Discussion Paper - Part A - Victorian Environmental Assessment ...

Egrets generally only breed in living trees with at leasthalf a metre of water beneath them. If the waterrecedes, the egrets will abandon the nest, even if theyoung are close to fledging. Following spring floods, theextensive river red gum forests of the Barmah andGunbower areas provide the only Victorian breedingsites for colonies of great and intermediate egrets, andmajor breeding colonies of other herons, cormorants,ibis and darter.The lack of adequate spring floods in recent decades hasresulted in an almost complete lack of breeding by manycolonial waterbirds, particularly intermediate and littleegrets, which are classified as critically endangered inVictoria, and also the great egret, which is endangered.Little egrets bred in Gippsland in 1993, near Geelong in1998-2004 and in Gunbower Forest in the early 1970s.Intermediate egrets are known to have bred at only twosites in Victoria: Ryans Lagoon (near Wodonga) in 1981and Gunbower Forest in the early 1970s and one nest in1993. Great egrets bred at many sites in the 1970s and1980s but had not been recorded breeding in Victoriasince 1993. There are probably fewer than 200 breedingpairs remaining. Increased environmental flows in 2005under the Living Murray initiative (see chapter 15)resulted in great egrets breeding in Gunbower Forestand both great and intermediate egrets breeding inBarmah Forest.The carpet python is another threatened species foundwithin riverine forests. This species inhabits two distincthabitat types within Victoria: river red gum forests andassociated black box woodlands along rivers andstreams, and also rocky hills with Blakely’s red gum.Increased predation and habitat clearing as well asdecreased prey availability are thought to reduce carpetpython populations (Allen et al. 2003). Carpet pythonsare ambush predators which use fallen timber, groundcover and rocks to hide from potential prey and toshelter from predators. Removing this cover for firewoodand landscaping, threatens the survival of carpetpythons. Carpet pythons are also sometimes killed byhumans.River red gums are a keystone eucalypt tree species forterrestrial invertebrates because of they provide bothfood and shelter, as well as leaf litter and coarse woodydebris on the forest floor. Recent research indicates thatflooding has significant food-chain implications forterrestrial invertebrates. Larger invertebrate predators,such as carabid beetles and lycosid spiders, increase inresponse to flooding thereby sustaining largerpopulations of insectivorous vertebrates that prey uponthem.Aquatic species are likely to be particularly sensitive tochanges in the river system. The critically endangeredsilver perch, for example, spawns partly in response torises in water level and temperature. Given the greatchanges in the region’s hydrology since Europeansettlement (see chapters 3 and 15), it is perhapsunsurprising that seven of the 21 native fish speciesrecorded in the study area are threatened. Many of thestudy area’s streams and rivers now provide the mostimportant Victorian habitat for species such as thecritically endangered trout cod and Murray hardyhead,and the endangered Murray cod (see box 5.2),freshwater catfish and Macquarie perch.In addition, the Lowland Riverine Fish Community of thesouthern Murray-Darling Basin is listed under the Floraand Fauna Guarantee Act 1988. This community has 15fin fish species: ten that are listed individually under thatAct, and five that are not—golden perch, flat-headedgalaxias, bony bream, flat-headed gudgeon and westerncarp gudgeon.Eucalypt (Box) WoodlandWoodlands dominated by eucalypts other than river redgums and black box, particularly grey box and yellowbox, also provide significant habitat for woodland birds,small mammals and reptiles. These woodlands providesimilar kinds of ecological services as the river red gumforests, but have fewer wetlands and do not usuallyflood naturally. The dominant eucalypts are not adaptedto periodic inundation and consequently have notdeclined with reduced flooding. However, Margules andPartners et al. (1990) estimate that approximately 33percent of the floodplain vegetation along the RiverMurray has been cleared and much of this would havebeen box woodland (not necessarily all in the River RedGum Forests study area).Grey box has a wider distribution in the study area thanblack box, occurring from Wodonga in the east toKerang in the northwest with an outlying populationnear Robinvale (see Figure 5.1). Grey Box is thedominant eucalypt on many roadsides in the VictorianRiverina Bioregion. Like black box and river red gum,grey box wood is strong and durable and widely usedfor products such as fence posts. It was widely clearedfrom its pre-European distribution and remains mostly onroadsides and as single paddock trees.Yellow box is widely distributed across Victoria but islargely absent from the north and south west and alpineareas (see Figure 5.1). Yellow box wood has similarcharacteristics to grey box wood and the trees are alsogood honey producers, flowering from September toJanuary.Buloke is a leaf-less tree that grows to 5-15 m. It isdistributed in north and west Victoria and is commonlyfound with grey box and slender cypress-pine.Approximately 97 percent of the original bulokewoodland in Victoria has been removed (DNRE 1997b).Most remnant buloke trees occur as scattered trees,many in paddocks and along roadsides. This history hasnegatively affected many species that inhabit bulokewoodlands, such as the grey-crowned babbler.Buloke Woodlands of the Riverina and Murray-DarlingDepression Bioregions have been listed as anendangered community under the CommonwealthEnvironment Protection and Biodiversity ConservationAct 1999. Remaining examples are threatened bycontinued clearing, weed invasion, fertiliser andherbicide drift and grazing by rabbits and stock. Thiscommunity is poorly represented in conservation reservesthroughout its range.Large old tree sitesLarge old trees are particularly important in both riverineforests and eucalypt woodlands. Large trees provide amore open forest structure, with a greater area andvariety of foraging substrate for insectivorous fauna.They also provide abundant bark and fallen timber,Discussion Paper71