Removing Lantana: a gradual and bird-friendly approach

Introduction
A basic goal for all restoration efforts in natural areas is to retain and enhance habitat values. Establishing a diverse range of habitat structures (canopy, mid-storey, ground cover) using a species-rich range of native plants is fundamental. At the same time, the high risk of removing small bird shrub-level habitat means preserving weedy dense mid-storey until replacement native vegetation is fully established is similarly fundamental. Due to its dense habit and ubiquity, Lantana camara is an exemplary case for careful, gradual removal.

Many of our local small bird populations have come to rely on lantana: for foraging, roosting, preening, courting, nesting, rearing young and socialising generally. Alarmingly, however, many small bird species are in decline, especially in urban areas. A decade ago, local researcher Holly Parsons warned “... birds such as the white-browed scrubwren (Sericornis frontalis), brown thornbill (Acanthiza pusilla), superb fairy-wren (Malurus cyaneus) and new holland honeyeater (Phylidonyris novaehollandiae), once more common, appear to be in decline ...” (p32).

Rapid removal of lantana thickets can leave family groups of small birds with nowhere to go, a likely death sentence for most family members. In the management of our natural areas, more graduated approaches to the removal of lantana would help counteract habitat loss without compromising the management goal to recover and maintain native plant biodiversity.

The problem
Lantana is particularly notorious for its capacity to form dense thickets replacing the original shrub layer. At the same time, lack of shrub understory typifies urbanised areas. “In Australia, the loss of the shrub layer is thought to be partially responsible for the decline in small bird abundance witnessed in urban areas” (Parsons, p204). Local bird species that depend to varying degrees on shrubbery include the Fairy-wrens, (Variegated and Superb), Fantails (Grey and Rufous), the Red-browed Finch, Eastern Spinebills, Silvereyes, Thornbills (Yellow and Striated), Weebills and the White-browed Scrub Wren (also for not-small-for-long Brush-turkey chicks http://www.birdsinbackyards.net/Weeds). These species need the protection of dense shrubbery against predators: cats, rodents and also the bigger, omnivorous birds favoured by urbanisation, such as Pied Currawongs, Ravens, Butcherbirds and Magpies.  Small birds, their eggs and young are at high risk of predation. Lantana has become their refuge.

Hooka Point on Lake Illawarra, Berkeley, is well-known to local birdwatchers. Members of the Illawarra Birders have expressed concern about the removal of areas of lantana from Hooka Pt Park. They have seen a reduction in small bird life in pockets of trees where lantana mid-storey has been removed.

Case study: Superb Fairy-wrens
Superb Fairy-wrens are a stand-out example among small bird species with a well-documented reliance on lantana. Sedentary and territorial, they live in communal cooperative breeding groups. Each group depends on an inherited territory, which in urban areas is somewhere between 1.4 ha and 2.6 ha (Parsons, p208). Although they forage at ground level in open grassed areas, they have been found to spend most of their time in shrubbery (Parsons, p18).  A Superb Fairy-wren territory requires “ ... dense shrub cover interspersed with open ground for foraging” (Parsons, p47).  If a significant part of its shrub cover is suddenly removed, the group will be left homeless or forced to select low quality habitat offering poor survivorship.

Fairy-wrens are also weak fliers with small home ranges. Their territories need to be in close proximity (ideally adjacent) to accommodate their life-history characteristics of extra-pair copulation and post-natal dispersal of young females (Parsons p215). Loss of one family group increases the vulnerability of all their neighbours.

Weed slowly!
To manage lantana’s habitat value and prevent soil erosion, staged and gradual removal of lantana is established best practice (ABBR, p7; Stocks, Section 1, p25). As urged by Birds in Backyards, we need to: “Remove established weeds slowly and in small patches and relace the weeds with an equivalent native plant where possible (e.g. something that provides dense cover). Allow new plantings to establish before moving on to the next patch” http://www.birdsinbackyards.net/Weeds

Lack of funding and pressure of time afflict both professional and volunteer bush restoration and encourage quick removal, as does the relative ease of cut-and-crush methods of removal, whether manual or mechanical. However, local populations of small birds may be lost (possibly reptiles as well). They can’t put their lives on hold for the several years needed by plants to grow to a height and density that provides protection and suitable breeding sites. 

Graduated removal: suggested methods
Hedging
If bird use is high or time not right for gradual removal for operational reasons, control stretches of dense lantana by trimming and turning into hedge as interim habitat while adjacent new shrub layers are establishing. This is particularly suitable for streetscapes, achieving a cared-for look, possible shelter for the emerging native shrubs and maybe less rubbish dumping. The habitat provided by the lantana will be preserved until its native replacement is established.


Examples of hedged lantana at a site on Berkeley Rd, Berkeley. The hedge looks surprisingly good; its flowering has been reduced; and it provides shelter for the replacement native plants as they grow, as well as important habitat for the small birds.





