Water level affects availability of optimal feeding habitats for threatened migratory waterbirds

Title
Water level affects availability of optimal feeding habitats for threatened migratory waterbirds
Publication Date
2017-12
Author(s)
Aharon-Rotman, Yaara
( author )
OrcID: https://orcid.org/0000-0002-2142-2718
Email: yaharonr@une.edu.au
UNE Id une-id:yaharonr
McEvoy, John
Zhaoju, Zheng
Yu, Hui
Wang, Xin
Si, Yali
Xu, Zhenggang
Yuan, Zeng
Jeong, Wooseog
Cao, Lei
Fox, Anthony D
Type of document
Journal Article
Language
en
Entity Type
Publication
Publisher
John Wiley & Sons Ltd
Place of publication
United Kingdom
DOI
10.1002/ece3.3566
UNE publication id
une:1959.11/30381
Abstract
Extensive ephemeral wetlands at Poyang Lake, created by dramatic seasonal changes in water level, constitute the main wintering site for migratory Anatidae in China. Reductions in wetland area during the last 15 years have led to proposals to build a Poyang Dam to retain high winter water levels within the lake. Changing the natural hydrological system will affect waterbirds dependent on water level changes for food availability and accessibility. We tracked two goose species with different feeding behaviors (greater white‐fronted geese Anser albifrons [grazing species] and swan geese Anser cygnoides [tuber‐feeding species]) during two winters with contrasting water levels (continuous recession in 2015; sustained high water in 2016, similar to those predicted post‐Poyang Dam), investigating the effects of water level change on their habitat selection based on vegetation and elevation. In 2015, white‐fronted geese extensively exploited sequentially created mudflats, feeding on short nutritious graminoid swards, while swan geese excavated substrates along the water edge for tubers. This critical dynamic ecotone successively exposes subaquatic food and supports early‐stage graminoid growth during water level recession. During sustained high water levels in 2016, both species selected mudflats, but also to a greater degree of habitats with longer established seasonal graminoid swards because access to tubers and new graminoid growth was restricted under high‐water conditions. Longer established graminoid swards offer less energetically profitable forage for both species. Substantial reduction in suitable habitat and confinement to less profitable forage by higher water levels is likely to reduce the ability of geese to accumulate sufficient fat stores for migration, with potential carryover effects on subsequent survival and reproduction. Our results suggest that high water levels in Poyang Lake should be retained during summer, but permitted to gradually recede, exposing new areas throughout winter to provide access for waterbirds from all feeding guilds.
Link
Citation
Ecology and Evolution, 7(23), p. 10440-10450
ISSN
2045-7758
Pubmed ID
29238566
Start page
10440
End page
10450
Rights
Attribution 4.0 International

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