAL PLAIN,

ERIC J. T^YLOR• Departmentof Wildlifeand Fisheries Sciences, Texas A&M University, CollegeStation, Texas 77843, USA

ABSTRACT.--Iexamined patterns and chronologyof the prebasicmolt and primary-feather growth rate of nonbreeding and postbreedingBlack Brant (Brantabernicla nigricans) on the Arctic CoastalPlain, Alaska. I estimatedmolt intensity for adults and subadultsof both sexes with molt rate (MR, proportion of feathers in blood quills) and percent new feathers (PN, proportionof feathersthat recentlycompleted growth) for 26 feathertracts. I then calculated mean total molt score(TMS) and mean total percent new score(TPN) for each sex,age class, molt stage(arrival, start, early, mid-, and late molt), and Julian date. TMS increasedfrom arrival to early molt (14 June-22 July). Subadultsmolted at greater intensity than did adults during early, mid- and late molt (20 July-1 August);however, malesand femalesin both age classesdid not differ. TPN scoreswere significantly (P < 0.05) greater from 25 July to 1 August than from 20 to 22 July, primarily as a result of maturation of remiges and wing coverts. Brant replaced body and wing feathers concurrently. Back, rump, breast, and side regions were comprisedof 25% or more blood quills in adults to 50% or more blood quills in subadultsduring the flightlessperiod. Brant departing the molt area completedgrowth of only 11 to 21% of all feathers.Ninth-primary growth rate (œ= 7.2 + SE of 0.1 mm/day) did not vary over sexand age classesnor betweenyears (1988 vs. 1989).Remex growth rate declined significantly (P < 0.001) through molt but was not related to Julian date nor initial body mass.Most Black Brant began remex growth 4-10 July; however, some postbreeding adultsdid not arrive and startmolt until 24-25 July. Brantmade short flights when the ninth primary averaged 62% of its mean final length; sustainedflight occurredat about 70% of completedgrowth. The duration of flightlessnesswas 23 and 24 daysfor femalesand males, respectively.Flightless Black Brant were present in the Teshekpuk Lake molting area from 26 June through 19 August. Upon regaining flight ability, Black Brant moved to coastal staging areas.The chronology and intensity of feather replacement for Black Brant may be important when determining the appropriate management of habitats where molt occurs, especiallywhen theseare disturbedby human activities.Received 16 August1994, accepted 27 January1995. THE POSTBREEDINGPERIOD for migratory wa- Brood-rearinggeese initiate remigial molt two terfowl is between reproduction and fall mi- to three weeks after their young hatch (Barry gration (Hohman et al. 1992;but see Fredrick- 1962, Owen and Ogilvie 1979). Failed breeders sonand Drobney 1979).During this stage,most and nonbreedersoften migrateto specificmolt- ducks and geesemolt wing and body feathers ing areaspresumably to: (1) decreasethe risk (Palmer1976, Hohman et al. 1992:app.5-1) and, of predation and avoid human disturbance subsequently,store adequate nutrient reserves (Sterling and Dzubin 1967); (2) avoid compe- for fall migration.Because postbreeding anatids tition with successfulbreeders molting on nest- are secretive and usually seek protective and ing areas(Salomonsen 1968); and/or (3) forage inaccessible habitats during flightlessness on higher-qualityvegetation available at earlier (Fredricksonand Drobney 1979),little is known growth stagesin northern areas (Owen and aboutthe chronology,duration, or intensity of Ogilvie 1979). remigial molt. In BlackBrant (Branta bernicla nighcans), failed breedersand nonbreedersmigrate from nesting areas along the Yukon and Kuskokwim river • Presentaddress: Texas Parks and Wildlife Depart- deltas (Alaska), the Canadian Arctic, and the ment, J. D. Murphree Wildlife ManagementArea, 10 Chukotski Peninsula(Russia) to the Teshekpuk Parks and Wildlife Drive, Port Arthur, Texas 77640, Lake molting area on the Arctic CoastalPlain USA. of Alaska(Derksen et al. 1979,1982). Teshekpuk

904 October1995] BlackBrant Molt 905

Lake lies within the boundaries of the National thaw lakestogether with low- and high-centerpoly- Petroleum Reserveand supports8,000 to 32,000 gons,comprise 50 to 75%of the CoastalPlain (Black Black Brant, 5,000 to 27,000 Canada Geese (Bran- and Barksdale 1949, Hussey and Michelson 1966). ta canadensis),1,000 to 7,000 White-fronted Geese Derksen et al. (1981, 1982) described shoreline hab- (Anseralbifrons), and 100 to 700 LesserSnow itatsof the principal studysite locatedat Island Lake (70ø39'N, 153ø15'W). Geese (Chen caerulescenscaerulescens; Derksen et I collectedBlack Brant at the IslandLake study area al. 1979). The U.S. Department of Interior des- between 14 Juneand 5 August in 1988and 1989. ignated the area surroundingTeshekpuk Lake were frozen within 24 h of collection and later trans- asa SpecialArea, thereby temporarily suspend- portedto TexasA&M University. In the laboratory,I ing petroleumdevelopment (U.S. Department sexed specimensby cloacal examination. The pres- of Interior 1977). However, activities associated ence of white-tipped middle wing covertsindicated with future petroleumexploration could threat- second-year(SY) or subadult Black Brant (Harris and en CoastalPlain wetland habitatsused by molt- Shepherd 1965).The absenceof white-tipped coverts ing waterfowl (Derksen et al. 1979, 1982, Hoh- in conjunctionwith a sheathedpenis (males) and/or man et al. 1992). Aircraft disturbance caused brood patch (females)indicated postbreeding,after- second-year(ASY) Black Brant (i.e. birds in at least flightlessBlack Brant to be alert, to be evasive their third summer).I excludedlocally nesting Black (running, swimming,flightless flapping), or to Brant to restrict analysesto nonbreedersand failed leave preferred molting sites (Derksen et al. nesters.Locally breeding females had developingfol- 1979, 1982, Jensen 1990). Moreover, molting licles, oviducal eggs,or a bare brood patch. I consid- BlackBrant (Jensen1990), like wintering Brent ered locally breeding malesas those collectedin the Geese(Branta bernicla) in England (Owens 1977) presenceof a potentialmate, and that had testeslarger and Pink-footed Geese(Anserbrachyrhynchus) in than 17 x 9 mm. I classifiedmales with testeslarger (Madsen 1985), do not habituate to than 17 x 9 mm, which were collected in a feeding helicopter disturbance. flock or without an apparent mate, as failed nesters The moltingpattern, molting chronology, and and included them in the molt sample. Overall, I analyzed 100 ASY (60 males, 40 females)and 79 SY feather-growth rates have not been adequately Black Brant (41 males, 38 females) described in Anserinae (Hohman et al. 1992, I categorizedBlack Brant in five molt stages:(1) Gates et al. 1993). Little is known about factors arrival,Black Brant collected prior to the startof remex (e.g. photoperiod,migration chronology,nu- molt; (2) startof molt,ninth-primary length 0-19% (t tritional status)influencing molt of nonbreed- = 10%)of mean final length, where mean final length ing and postbreedinggeese, and the extentand was 223 and 214 mm for ASY males and ASY females, sequenceof body feather molt in relation to respectively;(3) earlymolt, ninth primary 20-45% (t remigial molt is poorly understood(Derksen et = 37%) of mean final length; (4) midmolt,ninth pri- al. 1982, Hohman et al. 1992, Gates et al. 1993). mary 46-60%(t = 53%) of mean final length; and (5) Although Derksenet al. (1979,1982) used aerial late molt,ninth primary more than 60% (œ= 66%) of mean final length. I selectedninth-primary percent- and ground surveysto estimatethe chronology ages(and molt stages)a priorito approximateprevi- and duration of flightlessnessin Black Brant, ouslyreported values (Ankney 1984)and to maintain they did not examinemolt and remexregrowth adequate sample sizes among molt stages. in relation to age, sex, and breeding status.! The proportionof bloodquills typically is the num- conductedresearch to answerquestions regard- ber of exposedquills on the inner side of the skin ing the prebasicmolt of wing and body feath- scrapedfree of fat (seeOring 1968).However, because ers, and to addressmanagement and conser- I required the skin, subcutaneousfat, and remainder vation issues.My goalsin studyingBlack Brant of the carcassfor lipid analyses,I exposed feather at the TeshekpukLake molting areawere to: (1) sheaths (calamus and inferior umbilicus) of contour characterizethe chronology, intensity, and feathers using a dissectingprobe. I estimated molt rate (MR) as the proportion of contourfeathers in the variability in remigial and body-feathermolt; blood-quill stage,and percent new (PN) as the pro- (2) estimate primary-feather growth rate; and portion of new feathersthat had recently completed (3) examine chronologyand duration of molt growth in each of 26 feather tracts (see Billard and as influencedby age, sex,and breeding status. Humphrey 1972, Young and Boag 1981, Miller 1986). I defineda blood quill as any new, emergingcon- STUDY AREA AND METHODS tour feather containingblue color within the shaft. I consideredfeather sheathsat or slightly above the The TeshekpukLake study area lies on the Arctic skin surface, and missing rectrices and remiges, as Coastal Plain of Alaska. Large, NNW-SSE oriented blood quills. I scoredMR and PN for each feather 906 EmcJ. TAYLOR [Auk,Vol. 112

