Corella, 1995, 19(1): 2-7 DIEL TEMPORAL VOCALIZATION PATTERNS IN THE MISTLETOEBIRD ( hirundinaceum) AND SEASONAL ABUNDANCE RELATIVE TO THE FLOWERING AND FRUITING OF THE vitellina

ALLEN KEAST D<.:partmcnt of Biology. Queen's University. Kingston. Ontario K7L 3N6 Canada

Received 23 March. /993

Mistletoebirds inhabiting open eucalypt forest at Ebenezer, near Windsor, New South Wales, vocalized maximally from about 15 minutes before, until two hours after, sunrise. This contrasted with most other whose peak vocalizations were before sunrise. There was negligible singing through the day, as in other species. An annual influx of into the areas of flowering, then fruiting, mistletoe (Oendrophthoe vitellina) was documented annually in late November-early December over five summers using levels of territorial song. numbers were high during years of good mistletoe abundance and productivity, low in the poor years that followed die-off. Seasonal movements relative to the berry production cycle in mistletoe are confirmed as a major adaptation in Mistletoebirds.

INTRODUCTION clumps. These. the best group in the immediate area were seasonally the focus of attention by the hirds. Song was The study has two ohjcctives: (I) To document documented and quantified in successive 5-minutc segments. die! temporal vocalization patternsin the Mistletoe­ In the first year data gathering extended from .\0 minutes bird Dicaewn hirundinace11111; and (2) To quantify before. and continuing until 2.5 hours after. sunrise. by which time singing rates had dropped considerably. Thereafter it was the seasonal occurrence of Mistlctocbirds relative then continued in half-hourly segments through the day using to the annual flowering and fruiting cycle of the the first 10 minutes of each. Data from different days and common mistletoe De11drop/11hoe vite/lina. The seasons were related 10 sunrise as the common reference point. first part was carried out over eight 4-clayperiods After the first year. when focus was on seasonal attendance about 10 clays apart from September. 1986 to at the . monitoring of song was limited to the first two January. 1987. with an additional April ( 1988) hours after sunrise. the most productive period (sec later). elate being added to increase seasonal coverage. Quantificationof vocalization levels entailed multiplying the The second part entailed studies between October numbers of songs uttered per minute by an average length of and January over five years between 1988 and song, determined from sonograms (Keast 1993): This produced 1993. a flgun.: for numbers of seconds sound production per minute for each 5-minutc. and half-hourly. segment. The results were then plotted sequentially to give the complete song output METHODS pattern for the morning and day (Fig. 1.). The siudy site wa, a section of open eucalypt forest on To comparatively quantify vocalization levels through the I lawkcsbur\' sandstone at Ebenezer. near Windsor. New season. and to compare these from year to year for the longer South Wal;, - sec Keast ( I99.\a). Dendroph1hoe vi1e!li11a is 1nm study, the 5-minutc data sets for the two-hour post­ the dominant mistletoe species in the area. outnumbering the sunrise period were added and averaged to give a figure (with othn summer-fruiting one. A111re111a pe11d1i/a111111. by about 10 standard deviations) for sound output in numbers of seconds to one. Its major hosts are E11calrp111s gwnmifera. E. exi111a. per minute for each set of dates. The figures were then plotted E. pa11ic11/111a. Arncia parra11u111e11sis and. occasionally. linearly (Fig. 2) to bring out changes in song output through comm<.:rcial citrus. It annually produces its hrilliant red-and­ the season. Times of flowering and fruiting of Oendrophrhoe ycllow flowers in November-December. and fruits in Deccmber­ were superimposed on this. This is shown for each of the five January. years (Fig. 2).

In tkvdoping the ,ong data the procedures and methods The annual flowering and fruiting of De11droph1hoe was outlined in Keast (I99.Ja and b) were followed. I operated monitored at I 0-clay intervals (Table I. Fig. 2) over three 500 from under cover at a fixed site at the top of a small escarp­ (width, 50) m transects along a I 500 m section of dcmarked ment and adjacent 10 cucalypts that supported 4--5 mistletoe trail. To establish basic seasonal occurrence/abundance

2 March, 1995 A. Keast: Vocalization and abundance of Mistletoebird 3 MISTLETOEBIRD 1986 MORNING DAYLONG SUNRISE SUNRISE ' ... SUNSET... 30 ?O ,o O 10 20 JO ,o 50 60 10 SO 90 100 110 120 130 140 150 160 30 -2 -1 0 1 1 l L S fi 78910 11 11 1) 1', APRIL 15-21 15 1988

