Abstract
Simple SummaryWith increasing human activity, bird habitats are being degraded and lost. In order to survive, birds have to adapt to the deteriorating environment. In this study, we surveyed the availability of food resources to Hooded Cranes in a degraded wetland. We found that cranes adopted flexible foraging strategies in response to the abundance and availability of different food resources in mosaic wetland landscapes at different periods during winter. The results also showed that the deeper the food was buried, the more time the cranes spent, and foraging frequency and foraging success rate were based on food abundance. It provided an evidence basis for the protection and management of waterbirds, especially Hooded Cranes.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.
Highlights
Foraging is a critical component of the annual life history of animals [1,2] and is a major determinant of survival [3,4], requiring the balancing of risk and reward [5,6]
Animals have likely developed flexible foraging strategies to optimize the benefits of foraging to facilitate survival, and they are able to respond to the complex environment in a timely manner and adjust their foraging behavior to attempt to consume food resources that offer the greatest energy gain at the least cost [13,14,15]
Several recent studies have focused on the ability of waterbirds to use flexible foraging strategies when utilizing different landscapes to obtain sufficient food, in areas subjected to habitat degradation and loss [14,31]
Summary
Foraging is a critical component of the annual life history of animals [1,2] and is a major determinant of survival [3,4], requiring the balancing of risk and reward [5,6]. The quality and quantity of food may be inversely correlated [10], with areas containing less nutritious items tending to cover larger areas [11] These constraints constitute an important ecological problem for species, with factors other than food likely altering the foraging behavior of animals [12]. Several recent studies have focused on the ability of waterbirds to use flexible foraging strategies when utilizing different landscapes to obtain sufficient food, in areas subjected to habitat degradation and loss [14,31] These adaptive responses might not be typical across species or geographic regions, with additional research being required
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