TABLE1. Regressionequations to predict ninth- nificant F-value was found, I evaluated differences in primary feather insertionlength (Y) for 1988 data meanswith a Tukey's HSD test (seeYoung and Boag basedon 1989wing length (W) and ninth-primary 1981).I comparedthe mean number of rectricesacross feather-tip length (T) data. molt stageswith ANOVA, and acrosssex and age classes with a 2 x 2 factorial ANOVA. Means were Pre- comparedusing contrasts.All statisticalprocedures diction' Equation R2 were conductedusing SAS (SAS Institute 1985). ASY-M (n = 574) I assessedninth-primary growth rate by trapping 1 Y = -77.5 + 0.67W + 0.40T 0.97 flightlessBlack Brant on six lakesduring 10-29 July 2 Y = -135.8 + 1.02W 0.96 in 1988 and 1989. In 1988, I measured most ninth- ASY-F (n = 432) primary feathers (mm) from the distal edge of the 1 Y = -47.3 + 0.48W + 0.68T 0.95 blue blood quill (sheath)to the feather tip; I did not 2 Y = -131.1 + 1.02W 0.91 measureemerging ninth-primary blood quills with- SY-M (n = 159) out exposedfeather tips. Blood-quill distal edgesbe- gan to slough off as remigesmatured, producinga 1 Y = -54.2 + 0.54W + 0.53T 0.97 2 Y = -137.2 + 1.03W 0.94 variablereference point to determinelength. In 1989, I measuredboth the feather-tip length and the in- SY-F (n = 152) sertion or total length (definedas distancefrom in- 1 Y = -44.3 + 0.48W + 0.66T 0.93 sertionof remexblood quill at skin surfaceto distal 2 Y = -135.6 + 1.05W 0.90 end of feather tip; Hanson 1962, Gateset al. 1993). I ßPrediction 1 basedon wing length and ninth-primaryfeather-tip recordedthe flattened wing length (distancefrom length, while prediction2 basedonly on wing length. blunt end of wrist joint to distal tip of longestpri- mary; ram) in 1988 and 1989. Two regressionequa- tions for each age and sex group based on the 1989 tract from 0 to 4: (0) 0%; (1) 1-25%; (2) 26-50%; (3) 51- data set were developed to predict the primary in- 75%; and (4) 76-100%. I combined feather tracts to sertionlength for the 1988 data set (Table 1). groupsbased on eight regions(Billard and Humphrey I estimated the ninth-primary growth rate (mm! 1972, Miller 1986): (1) head and neck (crown, facial, day) for molting BlackBrant banded and recaptured chin ! throat, and neck);(2) backand rump (upper and during the same summer in both 1988 and 1989. I lower back, scapulars,rump); (3) breast(belly, chest calculateddaily growth rate (G) as: tracts);(4) side (side, flank); (5) outer wing coverts G = (LB -- LR)/t, (2) (outer lesser, middle, primary, and secondary co- verts); (6) remiges (primaries, secondaries,tertials); where L• is the initial ninth-primary length at band- (7) inner wing coverts(inner lesser,middle, primary ing, LRis the length at recapture,and t is the time in and secondarycoverts); and (8) tail (rectrices,upper number of days between banding and recapture. I and lower tail coverts). I calculated the mean MR- and testedfor potentialdifferences in primary-growthrate PN-region scoresas: between sex and age classeswith ANOVA, and be- tween years (1988 vs. 1989) with a t-test. I regressed œ= Z x/(%n,), (1) feather-growth rates against initial ninth-primary where œis the averageMR- or PN-region score,x is length, Juliandate, and initial body mass. an individualMR or PN score,n I is the numberof Primary growth ratesof six ASY (three male, three feather tractswithin a region, and nbis the number female) captive Black Brant were recorded from 10 of birds examinedwithin a group (e.g. by age, sex, through29 July1989. The birdsfed on naturalgrasses, molt stage,or feather region). The maximum mean sedges,forbs, game- chow, and oyster-shellgrit. MR or PN regionscore is 4. BecauseI collectedarrival I recorded primary lengths at 4- to 10-day intervals. BlackBrant from 14 Juneto 15 July,and remigialmolt The startdate of remexgrowth (i.e. primary length beganfrom 26 Juneto 25 July,molt stagesoverlapped; = 0 mm) was estimatedby dividing the mean ninth- therefore,I could not define changesin molt pattern primarylength recorded during the firstbanding drive relative to calendar-date intervals. in 1988 (10 July) and 1989 (12 July) by the mean I calculatedthe total molt scoresand total percent- primary growth rate;the numberof growth dayswas new scoresby summingall feather tract MR or PN subtractedfrom the two banding datesto estimatethe scoresfor each bird, with the maximumscore being start date of remex growth. 104 ([score of 4] x [26 feather tracts] = 104). I deter- mined the mean total molt score (TMS) and mean totalpercent-new scores (TPN) for eachsex, age class, RESULTS molt stage,and Julian date range. I examinedTMS and TPN scoresacross sex and age classeswith a 2 x Body-and wing-moltpattern.--Brant had not 2 factorial analysisof variance (ANOVA), and across startedwing molt before arriving on the molt- molt stagesand dateswith an ANOVA. When a sig- ing area(Figs. 1-4). Bodymolt waslight (MR • October1995] BlackBrant Molt 907

MEAN MOLT- RATE SCORE ADULT MALES

i MEANPERCENT-NEWSCORE

Fig. 1. Mean molt-rateand percent-newscores for adult male BlackBrant from arrival through late molt.

