Document: JAL-3-81-4

Pond selection and use by migrating trumpeter swans in Southern Alberta.

LAMONTAGNE, J.M.*

University of Calgary Calgary Alberta Canada ¹

Abstract:
Waterfowl migratory stopping areas provide energy reserves that are critical to subsequent success in breeding and rearing young. Trumpeter swans (Cygnus buccinator) are considered 'at-risk' in Alberta, yet little is known of what constitutes a suitable spring migratory stopping area. I investigated spring pond use during migration in an area 60km west of Calgary, Alberta. This foothills region contains many ponds, some of which are used by trumpeter swans every spring while others are never used. My objectives were to: 1) Determine activity budgets of trumpeter swans; 2) determine habitat characteristics of ponds used by swans; and 3) determine the impact trumpeter swans have on macrophyte growth. Behaviors were measured with focal-animal techniques. I assessed habitat characteristics such as pond morphometry, macrophyte species composition, tuber density, and water chemistry. Swan impact was measured using exclosures and comparing tuber densities in the excluded versus used areas of ponds. Trumpeter swans spent >50% of their time feeding and decreased tuber densities of Potamogeton pectinatus and P. richardsonii by 1/2. Trumpeter swans used shallow areas of ponds (depth < 1m), if tubers were present. Swans greatly impact those areas of ponds they use. Areas greater than 1m deep that support macrophyte growth may help recolonize impacted zones, thus maintaining the food of trumpeter swans. The information gained on migratory habitat is important to trumpeter swan conservation and reintroduction programs, as the preservation of this species requires knowledge of habitat requirements in not only wintering and breeding areas, but also during spring migration.

Keywords: habitat selection; trumpeter swan; spring migration; activity budget; pond characteristics; sustainable use

This abstract is being presented at: 4:00 PM in session:
Oral Session #14: Disturbance Effects on Bird Populations.