Do the high energy lifestyles of shorebirds result in high maximal metabolic rates? - Basal and maximal metabolic rates in least and pectoral sandpipers during migration

Shorebirds have high resting and field metabolic rates relative to many other bird groups, and this is posited to be related to their high-energy lifestyle. Maximum metabolic outputs for cold or exercise are also often high for bird groups with energetically demanding lifestyles. Moreover, shorebirds demonstrate flexible basal and maximal metabolic rates, which vary with changing energy demands throughout the annual cycle. Consequently, shorebirds might be expected to have high maximum metabolic rates, especially during migration periods. We captured least (Calidris minutilla) and pectoral (C. melanotos) sandpipers during spring and fall migration in southeastern South Dakota and measured maximal exercise metabolic rate (MMR; least sandpipers only), summit metabolic rate (Msum, maximal cold-induced metabolic rate) and basal metabolic rate (BMR, minimum maintenance metabolic rate) with open-circuit respirometry. BMR for both least and pectoral sandpipers exceeded allometric predictions b...