< 1) in all Black Brant except for on the sides region (broodpatch) of ASY femalescontained of SY males(MR œ= 1.6;Fig. 3) and breasts(old new feathersthat had completedgrowth. broodpatches) of ASY females(MR œ= 1.8;Fig. During midmolt, overall mean MR scores 2). ASY males had the lowest overall mean MR peaked for ASY males,ASY females,and SY score.ASY BlackBrant did not completegrowth males as the result of remex and outer wing of new feathers(PN œ= 0) in any region (Figs. covert molt. Similar to early molt, outer pri- 1 and 2), althoughSY Black Brant had new, fully mary, secondary,and lessercoverts, and inner emerged feathers in the breast, side and tail secondarycoverts contained the greatestper- regions(Figs. 3 and 4). centageof blood quills. Backand rump, breast, During the start of molt, all BlackBrant ini- and inner wing covert mean MR scoresin- tiatedremigial and covert(predominantly outer creasedrelative to early molt. The breastregion primary, outer secondaryand outer lesser;Figs. of ASY femalescontained the greatestpropor- 5 and 6) molt. SY males and ASY females con- tion of completednew feathergrowth (PN œ= tinued to replacefeathers in the side and breast 2.8). regions, respectively.The mean PN scoresap- Overall mean MR scores in late molt declined proximated those at arrival. for ASY males, ASY females, and SY males as Bloodquills comprisedabout 75% of remiges new remigesand outerwing covertscompleted (MR œ= 3.9; Figs. 1-4) at early molt. Molt of growth. The overall mean MR scorepeaked for outerwing covertspeaked as blood quills formed SY females because mean MR scores for six out 75 to 100% (MR œ = 4.0) of the primary and of eight feather regionsranked highestamong secondarycoverts and 50 to 75% (MR œ-> 3) of the four age/sexgroups. The inner wing covert the lessercoverts. Black Brant replacedinner mean MR scores increased (SY brant) or re- wing coverts,predominantly secondaries (Figs. mainedat their maximum(ASY brant). Replace- 5 and 6). SY males continued replacing side ment of outer middle and inner primary coverts feathers (MR œ= 3.0). About 25% of the breast lagged behind that of other coverts.Mean PN 908 ERICJ. TAYLOR [Auk, Vol. 112

MEAN MOLT- RATE SCORE ADULT FEMALES

Fig. 2. Mean molt-rateand percent-new scores for adult femaleBlack Brant from arrivalthrough late molt.

SUBADULT MALES MEANMOLT- RATE SCORE

' MEAN PERCENT- NEW SCOR•:

Fig. 3. Mean molt-rate and percent-newscores for subadultmale BlackBrant from arrival through late molt. October1995] BlackBrant Molt 909

SUBADULT FEMALES J4• MEAN MOLT- RATE SCORE

MEANPERCENT-NEW SCORE >v•' v •' • • • • o_•o.•_• "•'•' X Fig. 4. Mean molt-rate and percent-newscores for subadultfemale BlackBrant from arrival through late molt.

ADULT MALES ADULT FEMALES

MEANMOLT-RATE SCORE

MEAN MOLT- RATE SCORE MEAN MOLT- RATE SCORE

Fig. 5. Mean molt-ratescores of outer and inner wing covertsfor adult male and adult femaleBlack Brant from arrival through late molt. 910 ERICJ. TAYLOR [Auk, Vol. 112

SUBADULT MALES SUBADULT FEMALES

4 MEANMOLT-RATE SCORE

MEANMOLT-RATE SCORE ,

o

scoresfor SY and ASY males (both 0.8) exceeded during arrival. TMS scoresin SY Black Brant those for ASY and SY females (both 0.5). were higher than ASY brant during early molt Mean total molt score (TMS).--As a result of (P < 0.05), midmolt (P < 0.05), and late molt remex molt, TMS scores at the start of molt ex- (P = 0.08). There were no differences in TMS ceededsignificantly (P < 0.05) those at arrival scoresbetween sexes except during early molt (Table 2). TMS scoresfrom early to late stages (F > M, P < 0.05). were statisticallyequal, but exceededthose dur- To determine the chronology and intensity ing the start of molt. Results of age and sex of molt with respectto date, I examined TMS factorial analysesvaried by molt stage.The age scoresduring four periods(selected to equalize x sexinteraction was only significant(P < 0.01) samplesizes among sex and ageclasses): 14 June- 15 July (arrival), 4-19 July, 20-22 July, and 25 July-1 August(Table 3). Becausewing molt had not startedand bodymolt wasminimal, arrival TAI•I,E2. Mean total molt scores(TMS) of adult (ASY), TMS scoreswere significantlyless than during subadult (SY), male (M), and female (F) Black Brant. Scoresunderlined with same line not statistically 4-19 July. TMS scoresincreased through 20-22 different (P > 0.05). Lack of common underscore July and remained unchanged during the 25 indicatesthat TMS differed significantly(P < 0.05; July-1 Augustperiod exceptfor SY males,where Tukey'sHSD multiple-comparisontest). TMS scoresdeclined significantly.TMS scores of SY birds were higher than thoseof ASY birds

Ageand Moltstage during the last two periods examined: 20-22 sex Arrival Start Early Mid- Late July(P < 0.01)and 25 July-1 August(P < 0.05), ASY-M 1.4 22.4 40.3 48.1 42.4 but did not differ 4-19 July (P = 0.67). TMS scores of males and females were not different ASY-F 6.2 29.8 42.1 46.5 43.0 SY-M' 6.2 26.2 42.0 55.7 46.1 during the latter three time periods. Mean total percent-newscore (TPN).--Late-molt SY-F 4.7 29.0 53.8 55.0 55.0 TPN scores exceeded those of arrival, start, ear- Early and late underscoredwith sameline, as are mid- and late. ly, and midmolt, exceptin ASY females(Table October1995] BlackBrant Molt 911

TABLE3. Mean total molt scores(TMS) of Black Brant TABLE5. Mean total percent-new scores(TPN) of by date. Scoresunderlined with sameline not sig- BlackBrant by date. Scoresunderlined with same nificantly different (P > 0.05). Lack of commonun- line not statisticallydifferent (P > 0.05). Lack of derscoreindicates TMS differed significantly (P < commonunderscore indicates TPN differed signif- 0.05; Tukey's HSD multiple-comparisontest). See icantly (P < 0.05; Tukey's HSD multiple-compari- Table 2 for definitions. son test). See Table 2 for definitions.

