LE3 .A278 1985

1985

Smith, Peter

Acadia University

Master of Science

Masters

Biology

Biology

The purpose of this study was to examine some aspects of the foraging and energetics of migrant Black-bellied Plovers (Pluvialis squatarola (Linnaeus)) on the Starrs Point mudflat in the Southern Bight of the Minas Basin during the months of May through September 1980 and 1981. Dietary studies and field observations revealed that on Starrs Point the large predaceous polychaete worm Glycera dibranchiata was the major prey item of foraging Black-bellied Plovers representing 49.6% of the identifiable biomass in the gut. On the mudflat, G. dibranchiata was widespread but showed a patchy distrioution. In the study area, an average density of 28.3 + 16.4 worms / m was calculated during August and September, 1981. Within patches, worms appeared to be randomly distributed. A capture rate of 0.28 + 0.32 worms/ min was observed during the study and the average size of G. dibranchiata in the gut was 0.161 + 0.101 g dry weight. Caloric content of G. dibranchiata was 23.23 kJ /gash-free dry weight and an average daily intake rate of 541.3 kJ / day was estimated. This led to a potential rate of fat deposition of 5.1 g / 24 h. I estimated that 68 g of fat were necessary to fuel the birds on a non-stop migration to Surinam. On Starrs Point, Black-bellied Plovers foraged in the typical 'run-stop-peck' fashion associated with plovers. As visual predators they appeared to exploit the brief periods of surface activity of the worms. Birds frequently foot-trembled, an activity believed to enhance prey availability. Size distribution of G. dibranchiata in the gut did not differ greatly from that found in the mud. Distribution of foraging birds was not similar to that of G. dibranchiata. Prey availability appeared to be the most crucial factor affecting foraging behaviour.

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