Exploitation of intertidal feeding resources by the Red Knot Calidris canutus under megatidal conditions (Bay of Saint-Brieuc, France)

Type Article
Date 2015-02
Language English
Author(s) Sturbois Anthony1, 2, Ponsero Alain1, Desroy Nicolas3, Le Mao Patrick3, Fournier Jerome4, 5
Affiliation(s) 1 : Reserve Nat Baie St Brieuc, F-22120 Hillion, France.
2 : VivArmor Nat, F-22000 St Brieuc, France.
3 : IFREMER, Lab Environm & Ressources, Stn Dinard, F-35801 Dinard, France.
4 : CNRS, UMR BOREA 7208, F-75231 Paris 05, France.
5 : MNHN, Stn Marine, F-35801 Dinard, France.
Source Journal Of Sea Research (1385-1101) (Elsevier Science Bv), 2015-02 , Vol. 96 , P. 23-30
DOI 10.1016/j.seares.2014.11.001
WOS© Times Cited 1
Keyword(s) Diet, Benthos, Intertidal flat, Megatidal environment, Bay of Saint-Brieuc
Abstract The feeding ecology of the red knot has been widely studied across its wintering range. Red knots mainly select bivalves and gastropods, with differences between sites due to variation in prey availability. Shorebird’s diet is also influenced or controlled by the tidal regime. The aim of this paper is to demonstrate the adaptation of foraging red knots to the megatidal environment. The variation in their diet during tidal cycles was studied in the bay of Saint-Brieuc, a functional unit for this species. The method used combined macrofauna, distribution of foraging birds and diet data. Comparative spatial analyses of macrofauna and distribution of foraging red knots have shown that the bay's four benthic assemblages are exploited by birds. By analysing droppings, we highlighted that bivalve molluscs are the main component of their diet, as shown in most overwintering sites. Fifteen types of prey were identified and Donax vittatus was discovered to be a significant prey item. The relative proportion of each main prey item differs significantly depending on the benthic assemblage used to forage. All available benthic assemblages and all potential feeding resources can be used during a single tidal cycle, reflecting an adaptation to megatidal conditions. This approach develops accurate knowledge about the feeding ecology of birds which managers need in order to identify optimal areas for the conservation of waders based on the areas and resources actually used by the birds.
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