Do Pallid Cuckoo in southern Tasmania regulate the numbers of Black-headed Honeyeaters, a preferred host species?

Mike Newman 72 Axiom Way, Acton Park 7170 [email protected]

Abstract preferred host in my study area, using the results of six Birdata surveys in an area of south-east Tasmania were years of Birdata monitoring using standardised survey used to assess the status of the Pallid Cuckoo, Heteroscenes methods. Pallid Cuckoos prefer open-cupped nests, pallidus, and the Black-headed Honeyeater, Melithreptus often parasitising honeyeaters: Black-headed and affinis, a preferred host, between 2014 and 2019. Pallid Strong-billed Honeyeaters, M. validirostris, are known Cuckoos were abundant in lightly developed areas of hosts in Tasmania (Higgins 1999). However, the latter dry woodland and avoided areas dominated by Noisy species is absent from the South Arm peninsula. Miner, Manorina melanocephala. The breeding season Home ranges for Pallid Cuckoos appear to vary population of territorial males at the location of highest between regions. In a previous paper (Newman 2019), I occupancy was estimated to be 3.4/km2 between 2014 speculated that the breeding season home ranges might and 2017, before falling to 1.7/km2 in 2018 and 2019. be larger in the Hunter, possibly of square kilometre Both Pallid Cuckoos and Black-headed Honeyeaters magnitude, than in south-east Tasmania. In contrast, decreased during the six-year period. These decreases Kennerley et al. (2019) suggested that, in near coastal may have been caused by drought. However, it is also south-east Queensland, the breeding season home range possible that continual parasitism by Pallid Cuckoos of female Pallid Cuckoos might be as small 3–5 ha with resulted in decreased breeding success for the honey- males having territories of at least 25 ha. This paper eaters, ultimately resulting in part of the Pallid Cuckoo seeks reasons for the discrepancies in these estimates of population deserting their territories in 2018 and 2019. Cuckoo home ranges. Additionally, it places on record Some new aspects of the breeding season behaviour novel observations of new courtship display by a pair of of Pallid Cuckoos are presented, including a raptor-like Pallid Cuckoos. courtship display. Methods Introducon Observations of Pallid Cuckoo and Black-headed Honey- Kennerley et al. (2019) have highlighted the lack of eater were made while conducting Birdata surveys in information concerning the natural history of the Pallid south-east Tasmania in an area extending approxi- Cuckoo, a brood parasite, and the need for increased mately 25 km south from Stringybark Gully in the research into its breeding behaviour. Meehan Range to the end of the South Arm peninsula Because one female cuckoo can affect many host (figure 1, page 00). breeding attempts, cuckoos clearly have the potential to The results presented below (pages 00–00) are based impact adversely the breeding productivity of host predominantly on standard Birdata 2-ha surveys, which species, at least locally (Newton 2013). For instance, in record all birds seen and heard within a 2-ha area an extreme case (Bayliss 1988), one female Common during a period of 20 minutes. These surveys provide Cuckoo, Cuculus canorus, parasitised in one season the more reliable information for determining temporal nests of 24 different female Reed Warblers, Acrocephalus trends than Birdata 500-m and 5-km area searches scirpaceus, one twice. To investigate this possibility, I because the area and duration of the survey are fixed. examined the relationship between the occurrence of The results of the less standardised 500-m were used to Pallid Cuckoos and Black-headed Honeyeaters, the corroborate the results of the 2-ha surveys. Article In Press, Tasmanian Bird Report 41 (2021), final pagination to be advised 1 Figure 1: Distribuon of 2 ha survey sites in study area in south-east Tasmania near Hobart.

