Parental Attendance and Brood Care in Four Argentine Dabbling Ducks
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TheCondor91:131-138 0 TheCooper Ornithological Society 1989 PARENTAL ATTENDANCE AND BROOD CARE IN FOUR ARGENTINE DABBLING DUCKS FRANK MCKINNEY AND GWEN BREWER Bell Museum of Natural History and Department of Ecology and BehavioralBiology, Universityof Minnesota, Minneapolis,MN 55455 Abstract. The presenceof males with broods of Silver Teal (Anus versicolor),Speckled Teal (A. fluvirostris), Red Shoveler (A. plutaleu), and Brown Pintail (A. georgica)was re- corded, and the behavior of brood-tending males and females was observed, during parts ofthree breedingseasons, November-December, 1985-1987, on variouswetlands in Buenos Aires Province and in the vicinity of Bariloche, Rio Negro Province, Argentina. Biparental care was well developed in Silver Teal. Some SpeckledTeal broods were escortedby both parents, but others were cared for by the female only. Brown Pintail males were present at times with one-third of the broods seen, but they showed no brood-care behavior. Males were rarely seenwith Red Shoveler broods and there was no indication of male brood care. Our observationssuggest that pair bonds may be long-term in Silver Teal and perhaps in some SpeckledTeal, but males desertedtheir brood-tending females in Red Shoveler and Brown Pintail. We emphasizethat behavioral observationsare needed to determine whether males associatingwith broods are really contributing to parental care in Southern Hemi- sphereAnus species. Key words: Argentina;parental care;pair-bond duration; wing molt during broodcare; Anas versicolor; Anas flavirostris; Anas platalea; Anas georgica. INTRODUCTION parental investment, and the factors that influ- In Northern Hemisphere dabbling ducks (genus ence these patterns. Anus) only females care for the ducklings, but in In this paper, we present observations on the certain Southern Hemisphere speciesmales also behavior of the adult(s) escorting broods of four accompany broods &ear 1970; Siegfried 1974; poorly-studied species:Silver Teal (A. versicolor Weller 1975a, 1975b, 1975~). However, few of versicolor), Speckled Teal (A. jluvirostris jluvi- the latter specieshave been studied intensively rostris), Red Shoveler (A. plutuleu), and Brown and evidence on active male participation in Pintail (A. georgicu spinicuudu) (nomenclature brood care is scarce.Gross species-characteristic follows Johnsgard 1978). We paid special atten- differences in the behavior of males accompa- tion to the behavior of males when they were nying broods have been noted for certain South- present, but brood-care behavior of females, ern Hemisphere Anus species (reviewed in duckling behavior, and brood-habitat prefer- McKinney 1985). For example, biparental care ences are also reported. is the usual pattern in the Cape Teal (A. cape&s), Chestnut Teal (A. castuneu), and Chiloe Wigeon METHODS sibilutrix), while female-only care is usual in (A. Records of the presence of one or two parents the African Black Duck (A. spursa) and Pacific with broods were collected in Argentina during Black Duck (A. superciliosu). For most of the parts of three breeding seasons,November-Feb- other Southern Hemisphere species,including A. ruary, 1985-1987. Locations at which the broods jluvirostris and A. georgicu discussedhere, rec- were observed are grouped in four categoriesac- ords are inconsistent; either one or two adults cording to regions and habitat differences (Fig. have been noted with broods. The possibility 1): (1) Buenos Aires Province: Costanera Sur Re- that brood-care patterns are variable within these serve on the edge of the city of Buenos Aires, speciesraises intriguing, and as yet unexplored, wetlands near Trenque Lauquen, Coronel Prin- questionsabout the duration of pair bonds, male gles, Claromeco, and Juarez; (2) Bariloche area: various wetlands within 60 km of Bariloche, Rio I Received16 May 1988. Final acceptance28 Sep- Negro Province (Fig. IA-G); (3) Laguna Los Jun- tember 1988. cos: a small lake 35 km east of Bariloche; and [I311 132 FRANK McKINNEY AND GWEN BREWER broodsof Brown Pintail and one brood of Speck- led Teal which were reclassifiedwhen a male was later seen with them. Almost all broods were 3 watched for at least several minutes after being . sighted, and some broods were watched for up to 3 hr. No birds were individually marked, but we could identify some families by their location, number and size of ducklings, and sometimes by adult plumage features. Observations of brood behavior were made using 20x scopesfrom a parked car or from vantage points overlooking wetlands.Although broods usually retreatedfrom us when we first arrived, most attending adults habituated to our presenceand permitted obser- vations of apparently undisturbed behavior. Trenque Lauquen. We attempted to age broods using the criteria of Gollop and Marshall (1954) assigningeach to Coronel Ringlesm one of seven categories(Ia, Ib, Ic, IIa, IIb, IIc, III). In view of the many variables