VOL. 15 (2) JUNE 1993 49

AUSTRALIAN WATCHER 1993, 15, 49-59 Seasonal Variation in the Distribution of the Noisy Philemon comiculatus and the Anthochaera carunculata in Eastern New South Wales by A.S.J. SAUNDERS, 8 Polworth Close, Elderslie, N.S.W. 2570

Summary Seasonal variations in the distribution of the Noisy Friarbird and the Red Wattlebird are compared with respect to habitat, altitude and latitude in eastern New South Wales, from data collected from March 1982 to November 1991. The habitats most frequently used by both species were open forest and woodland, with Noisy recorded more frequently in open forest and Red Wattlebirds recorded more frequently in woodland. There is some segregation by altitude and latitude. Noisy Friarbirds are generally absent on the Divide and low in numbers on the southern New South Wales coast during winter, when Red Wattlebirds can be found. This pattern for Noisy Friarbirds suggests that in these two areas they are summer breeding migrants. The pattern for Red Wattlebirds is not clear and it is likely that this species is more nomadic. The occurrence of Red Wattlebirds in lower numbers and their arrival just after the departure of Noisy Friarbirds from many localities suggest that the Noisy Friarbird is the more dominant species in most localities. In some localities where both are resident, they are segregated by altitude, with Red Wattlebirds being restricted to the higher altitudes. These two were not observed together very often. Aggression between them has been observed, and they have also have been observed foraging together without aggression at abundant nectar sources.

Introduction Competition can take place when two species exploit common resources which are in short supply, or when they exclude each other from resources even when they are not in short supply (Birch 1957 cited by Ford 1979). Competition between two species can be measured by the degree of overlap in utilised resources or niche overlap (Krebs 1978). However, this may only be true when the utilised resources are in short supply (Pianka 1976, Ford 1979) . Also, if resources are only temporarily abundant and relatively unpredictable in space and time a high niche overlap may occur and interspecific competition may be indistinguishable from intraspecific competition, e.g. territoriality (Cody 1974). Caution should be exercised in assessing the degree of competition from niche overlap, but in a comparison of two or more species, an examination of similarity is inevitable and this leads to measures of niche overlap. Measures of niche overlap between the Noisy Friarbird Philemon corniculatus and the Red Wattlebird Anthochaera carunculata are high (e.g. Ford et al. 1986). They have a large area of sympatry in New South Wales (Figure 1) and are the twb largest honeyeaters in this state. Bill length, body length and mass for the Noisy Friarbird are 39 mm, 360 mm and 107 g respectively and for the Red Wattlebird 25 mm, 360 mm and 125 g respectively (Ford et al. 1986, Longmore 1991). They are principally nectar feeders, taking nectar mainly from eucalypt blossom., but they also consume insects, particularly in summer (Ford et al. 1986; ASJS pers. obs.). Their preferred habitats are open eucalypt forests and eucalypt woodland (Pizzey & Doyle 1980, Blakers et al. 1984, Simpson & Day 1984, Longmore 1991). These similarities in size, foraging and habitats suggest that competition may occur. This is supported by frequent observations of aggression between the two species (Ford et al. 1986; ASJS pers. obs.). Where interspecific competition moulds a species' niche, the competing species are frequently different along another resource dimension (Ford & Paton 1976). High niche overlap can exist between two species, but they may reduce competition through temporal segregation, in other words by using the resources in AUSTRALIAN 50 SAUNDERS BIRD WATCHER

Figure 1. Distribution of the Noisy Friarbird and ~ Noisy Friarbird the Red Wattlebird (after Blakers et al. ~ Red Wanlebird \j 1984).

an area at different times in a diurnal or annual cyclic manner (Cody 1974). The seasonal distributions of the Noisy Friarbird and the Red Wattlebird in New South Wales are not well understood and may be very complex. They are often described as being 'migratory or nomadic' (Longmore 1991). I suggest that local and seasonal resource abundance and competition when resources are scarce affect the seasonal distribution of these two species. In this paper the following questions were asked of the data: 1. What are the more frequently used habitats for each species? 2. Is there a significant difference in habitat use between the two species? 3. Is there seasonal variation in habitats where each species was encountered? 4. Is there seasonal variation in altitudinal distribution for each species between the Great Divide and the coastal plain? 5. Is there seasonal variation in latitudinal distribution north and south of latitude 33 as · for each species within the coastal plain? 6. Do 'actual counts' show similar trends to 'percentage of visits where a species was recorded', and hence is the latter a valid method for evaluating the distribution of a species? 7. Is there a relationship between resource abundance and interspecific interactions?

