Research Scientist, Wildlife Research Division, Science and Technology Branch
- Research Scientist, Wildlife Research Division, Science and Technology Branch, Environment Canada
- Primary research interests: winter ecology and migration ecology of Arctic geese and sea ducks (+ Eared grebes)
- PhD: Simon Fraser University, B.C.; Wrangel Island Snow Geese: population dynamics and interactions with bulrush marshes on the Fraser River delta
Title: Eared Grebes (Podiceps nigricollis): Changes in Affiliation Patterns Between British Columbia and Two Hypersaline Lakes in the USA
Friday, May 11th, 8:50 AM
Almost all N.A. Eared Grebes (Podiceps nigricollis) undertake a post-breeding migration to two hypersaline lakes, Mono Lake CA and Great Salt Lake UT. In 1996, grebes breeding in interior British Columbia were implanted with VHF transmitters to describe affiliation patterns with these lakes. Aerial telemetry surveys in the fall of 1996 indicated that ca. 50% of the tagged birds were on Mono Lake whereas only ca. 10% were on Great Salt Lake. Abundance patterns on these lakes appear to have changed in recent years, suggesting that some grebes may have switched affiliations from Mono Lake to Great Salt Lake. To assess this possibility, we captured grebes breeding on the same ponds in 2017 and implanted 30 birds with the same type of transmitter used in 1996 and attached light-level geolocators to their leg bands. Early fall telemetry surveys indicated that only 4 (15%) of the tagged birds were on Mono Lake whereas 12 (44%) were on Great Salt Lake. These findings suggest that the affiliation patterns of British Columbia grebes have changed over the last 20+ years. Interestingly, only 4 tagged birds were detected on the lakes during late fall surveys when more than 16 transmitters should have been present. The grebes accumulate a thick layer of body fat prior to migrating south and that is suspected to have reduced the signal strength of the internal transmitters. To circumvent this problem, we are planning to deploy backpack transmitters with external antennae on 30 breeding adults in 2018. Data from the 2017 VHF transmitters, the new 2018 tags, and retrieved geolocators will be used to determine the final proportional distribution of grebes on Mono Lake versus Great Salt Lake. They will also generate new information on migration patterns and overwintering areas.