SEPTEMBER, 1977 199 THE ECOLOGY OF HONEYEATERS IN SOUTH AUSTRALIA (A lecture presented to the S.A.O.A. on June 25, 1976) HUGH A. FORD Accepted September, 1976 I shall present this evening a summary .of the The 22 species of honeyeaters regularly found work which has been carried out on honey­ near Adelaide can be separated into two main eaters in the Department of Zoology at .groups; the short-beaked and. the long-beaked Adelaide University over the past three years honeyeaters. In a study of the feeding habits by myself, David Paton and Neville Forde. and food of these species in the sclerophyll The initial reason for my interest in honey­ forest and woodland habitats of the Mount eaters was that I was interested in the ecological Lofty Ranges, I have shown that the short­ phenomenon of interspecific competition. Inter­ beaked species feed more on insects than nectar, specific competition can be defined as the en­ and the long-beaked ones more on nectar than deavour of two or more species to consume a insects. The short-beaked species belong to the common resource which is in short supply, or, genera Meliphaga (or Lichenostomus) and if it is not in short supply, then nevertheless to Melithreptus. The Yellow-faced Honeyeater harm each other in some other way, for Meliphaga chrysops is a bird of the forests and example by aggression. This is an important neighbouring woodland, and takes a lot of in­ concept in ecology, and has been extensively in­ sects by hawking and also by gleaning from vestigated theoretically, in plants and laboratory leaves and bark, whereas the White-plumed populations of invertebrates; but the impor­ Honeyeater M. peniciUata is a bird of wood­ tance of competition in natural populations of land, especially along red-gum creeks, and feeds vertebrates is not understood well. The honey­ by gleaning from leaves and bark, and by hawk­ eaters are a particularly suitable group for the ing. The White-naped Honeyeater Melithreptus study of competition, as there are frequently lunatus, Brown-headed Honeyeater M. breviros­ many species in one habitat, and they often use tris and Black-chinned Honeyeater M. gularis a series of common resources, i.e. nectar from all take small insects from both leaves and bark, a range of flower species. In addition this re­ and appear to occupy different habitats; tall source is relatively easy to measure and manipu­ forest, scrubby forest and drier woodland, and late. savannah woodland respectively. All of these Although I was initially interested in compe­ five species will visit flowers, especially of tition, my approach has broadened consider­ Eucalyptus, when they are available. ably; and our studies in Adelaide have become On the other hand the long-beaked species more concerned with exploring the importance appear to rely largely on nectar and move, at of honeyeaters in the community, that is the least locally, in search of flowering bushes and whole assemblage of living organisms and non­ trees. The Yellow-winged Honeyeater Phyli­ living entities in their environment. In any com­ donyris novaehollandiae visits a very broad munity the green plants capture the sun's array of flowers in forest, heath and woodland. energy and convert it into chemical energy, The Crescent Honeyeater P. pyrrhoptera and which is in turn consumed by animals. Honey­ Eastern Spinebill Acanthorhynchus tenuirostris eaters consume a large amount of this energy live mostly in forest, and feed rather more selec­ in a very simple form from the plants, nectar, tively on flowers of mistletoe, heaths (Astroloma which is a solution of sugars. In return honey­ and Epacris) and Correa, as 'Well as Eucalyptus. eaters effect pollination in the plants they visit. However these three species are frequently They also consume many herbivorous insects, found in the same area feeding on the same which feed on plants, and predatory insects species of flower. The Tawny-crowned Honey­ which consume mostly herbivorous insects. As eater P. melanops inhabits more heathy open well as competing amongst themselves for these areas, and feeds on flowers of low bushes such foods, they compete with a range of insects as Adenanthos and Grevillea. The Red Wattle­ which feed on nectar and an array of insecti­ bird Anthochaera carunculata inhabits wood­ vorous birds. Honeyeaters are themselves food land more than forest and feeds principally on for predatory birds, reptiles and mammals, and Eucalyptus flowers. All of the long-beaked are parasitised by a range of micro-organisms. species take most of their insects by hawking, Thus by studying honeyeaters we can start to except for the Tawny-crowned which takes in­ fill in a few pieces of the picture of a com­ sects from low shrubs and the ground. Although munity in an Australian environment. these species spend nearly as. long feeding on 200 SOUTH AUSTRALIAN ORNITHOLOGIST, 27 insects as on nectar, we