Article In Press, Tasmanian Bird Report 41 (2021), final pagination to be advised 2 Surveys were conducted in the morning, mostly Cohen 1986). between one and three hours after sunrise, when the Territory sizes were calculated based on the birds were active. Although other observers contributed assumption that 2-ha records of Pallid Cuckoos relate to to the dataset, all of the surveys at the 20 most inten- an area of 5 ha because of the difficulty of estimating sively surveyed sites were made by the author, thus the position of calling birds in relation to the notional providing a consistent approach. boundaries of the 2-ha survey site. It is also assumed The initial analysis considered all available Birdata 2- that the detection rate of male cuckoos will be very high ha survey data for the period 1/7/2014 to 1/3/2020. because they call extremely frequently early in the With one exception, all the Pallid Cuckoo records in the morning when the surveys were conducted (Keast study area (including those by other observers) occurred 1985). The estimated population densities and territory in the months September to January, with the earliest sizes in this report are proportional to the assumed area arrival on 2 September. Consequently, annual breeding in which cuckoos were detected (5 ha) and the detection season occurrence was assessed for those months in rate (100%). order to minimise any bias associated with variations in survey effort in other months. Breeding seasons are Results identified by the year in which the cuckoos arrived (e.g. For both the Pallid Cuckoo and Black-headed 2014 refers to the 2014–15 breeding season). Honeyeater, the breeding season statistics from 2-ha and A subset of 20 survey sites, involving three locations 500-m Birdata surveys for the six-year period 2014–19 within the study area (figure 1), were monitored once in are summarised in table 1 (page 00). The Black-headed most months over six successive breeding seasons Honeyeater was the only brood host identified during between 2014 and 2019 (i.e. c.30 breeding season the study (three instances). surveys per site). The results from these sites provide There were 161 breeding-season records (September– much of the analysis presented below. These sites were December) of Pallid Cuckoo in 933 Birdata 2-ha grouped as follows: surveys: a reporting rate (RR) of 17.3%. Pallid Cuckoo 1. Meehan (42.840°S, 147.401°E) — six sites in dry occurred at 25 of the 50 sites at which surveys were sclerophyll woodland located on 3.5 km of track in conducted. However, some of the sites received the vicinity of Belbins Creek, including one site on insufficient survey effort to conclude that the species was the escarpment above Stringybark Gully within the absent. There was evidence of a 53% decrease in Meehan Range. annual RR over the six years. However, this decrease 2. Acton (42.855°S, 147.487°E) — two sites on the may have been exaggerated by increased survey effort in Tangara Trail surrounded by small acreage the latter years of this study at sites that were less properties with some retained native vegetation. suitable to Pallid Cuckoo. Consequently, it was decided 3. South Arm (43.006°S, 147.479°E) — 12 sites on the that the detailed temporal analysis presented here would South Arm peninsula, mainly in dry woodland with only consider the 20 survey sites that had been surveyed limited understorey vegetation. Most of the sites consistently at three locations where Pallid Cuckoo were located in roadside vegetation along a 100 m occurred regularly (South Arm, Acton and Meehan) high ridge extending 14 km north from the southern and where surveys had been conducted in all six end of Gellibrand Drive to another ridge on Dixon breeding seasons. At Acton the sites were surveyed more Point Road. The woodland is more continuous than frequently in some years. There were 633 surveys at at the Acton sites. these three locations (i.e. 69% of all 2-ha surveys for the An additional two sites at Acton, in a more extensively area shown in figure 1). cleared area edging open paddocks, were surveyed The Birdata 500-m surveys (343 surveys at 33 sites) intensively by the author for four years. increased the spatial sampling of the study area and The 2-ha survey sites at Meehan, Acton and South provided an independent measure to the 2-ha surveys. Arm were located 500 m or more apart. This is a Pallid Cuckoo were recorded at 42% of these sites. The standard Birdata protocol designed to prevent birds results were superficially similar with evidence of a 20% being recorded at more than one site on the same day. decrease in breeding season RR towards the end of the Newman (2018) provides habitat descriptions for six years. However, this decrease was not statistically survey sites typical of the three locations. significant (χ² = 1.38, p = 0.24). A detailed analysis of Reporting rate (RR), the ratio of the number of the 500-m survey results was not conducted because records to the number of surveys expressed as a percent there were fewer observations and the results would value, was used to assess variations in the annual have been less reliable. Only three sites were surveyed breeding season and monthly occurrence. monthly in all six years. The Chi-square test χ2 was used to determine the Comparison of locations statistical significance of differences in RRs between The 2-ha survey RRs for the Pallid Cuckoo and Black- several periods of pooled years (e.g. 2014–17) using headed Honeyeater are compared for the three Yates’ correction for 1 degree of freedom (Fowler and locations in the figure 2 scatter diagram (page 00). Article In Press, Tasmanian Bird Report 41 (2021), final pagination to be advised 3 Table 1: Breeding season stascs for the Pallid Cuckoo and Black-headed Honeyeater in an area in south-east Tasmania near Hobart for the period 2014–19. The Reporng Rate (RR) is the proporon of surveys, expressed as a percentage, in which a species was recorded. South Arm Acton Meehan All 2-ha sites All 500-m sites 2-ha sites 2-ha sites 2-ha sites Pallid Cuckoo (RR%) 17.3 29.9 24.3 7.1 38.19 Black-headed Honeyeater (RR%) 8.5 13.4 0.0 11.8 10.5 Number of sites 50 12 2 6 33 Number of surveys 933 381 111 169 343

Figure 2: Comparison of the occurrence (as RR%) of Pallid Cuckoo and Black-headed Honeyeater at three locaons (Meehan Range 6 sites, Acton 4 sites, South Arm 12 sites, which include Dixon Point and Paroa survey sites).

