Red Knot (Calidris canutus) Science Article 12 abstract Bird migration systems must have changed dramatically during the glacial-interglacial cycles of the Pleistocene and as novel habitats became available since the last glacial maximum. This study combines molecular dating of population divergence times with a review of polar-centred palaeovegetation and intertidal habitats world-wide to present a […]
Category: Scolopacidae
Modelling phenotypic flexibility: an optimality analysis of gizzard size in Red Knots Calidris canutus
Red Knot (Calidris canutus) Science Article 13 abstract Reversible phenotypic changes, such as those observed in nutritional organs of long-distance migrants, increasingly receive the attention of ornithologists. In this paper we review the cost-benefit studies that have been performed on the flexible gizzard of Red Knots Calidris canutus. By varying the hardness of the diet […]
Digestive bottleneck affects foraging decisions in red knots Calidris canutus. I. Prey choice
Red Knot (Calidris canutus) Science Article 14 abstract Rate-maximizing foragers that only divide their time between searching and handling prey should, according to the classical contingency model (CM), only select those prey whose energy content per unit handling time (i.e. profitability) exceeds or equals long-term average energy intake rate. However, if digestively constrained foragers were […]
Distribution, migrations and biometrics of Knots Calidris canutus canutus on Taimyr, Siberia
Red Knot (Calidris canutus) Science Article 7 abstract Studies carried out in northern Taimyr in 1982-84 and 1990-92 were combined with data from other sources to describe the breeding distribution and densities and the migration of Knots at Taimyr Peninsula, north-central Siberia. Morphometrics, recent ring recoveries, dates and directions of migration all support the idea […]
Cost-benefit analysis of mollusc eating in a shorebird I. Foraging and processing costs estimated by the doubly labelled water method
Red Knot (Calidris canutus) Science Article 4 abstract Although the energy costs of foraging and food processing in vertebrates may be considerable, they have rarely been quantified separately. Here we present estimates for both cost factors based on a series of trials with a shorebird, the red knot Calidris canutus, fed natural and artificial prey […]
Endogenous circannual rhythmicity in a non-passerine migrant, the Knot Calidris canutus.
Red Knot (Calidris canutus) Science Article 8 abstract We present experimental evidence for endogenous control of circannual rhythms in a long-distance migratory wader, the Knot Calidris canutus. Six individuals of the subspecies canutus were caught during northward migration whilst staging in France, and were held together under constant temperature and photoperiodic conditions (15 degree C, […]
Where waders may parallel penguins: Spontaneous increase in locomotor activity triggered by fat depletion in a voluntarily fasting Knot.
Red Knot (Calidris canutus) Science Article 6 abstract A Knot Calidris canutus, kept with four conspecifics on an enclosed artificial outdoor tidal flat in The Netherlands, refused to feed on the available bivalve prey for a period of 18 days and thereby decreased in mass from 209 g to 107 g, at which point the […]
Length of stopover, fuel storage and a sex-bias in the occurrence of two subspecies of Red Knots Calidris c. canutus an d C.c. islandica in the Dutch Wadden Sea during southward migration.
Red Knot (Calidris canutus) Science Article 1 abstract During southward migration the Wadden Sea is the meeting place of Red Knots Calidris canutus of two subspecies that breed in either western Siberia (C. c. canutus) or north Greenland and north-east Can ada (C. c . islandica), but the details of their co-occurrence have not been […]
Population structure and origins of Purple Sandpipers Calidris maritima in north Norway during winter
Purple Sandpiper (Calidris maritima) Science Article 2 abstract Wintering Purple Sandpipers Calidris maritima were captured at Varangerfjorden, Finnmark, in March 1992, and compared with samples from Troms county in November 1988 to describe the population structure in north Norway in terms of age and sex classes, and to determine the origins of these wintering birds. […]
How do Purple Sandpipers Calidris maritima survive the winter north of the Arctic circle?
Purple Sandpiper (Calidris maritima) Science Article 1 abstract Winter north of the Arctic circle in northern Norway is colder, windier and there is less solar radiation than in eastern Scotland, at a latitude 13degree further south. We predicted from equations derived from heated taxidermic mounts that the maintenance metabolism (Basal Metabolic Rate plus extra costs […]