30 • +U. ·•• I' +•1 • 1 Q) ..... -:J ' 1986 OCTOBER 16-25 C 15 ... E '- Q) 30 ' NOVEMBER 7-14 Cf) "O 15 ... C 0 u 30 �ultLt •...... �••♦♦ .u ••• Cf) ' NOVEMBER 21-26 ... 15 C :J 30 + H, .h•+•·'- 0 1JJ1ll' •• 1lliill11 ... ,ut ·*•� ro 15 ... 0 30 UwiJ1II� ,.iu.U. .,.. 'I ++t ' JANUARY 13-19 ... 15 1 ... 98 7 L.t JO <&0 SO 60 80 90 100 I 10 120 tJO 1-40 \!)() 160 JO •10 ·10 0 10 20 10 -2 _, ) 12 13 1L 4 0 ' 2 ' ' . 1 • ' 10 II MINS. post sunrise HOURS post sunrise

Figure I . .\lomi11i:: a11d day/011g l'Ocalizatio11 pal/ems i11 the Mistletoebird. five 4-day data sets from 111id Ocrol>er. /986. 11llfil mid Ja1111ary /987. p/11, w, April /988. ser. The 11wmi11g data is hased 011 5-111i111t1e divisions a11d data is arranged relative to .rn11rise as the co111111011 poi111. The da_v/011g da/11 is based 011 ha!J-ho11rly divisions, the first ten mi1111tes l>ei11g 11sed. Means a11d stwu/ard del'iations.

pattern, of th.: Mistktoebinls numbers of birds were counted RESULTS each morning between 0800----0900 hours along the transects. The counts were part of a wider seasonal inventory of bird Basic song types and lengths species. Twelve counts (three of 25 000 m1 per day) were made for each ➔-day cluster. It was found. however. that the The songs fell into two categories: (1) pro­ high mobility of the Mistletoebirds limited the value of strip tracted, multi-syllabled ones. with durations of counts to indicating presence/absence and major numerical 2.8-3.8 seconds and; (2) short, sharp, ones about shifts in abundance - sec high standard deviations in Figure 0.6 seconds long (Keast l 993). The latter were 3. Subsequently. hence. reliance was placed on the monitoring of vocalization levels at the plants as the more appropriate commonly uttered in flight. Pizzey ( 1980) has assessor of seasonal abundance. likened the former to ·swizit-swizit, weet-weet 4 A. Keast: Vocalization and abundance of Mistletoebird Corella 19(1)

1 986 -7 1988 1986 1991 1993 SEPT OCT NOVEMBER DECEMBER JAN APR NOV21-0EC 8 23-30 16-25 7-14 21-26 2-8 14-18 26-31 13-19

C\J

0 0 0 2

0 * * * * * * * indicates significant difference between dateand preceeding date

Figure 2. r\ l'<'mge so1111d prod11c1io11 levels (wi1h sw11dard devialions) in sccond.1· per 111i11111e for 1he firs/ 111·0 hours fol/011·i11g .rn11ri.1e. spring 11nd s11111111er. five _ve11rs comp11red.

kinscy'. and ·wait-abit, wait-abit, shipp', and the The seasonal cycle of Denclrophthoe latter to 'clzee·. and 'tscw·. The longer callswere uttered by individuals at maximum rates of 4-7 Dendrophthoe vitellina began floweringin typical per minute in late November-early December. years ( 1986-89) about the third week in November, and continued for about 2.5 weeks (Table I). Berries were first harvested by the Temporal vocalizr11io11 pallerns, diet and seasonal birds about December 5-10 when three-quarters grown and still green. By late December much of Singing began about 15 minutes before, and the bulk of the berry crop had been harvested. continued at a maximum level until two hours Few berries remained by late January. after sunrise. then dropped precipitously. The birds sang only occasionally during the hotter Numbers of mistletoe plants and berry parts of the clay (Fig. I). The basic pattern also production levels were high in I 986-7 , 1987-8, characterized vocalizations in October, early and 1989-90 (Table I). A dry winter and spring November. January, and April. when few birds in 1990 killed about half of the plants in the area, were present. especially those on the smaller saplings. The year

TABLE 1

Number, L>f plants of ne11droplt1/we 1·i1el/i1111 (means and standard devi,11ions) in twelve 500 x SO 111 transects (2.'iOil() 111 2). and !lowering and fruiting dates. November 21-Dccemher 8. five summers com parcel.

Years 1986 1987 1989 199 1 199:1

MistlCtL>C plants 2.5 ± 1.9 2.2 ± 1.4 2.:1 ± 1.6 0.8 ± 0.8 0.-l ±

flowering berries shrivelled and aborted. (Subsequent rain in. early February produced greening of the �' rrnstletoc plants and their hosts but no new �. ., .. � ·:::: flowering). i Fruit resources available to Mistletoebirds in Novcmber-Dcecmbcr, 1990. were estimated to be about half, in 1993 one-quarter, of those available in 1986-88.

