Diseases of perching ducks in captivity N. HILLGARTH and J. KEAR This is the third of a series of reports that fowl. Carolinas were held and bred in will analyse post-mortem findings of birds captivity in North America as early as the dying in the Wildfowl Trust collections 17th century; they were introduced to since 1959. D etailed records have been Europe at about the same time (Delacour kept by J. V. Beer (1959-1969), by N. A. 1959) and were recorded as breeding at Wood (1970-1973) and by M. J. Brown London Zoo in the earliest published list of subsequently. 1831. The M andarin has been kept in its Within the wood ducks, or perching native China and in Japan for centuries; it ducks of the tribe Cairinini, we have in­ first bred in Britain, again at London Zoo, cluded the following genera: the Brazilian in 1834 (Sclater 1880). Teal Amazonetta, Maned Goose Che­ Muscovys were brought to Europe in the nonetta, Mandarin and Carolina A ix, Ring­ 16th century from Columbia and Peru ed Teal Callonetta, Pygmy Geese Netta- where they had already been domesticated pus, Comb Duck Sarkidiornis, Muscovy by the American Indians (Delacour 1959). and White-winged Wood Duck Cairina, The first wild Muscovy appears to have Spur-winged Goose Plectropterus and reached London Zoo in 1851 (Sclater Hartlaub’s Duck Pteronetta. 1880), but it is not a bird that is often seen Perching ducks occur in the equatorial in waterfowl collections. Its supposed rela­ regions or at low temperate latitudes. The tive, the White-winged Wood Duck bred in Mandarin and Carolina are apparently re­ captivity only once before the 1970s in lics of an early radiation of perching ducks Holland in 1936 (Schuyl 1937), but now into the north temperate zone, a radiation reproduces successfully at most Wildfowl that has been replaced by the more recent Trust centres. evolution of the Anas dabbling duck. All Hartlaub’s Duck first nested, at Slim­ perching duck tend to perch in trees, as the bridge, as recently as 1958, and is still not name suggests, but in general the group is often seen in captivity. The same applies to extremely heterogenous. They are mainly the Gambian Spur-winged Goose which plant eaters, and food of animal origin laid at London Zoo in 1868 but did not does not predominate in the diet of any of breed successfully until 1933 at Whipsnade them. None are marine. Hartlaub’s Duck, (Delacour 1959). The Black Spur-winged Muscovy and White-winged Wood Duck Goose does not appear to have been cap­ occur exclusively in tropical rain forest. tive-bred at all. The Maned Goose is a grazer and there­ Captive Old World Comb Duck bred at fore might be expected to suffer from the Lilford in 1931, and the American Comb usual internal parasities of other grazing Duck in 1939 at Cleres, France. The Au­ waterfowl. Many, indeed the majority, stralian Maned Geese were first reared in nest in the potentially damp, mouldy captivity in France in the late 19th century atmosphere of holes and have long incuba­ by Courtois and others (Delacour 1959), tion periods. They exhibit a variety of and now breeds fairly frequently, as does social patterns, some apparently pair for the Brazilian Teal which first nested at life and have obvious family ties, while in London Zoo in 1878. others the pair bond is fleeting and the Ringed Teal probably first bred in male takes no part in the rearing of the Europe in the early 20th century since young. About half the species are sexually young birds were sold in Germany in 1911 dimorphic, and in the Carolina and Man­ (Delacour 1959). The Pygmy Geese are darin the brightly coloured males compete uncommon in zoos and collections: the vigorously for mates before each breeding Indian species bred at Bronx Zoo, USA, in season. Some breed when they are a year 1978 (Bruning 1979), the African Pygmy old, others not until they are two or three. Goose in early 1975 in Rhodesia. Thus times of stress, when individuals might be expected to succumb to disease, vary greatly from species to species. Materials The Carolina and the Mandarin have a long history in captivity and are among the Post-mortem data from 1843 perching most commonly kept ornamental water- ducks dying between 1959-1980 have been 156 Wildfowl 32 (1981): 156-63 Perching duck deaths 157 examined. These consist of 724 adults, 202 Males died at an average age of 3-5 years juveniles and 917 downies (Table 1). An and females at a very similar 3-4 years. The adult bird is defined as one that has sur­ oldest recorded birds