Potential implications of sea level rise on important bird areas, Victoria, Australia

Globally, a number of coastal localities have been classified as Important Bird Areas (IBA) as they contain favourable environments for feeding, breeding, nesting or stopover sites, and support a rich diversity of water birds. However, these habitats are vulnerable to inundation due to sea level rise (SLR). The state of Victoria, Australia, has 16 coastal IBAs, which contain saltmarshes, mangroves and intertidal flats that support a variety of resident and migratory birds. We assessed the potential inundation of these regions under SLR scenarios projected for this century. We used inundation layers, previously developed using a bathtub model, which projected SLR of 0.2m, 0.46m and 0.82m for 2040, 2070 and 2100, respectively. IBA and habitat shapefiles were overlaid with each scenario to calculate the area of each IBA and habitat type projected to be lost under the SLR scenarios. On average, 27% (sd ± 24%) of the area of IBAs is projected to be inundated with a 20 cm SLR, with this value rising to 40% (sd ± 28%) under the 82 cm scenario. Within IBAs, saltmarsh and intertidal flats may face substantial inundation, with an average loss of 46% (sd ± 33%) and 45% (sd ± 33%), respectively, under the 20 cm scenario. IBAs important for the critically endangered Orange Bellied Parrot and endangered Austral Bittern were projected to have the greatest exposure to inundation. Although all 16 IBAs have some land designated as protected, few have management strategies that explicitly account for SLR. Given the importance of these areas for birds, high resolution models of inundation that incorporate geomorphological characteristics of associated estuaries would greatly assist with identifying risks and designing appropriate adaptation strategies.