Time period Time period Age Age and 14 June- 4-19 20-22 25 July- and 14 June- 4-19 20-22 25 July- sex 15 July' July July 1 August sex 15 July ß July July 1 August ASY-M 1.4 24.1 46.6 42.7 ASY-M 0.0 0.6 4.4 15.6 ASY-F 6.2 31.0 44.2 43.2 ASY-F 0.0 2.1 5.7 11.6

SY-M 6.2 29.8 55.2 45.5 SY-M 0.8 1.3 3.6 16.6 SY-F 4.7 29.0 55.7 52.7 SY-F 0.8 1.3 1.6 11.1

Arrival Arrival.

4). Arrival TPN scoresdiffered significantly (P feathers),80 (64%) had 16 rectrices,26 (21%) had < 0.001) between age classes(SY > ASY). TPN 15, 7 had 17, 5 had 14, 5 had 18, and 1 each had scoresvaried between sexes(M > F) only dur- 13 and 10. The mean number of rectrices for ing the late molt. TPN scoresduring 25 July-1 ASY males (15.9 _+ 0.2, n = 40), ASY females Augustexceeded those during all previousdates (15.7 + 0.1, n = 29), SY males (16.1 + 0.2, n = (Table 5), similar to resultsbased on molt stage. 30), and SY females (15.4 _+0.3, n = 26) differed Age and sexeffects and the age x sexinterac- between SY Black Brant only (M > F; P < 0.05). tion of TPN scores within the latter three time The numbers of rectrices examined across molt periods were not significant. stages (arrival to late molt) were not signifi- Rectrix molt.--Both the percent frequency cantly different: ASY males(F = 1.06,P = 0.39), (Table 6) and intensity (Fig. 7) of rectrix molt ASY females (F = 0.71, P = 0.60), SY males (F increasedin later molt stages.New rectricesoc- curred most often in SY females followed by SY malesand ASY females.Only 3% of 60 ASY malesincurred any tail molt during the flight- MEAN MOLT- RATE SCORE less period. Rectrix molt pattern (recorded for 21 of 29 Brant molting one or more rectrices) indicated featherswere generally replacedin a symmetricalpattern (Fig. 8). Of 125 Black Brant examined for rectrix num- ber (i.e. number of old, new, and blood-quill

TABLE4. Mean total percent-new scores (TPN) of Black Brant acrossstage of molt. TPN scoresun- derlined with sameline not statisticallydifferent

(P > 0.05). Lack of common underscore indicates MEAN PERCENT- NEW SCORE that TPN differed significantly (P < 0.05; Tukey's HSD multiple-comparisontest). See Table 2 for def- initions.

Ageand Moltstage sex Arrival Start Early Mid- Late ASY-M 0.0 0.6 0.0 2.9 21.2 ASY-F 0.0 1.8 4.1 11.7 11.8 SY-M 0.8 0.5 1.3 6.5 21.3 Fig. 7. Mean molt-rateand percent-newscores of SY-F 0.8 1.3 1.8 2.0 13.7 rectricesfor Black Brant from arrival through late molt. 912 EmcJ. TAYLOR [Auk, Vol. 112

T•,Bt,E6. Percentfrequency and number of BlackBrant that molted rectrices(as indicatedby missingand/ or presenceof blood quills) from arrival through late-molt stages(see Table 2 for definitions).

Age/sex group Stage ASY-M ASY-F SY-M SY-F Total Percent Arrival 1/27 0/10 0/11 2/10 3/58 5.2 Start of molt 0/8 1/9 0/6 1/8 2/31 6.3 Early molt 0/3 1/9 0/6 6/8 7/26 26.9 Midmolt 0/11 0/6 3/11 4/6 7/34 20.6 Late molt 1/11 3/6 3/7 3/6 10/30 33.3 Total 2/60 5/40 6/41 16/38 29/179 16.2 Percent 3.3 12.5 14.6 42.1 16.2

= 0.66, P = 0.63), and SY females (F = 0.89, P As molt progressed,proximal primaries reached = 0.49). their total length earlier than did distal pri- Remexmolt and growth rate.--Primary and sec- maries, and secondariesattained final length ondaryremiges molted at aboutthe sametime. earlier than primaries(Table 7). When the ninth- However, distal primaries (nos. 6-10) dropped primary length ranged from 151 to 180 mm, an prior to proximal ones(nos. 1-5), whereasprox- average of only 5 primaries had completed imal secondaries were molted first. The tenth growth comparedto 10 secondaries. primary emerged prior to the ninth primary, Estimationof the primary-feathergrowth rate and exceededit in length until the ninth reached was based on 247 Black Brant (1988 and 1989 approximately15% (• 34 mm) of its total length. combined) recaptured during the summer of

T•,BI_E7. Number and locationof fully emerged(based on clearrachis color) primary and secondaryfeathers of BlackBrant (collected July-August 1988-1989) with at leastone fully emergedremex.

Ninth- primary Remigelocation a Bird length no. (ram) 1 2 3 4 5 6 7 8 9 10 1 120 ß ß ß 2 121 •) •) •) •) •) O O O O O 3 128 •) •) •) •) •) O O O O O 4 129 •O •O •O •O 5 130 ß 6 131 ß 7 133 • • • O O O O O O O 8 134 •O •O 9 134 • • • • • O O O O O 10 136 ß ß 11 140 •) •) •) O O O O O O O 12 141 •) •) •) O O O O O O O 13 143 • • • • O O O O O O 14 145 • • 15 145 •) •) •) O O O O O O O 16 145 •) •) •) O O O O O O O 17 147 • • • O O O O O O O 18 148 •) •) •) O O O O O O O 19 150 • • • • • • O O O O 20 151 •) •) •) •) •) •) O O O O 21 152 •) O O O O O O O O O 22 155 • • • • O O O O O O 23 156 • • • • O O O O O O 24 174 •) •) •) •) •) •) •) 0 0 0 25 180 •O •O •O •O •O •O O O O O

aß primary;O secondary. October1995] BlackBrant Molt 913

16 16 15

SY-F AR SY-F AR SY-F SM

16 10 14 16 16

SY-F EM SY-F EM SY-F EM SY-F EM SY-F EM

16 15 15 15 16 18

SY-M MM SY-M MM SY-F MM SY-F MM SY-F MM SY-F MM

15 15 17 16 16 16 16

SY-M LM SY-M LM SY-M LM SY-F LM ASY-M LM ASY-F LM ASY-F LM Fig. 8. Rectrix molt of adult male (ASY-M), adult female (ASY-F), subadult male (SY-M), and subadult female (SY-F) BlackBrant during arrival (AR), start (SM), early (EM), mid- (MM), and late (LM) molt. Total number of rectricespresent indicatedabove each subfigure.Solid thin line = old feather; dashedline = incomingblood quill; solid thick line = recentlyreplaced feather; m = molted and not yet emerged.