Methods Data on each species were collected opportunistically from March 1982 to November 1991 inclusive. A species was recorded for each locality visited if it was positively identified by sight or call. The habitat of each locality was described according to the structural form of the vegetation (Specht et al. 1974). Date, time of day and weather conditions were also recorded. Counts for both species were done at Wallacia (33°52 'S, 150°37 'E), altitude 200m, for the years 1990 and 1991 using a fixed-width transect method. Three areas each of 3 ha were surveyed once a month, were counted for 20 minutes in each area, and all counts began at 2 ± 0.5 hours after sunrise. Conditions for each transect count were calm and sunny. The total area surveyed was 9 ha and the duration of the total count was I hour. Counts are expressed as no. of birds/9 ha/hour. The natural habitats where each species were recorded have been divided into closed fore:;t, open forest, woodland and mallee/heath (Specht et al. 1974) and all these habitats were dominated by eucalypts. Localities were also separated into the Great Divide and the coastal plain. The coastal plain is defined as the area generally below 100m a.s.l. extending from the sea to the nearest elevated land, and the Great Divide includes all adjacent plateaus and mountains to the west of the coastal plain. Data for localities west of the Great Divide were few for both species and so these data are not considered in this paper. The coastal plain is divided into two regions, north of 33 °S and south of 33 °S. As most of the observations were recorded as presence or absence, the data are expressed as percentage of monthly visits where each species was recorded. As visits were infrequent for many of the months, it was necessary to group data into seasons for analysis. As localities were not visited equally and visits were not divided equally over all seasons of the year, observed and expected frequencies are compared using a Contingency Chi-squared test C?e). VOL. 15 (2) Noisy Friarbird and Red Wattlebird, JUNE 1993 Seasonal Variation in N.S.W. 51

100

90 m=Noisy Friarbird 80 ~ = Red Wattlebird !!! 70 u; > 60 0 :g. 50 c"' fl 40

~ 30

20

10

C. F. 0. F. W. M.+ H. (n = 49) (n = 270) (n = 102) (n = 33)

Figure 2. Percentage of visits to various habitats where Noisy Friarbirds and Red Wattlebirds were recorded. (C.F. = Closed Forest, O.F. = Open Forest, W = Woodland, M + H = Mallee/Heath, n = number of visits to each habitat). Results

Frequencies in each habitat The percentage of visits where each species was recorded, in the four vegetation groups, is shown in Figure 2. Open forest and woodland show a higher percentage of records/visits than other habitats for both species. The Noisy Friarbird appears to have nearly equal frequencies for both of these vegetation types, however the preference for open forest was more significant in the analysis, i.e. observed frequencies were higher than expected frequencies for open forest when compared with the frequencies for woodland. Observed frequencies for closed forest were lower than expected, and zero for mallee/heath (X2 = 38.50, d.f. = 3, P(O.Ol). For the Red Wattlebird in woodland, the observed frequencies were significantly higher than the expected frequencies and Figure 2 shows that the highest percentage of records/visits occurs for this habitat. Observed frequencies in closed forests and mallee/heath were lower than expected and were about equal to expected frequencies for open forest (X2 = 13.36, d.f. = 3, P(O.Ol).

Differences in habitat use between species When the numbers of records for each habitat were compared between species, a significant difference was found with the mallee/heath habitat. The Noisy Friarbird was not recorded in mallee/heath and the Red Wattlebird was recorded on 4 out of 33 visits to this habitat. For closed forest there was little difference between observed and expected frequencies. Observed frequencies were higher than expected frequences in open forest for the Noisy Friarbird and higher in woodland for the Red Wattlebird (X 2 =8.29, d. f. =3, P(0.05). AUSTRALIAN 52 SAUNDERS BIRD WATCHER

Noisy Friarbird Closed Forest (n = 49) Red Wattlebird 100 100

80 80

60 60 % % 40 40

20 20

10 12 10 17 Sum. Aut. Win. Spr. Sum. Aut. Win. Spr.

