The Status of Estrildid Finches in North-Western Australia
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VOL. 19 (5) MARCH2002 147 AUSTRALIAN BIRD WATCHER 2002, 19, 147-160 The Status of Estrildid Finches in North-western Australia ANDREW C. BIRCHENOUGH, GARETH W. DOUGLAS and S1EWART M. EVANS Dove Marine Laboratory (Department of Marine Sciences and Coastal Management, Newcastle University), Cullercoats, Tyne and Wear NE30 4PZ, U.K. Summary There is concern that populations of some estrildid finches have declined in northern Australia. The object of the present study was to investi8ate the current status of estrildid species in the Kimberley region. This was done by countmg numbers of finches drinking at waterholes in 1996, 1997 and 1999. Additional counts were made during timed walks in areas adjacent to 10 waterholes and in the Ord River Irrigation Area in 1999. Three species of grass finch (Double-barred Finch Taeniopygia bichenovii, Long-tailed Finch Poephila acuticauda, and Masked Finch P. personata) were abundant and widely distributed throughout the study area but other estrildids were seen less frequently. Nevertheless, the Gouldian Finch Erythrura gouldiae was observed at sites in eastern, central and northern parts of the study area, sometimes in large flocks (50 to > 100 individuals). The Star Finch Neochmia ruficauda was recorded at relatively few sites but was abundant at places in the eastern Kimberley, including the Irrigation Area. 1Wo other species, the Yellow-rumped Mannikin Lonchura flaviprymna and the Chestnut breasted Mannikin L. castaneothorax, were present in large numbers in the Irrigation Area but were not recorded elsewhere. The Pictorella Mannikin Heteromunia pectoralis was recorded in large numbers drinking at one waterhole site in 1996 and at two sites in 1997 but was sighted infrequently in 1999. Introduction Although northern Australian savannas remain largely untouched by intensive agriculture, populations of ground-dwelling fauna of the region, and in particular granivorous birds, are in a state of flux. Franklin (1999) provided quantitative evidence that 12 of 49 indigenous granivorous bird species have declined over the past 150 years, including four species or subspecies of estrildid finch: the Gouldian FinchErythrura gouldiae, the Star Finch Neochmia ruficauda, the Black throated Finch Poephila cincta and the nominate subspecies Lonchura castaneothorax castaneothorax of the Chestnut-breasted Mannikin. Two of these have been accorded threatened status: the Gouldian Finch is Endangered, and the Star Finch is Vulnerable (Garnett 1992, Collar et al. 1994). Franklin (1999) was unable to identify quantitative trends over this time period in either the Pictorella Mannikin Heteromunia pectoralis or the Yellow-romped Mannikin Lonchura fiaviprymna, in the latter case through lack of data. Nevertheless, there is anecdotal evidence that both are in decline (Blakers et at. 1984, Bell 1995), and they have been classified as near-threatened by Collar et al. (1984). Declines in the abundance and distribution of estrildid finches appear to have been most severe in the eastern region of northern Australia. Three species that have been particularly affected are the Gouldian Finch (Holmes 1995), Chestnut breasted Mannikin (Franklin 1999) and Star Finch (Holmes 1996, 1998). The western region of northern Australia has probably been less badly affected (Evans & Bougher 1987). The object of the present study was to assess the current status of estrildids in the Kimberley region, which may be the last remaining stronghold for some species. Since, historically, declines in bird life in northern Australia are probably related to changes in land use brought about by European settlers (Franklin 1999), records were kept of the occurrence of finches in both areas of BIRCHENOUGH, AUS1RALIAN 148 DOUGLAS & EVANS BIRD WATCHER Ord River Irrigation Area r--------- Great Northern NT. ffighwoy SOkm WA. !-------1 Figure 1. Map of the study area showing major roads and towns. Recording sites are indicated by numbers. W.A. = Western Australia, N.T. = Northern Territory. Further information is given in Table 1. 'native vegetation' and agricultural land in the Ord River Irrigation Area. Three recording methods were used to survey finches in areas of native vegetation. First, counts of the numbers of finches drinking at waterholes were made. Evans & Bougher (1987) devised a standard technique for doing this, and it has been used in subsequent surveys by the Northern Territory Conservation Commission in 1987, 1989, 1991 and 1995 (Bell1995). Second, counts were made of numbers of finches seen on standardised timed walks. Third, records were kept of any VOL. 19 ~5) MARCH 002 Estrildid Finches in North-western Australia 149 Table 1. Location of study sites in 1999 and dates (day, month) on which recordings were made. *Sites at which there were casual sightings of finches but no formal counts. Site Date Site Date 1 Timber Creek 7.7 25 Sawpit Spring 23.7 2 Dingo Springs 8.7 26 Sawpit Gorge 23.7 3 Donkey Gap