Do Geese Facilitate or Compete with Wintering Hooded Cranes (Grus monacha) for Forage Resources?

Abstract

Foraging is the key behavior of waterbirds, which profoundly affects the survival of their population, and it is affected by interspecific interaction. At Shengjin Lake in China, owing to the reduced availability of suitable habitats for a large population of migratory waterbirds (especially wild geese) over winter, mixed species foraging inevitably occurs. This study aimed to investigate whether mixed-species foraging affects the foraging of hooded cranes (Grus monacha). Fields surveys were carried out at Shengjin Lake from November 2018 to March 2019. Mixed-species foraging was surveyed between the flocks of hooded cranes and three species of geese, greater white-fronted geese (Anser albifrons), lesser white-fronted geese (Anser erythropus) and bean geese (Anser fabalis). Instantaneous scanning and focal animal methods were used to collect behavioral samples of hooded cranes. The quadrat method was used to survey the food density in three habitats: meadows, mudflats, and paddy fields. The results showed that the foraging success rate of hooded cranes was not significantly correlated with food density and the relative flock size in the mixed-species foraging flock in meadows, but a significant negative correlation with the relative flock size in mudflats. However in paddy fields it was a significant positive correlation with the relative flock size. Foraging efforts of hooded cranes were negatively correlated with food density and positively correlated with the relative flock size in meadows. In mudflats, foraging efforts of hooded cranes had a significant positively correlation with the relative flock size, however, there was a significant negative correlation with the relative flock size in paddy fields. To sum up, larger numbers of geese mixed with hooded cranes has a favorable effect on the foraging of hooded cranes in meadows and mudflats, however, the reverse was observed in the paddy fields.

Intestinal Microbes of Hooded Cranes (Grus monacha) Wintering in Three Lakes of the Middle and Lower Yangtze River Floodplain

“…As waterbird is a mobile entity, there could be a higher frequency of encounters and more interactions among the waterbirds at Shengjin Lake. Every year, many geese (e.g., Bean Geese, Greater White-Fronted Geese, and Swan Goose) overwinter at Shengjin and Poyang Lakes [ 15 , 37 ]. Previous studies have shown that there was the sharing intestinal microbes between the Hooded Cranes and sympatric other waterbirds, such as the Greater White-Fronted Goose [ 38 ], and a recent study demonstrated that the social behaviors (direct or indirect contact) between the Hooded Cranes and the sympatric Bean Goose caused the intestinal bacteria to spread and increased the diversity of intestinal bacteria for both [ 11 ].…”

“…It has been listed as a vulnerable (VU) species by the International Union for Conservation of Nature (IUCN) and is a national first-class key protected wild animal in China. Hooded Cranes usually forage in clusters within family units, and their wintering habitats are relatively fixed [ 15 ]. After arriving at the wintering site from the breeding site, Hooded Cranes mix-forage with other waterbirds and spend nearly 6 months (from October to April) there [ 16 ].…”

“…After arriving at the wintering site from the breeding site, Hooded Cranes mix-forage with other waterbirds and spend nearly 6 months (from October to April) there [ 16 ]. Because of the degeneration of natural wetlands and habitat loss, there are only approximately 1050–1150 individuals that winter in China [ 15 ]. Poyang, Shengjin and Caizi Lakes are three lakes in the middle and lower Yangtze River floodplain with similar climatic conditions, serving as the main wintering grounds for Hooded Cranes in China [ 16 ].…”

“…Poyang, Shengjin and Caizi Lakes are three lakes in the middle and lower Yangtze River floodplain with similar climatic conditions, serving as the main wintering grounds for Hooded Cranes in China [ 16 ]. The population numbers of the cranes wintering in these three lakes are very similar, with approximately 300 individuals in each lake [ 15 , 17 , 18 ].…”

Behavioral Response of Bean Goose (Anser fabalis) to Simulated Ship Noises at Lake

“…Bean geese are a common waterbird species wintering in the lakes of the middle and lower Yangtze River floodplain with the largest populations and widest distribution [ 23 ]. Their habitats are mainly in the shallow waters of lakes, lakeside meadows, and farmlands and are often mixed with other swimming birds (e.g., spot-billed ducks ( Anas zonorhyncha ) and mallards), waders (e.g., little egrets ( Egretta garzetta ), and herons ( Ardea cinerea )).…”