Abundances of Mistletoebirds, responses to rhe cycle in Dendrophthoe � (I) a. The strip counts (Fig. 3) showed that the areas en -0 supported a small resident or semi-resident popula­ C 0 tion of Mistlctocbirds (see September data). (.) (I) en These counts. and the vocalization data, confirmed that there was a major influx of birds in late -0 C November-early December when De11drophrhoe ::::, 0 started to flower. The numerical increase in en abundance suggested by the counts was a signifi­ ro 0 1 cant 7-10 fold (Mann-Whitney U Test, P ,0.05) I- : ..... over the October figures. Vocalization levels at 1 991 · ·· · --··· •····· ___ 1 the clumps of plants increased by a comparable __�---....---....•-- --•-.....�- L...- L.-_. degree (Fig. 2). The males were highly vocal in late November · ·._·.. and through the first half of December. Most of ':-+1_1_9_9_3_n_o_d _a1_a____.lli!l ..111i11_ ·..J·--■•■· ·L..··_.·.;..■ _....-. the song was uttered in the immediate vicinity of 0 _ (') ID the mistletoe clumps and whilst flying rapidly M "' 'q' � (') N N ­ � UJ Cl) Cl) Cl) Cl) a: second variety. Individuals sometimes uttered UJ Cl) � � � � � > u u u z time. When two males alighted near the same UJ u 0 0 UJ UJ UJ aw from various for late November- early December in the 'good' sources (see Ack11ow/cd[!.111e111s). year of 1986 to the increasingly depauperate ones of 199 1-92 and 1993-94, strip counts showed a statistically significant drop in numbers (Fig. 3). In its close relationship with the Vocalization levels at the plants were markedly ( and Viscaceae), whose berries less (Fig. 3). down to about 1/5 of the earlier years form its major food (Brittlebank 1908; Chandler (Fig. 2). 1912; Blakely 1922; Reid 1986, 1987), and with adaptations for berry feeding even extending to gut morphology (Salomonsen 1961), the Mistletoe­ bird is perhaps 's most interesting DISCUSSION . Seasonal influxes of Mistletoebirds Compared to most other bird species at coincident with the fruiting of mistletoes have Ebenezer (Keast I 994b) the Mistletocbird started now been documented for many areas: e.g. the to sing relatively late: the bulk of the singing arid interior (Mathews 1923-1924; McGilp 1923); being after sunrise. The reason for this is not clear eastern New South Wales (Hindwood 1936); the unless it was related to feeding times, and inter­ Pumiceton Passage area of southeasternQueensland male competition, at the plants. The main functions (Liddy 1982), and Adelaide region (Reid 1983). of song in birds are territorial probing and Liddy provides by far the most comprehensive defence. and courtship and pair maintenance account: his nettings of birds increased 10-60 (Howard I 920; Marler and Peters 1980; McDonald times over those of the small resident population in July-November when the mistletoe 1991). No data were developed on which was the cambagei more important here. Territorial association with fruited. the mistletoe plants was, however, marked. This paper confirms that seasonal movements Whether or not the birds defended these plants in association with the annual cycle of dominant was not studied. Note that whilst many bird mistletoes are a major adaptation in the Mistletoe­ species '·defend" nectar sources few defend fruit bird. sources (Snow 1966; Snow and Snow 1984, 1986). This aspect merits examination. ACKNOWLEDGMENTS Although little evidence of breeding was found The present study was carried out when the writer was the the time of arrival of the birds was several weeks holder of a Canadian National Science and Engineering in advance of the documented breeding season Research Council Award and I would like to thank this body for its support. Breeding (clutch initiation date) data on the near Sydney (Fig. 4 ). On this basis the high late Mistlctoebird in the Sydney area was kindly supplied by the November-early December vocalization levels following colleagues: N. W. Chaffer. R. P. Cooper. K. A. could have had a courtship role. Alternatively, if 1-lindwood. S. G. Lane. J. Rhodes, and E. Woods. Sincere the birds were ultimately to breed only in thanks are also expressed to these workers. January, the song activity could have beenlargely territorial in nature. (Note that the bulk of REFERENCES Sydney breeding records given here are from the Cumberland plain (suburbs of Doonside, Black­ Blakely, W. F. (1922). The Loranthaceae of Australia I. Proc. town, St. Marys) where, before the clearing for Linn. Soc. NSW 47: 1-25. Brittlebank, C. C. (1908). The life-history of Loramhus housing in the 1960's. large numbers of birds con­ exocarpi Behr. Proc. Linn. Soc. NSW 33: 650-{556. centrated annually on the berries of Amyema Chandler. l.. G. (1912). Notes on theMistlctoebird (Dicaewn gaudichaudi on the paperbarks () hirundinaceum). Emu 12: 1-30. (Keast 1958).) 1-lindwood, J. A. (1936). Mistletocbird. Emu 35: 361-362. March. 1995 A. Keast: Vocalization and abundance of Mislletoebird 7

