Molluscivorous red knots rapidly adjust to a plant diet.
De Wilde M, Maarsingh B, de Monte LGG, Dekinga A, Bijleveld AI
Dietary Flexibility
PubMedSeagrass meadows, the same coastal plants that filter your local estuary and nursery fish you might eat, turn out to be a genuine food source for migratory shorebirds when shellfish run scarce—making seagrass conservation even more critical to coastal food webs.
Scientists thought red knots absolutely had to eat clams and mussels to survive. Then birds in Mauritania were spotted munching on the underground stems of seagrass instead. A lab experiment confirmed it: given plant-based food, the birds lost a little weight at first but stabilized within days, showing their guts can rewire surprisingly fast to handle a plant menu.
Key Findings
Birds lost 14% of body mass in the first days after switching to the plant diet before recovering and stabilizing at a new, lower baseline.
Fecal output shifted from green (a sign of starvation) to brown and increased in volume on the plant diet, indicating active digestion of plant material.
Gut adjustments—including changes to digestive anatomy and gut microbiome—occurred within just a few days of the diet switch.
chevron_right Technical Summary
Red knots—shorebirds thought to depend entirely on shellfish—can successfully switch to eating plant material. A captive experiment showed the birds adapted to a plant-based diet within days, with digestive system changes supporting the shift.
Abstract Preview
Dietary flexibility is key to adjusting to environmental change. In Mauritania, the seemingly obligatory molluscivorous red knots Calidris canutus were observed to eat seagrass rhizomes. To study t...
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Seagrasses are the only flowering plants which grow in marine environments. There are about 60 species of fully marine seagrasses which belong to four families, all in the order Alismatales. Seagrasses evolved from terrestrial plants which recolonised the ocean 70 to 100 million years ago.