Open Forest (n =270) 100 100

80 80

60 ~ 60 % ~ :'1 ::::-: % 40 40

20 « :-: 20 1~ ~5 ·~ ~~ Sum. Aut. Win. Spr. Sum. Aut. Win. Spr.

Woodland (n=102)

100 100

80 80

60 60 % 40 . :-: 40 %~~~a~~20 ':-.~: :-:~ 20 20 "•21 ~f24':R3?i Sum. Aut. Win. Spr. Sum. Aut. Win. Spr.

Figure 3. Seasonal variations in habitat distribution for Noisy Friarbird and Red Wattlebird. (Numbers at base of each season column equal the number of visits to each habitat in that season. All other symbols as for Figure 2). Seasonal variation in habitat use Seasonal variations for closed forest, open forest and woodland are compared in Figure 3. Records for mallee/heath have not been included as they were few in number. For the Noisy Friarbird the percentages of records/visits were low for winter in all three habitats but the seasonal variation is not significant Cx.Z = 0.59, d.f. = 3, P)O.lO). For the Red Wattlebird the percentages of records/visits show peaks for autumn in woodland, winter-spring in open forest and spring-summer in closed forest. There appears to be a movement from open to closed habitat from winter through to summer (X2 = 2.43, d.f. = 3, P(0.05). VOL. 15 (2) Noisy Friarbird and Red Wattlebird, JUNE 1993 Seasonal Variation in N.S.W. 53

Noisy Friarbird Divide (n = 155) Red Wattlebird

(a) 100 (c) 100

80 80

60 60 % % 40 40

20 20 40 43 IQ39} 33 Sum. Aut. Win. Spr. Sum. Aut. Win. Spr.

Coastal Plain (n = 197)

(b) 100 (d) 100

80 80

60 60 % % 40 40

20

Sum. Aut. Win. Spr. Sum. Aut. Win. Spr. Figure 4. Seasonal variations in altitude distribution for Noisy Friarbird and Red Wattlebird. (n = total number of visits to each region. Numbers at base of each season column equal the number of visits to each region within that season).

Altitude Seasonal variations between the Great Divide and the coastal plain are shown in Figure 4. On the Great Divide records for the Noisy Friarbird were lowest during winter and highest during spring. On the coastal plain they were highest during spring, but were lowest in autumn. Figures 4a and 4b do not appear to show a complementary variation of records/visits. However, when observed and expected frequencies are compared, a complementary variation in seasonal records becomes more evident. Observed frequencies for the Great Divide are higher than expected for summer and autumn and lower than expected for winter and spring. The trend for the coastal plain is the reverse of this, however it is not significant (X2 = 7.11, d. f. = 3, P(O.lO) . Only if the data are grouped as summer/autumn and winter/spring does this trend become significant (X2 = 6.86, d.f. = 1, P(O.Ol). Figures 4c and 4d show the seasonal distributions for the Red Wattlebird on the Great Divide and on the coastal plain respectively. No seasonal trend is apparent. A comparison between observed and expected frequencies for 'each season on the Great Divide indicates, in part, a similar trend to the Noisy Friarbird. The data for the coastal plain show a complementary variation of frequencies (X2 = 3.59, d.f. = 3, P(0.05). Grouping the data into summer/autumn and winter/spring reveals no significant association between these seasonal groupings and altitude (X 2 = 0.007, d. f. = 1, P)0.05). At Back Yamma State Forest near Forbes in July 1991 White Box Eucalyptus albens was flowering prolifically and counts for Noisy Friarbirds were as high as 44 birds/ha. Red Wattlebirds were also present but the maximum density recorded in the E. albens forest was 3 birds/ha (pers. obs.). A return visit in October 1991 revealed no Noisy AUSTRALIAN 54 SAUNDERS BIRD WATCHER

Noisy Friarbird North of 33' S (n = 32) Red Wattlebird

(a) 100 (c) 100

80 80

60 60 % % 40 40

20 20 ~=-2=-: i': 1 Sum. Aut. Win. Spr. Sum. Aut. Win. Spr.

