Diet and energy intake of Grey and Ringed plovers, Pluvialis squatarola and Charadrius hiaticula, in the non‐breeding season

• Published in: Journal of Zoology
• Main Author: Pienkowski, Michael W.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 1982
• Subjects: Charadrius hiaticula
• Online Access: http://dx.doi.org/10.1111/jzo.1982.197.4.511; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fjzo.1982.197.4.511; https://onlinelibrary.wiley.com/doi/pdf/10.1111/jzo.1982.197.4.511; https://zslpublications.onlinelibrary.wiley.com/doi/pdf/10.1111/jzo.1982.197.4.511

The diets, feeding rates, foraging times during daylight, the extent of nocturnal feeding and food intakes of Grey and Ringed plovers Pluvialis squatarola and Charadrius hiaticula are described or estimated from field observations, checked by ciné‐film, in Northumberland, England, from autumn to spring of the years 1973–76. (Gut analysis was unreliable as a quantitative guide to diet.) Main prey at Lindisfarne for both plovers were the polychaete worms Notomastus, Arenicola and probably Scoloplos and Phyllodoce and, for Ringed plovers, also various small Crustacea, particularly Bathyporeia and Eurydice . Comparisons with diets of the same species elsewhere showed that they are not specialized but vary their diet in accordance with the prey species common in a particular area. In autumn and spring, but not in winter, food requirements could be met during daylight. An increase in the percentage of the daylight hours spent feeding in winter was inadequate to compensate for the decreases in both hours of daylight and feeding rate which occur at this season. Both plovers were able to feed at night, but, on dark nights at least, at a slower rate than by day. High winds apparently depressed the extent of nocturnal feeding. In mid‐winter, the birds maintain high fat levels, probably to buffer the effects of days when they have difficulty in obtaining their energy requirements, such as during cold and windy weather. Because plovers' feeding rates are reduced more by low temperatures than those of waders foraging by touch, their rates of energy intake fall more in such conditions. An attempt is made to predict the minimum densities of prey required for energy balance in various conditions and to compare the foraging strategies of visually foraging plovers and tactilely‐foraging sandpipers.