Elevated artifi cial nest sites for Mallard Anas platyrhynchos in Latvia

The use of elevated covered nest sites for Mallard Anas platyrhynchos was studied in 1999-2003 on coastal lakes and ponds of different origin. Within the 5-year period, a total of 723 checks of nest sites were made. Nest site occupancy by Mallard was much higher on ponds (46.8 %) than on large lakes (3.3 %). Occupancy of nest sites increased by years, likely due to increased experience by both managers and ducks. Nest sites appearing more natural seemed to be preferred by ducks. No signifi cant difference was found in occupancy between two-entrance nest sites (hay cylinders, wooden boxes) and one-entrance nest sites (53.4 % and 50.0 %, respectively) in 2003. Nesting success within a pond was higher in elevated nest sites with predator guards (87.7%) than in those without them (67.6 %). In the nest sites with predator guards nesting success averaged as high as 89.4 % (all locations combined) which is much higher than recorded in natural nests during the same period (L. Engure-23.3 %, L. Kanieris-54.3 %, ponds-25.0 %). In the nest sites with predator guards, 7.6 % were abandoned nests and 2.9 % were predated (only American mink Mustela vison). No predation by Marsh Harrier Circus aeruginosus, Hooded Crow Corvus corone cornix and Raven Corvus corax was observed in the elevated nests. The best results were achieved in the fi fth year: 55 nest sites, 35 occupied, and 27 successfully hatched in a 10 ha pond.

Arturs Laubergs and Janis Viksne, Acta Universitatis Latviensis, Biology, 2004, Vol. 676, pp. 107-118