banding. Of these,I recaught 231 (94 ASY male, rate (7.3 + 0.1, n = 226) calculatedfor primaries 77 ASY female, 36 SY male, 24 SY female) once greater than or equal to 1 mm. The primary and 16 (5 ASY male, 9 ASY female, 2 SY female) growth rate did not changein relation to Julian twice. The interval between the first and second date (P = 0.63, Fig. 9A) or initial body mass(P capturesranged from 1 to 16days and averaged: = 0.40, Fig. 9B). ASY males, 6.6 + 0.3; ASY females, 7.1 + 0.3; The mean primary growth rate of six captive SY males, 7.4 + 0.4; and SY females, 6.7 + 0.6. BlackBrant (derived from initial ninth primar- The meanninth-primary growth rate was 7.2 ies greater than or equal to 1 mm; n = 19) av- + 0.1 mm/day. Ninth-primary growth ratesde- eraged7.0 + 0.3 mm/day. The primary growth rived when initial feathers measured ->0 mm rate (derived from initial ninth primariesgreat- (i.e. when a delay in feather emergencemay er than or equal to 1 mm) slowed (P < 0.001) influence growth-rate calculations)or >-1 mm as the length of the primary increasedin both did not differ acrossage and sex classes(age, F wild-trapped (Fig. 10A) and captive (Fig. 10B) = 0.22, P = 0.88, n = 247; sex, F = 1.10, P = 0.35, Black Brant. n = 226). Overall (ages and sexes combined) Molt chronology.--Assumingtwo days be- growth ratesof primariesin 1988 (n = 98) and tween feather drop and emergence(Boyd and 1989 (n = 149) did not differ (œ= 7.2 + 0.1 mm/ Maltby 1980,Geldenhuys 1983, Panek and Ma- day; t = 0.51, P = 0.61). The primary growth jewski 1990), most Black Brant began primary rate based on an initial ninth-primary mea- molt during the first week in July (Table 8). surement equaling 0 mm (i.e. no emergence) However, someindividuals were flightlessby averaged 6.3 + 0.3 mm/day (n = 21) was sig- 26 June, and several ASY Brant began molt as nificantly (t = -3.12, P < 0.01) slowerthan the late as 25 July. 914 ERICJ. TAYLOR [Auk,Vol. 112

A A Y = 8.54- 0.007XR 2 = 0.001 12- Y = 7.63- O.007X R2 = 0.07 P < 0.001 n = 226

1 o 10.

o o o o o õ o lilP=0.63 n=226 .8 o ?0 0 O0 o o o 6 0 o o 3 O O OO

o O o o O O

o

190 194 198 202 206 210 4 60 80 100 120 140 160 JULIAN DATE NINTH-PRIMARYINITIAL LENGTH (MM) B B Y = 6.85+ O.0004XR 2 = 0.003 Y = 8.43- O.020XR 2 = 0.66 P < 0.001 n=19

10 o

o o o 128- 1P= 0.40o n=225 o oo o Oo

oTo-o• •o • 6- 0 0 0 •0 0 0 0 0 0 0 8-•o•øo ø 0 øo 4-

800 10•0 1200 1400 1600 0 2•0 4•0 dO 8•0' 100 ' ' 120' ' 140' ' 160' NINTH-PRIMARYINITIAL LENGTH (MM) INITIALBODY MASS (G) Fig. 10. (A) Ninth-primary growth rate of wild- Fig. 9. (A) Ninth-primary growth rate regressed trappedBlack Brant regressed against ninth-primary against Julian date (192, 195, 203 indicate 10, 13, 23 initial length (length at first capture if ->1 mm). (B) July 1988, respectively;196, 198, 199, 200, 202, 207 Ninth-primary growth rate of captiveBlack Brant re- indicate15, 17, 18, 19,21, 26 July1989, respectively). gressedagainst ninth-primary initial lengthfor feath- (B) Ninth-primarygrowth rate regressed against ini- ers with initial lengths of ! mm or more. tial body mass.

lengths for SY males and SY femaleswere not Black Brant began remex molt three to five shown to be significantlyshorter (P = 0.11 and days earlier in 1988 than in 1989 (Table 8). I 0.19, respectively)relative to this date in 1988; estimatedthe ninth-primary length of Black however, small samplesand the distribution of Brant banded 12 July 1989 (Julian date 193) for data likely influenced results (3 of 8 SY males 10 July 1988(Julian date 192)by subtracting7 and 4 of 8 SY femaleshad preadjustedprimary mm (growth for one day) from the 1989 data. lengthsof 0 mm and, thus,could not be further ASY malesand ASY femaleshad significantly corrected). (P < 0.001) shorter primaries on this date in The maximumnumber of flightlessbirds oc- 1989than in 1988.The estimated1989 primary curredabout 21 July.At this time, immigration October1995] BlackBrant Molt 915

T^BI,E 8. Ninth-primary length and estimatedmolt initiation of BlackBrant capturedon 10 July 1988 (Julian date 192) and 12 July 1989 (193). Estimateprovided for Julian date 192 in 1989 (see Table 2 for definitions).

Ninth-primary length (ram) Molt initiation Age and sex • + SE(rangea, n) œ(rangea) 10 July 1988 (Julian date 192) ASY-M 46 + 3 (0-100, 97) 4 July(26 June-25 July) ASY-F 39 + 3 (0-85, 59) 5 July(28 June-24 July) SY-M 26 + 3 (0-57, 42) 6 July(2-21 July) SY-F 28 + 4 (0-67, 19) 6 July(I-21 July) 12 July 1989 (Julian date 193) ASY-M 27 + 5 (0-100, 34) 8 July(28 June-25 July) ASY-F 14 + 3 (0-67, 42) 10 July(3-25 July) SY-M 20 + 7 (0-46, 8) 9 July(6-19 July) SY-F 19 + 11(0-88, 8) 9 July(30June-21 July) Estimate for Julian date 192 in 1989 ASY-M 22 + 5 (0-93) ASY-F 10 + 2 (0-60) SY-M 16 + 5 (0-39) SY-F 16 + 10(0-81)

