Thermal aerial culling for the control of vertebrate pest populations.

Helicopter-based shooting is an effective management tool for large vertebrate pest animals. However, animals in low-density populations and/or dense habitat can be difficult to locate visually. Thermal-imaging technology can increase detections in these conditions. We used thermal-imaging equipment with a specific helicopter crew configuration to assist in aerial culling for feral pigs (Sus scrofa) and fallow deer (Dama dama) in South Australia in 2021. Seventy-two percent of pigs and 53% of deer were first detected in dense canopy/tall forest habitat. Median time from the first impact shot to incapacitation was < 12 s. The culling rate (animals hour-1) doubled compared to visual shoots over the same populations and the wounding rate was zero resulting in a incapacitation efficiency of 100%. The crew configuration gave the shooter a wide field of view and the thermal operator behind the shooter provided essential support to find new and escaping animals, and to confirm species identification and successful removal. The crew configuration allowed for successful target acquisition and tracking, with reduced target escape. The approach can increase the efficiency of aerial culling, has the potential to increase the success of programs where eradication is a viable option, and can improve animal welfare outcomes by reducing wounding rates and the escape of target animals.

Identifying fossil Myrtaceae leaves: the first described fossils of Syzygium from Australia.

PREMISE OF THE STUDY: Although leaves of Myrtaceae are easily identified to family level, very few studies have convincingly identified fossil Myrtaceae leaves to living genera. We used a broadly comparative approach with a large data set of extant taxa to confidently assign the mummified remains of myrtaceous leaves from early Miocene sediments at Kiandra (New South Wales, Australia) to a living genus. METHODS: Fossils were identified using a nearest living relative approach, against a database of 232 extant broadleaf rainforest species of Myrtaceae. Leaf cuticles were prepared from 106 species, sourced from herbarium specimens as well as some living individuals, and a further 127 records were assembled from the literature. A set of simple but phylogenetically informative cuticular characters were observed, described, and recorded under both scanning electron microscopy and standard light microscopy. KEY RESULTS: A new fossil species of Syzygium Gaertn. is described from mummified remains found in early Miocene (21.5-21.7 Ma) sediments. The fossil taxon is here named Syzygium christophelii sp. nov., in honor of the late Australian paleobotanist David Christophel. CONCLUSIONS: These fossils represent some of the most confidently described Myrtaceae leaf fossils published to date and are the first and oldest described fossil record of Syzygium from Australia. While several fossil parataxa have been illustrated from New Zealand, and several fossil species of Syzygium have previously been proposed in the literature, many of these fossils lack characters for a confident diagnosis.

Two fossil species of Metrosideros (Myrtaceae) from the Oligo-Miocene Golden Fleece locality in Tasmania, Australia.

PREMISE OF THE STUDY: The capsular-fruited genus Metrosideros (Myrtaceae) is one of the most widely distributed flowering plant genera in the Pacific but is extinct in Australia today. The center of geographic origin for the genus and the reason for and timing of its extinction in Australia remain uncertain. We identify fossil Metrosideros fruits from the newly discovered Golden Fleece fossil flora in the Oligo-Miocene of Tasmania, Australia, shedding further light on these problems. METHODS: Standard paleopalynological techniques were used to date the fossil-bearing sediments. Scanning electron microscopy and an auto-montage camera system were used to take high-resolution images of fossil and extant fruits taken from herbarium specimens. Fossils are identified using a nearest-living-relative approach. KEY RESULTS: The fossil-bearing sediments are palynostratigraphically dated as being Proteacidites tuberculatus Zone Equivalent (ca. 33-16 Ma) in age and provide a confident Oligo-Miocene age for the macrofossils. Two new fossil species of Metrosideros are described and are here named Metrosideros dawsonii sp. nov. and Metrosideros wrightii sp. nov. CONCLUSIONS: These newly described fossil species of Metrosideros provide a second record of the genus in the Cenozoic of Australia, placing them in the late Early Oligocene to late Early Miocene. It is now apparent not only that Metrosideros was present in Australia, where the genus is now extinct, but that at least several Metrosideros species were present during the Cenozoic. These fossils further strengthen the case for an Australian origin of the genus.

Oldest record of Metrosideros (Myrtaceae): Fossil flowers, fruits, and leaves from Australia.

PREMISE OF THE STUDY: Myrtaceous fossil capsular fruits and flowers from the northwest of Tasmania, in the Early Oligocene-aged Little Rapid River (LRR) deposit, are described. The reproductive organs are found in association with Myrtaceous leaves previously thought to belong to a fleshy-fruited genus, Xanthomyrtus at both LRR, and an Eocene Tasmanian site at Hasties, which are reassessed with fresh morphological evidence. METHODS: Standard Light Microscopy (LM) and Scanning Electron Microscopy (SEM) were used to investigate cuticular characters and an auto-montage camera system was used to take high-resolution images of fossil and extant fruits. Fossils are identified using a nearest living relative (NLR) approach. KEY RESULTS: The fossil fruits and flowers share a number of characters with genera of capsular-fruited Myrtaceae, in particular sharing several synapomorphies with species of Metrosideros subg. Metrosideros (tribe: Metrosidereae). The fossil is here described, and named Metrosideros leunigii, sp. nov. CONCLUSIONS: This research establishes the presence of Metrosideros (aff. subg. Metrosideros) in the Eocene-Oligocene (∼40-30 mya) of Tasmania, Australia. This is the first fossil record of Metrosideros in Australia, as well as the oldest conclusive fossil record, and may provide evidence for an Australian origin of the genus. It is also yet another example of extinction in the Tertiary of a group of plants on the Australian mainland that is only found today on nearby Pacific landmasses.