Mosaic pattern of removal
Avoiding breeding season, dry times and areas with evidence of high bird use, select small patches of lantana from within the larger incursion, and clear in ways that foster native regeneration and facilitate re-vegetation (e.g. cut-and-crush or cut-and-pile). Planning mosaic layout is of course dependent on site characteristics. For example, and as a very rough guide, for a Swamp Oak riparian zone with dense lantana mid-storey, 10 m2 to 15m2 of lantana could be left intact for every 2m2 cleared. A similar effect can be achieved by clearing and maintaining narrow tracks through large lantana infestations, encouraging regeneration within the track and/or densely planting it with native shrubs.

Die-in-place / Vine Lattice
Combined with mosaic and tracking methods of removal, create a ‘lantana lattice’ for native vines to grow through. Begin by planting a range of native vines along lantana edge. Allow a number of weeks for the plants to take root. Then, instead of crushing or piling the lantana biomass, cut-and-paint lantana stems at base, leaving uncrushed stems and branches to die in place and provide lattice for vines. Try pumpkin vine for a quick temporary measure! Keep any regenerated or planted native plants free of vine; prune vigorous vines as necessary.

Conclusion
Scientific and anecdotal evidence in both agricultural and urban landscapes suggests that populations of fairy-wrens and other small native birds are in decline, and loss and fragmentation of habitat is the main cause. We need to be prepared to tolerate the presence of lantana thickets in our natural areas until new thickets of native shrubbery, equal to or greater than the size and density of the lantana thickets, have been established.

Besides being a joy to watch and get to know, small birds are integral to the health of any area of bush and to overall biodiversity. Most are insectivores helping to keep insects in balance. Some also feed on nectar, fruit and/or seed, thus helping in pollination and seed dispersal.  We can’t do without them!

References
AABR’s Guiding Principles for Ecological Restoration and Rehabilitation, 2013, section 4, p7 http://www.aabr.org.au/_upload/learn/WhatIsBR/ER_Statement_AABR_2013.pdf


Parsons, Holly M., The effect of urbanisation on the superb fairy-wren (Malurus cyaneus) PhD thesis, School of biological Sciences, University of Wollongong, 2009 https://ro.uow.edu.au/theses/821/

Stock, Daniel, Lantana Best Practice Manuel & Decision Support Tool, Queensland Primary Industries & Fisheries, August 2009 Section 1, p25 https://www.academia.edu/1602666/Lantana_Best_Practice_Manual_and_Decision_Support_Tool.

Further reading

Crate, RA, French K, Mclean, CM (2011) The abundance and distribution of two species of fairy-wren in suburban and natural habitats, Emu-Austral Ornithology, 111:4, 341-349, https://doi.org/10.1071/MU10057

Skroblin A. & Murphy A., The conservation status of Australian malurids and their value as models in understanding land-management issues, Emu 2013, 113, 309-318, https://doi.org/10.1071/MU12075

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APPENDIX
Illawarra native plants that provide habitat for small birds
PLEASE add your suggestions to these lists and start lists for other veg communities, e.g. riparian sites; coastal plain woodlands; wet and dry sclerophyll forest.

Coastal/hind dune sites
Shrubs/small trees: Indigofera australe, Leucopogon parviflorus, Melanthera biflora, Monotoca scoparia, Myporum boninense, subps. australe, Pittosporum revolutum, Rhagodia candolleana, Westringia fruticosa, (and maybe small saltbush species).
Climbers/scramblers: Hardenbergia violacea, Hibbertia scandens, Kennedia prostrata.

Rainforest edges (Dry Subtropical)
Shrubs/small trees: Abutilon oxycarpum; Acacia longifolia; Alcornea ilicifolia; Breynia oblongifolia; Clerodendrum tomentosum; Croton verreauxii; Glochidion ferdinandi; Hibiscus heterophyllus; Indigofera austral; Omalanthus populifolius; Pittosporum multiflorum; Pittosporum revolutum; Rhagodia candolleana; Solanum aviculare; Syzygium australe;
Climbers/scramblers: Aphanopetalum resinosum; Cayratia clematidea; Celastrus subspicata; Cissus antarctica; Cissus hypoglauca; Clematis aristata;  Eustrephus latifolius; Geitonoplesium cymosum; Glycine clandestina; Hibbertia scandens; Legnephora moorei; Maclura cochinchinensis; Marsdenia flavescens; Marsdenia rostrata; Pandorea pandorana; Parsonsia straminea; Rubus rosifolius; Rubus moluccanus; Rubus parvifolius; Rubus nebulosus; Smilax australis; Stephania japonica
Other: Lomandra longifolia; Austrostipa ramossisima; Carex spp; broadcast seed of other groundcovers

                                                                                    
Budjong Creek Berkeley Bushcare

COMMENTS VERY WELCOME: please send to julie.marlow @ bigpond.com

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