have calculated that mallee with shrubs such as Melaleuca uncinata, when they are hawking they spend far more in southern Eyre and Yorke Peninsulas, Kanga­ energy in capturing insects than they gain from roo Island and the Murray Mallee. The Yel­ them. On the other hand, they usually gain low-plumed Honeyeater M. ornata is a bird of more energy from nectar than they use. Nectar drier more open mallee, often dominated by E. is therefore the major source of energy. This is gracilis and E. oleosa with a semi-succulent or especially true in winter when demands are grassy understorey. The Singing Honeyeater M. high, and insects are small and so would pro­ virescens occurs in a range of open habitats: vide little energy. Insects are the major source coastal heath, saltbush-bluebush shrubsteppe of protein and other essentials. Neville Forde and Acacia woodland; but it also overlaps with has been collecting information on the kinds of the previous two species in mallee-heath and insects eaten by honeyeaters at different times mallee. However it usually feeds lower down of the year. than these two species, in shrubs or near the Thus the short-beaked species partition their ground. It also takes berries from plants such as environment chiefly on the basis of habitat, the native cherry Exocarpos, or the saltbushes while the long-beaked species overlap far more, Rhagodia and Enchylaena. The White-eared yet differ slightly in their preferences for differ­ Honeyeater M. leucotis proves to be the excep­ ent flowers. The short-beaked genus M eliphaga tion to the rule as it lives in a wide range of was studied in more detail to see if this pattern semi-arid habitats, and also in forest and wood­ of separation by habitat was repeated in the land on Kangaroo Island and in the South­ drier parts of South Australia. East. It differs markedly in feeding behaviour On a broader scale the Yellow-faced Honey­ from the other species, as it feeds almost en­ eater is a bird of sclerophyll forest in the South­ tirely on insects from bark, and rarely visits East, Mount Lofty Ranges and Southern Flin­ flowers. ders Ranges, and the White-plumed Honeyeater Two other species, the Yellow-fronted M. is a bird of savanna woodland, and tall trees plumula and Grey-headed Honeyeater lvI. along creeks in more arid areas. The Purple­ keartlandii, live in rocky mallee-spinifex and gaped Honeyeater M. cratitia lives almost ex­ arid woodland, but their detailed habitat -re­ clusively in mallee-heath, dense usually low quirements merit further study. The only 300 ,Ie, , \ , \ , \ I\ l(---l( PARAWIRRA I \ I / "\ + HALE :' \ , \ 0--0 MT. LOFTY , \ I X , I : I , I Figure 1. The numbers I I I , I of Yellow-faced Honey­ ~ 200 , , I I eaters seen each month Z I I , I in fifteen hours of obser­ o I I vation at Para Wirra :2 , I I I and Hale, and in six ~ I I hours of observation in 0: ,! tI the Mount Lofty area. W , I co >( , :2 II 'I :J II X' Z 100 , .. , \ , \ , \ ,, ,, I \ , \ , \ , \ : x............x ,I , , ,I , , , ~ --x _ • J FMAM J J ,A SON D SEPTEMBER, 1977 201 species of this genus on Kangaroo Island are the Mount Lofty Ranges would in time the White-eared and Purple-gaped Honeyeaters. provide very interesting information on the The former is found only in woodland, but the movements of these and other species. In the latter occurs in all habitats including forest and autumn of 1976 the arrival of Yellow-faced woodland occupied by the Yellow-faced and and White-naped Honeyeaters was more notice­ White-plumed Honeyeaters on the mainland. able than in previous years, as, they were seen in Before leaving the short-beaked species I reasonable numbers in the suburbs of Adelaide, should like to mention two species which are the far northern Mount Lofty Ranges and even apparently migratory in South Australia. The in the Murray Mallee. The most likely reason Yellow-faced and White-naped Honeyeaters for this was that the Mount Lofty Ranges were are almost absent from the Para Wirra area very dry, with little flowering except for E. (northern Mount Lofty Ranges) from October odorata on the lower slopes. Out-of-season to March, and are scarce in the Mount Lofty flowering, and a range of exotic plants in the area. (See Figs. 1 and 2.) Their numbers in­ Adelaide area, could well have been very im­ crease very markedly in April and reach a peak portant to the survival of these and other in May near Mount Lofty, and in June at Para species of honeyeaters during this time. Wirra, and fall gradually thereafter. Numbers For the rest of the talk I shall discuss the of most species of honeyeaters appear to in­ interactions between plants, the nectar they pro­ crease in autumn, partly owing to greater activ­ duce and their pollination systems, and honey­ ity by the birds; but the Yellow-faced Honey­ eaters, especially their use of nectar as a re­ eater changes almost overnight from a scarce source.