Howard. E. ( 1920). ·Territory in Bird Life.· (Murray: Mathews. G. M. (1923-24). •Bird, of Australia.' Vol. [I. London.) (Witherby: London.) Kea,t. A. ( 1958). The influence of ecology on variation in the Pizzey. G. ( I 980). · A field guide to the .' Mistktoebird ( Vicaeu111 hir111uli11ace11111). £11111 58: 195-206. (Princeton Univ. Press: Princeton.) K.:ast. A. ( 1993). Song structures and characteristics. mernbcrs R,;id. N. (1983). Seasonal occurrence of the Mistleto<.:hird in of a eucalypt fore,t bird community compared. £11111 93: the inner north-eastern suburbs of Adelaide. Sowh l111str. 2.'i9-267. Ornith. 29: 6(J-63. Kea,t. A. ( 199-la). Diel temporal vocalization pal!erns in Reid. N. (1986). Pollination and seed dispersal of mistletm:s members of a cucalypt forc,t bird community. with an (Lomnthaceae) by birds in southern Australia. In ·The analy,i, of the dfccts of weather on song production. £11111 Dynamic Partnership. Birds and Plants in Southern Aust­ 94: in press. ralia' (Eds H. A. Ford and D. C. Paton.) pp. (-.-1-.'W . (Govt. Keast. A. (199-lb). The dawn choru, in a cucalypt forest bird Printer: South Australia.) community. seasonal shifts in timing and contribution of R<.:id. N. (1987). The Mistletocbird and Australian mistletoes: individual ,pecies. Corella 18: 133-140. coevolution or coinciclence? £11111 87: 130-131. Liddy. J. ( 1982). Food of the Mistletocbird near Pumicestone Salomonsen. F. (1961). Notes on llowerpeckers (Aves, Pa»aj!e. south-eastern . Corella 6: 11-15. Dicacidae). Amer. M11.r. Novitat. 2057: 1-35. McDon;ld. M. V. ( 1991 ). Experimental manipulation of sing­ Snow, D. W. (1966). /\ possible selection factor in the ing rate and its effect on conspecifics. In 'Proc. XX Intern. evolution of fruiting seasons in tropical forests. Oikos 15: Ornith.Congr. 1990. Christchurch'. (Eds B. D. Bell et al.) 274-281. pp. 12-15- 125 I. (New Zealand Ornithological Trust Board: Snow. B. K. and Snow. D. W. (1984). Long-term defence of Wellington.) fruit by Mistie Thrushes, T11rd11s viscivoms. Ibis 226: 39-49. McGilp. J. N. (1923). Bird, of Lake Frome district. South Snow. D. W. anti Snow. B. K. (1986). Some aspects of avian Australia 11. E11111 22: 274--287. frugivory in a North Temperate areas relevant to tropical Marler. P. and Peters. S. (1980). Bird song and speech: forest. In · and Seed Dispersal.' (fab E. Estrada evidence for ,pecial processing. In ·Perspectives in the and T. H. Fleming. ) pp. 159-164. (Junk: Dordrecht.) Study of Speech.· (Eds P. Einasi and J. Miller.) pp. 75-93. White, S. A. (1923-24). Quoted by Mathew,, G. M. I3ird, of (Erlbaum: Hillsdale. New Jersey.) Australia 11. p. 76.

Corella, 1995, 19(1): 7-11 TEMPORAL AND SPATIAL VARIATIONS IN DENSITY OF LANDBIRDS AT AN URBAN BUSHLAND RESERVE K. A. WOOD 7 Eastern Avenue, Mangerton, NSW 2500

Received 2 July. 1993

INTRODUCTION 1983) to a long rectang�la_r transect of _58 ha (Collins el al. 1985). Within each plot, 1t was Densities of landbirds have been estimated in implied (or assumed) that the habitat was hcathlands (Pyke 1983), woodlands (Ford and homogeneous. Bell 1981; Ford et al. 1985; Gilmore 1985; Keast 1985; Wonarski 1985; Arnold et al. 1987) and Comparisons in bird density can be made forests throughout Australia (Recher el al. 1971; between similar habitats in different places Bell 1980; Loyn l 980; Shields and Recher 1984; and between different habitats. But for these Wardell-Johnson 1984; Collins el al. 1985; comparisons to be meaningful, variations in Kavanagh et al. 1985 ; Pyke 1985; Shields et al. density which occur with month. of year and 111 1985). To perform these estimates, standard particular pockets of the habitat should be procedures were adopted (Pyke and Recher 1984; considered. The aim of the present study was to Bell and Ferrier 1985) and the surveyed plots quantify these variation� in an urban reserve with varied in size from a circular area of0.13 ha (Pyke a mosaic of different m1crohab1tats.