NT Naturalist - Number 21, Published November 2009
ISSN: 0155-4093
Editor: Michael Braby
Pre-release Articles
| Download | 1. Invertebrate diversity associated with tropical mistletoe in a suburban landscape from northern Australia |
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| Authors | Stacey J. Anderson and Michael F. Braby |
| Abstract | The invertebrate fauna associated with the tropical mistletoe Decaisnina signata (Loranthaceae) parasitising a range of host trees was surveyed during the late dry-season (September-October) in suburban areas of Darwin, Northern Territory, a landscape which comprises extensive patches of natural vegetation within the urban matrix. A total of 113 species of insects and spiders representing 51 families and 12 orders was recovered from 38 samples. The estimated total species richness, however, suggests another 116 species are likely to occur on the mistletoe according to the incidence-based coverage estimator (ICE). Hymenoptera (especially Formicidae), Hemiptera (particularly Miridae), Araneae and Lepidoptera were the most dominant groups in our samples in terms of both species richness and relative abundance (measured as % site occupancy). Thysanoptera, Coleoptera and Psocoptera were also comparatively diverse but were substantially less abundant. Overall species and family richness were both positively correlated with mistletoe biomass, but the composition and taxonomic richness of invertebrates associated with mistletoes parasitising different host genera (Planchonia vs. Alstonia) or host species (Alstonia scholaris vs. A. actinophylla) were not significantly different. Our findings are in broad agreement with limited previous studies elsewhere that indicate mistletoes support a wide range of invertebrates, some of which are obligate specialists. We hypothesize that mistletoes support a unique assemblage of invertebrates that is independent of the host tree. |
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| Download | 2. A description of the primary habitat of the Purple-crowned Fairy-wren Malurus coronatus coronatus in the Victoria River District, N.T. |
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| Authors | Annemarie van Doorn and Jenni Low Choy |
| Abstract | The habitat of the Purple-crowned Fairy-wren in the Victoria River District is described, with particular reference to the density of the riparian grass Chionachne cyathopoda, based on 75 vegetation transects sampled in 39 fairy-wren territories. This paper also clarifies confusion about the primary habitat of the fairy-wren with respect to another riparian grass, Mnesithea rottboellioides, which shares with C. cyathopoda the common name Canegrass. To assist successful management and conservation we provide a guide to correctly distinguish these two grasses and recommend the use of the common name Rivergrass for C. cyathopoda and Northern Canegrass for M. rottboellioides. |
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| Download | 3. Seasonality of nectar production by woodland plants on the Gove Peninsula |
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| Authors | Christopher J. Brady |
| Abstract | In this paper I report flowering periods and indices of nectar availability over two years, for seven common plants regarded as being important nectar resources for birds in savannah woodland and rehabilitated mined land on the Gove Peninsula. Nectar availability varied seasonally, being lowest from December to February and highest in June and October each year. Nectar availability differed significantly between years, the difference being predominantly attributable to eucalypts, which exhibited large inter-annual differences in flowering, in contrast to the more consistent flowering of non eucalypts. Fern-leaved Grevillea contributed most to the nectar index (30%) across study sites. Darwin Stringybark contributed 10% to the overall nectar index, although this is considered an underestimate of its importance to nectar availability on the Gove Peninsula. Although birds were observed feeding on the nectar of all plant species for which the nectar index was calculated, Fern-leaved Grevillea (8 bird species) and Darwin Woollybutt (7 bird species) attracted the largest variety of birds. |
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| Download | 4. Evidence for predation on terrestrial Cane Toads Bufo marinus by the Sooty Grunter Hephaestus fuliginosus in northern Australia |
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| Authors | Aaron M. Davis and Colton Perna |
