View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by UNL | Libraries University of Nebraska - Lincoln DigitalCommons@University of Nebraska - Lincoln Paul Johnsgard Collection Papers in the Biological Sciences 1-1961 The Taxonomy of the Anatidae—A Behavioural Analysis Paul A. Johnsgard University of Nebraska–Lincoln, [email protected] Follow this and additional works at: https://digitalcommons.unl.edu/johnsgard Part of the Ornithology Commons Johnsgard, Paul A., "The Taxonomy of the Anatidae—A Behavioural Analysis" (1961). Paul Johnsgard Collection. 29. https://digitalcommons.unl.edu/johnsgard/29 This Article is brought to you for free and open access by the Papers in the Biological Sciences at DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in Paul Johnsgard Collection by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln. Published in THE IBIS 103a:1 (January 1961), pp. 71-85. Published by British Ornithologists' Union. 1961 P. A. JOHNSGARD : BEHAVIOURAL ANALYSIS OF ANATIDAl! 71 THE TAXONOMY OF THE ANATIDAE-A BEHAVIOURAL ANALYSIS P. A. JOHNSGARD Received on 14 May 1960 Delacour & Mayr's (1945) classic revision of the Anatidae took waterfowl behaviour into account to a much larger degree than had any previous classifications of the group. However, their utilization of behavi~>ur was primarily at the tribal and generic levels, and no real attempt was made to :use behaviour for det!!rmining intrageneric relationships. Thus far only Lorenz (1941, 1951-1953) has seriously attempteq this with waterfowl, and his analysis of the relatiOnShips within the genus Anas (sensu De1acour & Mayr) has provided a remarkable insight into the evolution of this group. I have attempted to expand LorenZ's behavioural delineation of relationships within this genus to include all the living species, and have also attempted to do comparative behavioural analyses for the other genera and tribes in the family Anatidae. The publication of these studies in full detail will be done at a later date (Johnsgard, unpublished) but their taxonomic implications can be summarized here. The purpose of this paper is therefore to provide a more detailed set of behavioural definitions for the anatid groups propolled by Delacour & Mayr, and to suggest ,changes in intrageheric sequences of species, in generic relation­ ships, and in a few cases the species composition of certain tribes of the Anatidae. Except where otherwise indicated, the species and generic nomenclature used is that of Delacour & Mayr (1945) or Delacour (1954-1959) .. Acknowledgments. This work was done while the author was studying at the Wildfowl Trust, Slimbridge, on a National Science Foundation postdoctoralfello"'!Ship. I would like to express my sincere appreciation to the National Science Foundation for making this study possible and to the Wildfowl Trust personnel for their assistance in every possible way. For stimulating suggestions and unpublished observations I owe D. F. McKinney, P. Scott, and W. Von de Wall my sincere thanks, and the great source ofinspiration that has been provided bythe writings of K. Z. Lorenz and O. Heinroth cannot go unmentioned. Observations. Each of the major taxonomic groups will· be listed below, and defined so far as possible in behavioural terms. Whenever feasible, intrageneric and inte~­ generic relationships that are indicated behaviourally will be mentioned. SUBFAMILY ANSERANATINAE Tribe ANSBRANATINI There is no doubt that the Magpie Goose Anseranas semipalmata, deserves at least subfamilial distinction from the rest of the waterfowl. Besides its numerous anatomical peculiarities (Miller 1919; Delacour 1954), it has several behavioural peculiarities which set it apart and which may indicate affinities with the South American screamers (Anhimidae). The female" at least in captivity, usually builds several" dummy" nests which are rather swan-like heaps of vegetation, either of grass or herbs. The male is known to assist in nest building and assists with incubation as well, especially at night. The male also defends the nest vigorously. Both parents feed the young, the only known instance of parental feeding in the Anatidae; and it is possible that the bright orange bill and cinnamon head of downies act as a feeding " target " in the same manner as do head and bill specializations in various other groups of birds. Mutual preening, which is frequent in screamers (Stonor 1939), is rare in Magpie Geese. Males assist 72 P. A. JOHNSGARD : BEHAVIOURAL ANALYSIS OF ANATIDAB IBIS 103a in rearing the young and family bonds are strong, as in geese and swans. Threat behaviour is not strongly ritualized. and consists of cocking the neck and rapidly striking with the bill. At higher intensities the male strikes with the wings or may fiy at the opponent, striking simultaneously with the bill and feet. Wing-shaking appears to be a low tensity threat, .and also seems to function as a rudimentary "triumph cere­ mony·J after· aggressive encounters. Copulation takes place on land., but