were a 16-year-old vived to its first January. A juvenile is fully female Comb Duck, two 15-year-old Comb feathered but dies in its first autumn or in Ducks and a 15-year-old Mandarin. (Fi­ early winter (before 1 January). A downy gure 1). is any young bird that is not fully feath­ ered. The only perching duck for which many records are available is the North Seasonal mortality American Wood Duck or Carolina, but unfortunately White-winged Wood Duck In Figure 2 we have examined the mortal­ are suffering high mortality in captivity ity of perching ducks month by month. To despite excellent breeding results. We are do this we have divided them into two unable to distinguish Indian and African groups, dependent on their type of breed­ Pygmy Geese: both have been kept by the ing pattern as defined by Murtón & Kear Wildfowl Trust, but the species is not (1979). The ‘primitive’ group (mostly of identified in most post-mortem records. tropical origin) are capable of nesting over a considerable period of the year, usually from March to September, while the Results temperate group nest in the spring but only until midsummer. In the first group we Longevity have included Maned Geese, Spur-winged Geese, Hartlaub’s, Comb Ducks, Muscovy The average age at death of captive per­ and Ringed Teal, in the second, White­ ching ducks (considering only the adult winged Wood Duck, Brazilian Teal, Caro­ class) was 3-5 years. This figure is based on linas and Mandarins. There is a significant the 46% of those examined whose age was difference in the mortality patterns be­ known, and excludes all wild-caught birds. tween the two groups of males ( j2 = 23, 70-1 ------- ALL D EA T H S ------- MALES 60- ------- FEMALES 50- 40- o u- 30- 20 - 10- 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 AGE AT DEATH (Y E A R S) Figure J. Age of perching ducks at death. 158 N. Hillgarth and. J. Kear CE TEMPERATE PERCHING DUCKS UJ ¿0 - -------- MALES = 188 FEMALES = 180 A 30- / \ ~ f / \ \ / X/ / \\ / r>s \\ 2 0 - - / / " V ' \ — _ / w 1 0 - \/ JAN 1 FEB 1 MAR 1 APR 1 MAY 1 JUN 1 JUL 1 AUG 1 SEP 1 OCT 1 NOV 1 DEC 1 MONTH OF DEATH Figure 2. Deaths per month of ‘primitive’ perching ducks. 0-02 < p > 0-01), but a highly significant of diseases the reader is referred to Hill­ difference if the deaths of females are garth & Kear (1979a), Beer & Stanley compared (x2 = 49-4, p = >0-001). Of 1975, Arnall & Keymer (1976) and the those birds with a ‘primitive’ type breeding Game Conservancy (1974). Trauma is pattern, females die principally in January, excluded; very few cases have been re­ February and March which are the cold corded, the perching duck are not highly months at Slimbridge. The temperate per­ territorial and rarely seem to fight one ching duck females, which are presumably another in any dangerous way. better adapted to cool temperatures, die mainly during the egg-laying season of April and May. Tuberculosis It is obvious that in comparison with the Cause o f death other waterfowl groups perching ducks are peculiarly and overwhelmingly susceptible At post-mortem examination a primary to avian tuberculosis. Of adults examined, cause of death was assigned and it is these 49% died from this cause (see Table 2) and conditions that are discussed below. For 4-5% of dead juveniles had also been information on treatment and prevention affected. Out of the 354 adults with tuber- Perching duck deaths 159 Table 1. Totals of perching ducks examined at Table 2. Incidence of avian tuberculosis in adult post-mortem. perching duck at post-mortem examination. Species Genera Totals ef ? Total % Brazilian Teal A m azonetta 46 adults 24 juveniles Brazilian Teal 12 9 21 45-7 17 downies M aned Goose 7 15 22 41-5 M andarin 23 14 37 50-0 Maned Goose Chenonetta 53 adults 28 juveniles Carolina 53 35 88 51-8 19 downies Pygmy Goose 14 13 27 37-5 12 30-0 Mandarin Duck Aix 244 adults Comb Duck 5 7 2 4 6 24-0 Carolina 67 juveniles H artlaub’s Duck 518 downies White-winged W ood Duck 21 38 59 79-7 Ringed Teal C alonetta 118 adults 37 juveniles Muscovy Duck 6 9 15 37-5 178 downies Spur-winged 1 2 3 25-0 Pygmy Geese Nettapus 72 adults Goose 0 juveniles Ringed Teal 36 28 64 54-2 0 downies 180 174 354 Comb Duck Sarkidiornis 40 adults 13 juveniles 51-0% 46-9% 48-9% 100 downies H artlaub’s Duck Pteronetta 25 adults culosis, the age is known of 173 of them, 12 juveniles and their age at death was compared with 21 downies that of birds dying of other diseases (see White-winged Cairina 114 adults Figure 3).