Figure 3: Variaon in the breeding season (September to January) Reporng Rates of Pallid Cuckoo at three locaons in south- east Tasmania between 2014 and 2019 (Birdata 2-ha 20 min surveys; South Arm 381 surveys at 12 sites; Acton 111 surveys at 2 sites; Meehan 169 surveys at 6 sites). There were no Pallid Cuckoo records at Acton in 2018. Article In Press, Tasmanian Bird Report 41 (2021), final pagination to be advised 4 1. Meehan — Pallid Cuckoo RRs were relatively low Black-headed Honeyeater Reporting Rates at all six sites and Black-headed Honeyeaters The annual breeding season RRs of the Pallid Cuckoo occurred more frequently at sites where Pallid and Black-headed Honeyeater, the only brood host Cuckoos were absent. identified in this study, are compared in figures 3 and 5 2. Acton — Pallid Cuckoo RRs were relatively high (page 00) respectively for South Arm survey sites. In and Black-headed Honeyeaters were absent. At an contrast to the Pallid Cuckoo, which showed a step additional two sites that were monitored for four change decrease in RR during the 2017 and 2018 years both species were absent. seasons, the Black-headed Honeyeater decreased 3. South Arm — The eight sites at South Arm were relatively continuously by 44% from its 2014 level with a differentiated from the Meehan sites by high Pallid near significant linear regression (p = 0.06). Cuckoo RRs (>20%) but similar Black-headed Host species — field observations Honey-eater RRs to the Meehan sites. These sites Three instances of Pallid Cuckoos breeding were were located in an area of approximately 4 km by 1 recorded, all involving fledged juveniles being fed by km in size. The two sites at the extremity of this area Black-headed Honeyeater at separate 2-ha survey sites were at slightly lower altitude and had more along Gellibrand Drive on the South Arm peninsula. In understorey vegetation. The other two sites, Paroa the first instance on 3 December 2015 a family of and Dixon Point, which were located further north, Black-headed Honeyeaters were almost constantly had higher Black-headed Honeyeater RRs than the feeding a well-developed fledgling that was calling South Arm sites (figure 2). incessantly, except when being fed. The second instance, There were differences in the monthly occurrence of on 2 January 2017, involved a fledged juvenile that flew Pallid Cuckoos between the years of high RR (2014–17) to the ground to forage on two occasions. Although the and lower RR (2018–19). The South Arm surveys were bird was not begging, an adult Black-headed Honey- used to demonstrate this effect (figure 3, page 00) eater flew down and fed it. The third instance, on 10 because they provided a large data set (12 survey sites) January 2018, again involved Black-headed Honey- with minimal bias in survey effort between months, sites eaters and a New Holland Honeyeater, Phylidonyris and years. The effect was also apparent in the 2-ha novaehollandiae, attempting to feed a fledged juvenile survey set for the study area (data not shown). During Pallid Cuckoo, which was not begging and seemed the initial four-year period RRs were high from disinterested in the attempts to feed it. September to December before falling in January (figure Courtship display 4, page 00). There were no records outside this period. On the 12th of September 2019 at about 9.45 in the In contrast, during the subsequent two years, RRs morning, a Pallid Cuckoo flew, calling loudly, from the peaked in October at a level slightly exceeding monthly vicinity of Musks Road on the South Arm peninsula rates in the previous four years, but were considerably across lightly timbered paddocks and disappeared across lower in all other months. Hence, some of the Pallid the South Arm road at least 300 m away. It sub- Cuckoos appeared to have a transitory presence, sequently returned to the area and was seen in the arriving later and leaving earlier than in the period company of a second Pallid Cuckoo flying above Musks between 2014 and 2017. Road. Two distinct types of synchronised display flight Population density were observed. Initially, the two cuckoos flew side by At South Arm the average breeding season RR (2-ha side towards me along Musks Road continually uttering surveys) for the months September to December was a combination of calls, including the scale and harsh 37.6% for the period from 2014 to 2017. This equates call (Kennerley 2019) as well as a variety of different to a male territory