neither precopulatory nor postcopulatory behaviour has been adequately observed. There. is apparently no wing-:-fiapping· or bathing after copulation. Flight intention signals are simply lateral head-shaking movements and associated calling: . Although it is apparent that the Magpie Goose is more closely related to the subfamily Anserinae than the Anatinae, it is not certain whether i~ most closely approaches the swans, geese, or whistling ducks. It seems most ~ely that the differentiation of these groups occurred after the isolation of ancestral"Anseranatinae stock. SUBFAMILY ~SERINAE The subfamily of geese, swans and whistling ducks agrees with the preceding one in .. that there is little or no sexual dimorphism in plumages, voices, and behaviour, and the pair bond is relatively strong and permanent. Although sexual behaviour is remarkably uniform throughout the entire subfamily, threat behaviour is complex, varies greatly, and is of greater value in assessing intratribal relationships. In b()th tribes the male assists with nest building and rearing the young, but in only some species does the male· take part in incubation. Of the two tribes, the Anserini might be considered to be the more gener~d, but the Dendrocygnini is the more isolated as indicated by the absence of intertribal hybrids (Johnsgard 1960 a) involving whistling ducks. Therefore this tribe will be discussed first. Tribe DBNDROCYGNINI The whistling ducks comprise a group of eight species which undoubtedly should be placed in a single genus Dendrocygna. Attesting to this is the fact that in their sexual behaviour (precopulatory and postcopulatory displays) all the species are nearly identical. Behaviourally the species differ primarily in their vocalizations and, to a lesser degree, their threat behaviour. Aggressive behaviour is highly developed and small groups often mutually threaten other birds. There does not, however, appear to be any real "triumph ceremony" present in the whistling ducks. There are two major threat displays, one being a " Head-back " posture with the neck cocked and ready to strike. and the other a "Head-low-and-forward" posture with the scapular feathers raised (Johnsgard, unpublished). Some species (D.guttata, D. tytoni) utilize the former pOsture almost entirely, whereas some (D. aboria. D. autu1linalis, D. fJiduata) mainly use the latter. Flight intention movements consist of lateral head-shaking. Males help with incubation in most if not all species, which may account for the fact that there is normally practically no down present in the nest, as the eggs are almost continuously incubated. Mutual preening occurs in most, if not all, species, and is not restricted to mated birds. Family bonds appear to be strong, and individual recognition appears to be at least in part based upon variations in calls. In some species (D. guttata, D; eytoni, D. bieolor) these calls tend to be simple and are usually of only two syllables, while in the other species they are much more complex and are highly distinctive. In all the species studied precopulatory behaviour is almost ide~tical, consisting of mutual behaviour that appears to be derived from bathing, drinking, or feeding movements. The birds usually copulate while in shallow water or when standing near shore. The male suddenly mounts the female before she assumes a prone posture, and treading lasts only a few seconds. As soon as it is completed, both birds call loudly and the pair rises in the water, f!ide by side, usually raising the wing farthest from the other bird to a position directly vertical but folded at 1961 P. A. JOHNSGAlID : BEHAVIOURAL ANALYSIS OF ANATIDAE 73 the wrist. This is oft~n accompanied by a vigorous paddling of the feet for a few seconds, after which the two birds return to their normal positions and usually go to shore where 'they both preen extensively. Two species (D. autumnalis and D. arborea) lack such an elaborate postcopulatory display, and copulation normally occurs on shore. .-1/1 0 0 0 C '- 0 to! 0 .. .. E '- 0 0 ::;J 0 c ::;J 0 ::;J .. .0 .. V ~ ::;J '- >- .-> 0 0 toI FIGURE 1. Evolutionary relationships in the Dendrocygnini (Dendrocygna). In this and the following figures the length of the branches indicates the probable degree of isolation from related species, and broken lines indicate uncertainty. On the basis of behavioural differences and differe,nces in the patterns of the downy young (Delacour 1954), the accompanying diagram (Fig. 1) illustrates the probable evolutionary relationships within the whistling dUj;:k group. Adult plumage patterns are of little value in showing relationships in this genus, and it is of interest that two species (D. guttata and D. arborea) which have outwardly similar adult plumages are .probably not at all closely related. Both are island species (arborea West Indies, guttata East Indies) which are allopatric with nearly aU other whistling ducks, and I believe that this dull, spotted adult plumage is a secondary, convergent, derivation.