Pool 8.7 27 Jack's Waterhol e 29.7 4 Donkey Gap Bore 8.7 28 Andy's Scrape 11.7 5 Pumpkin Spring 30.6 29 Dingo Creek 12.7 6 Quarry Pool 30.6 30 Ellenbrae 12.7 7 Ameythst Spring 2.7 31 Monica's Meadow 11.7 8 Cabbage 'free Creek 21.7 32 Billabong Crossing, Ellenbrae 12.7 9 Middle Creek* 26.6 33 Brolga Marshes 12.7 10 Kingston Rest* 20.7 34 Dawn Creek 11.7 11 60 kScrape 2.7 35 Fly Creek 7.8 12 Dunham River 20.7 36 Carson River Homestead* 6.8 13 Kilarney Bore 22.7 37 Bryony Creek 4.8 14 Kilarney Creek 22.1 38 Sarah Creek 4.8 15 Six Mile Bore, Thrkey Creek 22.7 Sarah Creek w) 5.8 16 Doon Doon Station* 23.7 39 Dominic Creek 4.8 17 Dingo Hole 24.7 40 McGowan Creek 3.8 18 Six Mile Bore 24.7 41 MonCreek 1.8 19 Wyndham Golf Club 25.7 42 Lil' Miners Pool 31.7 20 King River Creek 26.7 43 Meelarie Creek w31.7 21 King River Crossing 26.7 Meelarie Creek ) 11.8 22 Slaty Creek 27.7 44 Katie Creek 1.8 23 Brolga Scrape 28.7 45 Hair Creek 10.8 24 Pentecost River Crossing* 27.7 casual sightings (that is, sightings outside formal recording sessions) of species whose conservation status is of concern. Waterhole counts were inappropriate in the Ord River area because of the abundance of surface water, so surveys in this area were based solely on counts of birds seen during timed walks and casual observations. Methods Surveys were carried out during the period between June and August in 1996, 1997 and 1999. Study area The study area extended on an east-west axis from Timber Creek, in the western part of the Northern Thrritory, to the Kalumburu road, and on the south-north axis from Halls Creek to the Kalumburu Reserve (Figure 1) (exact sites withheld). Sites at which counts were made were close to the Great Northern Highway (a sealed road) and the Gibb River and Kalumburu roads (which are unsealed) (Figure 1, Thble 1). Records were kept at seven waterholes in 1996 and 1997, and at these same sites, together with an additional 33 waterhole sites, in 1999. Timed walks were made at ten waterhole sites in 1999. The Ord River Irrigation Area is a belt of agricultural land, approximately 50 x 5- 10 km, adjacent to the town of Kununurra. Timed walks were made at 1 km intervals along the road system throughout this Irrigation Area. There were 105 timed walks, 69 of which were within the area of agricultural land and 36 outside it (Figure 2). Recording procedures (i) Waterholes. Counts of individual finches were made at waterholes (consisting of springs, small pools along otherwise dry creeks and bore holes) between 0600 and 0800 h (Western Australian time), which covers the period of high finch drinking activity (Evans eta/. 1985). Observers ositloned themselves about 20m from the water in semi-concealment and counted Gouldian, Masked and Long-tailed Finches drinking at a waterhole in the Kimberley. 'late 37 Photo: Mike Fidler Pictorella Mannikins drinking at a waterhole in the Kimberley. 1te 38 Photo: Mike Fidler BIRCHENOUGH, AUS1RALIAN 152 DOUGLAS & EVANS BIRD WATCHER 0 I km Cultivated C? Area Q Survey Site ~ Road Figure 2. Map of the Ord River Irrigation Area, including the town of Kununurra. The cultivated area is enclosed by a bold line. one-minute intervals throughout the entire session. The method of counting finches is described more fully by Evans & Bougher (1987). (ii) Timed walks. Walks adjacent to waterhole sites in native bushland commenced at 0600 h. The recorder walked slowly in a circular track for 1 hour, covering a distance of about 1- 3 km. Walks in the Irrigation Area (within and outside agricultural land) lasted for 10 minutes, and were undertaken during the mornings (approximately 0600-1200 h). In both cases, records were kept of sightings of finches that were encountered. (iii) Casual observations. At times other than during waterhole counts or on timed walks, records were kept of sightings of any of the species whose conservation status is of concern or VOL. 19 (5) MARCH2002 Estrildid Finches in North-western Australia 153 Table 2. Numbers of finches recorded at seven waterholes which were visited in all of the years 1996, 1997 and 1999. There were no recordings from Andy's Scrape in 1996 because it was dry. Data are also provided for the rainfall recorded during the previous wet season at Kununurra. Site Year Finch species Gouldian Star Pictorella Double- Long- Masked Mannikin ba"ed tailed 5 Pumpkin Spring 1996 0 0 0 847 781 167 1997 1 0 0 206 180 76 1999 0 0 0 27 42 4 11 60 k Scrape 1996 0 0 1485 384 377 269 1997 0 0 4 13 37 3 1999 0 0 0 4 0 0 12 Dunham River 1996 0 52 0 153 484 233 1997 0 8 378 21 0 0 1999 0 0 1 QO 0 3 21King River Crossing 1996 34 2197 0 109 22 40 1997 0 13 0 2 4 0 1999 0 0 0 10 2 0 28 Andy's Scrape 1996 1997 0 0 785 0 1 5 1999 0 0 0 0 0 0 30 Ellenbrae 1996 283 0 0 170 638 18 1997 1 0 0 15 26 2 1999 0 0 0 0 5 0 34 Dawn Creek 1996 98 0 4 0 247 60 1997 0 0 0 0 0 0 1999 0 0 0 0 10 0 Means 1996 69.2 374.8 248.2 277.2 424.8 131.2 1997 0.3 3.0 166.7 36.7 35.4 12.3 1999 0 0 0.1 8.7 8.4 1.0 Rainfall (em) 1996 607 during previous 1997 942 wet season 1999 1011 which are believed to be in decline (i.e.