size of 13.3 ha, assuming that the types of single note calls. At one stage the pair records actually relate to an area of 5 ha (see Methods), performed a display flight above the road at near tree- and a population density of 7.5 territories/km2. On this top height in which they climbed side by side and then basis there could be as many as 30 territorial males in dropped together on closed wings in a raptor-like stall the 4 km2 of continuous woodland in which eight of the before repeating the sequence. An aerial chase followed, 2-ha sites were located, assuming that the 2-ha sites with the pair weaving rapidly through the tops of the were representative of the area, and that Pallid Cuckoos trees in a eucalypt plantation. They finally settled in were evenly distributed throughout the woodland. separate trees and duetted. In 2018 and 2019 the average RR was 17.2%, excluding the peak RR in October. Assuming that this Discussion underlying RR is the measure of the number of males Habitat factors that permanently occupied territories, the nominal When the RRs for Pallid Cuckoos and Black-headed population density had decreased by roughly 50% to 3.4 Honeyeaters are compared in a scatter plot (figure 2), territories/km2 or 17 territorial birds in the 4 km2 the results at individual survey sites for the three woodland patch. locations fall into three distinct clusters. Article In Press, Tasmanian Bird Report 41 (2021), final pagination to be advised 5 Figure 4: Monthly breeding season RRs for the four years (2014–17) compared with the years 2018–19. (Pooled results from 12 Birdata 2-ha sites at South Arm; nominal number of surveys/month; 48 for 2014–17 and 24 for 2018–19).

Figure 5: Variaon in breeding season Reporng Rate of Black-headed Honeyeater at 12 surveys sites on the South Arm Peninsula (n = the number of Birdata 2-ha surveys).

Article In Press, Tasmanian Bird Report 41 (2021), final pagination to be advised 6 At Meehan the riparian understorey vegetation maintaining breeding territories throughout the appears to make the area unsuitable for Pallid Cuckoos breeding season had indeed decreased as suggested by with only occasional records in the more open sites at the decrease in the annual RRs. The influx of Pallid the extremities of the area surveyed. This is consistent Cuckoos in October into the South Arm area in 2018 with the known preference of Pallid Cuckoos for open and 2019 may reflect the movement of a roving heterogenous landscapes and forested margins (Higgins population of cuckoos without viable breeding 1999). Black-headed Honeyeaters were more regularly territories. These birds may be birds displaced from recorded at sites where Pallid Cuckoos were absent. their normal breeding range in inland Australia by Ten of the South Arm survey sites had similar Black- drought conditions, which have moved to coastal areas, headed Honeyeater RRs (3 to 14%) to the three including Tasmania (Newman 2019; Kennerley et al. Meehan sites where Pallid Cuckoos were present. At 2019). eight of these sites the Pallid Cuckoo RRs were The availability of hosts may be a key factor attracting appreciably higher (21–59%) than at the Meehan sites. Pallid Cuckoos to the study area. Black-headed The two South Arm sites with low Pallid Cuckoo RRs, Honeyeaters, which appear to be the preferred host in similar to those at Meehan, were at the extremities of the study area (see next section), decreased during the area in which the eight sites discussed above were between 2014 and 2019 (figure 5). Hence, the decrease grouped. These sites were in less continuous woodland in Pallid Cuckoos at South Arm may at least in part and had denser understorey vegetation, which again reflect a local situation associated with the decreased emphasises the relationships between vegetation availability of brood hosts, as opposed to a regional structure and the occurrence of Pallid Cuckoos. The decrease of cuckoos (i.e. the cuckoo is strategically other two South Arm sites, Paroa and Dixon Point, had altering its regional distribution). However, cuckoos are higher Black-headed Honeyeater RRs: the habitat at also thought to adopt such strategies to prevent host both these sites, woodland with minimal understorey species becoming sensitised to their presence and vegetation, was superficially similar to the South Arm developing counter measures (e.g. detection of cuckoo sites. These sites were located to the north of the other eggs and abandoning