Changes in the Habitat Preference of Crested Ibis (Nipponia nippon) during a Period of Rapid Population Increase

Abstract

The number of breeding pairs of crested ibis (Nipponia nippon) in Hanzhong, China has recovered remarkably from 2 to 511 from 1981 to 2019. Although the crested ibis has been closely monitored, the habitat preference of the bird has not been well studied despite the extensive increase in abundance. We used nest site data from the past 39 years and 30 environmental variables to develop species distribution models for each year. We applied random forest to select important environmental variables, and used logistic regressions to quantify the changes in habitat preferences in 39 years, taking into account the effects of interaction and quadratic terms. We found that six variables had strong impacts on nest site selection. The interaction term of rice paddies and waterbodies, and the quadratic term of precipitation of the wettest quarter of the year were the most important correlates of nest presence. Human impact at nest sites changed from low to high as birds increased their use of ancestral habitats with abundant rice paddies. We concluded that during the population recovery, the crested ibises retained their dependence on wetlands, yet moved from remote areas to populated rural regions where food resources had recovered due to the ban of pesticide use.

Conservation Challenges: Climate and Land Use/Land Cover Changes Increasing Habitat Overlap Among Endangered Crested Ibis and Sympatric Egret‎/‎Heron Species

“…The divergence in their foraging behaviors reduces competitive pressures, allowing for their coexistence. However, increasing spatial overlap in their distribution after environmental alterations may lead to heightened competitive interactions, as they share the consumption of aquatic creatures within the same space [33][34][35][36] .…”

“…Our ndings align with these previous studies and emphasize the importance of controlling human activities that contribute to LULC changes, such as the extensive expansion of agricultural land and impervious areas. Although the Crested Ibis does bene t from human intervention to some extent 33,39 , it is crucial to regulate the intensity of human pressure and the rates of LULC changes to ensure the species' population recovery. It is worth mentioning that changes in climate and LULC will affect sympatric EHs differently.…”

“…This specialization makes the Crested Ibis more dependent on speci c resources and environmental conditions. Consequently, it is less competitive and more vulnerable to environmental changes, potentially facing increased competition from other species with similar but broader niche requirements 22,25,33 .…”

A Breeding Plumage in the Making: The Unique Process of Plumage Coloration in the Crested Ibis in Terms of Chemical Composition and Sex Hormones

“…The endangered status has shifted from critically endangered to endangered, with the current Crested Ibis population reaching 11,000 individuals. Scientists are actively conducting research in various aspects including population dynamics [3,4], genetics [5][6][7], disease management [8,9], habitat restoration [10][11][12], conservation efforts [13,14], and behavior observation [15]. One particularly intriguing aspect of this species is its distinct plumage color changes that occur throughout the year, especially during the breeding season.…”

An Automatic Identification Method of Crested Ibis (Nipponia nippon) Habitat Based on Spatiotemporal Density Detection

“…The crested ibis ( Nipponia nippon Temminck, 1835 ) is one of the national Class I key protected animals in China and is an endangered bird worldwide [ 1 , 2 ]. Since the 20th century, numerous institutes have carried out continuous protection activities and research on the crested ibis [ 3 , 4 , 5 , 6 , 7 ]. Through joint efforts, this endangered wild bird species [ 8 , 9 ] has been successfully protected, with a thousand-fold increase in its population.…”