Regurgitation of the koilin layer in chinstrap penguins (Pygoscelis antarcticus) and its association with gastric parasites

Abstract

The koilin membrane, formed by the secretions of the ventricular and pyloric glands, functions as a protective layer in the gizzards of most bird species. However, the ecological functions of koilin have never been studied in freeranging penguins. During the two austral summers from 2012 to 2014, we observed the regurgitated koilins of chinstrap penguins (Pygoscelis antarcticus) at Narę bski Point on King George Island, South Shetland Islands, and we detected a significant difference in the daily accumulation of regurgitated koilins between the pre-hatching and post-hatching periods in the rookery. We also found 233 gastrointestinal parasites, all Stegophorus macronectes (Nematoda, Acuariidae), from 26 out of 45 koilins freshly regurgitated by chinstrap penguins. We suggest that the regurgitation of koilins may benefit adult chinstrap penguins in the wild by reducing parasitic loads when they fast during incubation; it may also help decrease the risk of parasite transmission to chicks. Our results present the first observations of regurgitated koilins among breeding chinstrap penguins. How koilin regurgitation functions in penguins requires further study. Among the gentoo penguins (P. papua) co-occurring at the study site, we observed no regurgitated koilin layers.

Diet of adult and immature imperial cormorants, Leucocarbo atriceps, from southern Patagonia. A combined dietary approach and an exploratory analysis of stable isotopes of pellet membrane

“…This functions as a protective layer in the gizzard of birds and is formed both by secretion from glands (carbohydrate/protein complex) and by entrapped sloughed epithelial cells and cellular debris (Marshall 2013). This membrane has received little overall attention by ecologists (Kim et al 2016). To the researchers' knowledge, no SIA of this tissue has been undertaken in seabirds (or any bird species), even though the koilin membrane could potentially offer an easy and non-intrusive tissue to sample for SIA, which could be performed alongside the conventional analysis of the prey remains found in the pellet.…”

Health Surveillance of Penguins in the Barton Peninsula on King George Island, Antarctica

“…171; Narębski Point), located at the tip of Barton Peninsula on King George Island in the South Shetland Islands, Antarctica. This region hosts around 3,000 breeding pairs of Chinstrap Penguins (Pygoscelis antarcticus) and 2,300 pairs of Gentoo Penguins (Pygoscelis papua) annually (Kim et al 2016). After the Narębski Point Penguin Village of Antarctic King Sejong Station was designated as a protected zone in 2009, three types of monitoring on penguins were conducted: distribution of breeding birds, reproduction rate (egg production rate, hatching rate), and fluctuation of the breeding bird community.…”