Last date of molt initiation estimated from all banding records. of late, postbreedingASY BlackBrant had end- ninth-primary length of SY femalesand non- ed, and only about 4% of all Black Brant had brood-patch ASY females did not differ (P > regainedthe ability to fly (seebelow). By 26- 0.05); neither did SY males and ASY males. The 29 July, 9% of all molting Brant had flight ca- mean ninth-primary length of nonbrood-patch pability. ASY females exceeded(P < 0.001) that of brood- Between 17-19 July and 21-22 July banding patchASY females,as previously noted, for most periods,the meanninth-primary length of ASY bandingdates after 17July 1988and 1989.Brood- Black Brant declined, while the mean ninth- patch ASY females also had shorter (P < 0.01) primary length of SY BlackBrant increased. This ninth primaries than SY females. Coefficients difference was likely the result of a late immi- of variation were highest for brood-patchASY gration of postbreeders.This suppositionis sup- females(Table 9), indicating that postbreeding ported by recent remex molt (ninth primary = ASY females were least synchronized in molt 0 mm) for several ASY males and ASY females initiation. SY Black Brant began molt with during 21-22 July, comparedto the shortestSY greater uniformity than ASY Black Brant. ninth-primary length (16 mm). Also, prior to The availability of open water in early sum- 17 July (1988 and 1989), the ninth-primary mer did not affect molting chronology.Based lengths of brood-patchASY femalesand non- on three pairsof bandingdates, primary lengths brood-patchASY femaleswere not significantly of ASY Brant molting on EastLong and Island different (P > 0.05) basedon four banding dates on three lakes. However, from 17-27 July, the mean ninth-primary length of nonbrood-patch ASY femaleswas significantly(P < 0.05) longer TABLE9. Statisticsfor ninth-primary lengths (ram) of Black Brant measured 17-19 July 1989. than brood-patchASY females in six of nine comparisons.Finally, prior to 21 July, brood- Ninth primary patch ASY females comprised53% (1988) and Age and sex n œ+ SE CV 60%(1989) of all ASY females.After 21 July, the brood-patchASY femalesproportion increased ASY-M 268 88.5 + 1.8 32.7 ASY-F a 83 65.2 + 3.2 44.0 to 82% and 78%, respectively. ASY-F b 64 84.3 + 3.4 32.5 I compared the molt chronology between/ SY-M 87 84.3 + 2.1 23.3 among sexes,age classes,and between breeders SY-F 70 76.5 + 2.7 29.3 and nonbreeders(ASY femalesonly) from one Had brood patch (failed-nesting bird). lake complexon 17-19 July 1989(Table 9). Mean No brood patch. 916 ERICJ. TAYLOR [Auk, Vol. 112

lakes were not different (P > 0.05), although mexregrowth. Maximum molt intensity,as esti- EastLong Lake became ice-free 7 to 14 daysafter mated by the number of blood quills, occurred Island Lake. when primaries were about 50% grown (20-22 Flightless duration can be estimated from July). Still, Black Brant completedgrowth of ninth-primary lengths of captured birds that only 11 to 21%(TPN 12-21) of all feathersprior flew upon release.Some Black Brant (n = 36) to leaving the molting area. SY Black Brant re- regained flight when the ninth primary aver- placed more body feathersthan did ASY Black aged62% (range 53-73%) of its definitivelength; Brant during the flightlessperiod. Failed-nest- however,this estimateis potentiallybiased due ing BlackBrant, like CanadaGeese (Gates et al. to wind-aided flight, below averagebody mass, 1993),seem to postponereplacing most body or handling stress.Black Brant with ninth pri- feathersuntil after completingremigial molt. maries at this length had completed (on aver- My study supportsthe hypothesisby Gateset age)growth of only one to three primariesand al. (1993) that postbreedinggeese may concen- five to sevensecondaries. Sustained flight likely trate energyand nutrientson remexgrowth (in occurswhen the ninth primary reachesabout lieu of an extensivebody molt), which in turn 70%of final length. Of 2,265 Brant trapped and may allow a shorteningof the flightlessperiod. banded, I captured only four males with pri- Molt intensitygenerally did not differ between maries 156 mm or more in length and no fe- malesand femaleswithin age classes,concur- maleswith primaries150 mm or more in length. ring with Gates et al. (1993). Assuminga constantgrowth rate of 7.2 ram/ A partial rectrix molt occurred before and day, the ninth primary requires 30 to 31 days during wing molt. SY Black Brant rectrix molt to reach full length (ASY male = 223 ram; ASY frequency and intensity exceededthat of ASY female = 214 ram). Becausetwo days passbe- Black Brant, supporting the hypothesisof pro- tween molt and emergenceof remiges, and tein and lipid conservation by postbreeding growth rate likely declinesduring late molt, the adults (Gates et al. 1993). The average number ninth primary could require 35 days to com- of rectriceswas 16 (Cramp and Simmons1977, plete growth. However, if sustainedflight oc- my study); however, the number of feathers cursat 70%of the ninth-primaryfinal length, present ranged from 10 to 18. Although rectri- the actualflightless period--including lag time ceswere not shed simultaneously(see also Wel- (two days)and a slowedgrowth rate in late molt ler 1957, Oring 1968, Young and Boag 1981), (overall mean growth rate estimatedat 7.0 mm/ two to seven tail feathers were replaced con- day)--would equal 23 for femalesand 24 days currently in a symmetrical pattern. for males. Distal primaries (nos. 6-10) dropped prior to To estimatewhen 50%of the population could those more proximal. The tenth primary fly, ! used the mean ninth-primary length re- emerged first and exceededthe ninth primary corded 26-29 July, and added the number of in length until the latter reachedapproximately days (based on 7 ram/day) required for the 15% (•34 ram) of its final length. The shorter feather to reach70% total length. By 2 August, proximal primaries matured before longer dis- 50% (ASY males), 52% (ASY females), 55% (SY- tal remiges,as previously reported in Redheads males), and 52% (SY females) of Black Brant (Aythyaamericana; Weller 1957), Mallards (Anas coulddepart the molting areafor coastalstaging platyrhynchos;Young and Boag1981), and Less- areas. er Scaups(Aythya affinis; Austin and Fredrickson 1986). DISCUSSION Outer primary, secondary,and lesser wing coverts are replaced prior to their innerwing Previous studies have suggestedthat body counterparts,which likely decreasesthermo- molt in Anserinae is delayed until after the regulatory cost(Payne 1972) becauseexposure flightless period (Cramp and Simmons 1977, of vascularizedfeather papillae occurson only Ankney 1984,Hohman et al. 1992,but seeGates one wing surfaceat a time. BlackBrant are sim- et al. 1993). However, at Teshekpuk Lake, Black ilar to Redheads (Weller 1957) and Mallards Brant replacedwing and body feathersconcur- (Young and Boag1981) in molting outer middle rently. Body-molt intensity varied by feather and inner primary covertsat a slower rate and tract and time. Blood quills formed ->25% (ASY over a longer period compared with other co- Black Brant) to ->50% (SY Black Brant) of back verts. and rump, breast,and side regions during re- Comparisonof remigial growth ratesamong October 1995] BlackBrant Molt 917 species of waterfowl is confounded because three to five daysearlier in 1988when the mean previous studies often failed to record feather daily temperaturein Junewas 2øC warmer than type and position (Hohman et al. 1992). Fur- in 1989 (Taylor 1993:table0.2). Thus, the avail- thermore, becausegrowth rates of individual ability of open water may have been greaterin feathersare not constant,the rangeover which 1988, allowing earlier molt. However, molt measurements are recorded is critical if com- chronologyof Brantmeasured on two lakesdif- parisons between species and habitats are to fering in ice break-up and open water avail- have meaning. Realizing these limitations, the ability were not different. Early arriving Black ninth-primary growth rate (7.2 ram/day) de- Brant select shallow, turbid lakes that become rived for BlackBrant at TeshekpukLake is sim- ice-freebefore deeper lakes (Derksen et aL 1979). ilar to meanvalues previously reported for Can- Prior to becomingflightless, geese may shift to ada Geese(7.3 mm/ day;Hanson and Jones1976) deeper lakes with ice cakes,that are used for and BarnacleGeese (Branta leucopsis; 7.5 ram/ preening, resting, and escapesites (Derksen et day; Owen and Ogilvie 1979), but higher than al. 1979). the 5.9 ram/day rate measuredfor nine Brent Failed nesters and nonbreeders arrived in the Geese (Branta bernicla)in the Queen Elizabeth TeshekpukLake molting area primarily from Islands(Boyd and Maltby 1980). late Junethrough mid-July (Derksen et al. 1979, Primary growth rates of Black Brant (my 1982, my study). Remigial molt started during study), Geese (Owen and Ogilvie 1979), the first week in July (Derksen et al. 1979, my and Canada Geese (Gates et al. 1993) did not study),although some failed nestersarrived and differ betweenages and sexes.Primary growth beganmolt from mid- to lateJuly. At Teshekpuk rate in Black Brant declined in relation to remex Lake, molting-chronologyestimates must take emergence, supporting previous observations into consideration: (1) birds initiate molt over on Canada Geese (Hanson 1965), but contrast- a one-monthperiod; (2) variability in the arrival ing with the uniform rate observedfor Barnacle of SY, ASY, and nonbreeding versus failed- Geese(Owen and Ogilvie 1979). Changesin nesting BlackBrant; and (3) differencesin avail- feather-growth rate over the flightless period able molting habitat(open water) betweenshal- maybe obscuredbecause: (1) growth-rateesti- low and deep lakes.Furthermore, this molting matesoften are obtainedonly during early and population is comprised of individuals from midmolt as geeseusually attain flight before breeding colonies in Alaska, Canada, and Rus- feather maturation;and (2) growth rates based sia. Differencesin reproductiveeffort and mi- on feathersthat have not emergedare likely to grationlikely influencebody condition,which be underestimateddue to the lag time before thenultimately may affect the chronology,pat- visible growth occurs(see Owen and Ogilvie tern, and intensity of molt (seeGates et al. 1993). 1979,Boyd and Maltby 1980,Geldenhuys 1983, Environmentaland hormonalcues (Greij 1973) Panek and Majewski 1990). In my study, the may further affect the feather-replacement meanprimary growth ratedetermined from ini- chronologywithin and among age, sex, and tial primary lengthsof 0 mm (i.e. primary feath- breeding classes. Molt chronology and re- er had not emerged) was significantly slower growth appear similar between ASY and SY than that derived from primaries that had BlackBrant for birds initiating molt in early to emerged (6.3 vs. 7.3 ram/day, respectively). mid-July.The significantlylonger mean ninth The nonsignificantrelationship between pri- primary of nonbrood-patchASY females than mary growth rate and Julian date in my study brood-patchASY femalesfor mostsamples after probably reflects the range of molt initiation 17 July was likely the result of a late migration (26 June-25July). Primary growth rate alsowas of brood-patchASY femalesfrom breedingcol- not correlatedwith body mass,although body onies along the Yukon-Kuskokwim Delta, or mass(Taylor 1993)and primary growth rate de- perhapsRussia. Subadult and nonbreedingadult clinedin relationto ninth-primarylength. Owen Barnacle Geese also did not differ in molt chro- and King (1979)reported that Mallardbody mass nology, but breeding adults (malesand females) and early growth rates were positively corre- beganmolt 9 to 10 dayslater than nonbreeders lated; however, a later study (Panek and Ma- (Owen and Ogilvie 1979). As with Barnacle jewski 1990) found no such relationship. Geese,synchrony of molt was greatestamong Migration and molt chronologymay be di- SY Black Brant, followed by nonbrood-patch rectlyrelated to seasonphenology and icebreak- ASY females,while brood-patchASY females up (Sterling and Dzubin 1967).Brant beganmolt were most variable. 918 ERICJ. TAYLOR [Auk,Vol. 112

