Burning for Brolgas
...on the Townsville Town Common
by Elinor Scambler
The Townsville Town Common was famous for its large dry season flocks of Brolgas, with over 1,000 still regularly seen to the mid 1970s. The site is still famous for its birdlife, but expert Townsville birdwatchers now expect Brolga totals less than 100 (Ian Boyd, in Wetland Birds of the Townsville Region, 2011) and the highest count reported to the online bird database site eBird in the 10 years to 2017 is 160 (N Bruce, 30 November 2012).
What happened? In ‘Burning for Brolgas’ Ozcranes looks at how a ponded pasture grass became the dominant species in critical Brolga wetlands, and efforts to understand and control it.
Thousands of Brolgas
The Townsville Town Common some 3,000 Ha in area, is the most significant remaining wetland in the Bohle River catchment in the City of Townsville, coastal north Queensland. The Common is listed in the CAMBA and JAMBA international treaties protecting migratory waterbirds.
← Brolgas and other wetland birds need a diversity of plants, plus some open water and shallow edges (Peter Merritt)
Now a Conservation Park, it was long famous for its wetland wildlife and declared a ‘Sanctuary’ in 1936, the Town Clerk advertising on 29 September 1936 (Townsville Daily Bulletin, p. 2) that shooters would be prosecuted. Over succeeding years drainage and reclamation of low lying swampland for building, airport and other facilities took their toll, but totals of well over 1,000 Brolgas were still being seen up to the mid-1970s. These high numbers now seem almost legendary, perhaps because the readily available sources for ‘flocks of thousands’ are general, popular accounts. Actual data from hard-to-obtain references are presented here for information:
Brolga counts, Townsville Town Common, 1959-1992
|1959||Max. 1400||Lavery 1964|
|1960||Max. 2000||Lavery 1964|
|1961||Max. 2500||Lavery 1964|
|1962||Max. 2400||Lavery 1964|
|1963||Max. 1800||Lavery 1964|
|October 1968||Evening roost: 624||Walkinshaw 1973|
|December 1968||Morning roost: 1035||Walkinshaw 1973|
|1969||Max. 770 (Common dry)||Blackman & Locke 1985|
|1970||Max. 900 (Common dry)||Blackman & Locke 1985|
|August 1975||Ground counts: 2000±500||Blackman 1977|
|1968-77 excl 69/70||1975±344||Blackman & Locke 1985|
|1983||About 600||Garnett & Cox 1983|
|1992||About 350||Birtles & Sofield 1992|
Brolgas flocking on the Common and other Burdekin region dry season wetland refuges, disperse once the rains arrive. They breed in widely separated sites. On the Common, some pairs used to remain to breed, Walkinshaw reporting that in the 1968-69 wet season ‘many people’ helped search and found 4 nests, with first eggs from 2 January to late February. Breeding records reported in recent years appear to be all adult pairs with fledged young, presumably bred elsewhere.
Grazing goes, Para explodes
Para Grass (Urochloa [formerly Brachiaria] mutica) – an African semi-aquatic plant cultivated for ponded pasture – was well established in tropical America when recommended for import into Australia from Barbados under the auspices of Earl Grey, in 1849 (South Australian Register, 1 August 1849, p.3).
← Para Grass Urochloa mutica invades natural wetlands and blocks watercourses (Simon Burchill)
From multiple introductions in the 1880s, it expanded with the grazing industry to the wet north Queensland coast from the 1930s, by which time it was already noted as an invasive weed in waterways (Hannan-Jones & Csurhes 2012). Its spreading dense blanket smothers other vegetation, while beneath the top layer, living and dead stems intertwine to form a heavy thatch over the ground.
The Town Common was grazed from the 1880s to 1970s, with cattle removed in the late 1970s before its gazettal as an Environmental Park in 1980. Low density Para Grass on the Common expanded and increased once grazing was removed and birdlife dramatically declined (G. Blackman, in Williams et al. 2005). Aerial images in Grice and Nicholas (2011) show the spread of Para across the park by 1995. Strategic grazing trials were recommended many times and by 1996 were considered the only option (Luckas 1996).
- Birtles, A and THB Sofield. ‘Brolga Dreaming: A vision for the future of the Townsville Town Common.’ Department of Tourism, JCU North Queensland (1992).
- Blackman, JG. ’The development and application of aerial survey methods for population and ecological studies of the Brolga Grus rubicundus (Perry) Gruidae.‘ MSc Diss., JCU Townsville Queensland (1977). [Ground counts only were undertaken at the Common].
- Blackman, JG and DK Locke. ‘Quantitative analysis of seasonal wetlands in the Burdekin-Townsville region with special reference to waterbird habitat’. In Ecology of the Wet-dry Tropics, Proc. Ecol. Soc. Aust. Vol 13, (1985): 139-152 [1969 & 1970 were drought years and the Common dried out earlier than usual]
- Boyd, I. ‘The Townsville Town Common Conservation Park’ in: Acton, M. and A Sutton (eds) Wetland Birds of the Townsville Region. TRBOC (now BirdLife Townsville), Queensland. (2011): 5-7
- Garnett, ST and J Cox. ‘Birds of the Townsville Town Common.’. The authors, Townsville Queensland (1983)
- Grice, AC, DM Nicholas, P Williams and E Collins. ‘Wetlands going under: can invasive grasses be managed.’ In Proceedings of the 15th Australian Weeds Conference (2006): 807-10
- Grice, AC, JJ Perry, DM Nicholas, and PR Williams. ‘Managing complexity: the example of invasive wetland forage grasses.’ In Proceedings of the 16th Australian Weeds Conference: Weed Management: Hot Topics in the Tropics, ed. RD van Klinken, VA Osten, FD Panetta, and JC Scanlan. (2008): 27-29
- Grice, AC, and DM Nicholas. ‘Using Fire to Restore Australian Wetlands from Invasive Grasses’. RIRDC, 2011.
- Hannan-Jones, M and S Csurhes. ‘Invasive Species Risk Assessment: Para Grass (Urochloa mutica)’. Biosecurity Queensland, QDAFF, Brisbane: (2012)
- Lavery, HJ. ‘The brolga, Grus rubicundus (Perry), on some coastal areas in north Queensland : fluctuations in populations, and economic aspects.’ QJAS 21, no. 2 (1964): 261-264 [Lavery conducted monthly surveys in all years, the figures above are scaled off from Fig. 4].
- Walkinshaw, LH. ‘Cranes of the world.’ Winchester, NY (1973)
- Lucaks, G. ‘Wetlands of the Townsville Area: A Final Report to the Townsville City Council’. ACTFR Report 96/28, 25 November 1996
- Williams, PR, EM Collins and AC Grice. ‘Cattle grazing for Para Grass management in a mixed species wetland of north-eastern Australia.’ Ecological Management and Restoration 6, no. 1 (2005): 75-76.
- Historic Australian newspapers are sourced from Trove