Burning for Brolgas

...on the Townsville Town Common

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 Eremaea in recent years 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

Brolga flight

← The Townsville Town Common was once an important dry season site for Brolgas (Sandy Carroll)

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.

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

DateNumbersReference¥
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

¥ Reference list below

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Breeding

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). 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).

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NEXT: Burning for Brolgas 2: Grazing and burning trials, and outcomes»

References

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