Black Brant are capable of sustainedflight 19 August although pre- and postmoltersex- when the ninth primary is about 70% grown; tend both of thesedates by severalweeks. My however, some birds flew when the ninth pri- studysupports earlier recommendations(King mary averaged62% of its final length. Boydand 1970, Derksen et al. 1979, 1982) that the Tesh- Maltby (1981) reported brant could fly when ekpuk Lake molting area should be protected primaries reached65% of final length, and An- from petroleum exploration during the entire kney (1984)estimated primaries must be greater period Black Brant are present. than 75%of definitive length. Whereasit is pos- siblethat BlackBrant in this studywere capable ACKNOWLEDGMENTS of flight at primary lengths shorter than those recorded,handling stress, wind-aided flight, and Funding for this researchwas obtainedby D. Derk- below-averagebody mass probably induced sen, Alaska Fish and Wildlife Research Center (Na- early flight capability.Indeed, the mean fresh tional BiologicalSurvey) through grants provided by body massof Black Brant observedto fly was the Bureauof Land Management,Minerals Manage- 24 to 89 g lower than the mean mass for the ment Service, and U.S. Fish and Wildlife Service. Ad- overall late-molt population. This supportsear- ditional support was provided by Former Students, Memorial, Mendon B. Krischer, and James W. Lee lier studiesreporting that molterswith the low- scholarshipsfrom TexasA&M University. S. Adair, est body massesare the first birds capableof K. Bollinger, D. Esler,S. Garner, K. Jensen,F. Mann, flight (Owen and Ogilvie 1979, Geldenhuys C. Markon, J. Moore, L. Neely-Garner, and M. Wetter 1983). assisted with collection of field data. M. Wetter served Assumingthat (1) primariesrequire two days as graduatecommittee advisor, J. Matis provided an- to emerge after being dropped, (2) primary alytical assistance,and T. Odom granted use of lab- growth rate equals 7.2 ram/day and then de- oratory and computerfacilities. I thank J. Austin, F. clines,and (3) sustainedflight occurswhen the Mann, J. Marks, G. Schnell, M. Weller, and an anon- ninth primary hascompleted 70% of its growth, ymousreviewer for providing valuablecomments on the duration of the flightlessperiod is about 23 earlier drafts of this manuscript.J. Moore died while this manuscript was in press;his professionalethics, and 24 daysfor femalesand males,respectively, dedication, and enthusiasm for the waterfowl re- supporting an earlier estimateby Derksen et al. source will be missed. (1979) of 3 to 3.5 weeks. Previousstudies report similarfindings for brant (about21 days,Palmer 1976;22-25 days,Boyd and Maltby 1980), Bar- LITERATURE CITED nacle Geese(25 days,Owen and Ogilvie 1979), ANKNEY,C. D. 1984. Nutrient reservedynamics of Canada Geese(25 days, Sterling and Dzubin breeding and molting Brant. Auk 101:361-370. 1967),and GreylagGeese (Anser anser; 28 days, AUSTIN,J. E., AND L. H. FREDRICKSON.1986. Molt of Loonen et al. 1991). female Lesser Scaup immediately following Managementimplications.--The timing and breeding. Auk 103:293-298. duration of flightlessness,and the relationship BARRY, T. 1962. Effect of late seasons on Atlantic between molt and nutrient (lipid and protein) Brant reproduction. J. Witdt. Manage. 26:19-26. BILLARD,R. $., AND P. $. HUMPHREY. 1972. Molts and reserves, are critical in determining the time plumagesin the GreaterScaup. J. Witdl. Manage. frame and potential impacts of petroleum ex- 36:765-774. ploration. In 3.5 weeks, Black Brant molt and BI•CK, R. F., AND W. L. BARKSDALE.1949. Oriented regrow(to 70%maturity) all of their remigesin lakes of northern Alaska. J. Geol. 57:105-118. addition to renewing at least 25% of the back, BOYD,H., ANDL. $. MALTBY. 1980. Weights and pri- rump, breast, and side regions. Concurrently, mary growth of BrantGeese Branta bernicla moult- lipid reservesdecline 71 to 88% and comprise ing in the Queen Elizabeth Islands, N.W.T., Can- only 2 to 4%of correctedfresh body mass during ada, 1973-1975. Ornis Scand. 11:135-141. late molt (Taylor 1993). Although Arctic-nest- CRAMP,$., ANDK. E. L. SIMMONS(EDs.). 1977. Hand- ing geesebenefit from rapid feathergrowth and bookof the birdsof ,the Middle Eastand North Africa. The birds of the western Palearctic, early regainingof flight (asresult of massloss; vol. 1. Oxford Univ. Press, Oxford. Taylor 1993),these benefits are lost if environ- DERKSEN,D. V., T. C. ROTHE, AND W. D. ELDRIDGE. mental perturbationsand disturbancepreclude 1981. Use of wetland habitats by birds in the uninterrupted feeding to allow feather matu- National Petroleum Reserve--Alaska. U.S. Fish ration. and Wildl. Serv. Resour. Publ. 141. FlightlessBlack Brant are presentin the Tesh- DERKSEN,D. V., M. W. WELLER,AND W. D. ELDRIDGE. ekpuk Lake molting area from 26 June through 1979. Distributional ecologyof geesemolting October1995] BlackBrant Molt 919