South of 33°S (n=164)

(b) 100 (d) 100

80 80

60 60 % % 40 40

20

Sum. Aut. Win. Spr. Sum. Aut. Win. Spr. Figure 5. Seasonal variations in percentage of visits where species was recorded north and south of latitude 33 o S within the coastal plain of New South Wales for Noisy Friarbird and Red Wattlebird. (n = number of visits to each region; number at the bottom of each column is the number of visits to each region in that season.)

Friarbirds and only very few Red Wattlebirds. There were only a few E. albens, Grey Box E. microcarpa, and Red Ironbark E. sideroxylon in flower. At the same time Noisy Friarbirds were common on the Divide. In a comparison of the two species at the Warrumbungle National Park during January 1991, observations were made of distribution, densities and foraging. The Noisy Friarbird was found at all altitudes within the park up to 1000 m in dry open forest consisting mainly of Narrow-leaved Ironbark Eucalyptus crebra, Hill Red Gum E. dealbata, White Gum E. rosii, Rough-barked Apple Angophorajloribunda and Black Cypress Pine Callitris endlicheri. They were also found in River She-oak Allocasuarina cunninghamiana woodland along the creeks crossing the modified (mainly cleared) valley floor. Where Callitris endlicheri made up 50% or more of trees in the forest, Noisy Friarbirds were not found. It was the most common in the park and counts averaged 5.4 birds/ha/hour. The Red Wattlebird was recorded at only three localities within Warumbungle National Park; two of these were above 1000 m and the other was at 800 m. The habitat for all these localities was similar, consisting of mixed Eucalyptus/Angophora open forest. A major difference between the forest where Red Wattlebirds were found was that Red Stringybark Eucalyptus macrorhyncha made up a significant proportion of the trees (30% to 80%) in these forests, whereas it was much less common in forest where Noisy Friarbirds were found. Densities for the Red Wattlebird were not determined, as only five birds were observed within the pa~k. During three weeks of observation these species were never recorded together in this park. Their closest proximity was 100 m; however, there was also an altitude VOL. 15 (2) Noisy Friarbird and Red Wattlebird, JUNE 1993 Seasonal Variation in N.S.W. 55 difference of 100 m, with the Red Wattlebird at the higher altitude. Both species have been recorded for several seasons within the park, i.e. July 1987, October 1988 and January 1991 (pers. obs.).

Latitude The data show that the Noisy Friarbird's records/visits are lower in winter and autumn south of 33 os than for other seasons, whereas north of 33 os records/visits are highest for winter (Figures 5a and 5b). A comparison of observed with expected frequencies for winter and summer, north and south of 33 os supports this. However, there were insufficient data for a Ci'.i-squared test of significance. When the data were grouped as summer/autumn and winter/spring the results were still not significant

Transect counts Figure 6a compares actual counts for each species at Wallacia. Figure 6b indicates the percentage of monthly visits where each species was recorded at the same study site. During the years 1990 and 1991 th(.: Noisy Friarbird and the Red Wattlebird were not counted during the same month for any month. This pattern has been observed now for five years in succession. The only exception was the sighting of one Red Wattlebird in September 1989 when Noisy Friarbirds were common. Figure 6b shows some overlap for the months of May and July, but the two species were not recorded at the same time. Noisy Friarbird records in May are for early in the month whereas Red Wattlebird records are for later in the month. July records for the Noisy Friarbird were only made for unusually wet and very mild months whereas Red Wattlebirds were recorded for dry and very cold months. Similarities can be seen between Figures 6a and 6b. When densities are low or a species is absent, the percentage of visits where a species is recorded is also low. A comparison of the two figures, however, shows that presence/absence data methods do not distinguish between moderate and high densities as well as actual counts do.

