Energy budgets of curlew sandpipers at Langebaan Lagoon, South Africa

Abstract

The energy requirements and energy consumption of curlew sandpipers Calidris ferruginea at Langebaan Lagoon, South Africa, are described. The paper also includes estimates of the net annual production of the benthic invertebrates potentially available to the birds, and of the birds' impact on this.

Mean estimated energy requirement of a free-living curlew sandpiper was 125 kJ day⁻¹. Mean energy intake was 180 kJ day⁻¹, with 144 kJ assimilated at an assumed assimilation efficiency of 80%. Overwintering immature birds had a negative energy balance. A substantial positive balance existed in late summer and autumn, when adult birds moult and lay in fat reserves for migration. The estimated mean net annual production of benthic invertebrates potentially available to curlew sandpipers was 705±444 kJ m⁻² yr⁻¹. The birds took 12·3% of this or 86·7 kJ m⁻² yr⁻¹. It appears that the carrying capacity of Langebaan Lagoon for curlew sandpipers has not been reached with respect to food, but food is unlikely to be the only limiting factor.