breeding) that decrease the sites, with the Dixon Point site on an undeveloped ridge- cuckoo’s breeding success (Davies 2015). top woodland. It is possible that there is limited At the Acton survey sites, Pallid Cuckoos were not movement between these sites and the other ten sites, recorded in 2018 and 2019 (figure 3). These sites may which may form a discrete community. only support a very small number of Pallid Cuckoos Black-headed Honeyeaters were absent from the because the surrounding area is dominated by Noisy highly modified landscape at Acton where colonies of Miners (Newman 2018), which alienate potential hosts Noisy Miners were the dominant species. Pallid of Pallid Cuckoos. Black-headed Honeyeaters were not Cuckoos were only recorded from survey sites where a recorded at any of the Acton survey sites. There were combination of a continuous tree canopy and no Pallid Cuckoo records in the surrounding area at the understorey vegetation was sufficient to limit the other two 2-ha sites, which were totally dominated by presence of Noisy Miners and provide shelter for a Noisy Miners, even though cuckoos were occasionally number of smaller species providing potential hosts for heard in the distance. the cuckoos (Newman 2019). No host species were The main difference between the riparian sites at identified, but it is assumed that species other than Meehan and the drier woodland of the more open Black-headed Honeyeater were brood hosts at Acton. South Arm was the presence of understorey vegetation. Breeding season Reporting Rates Four of the Meehan survey sites were in riparian creek- The decrease in the breeding season RRs of Pallid line vegetation where Pallid Cuckoos were seldom Cuckoos at the South Arm survey sites in 2018 and recorded, with most of the records occurring at the sites 2019 (figure 3) coincided with a change in the profile of with more open habitat at the extremities of that study the species’ monthly occurrence (figure 4). Assuming site. At Meehan, Black-headed Honeyeaters had higher that high RRs reflect the abundance of Pallid Cuckoos, RRs than Pallid Cuckoos, further highlighting the it appears that the species was numerous throughout the difference in the suitability of the two sites. spring and early summer months, September through Impact on host species December, during the initial four years of the study. Pallid Cuckoos usually select insectivorous hosts, mostly Records in January probably reflect the presence of honeyeaters, that build open cup-shaped nests (Higgins fledged juveniles and possibly some adults that may stay 1999). The three instances of breeding interactions to help nurture fledged juveniles (Kikkawa and Dwyer directly observed in this study all involved Black-headed 1962). In contrast, when the annual breeding season Honeyeaters, a known host, feeding fledged Pallid RRs at South Arm decreased in 2018 and 2019, Pallid Cuckoos. However, species other than the host often Cuckoos were predominantly recorded in October, feed fledged cuckoos (Higgins 1999) and in one instance suggesting that there was a temporary influx of Pallid a New Holland Honeyeater was also involved. In other Cuckoos at that time and that the number of adults recent reports of fledged Pallid Cuckoos being fed in Article In Press, Tasmanian Bird Report 41 (2021), final pagination to be advised 7 south-east Tasmania (Hansson 2015 and 2016), Black- territories overlap (i.e. more than one territorial male headed Honeyeaters were again involved, although in cuckoo was present) the present estimates may be one instance four additional species participated. comparable to those of Kennerley et al. In the At South Arm, annual breeding season RRs of the subsequent two years, 2018 and 2019, the South Arm Black-headed Honeyeater were lower than those of the population density had decreased to 3.4 territories/km2, Pallid Cuckoo (figure 5). However, this may be a which was at the lower limit of previous estimates. consequence of the ease with which male cuckoos are In the above analysis it was assumed that most records detected when advertising territories, rather than an are of male cuckoos and that females were seldom actual difference in abundance of family groups of the detected. Kennerley et al. (2019) estimated the minimum host species. In addition, the 2-ha survey method, which home ranges of females in south-east Queensland to be was used extensively in this study, was not ideal because in the range 