involved, however,the recordshave been groupedinto three categoriesonly: I-downy, II-mixed down and feathers,and III-feathered. Broodswere not tal- lied unless they were seen well enough to allow an accurate count of the ducklings, an estimate of their age, and a clear decision on whether a male was with them or not. Ducklings without attending adults were not tallied as “broods.” FIGURE 1. Map of locationswhere broods were ob- served in Argentina. Inset map areasreferred to in the Although adult plumages of males and females text are as follows: (A) Puerto Panuelo, (B) Kilometer are similar in three of these species,we had no 14, (C) LagoGutierrez, (D) Nirihuau, (E) EstanciaJones, difficulty sexing birds accompanying broods by (F) Traful, (G) Estancia San Ramon, (H) Laguna Los differences in body size, head shape, calls, and Juncos,(I) Pilcaniyeu. other distinctive behavior. (See Johnsgard 1965, 1978 and McKinney 1970 for descriptions of (4) Pilcaniyeu: various wetlands near Pilcaniyeu, displays.) 70 km east of Bariloche. Typical aquatic vege- tation of Buenos Aires Province is described in RESULTS Weller (1968). Near Bariloche, reeds (Juncus spp.), milfoil (Myriophyllum spp.), and pond- SILVER TEAL weeds (Potamogetonspp.) are common. Local- Eight of 10 broods (80%) tallied were closely es- ities, dates, and other habitat characteristicsare corted by both male and female (Table 2). The detailed in Table 1. remaining two broods could have had a male Repeated visits were made to certain wetlands associatingloosely with them; both were in dense in the Costanera Sur Reserve and near Bariloche emergent cover, and single males were seen in and, in the course of intensive fieldwork on pa- the vicinity. All broods spent most of the time rental care in Chiloe Wigeon by GB, brood rec- in heavy cover provided by densestands of emer- ords were collected during November and De- gent aquatic plants (cattail, rypha latifolia, ar- cember at Laguna Los Juncos (1986) and rowhead, Sagittaria montevidensis,and smart- Pilcaniyeu (1987). Undoubtedly some of the same weeds, Polygonum spp.). Ducklings fed by broods were resightedrepeatedly at theseplaces, probing in mud and dabbling in shallow water; and we took care to eliminate all records that they were not seen to dive for food. When dis- might have been duplicatesfrom the totals.Adults turbed by people they retreated into cover or, present were reported in Table 2 for the initial when the zone of emergent plants fringing the sighting, with the exception of four identifiable shorelinewas narrow, by swimming rapidly across BROOD CARE IN ARGENTINE DABBLING DUCKS 133 TABLE 1. Habitat types, locations, and dates of observation for study areas. Habitat type Location Datesof observation Shallow ponds (field and roadside Juarez 18-19 November1987 ditches) Coronel Pringles 19 November1987 Trenque Lauquen 20 November1986 Nirihuau 28 November,3 and 7 December1985 Kilometer 14 6-19 December1986, 23 and 27 November1987 Ponds formed from rivers by dams Costanera Sur 6-16 November 1987, 9 December1987 or landfill EstanciaJones 28 November1985 EstanciaSan Ramon 17 January-3February 1987 Pilcaniyeu 26 November 1987-15 February1988 Shallow lakes with associated Claromec6 13-14 December1985 marshes Traful 28 November 1987 Shallow steppe lake with LagunaLos Juncos 3-10 December1985, Myriophyllum 29 November 1986-14 January1987, 22 November-2 December1987 Sheltered sectionsof large, deep Lago Gutierrez 22, 25,29 November1987 lakes Puerto Paiiuelo 30 November 1985,23 November 1987 open water to reach another section of secluded swam back toward them she gave a decrescendo cover. When surprised by us at close range, fe- call, the ducklings responded by swimming fast males gave squeaky quacks and quickly led their to her, and the male followed them. ducklings away. In one instance, the male gave Males escortingbroods were very vigilant and quiet alarm calls as he swam out from cover, and spent much time with head high in alert postures. then the female and ducklings swam to join him. Broods were difficult to watch because of their Once, when a female was away from her brood, preferencefor dense cover, but a time budget for the male stayed with the ducklings; when she the adults with five (Ic) ducklings was made (ac- TABLE 2. Presenceof both male (M) and female (F) with broodsobserved in four localitiesin centralArgentina between 6 November and 14 December 1985-1987. Broodswith M + F/total broods Duckling ageclass TOtiS Species Locality I II III M + F/all broods Silver Teal B.A. Province 515 l/2 2/3 8/l@ SpeckledTeal B.A. Province 2/2 l/l l/l 4/4 Nr. Bariloche l/2 l/l l/l 314 L. Los Juncos l/l o/3 - l/4 Pilcaniyeu l/2 l/l 2/3 Totals 5/7 3/6 2/2 10/15b Red Shoveler B.A. Province l/3 O/l - l/4 L. Los Juncos 4/12 - 4/12 Pilcaniyeu o/9 O/l - o/10 Totals 5/24 o/2 - 5/26 Brown Pintail B.A. Province 2/2 2/2 - 4/4 Nr. Bariloche 213 317 l/2 6/12 L. Los Juncos 2/4 O/l O/l 2/6 Pilcaniyeu l/11 O/6 - l/17 Totals 7/20 5/16 l/3 13/39d ans, binomial test (two-tailed;H,:p = p * = l/Z).