| Abstract | The Cane Toad Bufo marinus, a native of Central and tropical South America, was introduced to northern Queensland in 1935 as a biocontrol agent and is currently colonizing much of the Australian continent. With toxin-based anti-predator defences evident throughout all life history stages, the impacts of Cane Toad invasion on indigenous fauna, particularly naïve frog-eating predators, have attracted considerable scientific interest. Cane Toads have been implicated in declines of a range of vertebrate fauna throughout northern Australia, both anecdotally (Burnett 1997; White 2003) and quantitatively (Doody et al. 2006; Letnic et al. 2008). Much field survey effort regarding Cane Toads has focused on the potential impacts of toads on terrestrial and semi-aquatic vertebrates (reptiles and mammals), with evidence of effects, negative or otherwise, on native fish very rare in the Australian scientific literature. There are, however, recent accounts attributing fish kills in aquatic ecosystems in the Northern Territory to Cane Toads (Wilson 2004; Anon. 2006; Grace & Sawyer 2008). The Sooty Grunter Hephaestus fuliginosus is a widespread northern Australian freshwater fish with considerable ecological, recreational and spiritual importance (Pusey et al. 2004). Noted as an amphibian predator (Allen et al. 2002), the Sooty Grunter would accordingly be expected to be a significant Australian fish species potentially susceptible to toad toxicity. The following account documents predation on the terrestrial life history stages of Cane Toads by Sooty Grunters in northern Australia freshwater ecosystems, apparently with minimal evident adverse effect on the fish in question. |
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| Download | 5. False Killer Whales Pseudorca crassidens: regular visitors to Port Essington and Darwin Harbour in the Northern Territory, Australia |
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| Authors | Carol Palmer, Peter Fitzgerald, Andrew Wood, Samantha Harley and Adrian McKenzie |
| Abstract | Until recently there has been very little cetacean research undertaken in the Northern Territory (NT) (Chatto & Warneke 2000; Palmer et al. 2009). However, since 2007 the Coastal Dolphin Project has been focussing on the three species of coastal dolphins (Australian Snubfin Orcaella heinsohni, Indo-Pacific Humpback Sousa chinensis and Indo-Pacific Bottlenose Tursiops aduncus) and undertaking a range of research activities including monthly boat-based surveys at three sites in the NT: Coburg Marine Park, Darwin Harbour and the Alligator Rivers region. As the Coastal Dolphin Project has gained a profile both publicly and within various government agencies and non-government organisations, a further benefit has been the recording, reporting and collation of information on a typically ocean-going dolphin that appears to be a regular visitor to both Port Essington and Darwin harbours, the False Killer Whale Pseudorca crassidens. |
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| Download | 6. Notes on the form and habitat of nests of the Northern Shrike-tit |
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| Authors | Simon J. Ward, Mani Berghout and Bryan Baker |
| Abstract | The Northern Shrike-tit Falcunculus frontatus whitei is currently considered one of three subspecies of the Crested Shrike-tit (Christidis & Boles 2008). It is patchily distributed in the Top End of the Northern Territory (NT) and the Kimberley Region of Western Australia (WA), but there are relatively few records for the subspecies and it is listed as ‘Vulnerable’ nationally under the Environment Protection and Biodiversity Conservation Act, and in the Northern Territory under the Territory Parks and Wildlife Conservation Act. In WA, it is listed under Schedule 1 – “Fauna that is rare or is likely to become extinct”. Robinson and Woinarski (1992) found 21 records from 16 localities for the species in the NT and seven from the Kimberley prior to the date of their publication. The NT Fauna Atlas (a database held by the NT Department of Natural Resources, Environment, The Arts and Sport (NRETAS)) contains 28 records for the subspecies, from about 22 sites in the NT (to July 2007). Two of these records are of nesting shrike-tits, both from the Borroloola region almost a century ago from collections by H.G. Barnard in January 1914 (Barnard 1914; White 1914). Other nests have been seen by bird-watchers both in the NT (S. Keates, pers. comm.) and the Kimberley (G. Swann, pers. comm.), but there is no published description. Here we report on the features of nests of Northern Shrike-tits found in the Maranboy area, approximately equidistant between Katherine and Mataranka, near where the subspecies was previously recorded by Holmes and Noske (1990). |
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