Resource abundance and interspecific interactions Data on resource abundance and interspecific interactions were not quantified. However, observations suggest that there is a relationship between resource abundance and the frequency of aggression between Noisy Friarbirds and Red Wattlebirds. At Back Yamma State Forest in July 1991 nectar was abundant as greater than 70% of Eucalyptus a/hens were in heavy flower. Both species were foraging at this nectar source, often feeding as close as 0.5 m apart. No interspecific aggression was recorded between these two species during observations at this site. • Foraging in mixed flocks of both species at abundant food sources has also been observed at several other localities, e.g. New England National Park (March 1991) , Munghorn Gap (April 1990), and Araluen (October 1991). While they foraged at abundant food sources interspecific aggression between these two species was uncommon, and aggression towards much smaller species and conspecifics was far more common. In the Blue Mountains, however, no observations of foraging in mixed flocks of the two species at abundant food sources were made. Aggression between the species was observed when flowering density was very low or when both species were foraging in small areas of planted natives that supplied AUSTRALIAN 56 SAUNDERS BIRD WATCHER

20 Noisy Friarbird 18 16 ~ 14 0 .c 12 :; 10 .c 8 01 6 "E"' 4 iii 2 0 ci 8 z 6 Red Wattlebird 4 2

F M A M J A S 0 N D Figure 6a. Transect counts for Noisy Friarbird and Red Wattlebird at Wallacia, N.S.W. (Data are the means of 1990 and 1991.)

100 Noisy Friarbird

80

60 % 40

20

0

80 Red Wattlebird

60 % 40

20

0 F M A M A S 0 N D

Figure 6b. Percentage of visits where species was recorded at Wallacia, N.S.W. (Data are for each month from November 1986 to November 1991.) nectar. For the majority of encounters Noisy Friarbirds chased away Red Wattlebirds, and had a greater portion of time at the nectar sources. At some localities, however, the opposite was observed.

Discussion

Frequencies in each habitat The data support the view from the literature that Noisy Friarbirds and Red Wattlebirds are encountered more often in open forest and woodland but are rare in heath (Pyke 1988). Although each species will take nectar from other plant genera, e.g. Banksia and Angophora, they are primarily eucalypt specialists (Ford eta!. 1986). Both open forest and woodland in eastern New South Wales are dominated by eucalypt species. The density of eucalypts is probably not high enough in mallee/heath to support VOL. 15 (2) Noisy Friarbird and Red Wattlebird, JUNE 1993 Seasonal Variation in N.S.W. 57 either species in numbers. The small proportion of records/visits in closed forest cannot be accounted for in the same way. Many closed forests are dominated by eucalypts. More data are needed to explain-why open forests and woodland are preferred to closed forests.

Differences in habitat use between species The higher frequency of observations in woodland compared with open forest for the Red Wattlebird is in contrast with those observations in open forest compared with woodland for the Noisy Friarbird. Records for the Red Wattlebird in mallee/heath fit with the species' occurrence in more open habitat. Perhaps this is one of the ways in which these species minimise competition. More da!a are needed on foraging and interspecific behaviour of both species in open forest and woodland in order to compare the way each species uses these habitats.

Seasonal variation in habitat utilisation From the data there is no apparent seasonal variation in habitat preference for the Noisy Friarbird. All habitats reveal lower proportions of records for winter. A large portion of the data comes from the Great Divide and the coastal plain south of 33 os and, as will be discussed later, counts in both areas are low in winter. Hence any seasonal variation in habitat preference may be masked by winter migration for the Noisy Friarbird. The data appear to show seasonal variation in habitat preference for the Red Wattlebird. Birds appear to move from more open habitats in autumn and winter into more closed habitats in spring and summer. Many other forest species show a similar seasonal variation. The Golden Whistler Pachycephala pectoralis and the Rose Robin Petroica rosea are two species exhibiting this seasonal variation in habitat use (pers. obs.). In this study there are insufficient data to explain this trend.

