2023 Shorebirds expedition in NW Australia

by Bingrun -Drew- Zhu

It has been more than two years since the discovery of the bohaii subspecies of Black-tailed Godwits in the East Asian-Australasian Flyway (EAAF). While the pandemic brought fieldwork to a temporary halt, it provided an opportunity to delve into data exploration and summarisation. This period of research culminated in a PhD thesis interpreting fundamental aspects of the two Asian Black-tailed Godwit populations. This initiative signifies a gradual yet steadfast effort to develop our understanding of this species in the EAAF.

In our latest open access publication (Zhu et al. 2023), we proposed a hypothesis regarding the breeding grounds of the two Asian godwit subspecies, i.e., bohaii and melanuroides, positing distinct eastern and western breeding sites that lead to different non-breeding grounds through inland and coastal migratory corridors. To substantiate our theory and explore their breeding distributions, we conducted our first post-pandemic expedition in one of the non-breeding sites of melanuroides in Roebuck Bay, Northwest Australia. This site has been under the watchful eye of the Global Flyway Network (GFN) for over 16 years.

Shorebirds are caught on the shore of Roebuck Bay by cannon-netting. This can result in large catches of dozens of birds at a time, so we need a large team to process birds as quickly as possible.

Despite being one of the four GFN target species in the EAAF, the Black-tailed Godwit was the least studied, with only 394 individuals marked in NW Australia between 2006-2019, none of which were satellite tagged. The re-sightings indicate that NWA melanuroides use Lianyungang, China, and the Kamchatka Peninsula in the Russian Far East as stopping sites, but did not yield any information records at the breeding locations of this population. 

Our three-week expedition in Roebuck Bay involved leg flag and colour ring scanning, counts, and seven cannon nettings. In total, 1003 birds were captured, and we satellite tagged 29 Black-tailed Godwits along with 18 Bar-tailed Godwits, 31 Great Knots, and 29 Red Knots. While it will take several months before these individuals leave Australia for their breeding grounds, we have had the privilege of observing their non-breeding season movement patterns and habitat use in Roebuck Bay for the first time in history. During the dry season in NWA, godwits predominantly inhabit Roebuck Bay. Following February, with the onset of the rainy season, they depart from the Bay, and the destinations of their journey will hopefully be unveiled by these tracked individuals.

Daily distribution of satellite-tagged Black-tailed Godwits in Roebuck Bay from late October through mid-November. Never before did we have such detailed information about the species’ space use at this site.

Zhu, B. R., Verhoeven, M. A., Hassell, C. J., Leung, K. K., Dorofeev, D., Ma, Q., Zhengwang Zhang & Piersma, T. (2023). Predicting the non-breeding distributions of the two Asian subspecies of Black-tailed Godwit using morphological information. Avian Research, 14, 100069.

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