Flexible Foraging Response of Wintering Hooded Cranes (Grus monacha) to Food Availability in the Lakes of the Yangtze River Floodplain, China

Abstract

Wetlands are disappearing or degrading at an unprecedented rate due to the increase in human encroachment and disturbance, eventually leading to habitat loss for waterbirds, which is the primary cause of the decline in the Hooded Crane (Grus monacha) population. The Hooded Cranes have to constantly adjust their foraging strategies to survive to cope with this situation. In order to study how cranes respond to food resources in mosaic habitat, we surveyed a total of 420 food quadrats and 736 behavioral samples from three habitats during three wintering periods in Shengjin Lake and Caizi Lake. We measured temporal and between-habitat differences in foraging time budget, foraging frequency, and foraging success rate. Akaike’s information criterion was selected between the models of food abundance and availability. The results indicated that the wintering cranes spent the majority of their time (66.55%) foraging and shifted their foraging behaviors based upon food abundance and availability in different habitats. Our analyses also indicated that cranes were willing to forage more food with poor sediment penetrability in sub-optimal habitats. Foraging time budget was based on the food depth, and the foraging frequency and foraging success rate were based on food abundance. Cranes adopted flexible foraging strategies in response to the alternative food resources in mosaic wetland habitats, as it could mitigate the negative impacts of habitat loss and facilitate survival.

Retraction of invasiveSpartina alternifloraand its effect on the habitat loss of endangered migratory bird species and their decline in YNNR using remote sensing technology

“…However, these actions result in the decrease of benthic biomass and species in S. salsa marsh and habitat. Thus, it also affected the food supply of cranes and increased the difficulty of foraging to a certain extent (Yang et al., 2015; Wei & Wenbing, 2020; Li & Ge, 2013), thereby giving room for enough freshwater to be retained in YNNR, which gives P. australis leverage in its expansion and domination of 32.792 km 2 of the whole study area from the supratidal area.…”

Influences of submerged plant collapse on diet composition, breadth, and overlap among four crane species at Poyang Lake, China

“…Numerous examples of dietary flexibility exist. Dunlins ( Calidris alpine ) [ 11 ], Semipalmated Sandpiper ( C. pusilla ) [ 16 ], Hooded Crane ( Grus monacha ) [ 17 ], and Black-necked Crane ( G. nigricollis ) [ 18 ] have all varied their diets with changes in prey availability. In contrast, strong dependence on a few prey types can make birds vulnerable to the reduction of prey abundance, as has been the case for Red Knot ( C. canutus ) feeding on Horseshoe Crab ( Limulus polyphemus ) eggs [ 19 ].…”

Effects of Food Changes on Intestinal Bacterial Diversity of Wintering Hooded Cranes (Grus monacha)

“…All these factors lead to hooded cranes being under great pressure to survive [ 22 ]. In order to relieve the stress of survival, hooded cranes must constantly adjust their foraging strategies [ 23 , 24 ]. Changes in bird foods are an important factor influencing changes in the gut microbial community [ 25 ].…”