Altitude The most notable feature in the seasonal distribution of the Noisy Friarbird on the Great Divide is that records/visits are lowest during winter. The Noisy Friarbird is described as a summer breeding migrant on the Great Divide (Bell 1980, Ford et al. 1985). Data from Wallacia, in the lower Blue Mountains, also provide support for this (Figure 6). It is suspected that the Noisy Friarbird moves onto the coastal plain for winter. Near Sydney, on the coast, the Noisy Friarbird is described as a possible winter migrant as it is uncommon in winter and often absent or rare in summer (Morris 1986). Blakers et al. (1984) also suggest that it moves into lower altitudes during winter. The data show significant support for movement onto the coastal plain. It has also been suggested that much of the population of the Noisy Friarbird may migrate to the west of the Great Divide (H.A. Ford pers. comm.). Observations at Back Yamma State Forest near Forbes in July 1991 support tbis. They have also been recorded in valleys and on lower slopes on the western edge 9fthe Great Divide during winter, e.g. common in July at Rylstone (Filipczyk 1988). Further investigation of other sites west of the Divide will be necessary over all seasons in order to provide sufficient evidence for this movement. The data for the Red Wattlebird show no significant variation in records/visits on the coastal plain and only small variation on the Great Divide, i.e. records/visits are low for summer. The literature does not reveal any consistent interpretation of the status of the Red Wattlebird on the Great Divide. They are described as present most of the year on the New England Tableland (Ford et al. 1985, McFarland 1985) and AUSTRALIAN 58 SAUNDERS BIRD WATCHER as winter migrants in Canberra (Bell 1980). At Wallacia they are uncommon winter migrants (Figure 6), whereas near Sydney, on the coastal plain, they are described as being a common resident species (Morris 1986). Observations at Wallacia show that both species are normally not found together. The Noisy Friarbird is a summer breeding migrant and the Red Wattlebird is a winter migrant arriving about 10-15 days after the departure of the Noisy Friarbird (pers. obs.). A similar trend has been observed at Linden in the middle Blue Mountains, except that the departure of the Noisy Friarbird and arrival of the Red Wattlebird is a little earlier (W. Sweeney pers. comm.). It appears that these species avoid each other in the Blue Mountains. Overall it appears that the Noisy Friarbird may be migratory on the Divide, spending winter on the western slopes or on the coastal plain. The lack of a consistent pattern for the Red Wattlebird on the whole of the Divide suggests that it may be more nomadic than migratory. A study of seasonal variation in densities and foraging from the coast, over the Great Divide and onto the Western Slopes is presently underway in central New South Wales and should provide more precise data for these species on altitudinal migration patterns and the reasons for these patterns. Segregation by altitude for all seasons is suggested for the Warrumbungle National Park. It appears that here these two species avoid each other. They do not appear to be migratory. Both may be breeding residents within the park.

Latitude The data suggest some seasonal variation for the Noisy Friarbird within the coastal plain. Records/visits are higher in winter and spring in the north and lower in autumn and winter in the south. No trend is apparent for Red Wattlebird records within the coastal plain. In the literature the Noisy Friarbird is described as generally absent on the far south coast in winter (Rogers & Lindsey 1978, Blakers eta!. 1984, Smith 1989). The Red Wattlebird, however, is recorded in greater concentration on the far south coast during winter and spring (Smith 1989), and is considered a winter migrant (Keast eta!. 1985). Again it appears as if the Noisy Friarbird leaves an area for warmer locations and is replaced by the Red Wattlebird, although the data in this study are not sufficient to support this trend.

Transect counts As described in the methods, information was collected opportunistically as presence or absence data, and each of the localities was not visited equally. This is not an ideal method for the collection of data on changes in seasonal densities. The method correlates well with transect counts for low to very low densities. It does not, however, distinguish very well between medium and high densities. This is to be expected as both species are readily detectable and moderate to high densities would appear similar if birds were recorded simply as present or absent at each locality. If densities are very low it is likely that the birds could be missed by both methods.

