Kangaroo Island Rapid Bird Assessments, February 2020
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Kangaroo Island Rapid Bird Assessments, February 2020 March 2020 Rebecca L. Boulton, Thomas J. Hunt, Luke J. Ireland and Janelle L. Thomas Report produced by BirdLife Australia Suite 2-05 60 Leicester Street Carlton VIC 3053 T (03) 9347 0757 W www.birdlife.org.au © BirdLife Australia. This report is copyright. Apart from any fair dealings for the purposes of private study, research, criticism, or review as permitted under the Copyright Act, no part may be reproduced, stored in a retrieval system, or transmitted, in any form or by means, electronic, mechanical, photocopying, recording, or otherwise without prior written permission. Enquiries to BirdLife Australia. This report is licensed under Creative Commons Attribution 3.0 Australia licence (http://creativecommons.org/licenses/by/3.0/au/deed.en). Recommended citation Boulton, R. L., Hunt, T. J., Ireland, L. J. and Thomas, J. L. (2020). Kangaroo Island Rapid Bird Assessments, February 2020. Birdlife Australia, Melbourne. Disclaimers Every effort has been undertaken to ensure that the information presented within this publication is accurate. BirdLife Australia does not guarantee that the publication is without flaw of any kind and therefore disclaims all liability for any error, loss or other consequence that may arise from relying on any information in this publication. The views and opinions expressed in this publication are those of BirdLife Australia and do not necessarily reflect those of the Western Local Land Services. While reasonable efforts have been made to ensure that the contents of this publication are factually correct, BirdLife Australia does not accept responsibility for the accuracy or completeness of the contents, and shall not be liable for any loss or damage that may be occasioned directly or indirectly through the use of, or reliance on, the contents of this publication. Acknowledgments This project was supported by the Department of Environment and Water. February 2020 Contents Introduction ................................................................................................................. 1 Methods ...................................................................................................................... 3 Results ........................................................................................................................ 4 Discussion ................................................................................................................... 22 Recommendations ........................................................................................................ 23 References .................................................................................................................. 24 Appendix I ................................................................................................................... 25 February 2020 Introduction Wildfires fuelled by catastrophic fire conditions and below average rainfall swept across Kangaroo Island from the 20th of December 2019. Over several weeks, the fires burnt 210,606 ha, just under half of the island, including the vast majority of Flinders Chase National Park and Ravine des Casoars Wilderness Protection Area. Wildfires at this scale were last seen in the western parks of Kangaroo Island in 2007 when the majority of these two parks burnt (Fig. 1a). However, the 2007 fires were reasonably contained within the park boundaries, only burning 75,000 ha and burnt with much less intensity leaving a small but connected mosaic of unburnt habitat, particularly within the central Flinders Chase region (Fig. 1b). The 2019/2020 wildfires by comparison burnt with much more intensity, hence the inability to contain the fires within the park boundaries (Fig. 1c). As a result, large areas of native vegetation on private land was also burnt. Kangaroo Island, particularly the western half, has retained relatively high coverage and quality of its native vegetation, resulting in many species of animal and plants being either unique to the island (both species and subspecies) or faring considerably better than their mainland counterparts. The ecological impact of these fires – in addition to the economic impact, especially through tourism –is therefore likely to be high. Initial fire mapping has shown many bird species have lost major proportions of their habitat on Kangaroo Island. Understanding where these birds may now be residing within the burnt landscape is an important step towards enacting threat abatement actions and will provide baseline data to assess their future recovery and recolonisation as the habitat regenerates. February 2020 1 a b Figure 1. Fire severity index using Landsat (see methods