Predictors of Gull-billed tern (Gelochelidon nilotica) nest survival in artificial coastal saltpans, Bohai Bay, China

Fuxing Wu; Weipan Lei; Huw Lloyd; Zhengwang Zhang

doi:10.7717/peerj.10054

Predictors of Gull-billed tern (Gelochelidon nilotica) nest survival in artificial coastal saltpans, Bohai Bay, China

PeerJ. 2020 Oct 5:8:e10054. doi: 10.7717/peerj.10054. eCollection 2020.

Authors

Fuxing Wu^{1

2}, Weipan Lei¹, Huw Lloyd³, Zhengwang Zhang¹

Affiliations

¹ Ministry of Education Key Laboratory for Biodiversity Sciences and Ecological Engineering, College of Life Sciences, Beijing Normal University, Beijing, China.
² Fujian Provincial Key Laboratory of Marine Ecological Conservation and Restoration, Third Institute of Oceanography, Ministry of Natural Resources, Xiamen, Fujian, China.
³ Department of Natural Sciences, Manchester Metropolitan University, Manchester, United Kingdom.

Abstract

Background: Coastal saltpans are a common supratidal human-modified wetland habitat found within many coastal landscape mosaics. Commercial salt production and aquaculture practices often result in the creation of exposed coastal substrates that could provide suitable breeding habitat for waterbird populations; however, few studies have quantified waterbird breeding success in these artificial wetlands.

Methods: Here we examine the nesting behavior of the Gull-billed tern (Gelochelidon nilotica) breeding in the Nanpu coastal saltpans of Bohai Bay, Yellow Sea, China over three consecutive nesting seasons (2017-2019) by using nest survival model in Program MARK.

Results: The results revealed that nest survival of Gull-billed terns in coastal saltpans (0.697) was higher than previously published estimates from other regions, with an estimated daily survival rate (DSR) of 0.982 ± 0.001 (±95% CI). High nest survival was mainly attributed to low levels of human disturbances and low predation rates, while exposure to strong winds, flooding and silting were the main factors causing nest failure. Model-averaged estimates revealed that eggs laid in nests located on 'habitat islands' with feather or clam shell substrates were most likely to hatch. Initiation date, nest age, clutch size and quadratic effects of nearest-neighbor distance, nearest distance to road and nearest distance to water were all significant predictors of nest success, but the nest survival declined overall from 2017 to 2019 due to the degradation and loss of breeding habitat anthropogenically caused by rising water levels.

Discussion: Coastal saltpans represent an alternative breeding habitat for the Gull-billed tern populations in Bohai Bay, but conservation management should prioritize flood prevention to improve the extent and quality of breeding habitat, concurrent with efforts to create further 'habitat islands' with suitable nesting substrate.

Keywords: Breeding ecology; Gull-billed Tern; Nest success; Saltpans; Waterbird conservation; Yellow Sea.

Grants and funding

This work was funded by the National Natural Science Foundation of China (31572288, 31830089, 31801985) and support from the Paulson Institute, the Alashan SEE Foundation and Fundamental Research Funds for the Central Universities. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.