Scanning Electron Microscopic Observations of the Digestive Canal of the Great Bustard (Otis Tarda)

Abstract

This study focussed on the microstructure of the digestive canal of the Great Bustard ( Otis tarda). Under scanning electron microscopy (SEM), different morphological plicae (rounded protrusions about 10 μm in height) were observed at different locations along the inner surface of the oesophagus. Concentrated microvilli can be seen on the surface of the protrusions in high-power fields. There are papillae in the mucosal fold on the inner surface of the glandular stomach, with openings of about 250 μm in diameter. In high-power fields, the tops of rod cells could be seen in somewhat circular forms with microvilli on them. Inside the muscular stomach, the scraggly- or wavy-formed surface of the cuticle layer could be seen. Stripping off the cuticle layer, at the tops of mucosal folds row- or rope-like forms could be seen. The mucosa of the small intestine is thrown into ridges running longitudinally in a zigzag pattern along the intestine, rather than the finger-like intestinal villi observed in mammals. There are villi on the inner surface of the caecum with impressions on their domes (the troughs between which have diameters of about 200 μm). Villi on the inner surface of the rectum are even thicker, ranging from 200–500 μm in diameter, and could be seen on the inner surface of the caecum and rectum. Outlines of cell domes are clearer on the inner surface of the caecum than those on the rectum. Studies on the fine structures of the inner surface of the Great Bustard digestive canal will enrich the knowledge of the comparative histology of birds, and provide a reference for raising bustards, as well as preventing and curing its diseases.

Comparative Analysis of the Gut Microbiota of Three Sympatric Terrestrial Wild Bird Species Overwintering in Farmland Habitats

“…Gut microbial diversity was found to remain positively correlated with the gut retention time of the host. In addition, the Great Bustard, Common Crane, and Common Coot all have well-developed ceca, which increases the retention time of food in the gut and promotes the stability of gut symbionts ( Fanke et al, 2011 ; Crompton and Nesheim, 2016 ; Li et al, 2017 ). Via PCoA analysis coupled with ANOSIM statistical test, we consistently revealed that these three sympatric wild birds have significantly different gut microbiota.…”

“…During wintering, the Great Bustard, Common Coot, and Common Crane share the same habitat and feed mainly on plant seeds from farmlands and wastelands ( Johnsgard, 1983 ; Mouronval et al, 2007 ; Liu et al, 2018 ). These species all have a complex digestive system with a developed cecum ( Fanke et al, 2011 ; Crompton and Nesheim, 2016 ; Li et al, 2017 ) and share similar behavioral patterns, such as terrestrial living and group-living ( Alonso et al, 2004 ; Mouronval et al, 2007 ; Lu et al, 2021a ). Simplification of confounding factors can facilitate comparative analysis of the gut microbiota of wild bird species living under natural conditions ( Lee et al, 2020 ), and a shared overwintering habitat provides an ideal condition to compare the adaptive changes in the gut microbiota of different hosts.…”

Data_Sheet_1.docx

“…Gut microbial diversity was found to remain positively correlated with the gut retention time of the host. In addition, the Great Bustard, Common Crane, and Common Coot all have welldeveloped ceca, which increases the retention time of food in the gut and promotes the stability of gut symbionts (Fanke et al, 2011;Crompton and Nesheim, 2016;Li et al, 2017). Via PCoA analysis coupled with ANOSIM statistical test, we consistently revealed that these three sympatric wild birds have significantly different gut microbiota.…”

“…During wintering, the Great Bustard, Common Coot, and Common Crane share the same habitat and feed mainly on plant seeds from farmlands and wastelands (Johnsgard, 1983;Mouronval et al, 2007;Liu et al, 2018). These species all have a complex digestive system with a developed cecum (Fanke et al, 2011;Crompton and Nesheim, 2016;Li et al, 2017) and share similar behavioral patterns, such as terrestrial living and group-living (Alonso et al, 2004;Mouronval et al, 2007;Lu et al, 2021a). Simplification of confounding factors can facilitate comparative analysis of the gut microbiota of wild bird species living under natural conditions (Lee et al, 2020), and a shared overwintering habitat provides an ideal condition to compare the adaptive changes in the gut microbiota of different hosts.…”