Seasonal patterns in male Australasian Bittern Botaurus poiciloptilus calling at Bool Lagoon Game Reserve and Hacks Lagoon Conservation Park, South Australia

Abstract

Acoustic monitoring is widely used to support Australasian Bittern Botaurus poiciloptilus recovery, providing valuable records of potential breeding activity. We analysed calling patterns from recordings at Bool Lagoon Game Reserve and Hacks Lagoon Conservation Park, South Australia, across the 2022–2023 and 2023–2024 wet seasons. Specifically, we examined call distributions relative to sunrise and sunset and timing after inundation. At Bool Lagoon there were quite sharp peaks of calling within 1–2 hours of dawn and dusk (>84% of calls during these periods) but at Hacks Lagoon calling was spread more broadly through the night and morning. Booming began 22 and 7 days post-inundation in 2022–2023, and 34 and 24 days post-inundation in 2023–2024 at Bool and Hacks Lagoons, respectively. A late-season rise in water levels in 2023–2024 triggered a smaller peak in calling. These findings reveal temporal and site-specific variation in Australasian Bittern calling in response to hydrological conditions and can inform conservation efforts to maintain water levels supporting the species’ 60-day booming and 79-day breeding periods.