Resource abundance and interspecific interactions Interspecific aggression, appears to be low when resources are abundant. Other species feeding at these resources are often attacked and there is some conspecific aggression, but Red Wattlebirds and Noisy Friarbirds will forage together in close VOL. 15 (2) Noisy Friarbird and Red Wattlebird, JUNE 1993 Seasonal Variation in N. S. W. 59 proximity without aggression if the resource is abundant. Although the data were not quantified, observations so far support this. However, when resources are less abundant, aggression is observed and in most cases Noisy Friarbirds appear to dominate. As described earlier, for many localities in the Blue Mountains, e.g. Wallacia and Linden, these two species do not occur together but use resources within an area at different times. It may be that food resources never reach a level that can support both species simultaneously at higher densities in the Blue Mountains without resulting in significantly high levels of competition. The Noisy Friarbird and Red Wattlebird are often segregated in space and/or time, and show aggression when the species are sharing limited resources. These patterns are consistent with interspecific competition. More information is needed on the foraging and social behaviour of these two species in order to ascertain the extent of competition between them.

Acknowledgements I am grateful to Dr Hugh Ford (University of New England) and Dr Stephen Ambrose (RAOU) for their comments and suggestions on earlier drafts of this paper. Thanks are also due to Lynn Brunet for typing a draft, Warren Sweeney for his observations of these honeyeaters in the Blue Mountains, Ron Miller for the graphics and Jane Miller for proof-reading the manuscript. References Bell, H.L. (1980), 'The effects of a power-line clearing on birds of dry sclerophyll forest at Black Mountain Reserve, Australian Capital Territory', Corella 4, 8-19. Blakers, M., Davies, S.J.J.F. & Reilly, P.N. (1984), The Atlas ofAustralian Birds, Melbourne University Press, Melbourne. Cody, M.L. (1974), Competition and the Structure of Bird Communities, Princeton University Press, Princeton. Filipczyk, R. (1988), 'Winter records of the Noisy Friarbird', Cumberland Bird Observers Club News!. 10, 9. Ford, H.A. (1979), 'Interspecific competition in Australian honeyeaters: depletion of common resources', Aust. J. Ecology 4, 145-164. -- & Paton, D.C. (1976) , 'Resource partitioning and competition in honeyeaters of the genus Meliphaga', Aust. J. Ecology 1, 281-287. --,Bridges, L. & Noske, S. (1985), 'Density of birds in eucalypt woodland near Armidale, north­ eastern New South Wales', Corella 9, 78-UJ?. --, Noske, S. & Bridges, L. (1986), 'Foraging of birds in eucalypt woodland in north-eastern New South Wales', Emu 86, 168-179. Keast, A., Recher, H.F., Ford, H. & Saunders, D. (Eds) (1985), Birds ofEucalypt Forests and Woodlands, Surrey Beatty & Sons, Sydney. Krebs, J.R. (1978), 'Optimal foraging: decision rules for predators', in Krebs, J.R. & Davies, N.B. (1978), Behavioural Ecology: An Evolutionary Approach, Blackwell Scientific Publications, Oxford. Longmore, W. (1991), Honeyeaters & their Allies of , Angus & Robertson, Sydney. McFarland, D.C. (1985), 'Diurnal and seasonal changes in aggression in a honeyeater community', Corella 9, 22-25. Morris, A.K. (1986), 'The birds of Sydney Harbour National Park, New South Wales', Aust. Birds 20, 65-81. Pianka, E.R. (1976), 'Competition and niche theory', in May, R.M. (ed.) (1976), Theoretical Ecology: Principles and Applications, Blackwell Scientific Publications, Oxf~rd. Pizzey, G. & Doyle, R. (1980), A Field Guide to the , Collins, Sydney. Pyke, G.H. (1988), 'Seasonal patterns of capture rate and resource abundance for honeyeaters and Silvereyes in heathland near Sydney', Emu 88, 33-42. Rogers, A.E.F. & Lindsey, T.R. (1978), 'New South Wales bird report for 1977', Aust. Birds 13, 1-22. Simpson, K. & Day, N. (1984), The Birds of Australia, Lloyd O'Neil, Melbourne. Smith, P. (1989), 'Changes in a forest bird community during a period of fire and drought near Bega, New South Wales', Aust. J. Ecology 14, 41-54. Specht, R.L., Roe, E.M. & Boughton, V.H. (Eds) (1974), 'Conservation of major plant comunities in Australia and Papua New Guinea', Aust. J. Botany, Suppl. 7. Received 23 December 1991 •