near Teshekpuk Lake, National Petroleum Re- KING, J. G. 1970. The swans and geeseof Alaska's serve-Alaska.Pages 189-207 in Managementand arctic slope. Wildfowl 21:11-17. biology of Pacific Flyway geese: A symposium LOONEN,M. J. J. E., M. ZIJLSTRA,AND M. R. VAN EER- (R. L. Jarvisand J.C. Bartonek,Eds.). Oregon State DEN. 1991. Timing of moult in Greylag Geese Univ. Book Stores, Corvallis. Anseranser in relation to the availability of their DERKSEN,D. V., W. D. ELDRIDGE,AND M. W. WELLER. food plants. Ardea 79:253-260. 1982. Habitat ecologyof PacificBlack Brant and MADSEN,J. 1985. Impact of disturbanceon field uti- other geesemoulting near TeshekpukLake, Alas- lization of Pink-footed Geese in West Jutland, ka. Wildfowl 33:39-57. Denmark. Biol. Conserv. 33:53-63. FREVRICKSON,L. H., ANr• R. D. DROBNEY. 1979. Hab- MILLER,M.R. 1986. Molt chronology of Northern itat utilization by postbreedingwaterfowl. Pages Pintails in . J. Wildl. Manage. 50:57- 119-131 in Waterfowl and wetlands--An inte- 64. grated review (T. A. Bookout,Ed.). Proceedings ORING,L.W. 1968. Growth, molts and plumages of Symposium39th Midwest Fishand Wildlife Con- the Gadwall. Auk 85:355-380. ference, North Central Section, Wildlife Society, OWEN, M., AND R. KING. 1979. The duration of the Madison, Wisconsin. flightlessperiod in free-living Mallard. Bird Study GATES,R. J., D. F. CAITHAMER,T. C. TACHA, AND C. R. 26:267-269. PAINE. 1993. The annual molt cycle of Branta OWEN, M., AND M. OGILVIE. 1979. Wing molt and canadensis interior in relation to nutrient reserve weights of Barnacle Geese in Spitsbergen.Con- dynamics. Condor 95:680-693. dor 81:42-52. GELDENHUYS,J.N. 1983. Morphologicalvariation in OWENS,N. W. 1977. Responsesof wintering Brent wing-moulting SouthAfrican Shelducks.Ostrich Geese to human disturbance. Wildfowl 28:5-14. 54:19-25. PALMER,R. S. 1976. Handbook of North American GREIJ,E. D. 1973. Effectsof sex hormones on plum- birds.Vol. 2., Waterfowl, part 1. Yale Univ. Press, ages of the Blue-winged Teal. Auk 90:533-551. New Haven, . HI,SoN, H. C. 1962. The dynamics of condition PANEK,M., AND P. MAJEWSKI.1990. Remex growth factors in Canada Geese and their relation to sea- and body mass of Mallards during wing molt. sonal stresses.Arct. Inst. N. Am. Tech. Pap. 12. Auk 107:255-259. HANSON, H. C. 1965. The giant Canada . PAYNE,R.B. 1972. Mechanisms and control of molt. Southern Illinois Univ. Press, Carbondale. Pages104-155 in Avian biology, vol. 2 (D. S. Far- HANSON,H. C., AND R. L. JONES.1976. The biogeo- her and J. R. King, Eds.). Academic Press, New chemistryof Blue,Snow and Ross'geese. Ill. Nat- York. ural History Survey Publ. 1., Southern Illinois SALOMONSEN,F. 1968. The moult migration. Wild- Univ. Press, Carbondale. fowl 19:5-24. I'IARRIS,S. W., AND P. E. SHEPHERD.1965. Age de- SASINSTITUTE. 1985. SAS user'sguide: Statistics,ver. termination and notes on the breeding age of 5 ed. SAS Institute, Inc., Cary, North Carolina. Black Brant. J. Wildl. Manage. 29:643-645. STERLING, T., AND A. DZUBIN. 1967. HOLMAN, W. L., C. D. ANKNEY, AND D. H. GORDON. molt migrations to the Northwest Territories. 1992. Ecologyand managementof postbreeding Trans. N. Am. Wildl. Conf. 32:355-373. waterfowl. Pages 128-189 in Ecologyand man- TAYLOR,E.J. 1993. Molt and bioenergeticsof Pacific agement of breeding waterfowl (B. D. J. Batt, A. BlackBrant (Brantabernicla nigricans) on the Arctic D. Afton, M. G. Anderson, C. D. Ankney, D. H. Coastal Plain, Alaska. Ph.D. dissertation, Texas Johnson, J. A. Kadlec, and G. L. Krapu, Eds.). A&M Univ., College Station. Univ. Minnesota Press,Minneapolis. U.S. DEPARTMENT OF THE INTERIOR. 1977. Federal I.IussE¾, K. M., AND R. W. MICHELSON. 1966. Register.Vol. 42. No. 107. relief features near Point Barrow, Alaska. Arctic WELLER,M. W. 1957. Growth, weights, and plum- 19:162-184. ages of the Redhead, Aythya americana.Wilson JENSEN,K.C. 1990. Responsesof molting PacificBlack Bull. 69:5-38. Brant to experimental disturbancein the Tesh- YOUNG,D. A., AND D. A. BOAG. 1981. A description ekpuk Lake Special Area, Alaska. Ph.D. disser- of moult in male Mallards. Can. J. Zool. 59:252- tation, TexasA&M Univ., College Station. 259.