below) a) comparison of 2007 fire scar with 2019/2020 fire scar, b) fire severity index for 2007 fire and c) fire severity index for 2019/2020 fire. Maps produced by L. Ireland. c February 2020 2 Methods FIRE SEVERITY CALCULATION METHODS: Fire severity maps were created to assist in selecting unburnt or partially unburnt patches within the fire scar in which to target search effort. These maps were created by calculating the Normalised Burn Ratio (NBR) designed to highlight burnt areas and estimate burn severity. Near-infrared (NIR) and shortwave-infrared (SWIR) wavelength bands from Landsat 7 (for 2007) and Landsat 8 (for 2019) satellite imagery were used to calculate the following formulae for delta NBR: Pre-fire NBR = (NIR - SWIR) / (NIR + SWIR) Post-fire NBR = (NIR - SWIR) / (NIR + SWIR) Delta NBR = Pre-fire NBR – Post-fire NBR Healthy vegetation before the fire has very high near-infrared reflectance and low reflectance in the shortwave infrared part of the spectrum, in contrast to recently burned areas that have a low reflectance in the near-infrared and high reflectance in the shortwave infrared band. The NBR is calculated for images before the fire (pre-fire NBR) and for images after the fire (post-fire NBR) and the post-fire image is subtracted from the pre-fire image to create the differenced (or delta) NBR (dNBR) image. dNBR can be used for burn severity assessment, as areas with higher dNBR values indicate more severe damage whereas areas with negative dNBR values might show increased vegetation productivity. BIRD SURVEYS: From the 20–28th February 2020, three experienced ecologists undertook bird surveys across Kangaroo Island (Fig. 2 & 3). The major objective was targeted surveys of unburnt vegetation on public land within the fire scar to determine what species were still present. Given the nature of the fire, these unburnt patches varied considerably both in size and vegetation composition. Surveys were guided by maps provided by Department of Environment and Water that depicted prioritised unburnt patches within parks (Fig. 2), a fire severity map produced by Luke Ireland (Fig. 1c) and ease of access. Unburnt patches ranged in size from approximately 2 ha (Remarkable Rocks patch) to 1200 ha (“A-Wedge”). For smaller patches the whole area was traversed, but for larger patches a subsample was surveyed. Given the different sizes and vegetation structure, with some sites being almost impenetrable, standardised surveys were not possible. Where feasible, surveys followed the standardised 2 ha, 20 min active area search method (Loyn 1985) or a 500 m area search. Area searches generally lasted between 20–60 min to allow for good coverage of the patch; if the area was large enough each observer surveyed a different section (>500m apart). Incidental records of target species (Southern Emu-wren, Beautiful Firetails, Western Bassian Thrush, and Western Whipbird) were also taken. Call playback was occasionally used in suitable habitat to help locate Southern Emu-wren and Western Whipbird. February 2020 3 Figure 2. Priority unburnt patches within the park’s boundaries targeted during the rapid bird assessments, Kangaroo Island, South Australia, 20–28th February 2020. Map produced by D. Thompson (DEW). Distance to historic records of priority species (Table 1) dictated patch priority level. Results In total, 145 sites were surveyed, with 35 of these outside the fire area (Fig. 3). A mixture of incidental sightings of target species (n = 58), 2 ha 20 min surveys (n = 41) and 500 m area searches (n = 46) were undertaken. Table 1 lists the Kangaroo Island subspecies and other species of conservation concern identified by BirdLife Australia and the Department of Environment and Water and recorded during the surveys, with a total of 77 species and 2,654 individual birds recorded (see Appendix I). In general, the fire severity map was accurate. At times, areas that were depicted as having burnt at low severity, were tall Sugar Gums (Eucalyptus cladocalyx) with canopy leaves still attached but scorched, with little to no understorey remaining (Fig. 7). An area off Shackle Road in Ravine des Casoars Wilderness Protection Area was the only location where the surveyors found ‘patchily’ burnt vegetation, which was supporting Southern Emu-wrens and Western Whipbirds (see photos below). It was also around this area that the only Bassian Thrush were detected near a burnt-out swamp along Bull Creek. February 2020 4 Lathami CP Western River CP Cape Borda A-Wedge Shackle Rd Simpson CP West Bay Seal Bay Cape Cape Vivonne Seal Bay Vivonne Gantheaume Bouguer CP Cape du Bay CP Wilderness Couedic PA CP Figure 3. Bird survey sites across Kangaroo Island, South Australia from the 20–28th February 2020. Fire severity is depicted on the western end of the island where surveys were concentrated