3 to 5 ha. On the expectation that a female Pallid Cuckoos were mostly detected when males cuckoo may seek to parasitise as many as 20 or more advertised their presence. Kennerley et al. (2014) suggest host nests in a breeding season, based on the well- that their scale call may be audible over distances of at studied Common Cuckoo (Davies 2015, Williams 2016, least 1 km. Hence, it was necessary to judge whether Bayliss 1988), territories of this magnitude do not unseen Cuckoos were calling from within the boundary appear plausible. For instance, host-specific females of the 2-ha survey site. With hindsight it is probable that targeting Black-headed Honeyeaters, the only records reflect an area slightly in excess of 2-ha (i.e. commonly recorded host in the study area, must find there was a consistent bias to over-reporting Pallid multiple nests of a species that was typically present at Cuckoos). RRs less than half that of the cuckoo (table 1). Two factors may have contributed to the decrease in However, it may be courageous to draw parallels with Black-headed Honeyeaters. For instance, the breeding the south-east Queensland study, which involved Pallid success of the host species may have been adversely Cuckoos apparently displaced from inland areas by affected by a sustained period of parasitism. However, drought conditions, and inhabiting a pocket of near- south-east Tasmania experienced a period of prolonged coastal habitat where the species is only intermittently drought with rainfall only exceeding the long-term recorded. In contrast, the Pallid Cuckoo is a regular average in one of the six years of this study. This may visitor to south-east Tasmania, although there is have affected food availability, potentially resulting in evidence that the local population may have increased increased mortality and low breeding success in the host following the displacement of cuckoos from the inland population. areas of the Australian mainland (Newman 2019). Territory size and population densities Kennerley et al. (2019) suggest that future studies to Kennerley et al. (2019) discuss the complex issues resolve the above issues should involve telemetry. associated with determining the territory sizes of Pallid However, in the short-term, synchronised observations Cuckoos associated with underlying lack of knowledge by an array of observers could partially resolve how of natural history. For instance, the home range of one many territorial Pallid Cuckoos inhabit an extended male may overlap the home ranges of multiple females. area of woodland such as the South Arm study area. They also highlight the fact that Pallid Cuckoos lay eggs Courtship displays that mimic those of common hosts, suggesting the Instances of Pallid Cuckoos indulging in chases at the presence host-specific races, or gentes (Starling et al.). beginning of the breeding season are well known Hence, the concept of fixed territories may be (Higgins 1999). However, the flight display reported in misleading: a local population may involve a number of this study does not appear to have been described overlapping male and female territories in which the previously. Many raptor species perform similar displays males regularly advertise their presence to attract (Debus 1998) and the similarities between the flight females and females furtively seek the nests of host profiles of cuckoos and raptors are well known (e.g. species (Davies 2015). Davies 2015). While RRs can be used to monitor changes in the status of a species, the ultimate goal of bird monitoring Conclusions is to measure population densities and hence population This study, in accord with the work of others, highlights sizes. The estimated density of 7.5 territories/km2 for the paucity of knowledge concerning the natural history the South Arm sites is comparable to the levels of the 8 of the Pallid Cuckoo and the intricacies of its and 11 territories/km2 found by Lyon (1985) in relationships with its host species. Victoria, but lower than the 25 birds/km2 estimated by The extent to which Pallid Cuckoos contributed to the Baldwin (1975) in the Inverell district of NSW. The observed decrease in Black-headed Honeyeaters on the estimated territory size at South Arm was 13.3 ha, South Arm peninsula is unclear because interpretation which was lower than the minimum estimate of 25 ha of the results is confounded by a period of extended found by Kennerley et al. (2019) in near coastal south- drought that may have caused or contributed to the east Queensland. However, if, as discussed above, the observed population decrease. Conversely, it is unclear Article In Press, Tasmanian Bird Report 41 (2021), final pagination to be advised 8 whether the decreased occurrence of Pallid Cuckoos Hansson, V. 2015. ‘Observations of a Pallid Cuckoo towards the end of the study period is related to (Cacomanthis pallidus) raised by dual species (Scarlet Robin decreases in Black-headed Honeyeater numbers or a Petroica mulitcolor and Black-headed Honeyeater Meliphretus affinis)’. The Tasmanian Naturalist. 137: 57–59. ‘tactical decision’ to avoid habituating the host to the — 2016. ‘Multiple species feeding of a Pallid Cuckoo presence of cuckoos. Ongoing monitoring is required to (Cacmanthis pallidus)’. The Tasmanian Naturalist. 138: 48–50. provide insight into these questions. Higgins, P. J. (Ed.) 1999. Handbook of Australian, New Surrogate measures of the relative abundance of Zealand and Antarctic Birds. Volume 4: Parrots to Boatbill. species such as RRs need to be calibrated by species- Oxford University Press: Melbourne. specific field studies in order to determine reliable Keast, A. 1985. ‘Springtime song, periodicity, and sequencing: A comparison of a southern forest and northern woodland measures of territory size and population density. The bird community. Birds of Eucalypt Forests and Woodlands: crude estimates of Pallid Cuckoo population density Ecology, Conservation and Management. Pages 119–28. Eds. A. that are provided above need to be refined by Keast, H.F. Recher, H. Ford and D. Saunders. Surry Beatty conducting a cuckoo population census with an array of & Sons in association with the Royal Australasian observers deployed during the breeding season in the Ornithologists Union: Chipping Norton, NSW. regularly monitored area of South Arm. Kennerley, J. A., Grundler, M.R., Richardson, N.M., Marsh, M., Grayum, J. and Feeney, W.F. 2019. ‘Observations on the behaviour and ecology of the Pallid Cuckoo Heteroscenes Acknowledgments pallidus in south-eastern Queensland’. Australian Field Sue Jones reviewed this paper, making a number of Ornithology. 36: 109–15. comments, sometimes challenging, which have Kikkawa, J. and Dwyer, P.D. 1962. ‘Who feeds the fledged Pallid Cuckoo?’ Emu. 62: 169–71. improved the presentation and explanation of results. Lyon, R.H. 1980. ‘Bird populations in a mixed eucalypt forest Her shared enthusiasm for the natural history of used for production of wood in Gippsland, Victoria’. Emu. cuckoos was stimulating. Barry Baker provided valuable 80: 145–56. feedback on the population density estimates and Eric Newman, M. 2015. ‘Retention of native vegetation provides Woehler assisted with the trend analysis. Their support valuable habitat in acreage developments’. Tasmanian Bird is appreciated. Report 37: 12–19. Newman, M. 2018. ‘Comparison of bird populations at This paper was prepared to further the involvement Acton Park with surrounding woodland areas in south-east of the BLA members and the Tasmanian community in Tasmania’. Tasmanian Bird Report 39: 21–33. Birdata related projects. The Australian Bird Environ- Newman, M. 2019. ‘Why is the Pallid Cuckoo declining in ment Fund are thanked for their generous support. the Hunter Region, but relatively stable in Tasmania?’ The Whistler. 13: 69–80. References Newton, I. 2013. ‘Bird Populations’. The New Naturalist Library. 124: 221–22. HarperCollins Publishers. Baldwin, M. 1975. ‘Birds of Inverell district, NSW’. Emu. 74: Starling, M., Heinsohn, R., Cockburn, A. and Langmore, 113–20. N.E. 2006. ‘Cryptic gentes revealed in Pallid Cuckoos Bayliss, M. 1988. ‘Cuckoo X breaks records’. BTO News. 159: cuculus pallidus using reflectance spectroscopy’. Proceedings of 7. British Trust for Ornithology, Tring. the Royal Society B: Biological Sciences. 273: 1929–34. Davies, N. 2015. Cuckoo: Cheating by Nature. Bloomsbury Williams, H.M., Willemoes, M., Klaassen, R.H.G., Publishing Plc.: London. Strandberg, R. and Thorup, K. 2016. ‘Common Cuckoo Debus, S. 1998. The Birds of Prey of Australia: A Field Guide. J.B. home ranges are larger in the breeding season than in the Books Pty. Ltd: Australia. non-breeding season and in regions of sparse forest cover’. Fowler, J. and Cohen, L. 1986. ‘Statistics for ornithologists.’ Journal of Ornithology. 157: 461–69. BTO Guide. 22. British Trust for Ornithology, Tring.

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