TITLE:
Loon Nest Viability Model: A Performance Indicator for Improving Water-Level Regulation of Large Water Bodies
AUTHORS:
Marianne Bachand, Julien Hénault Richard, Sylvain Martin, Steve K. Windels, Jean Morin
KEYWORDS:
Gavia immer, Namakan Reservoir, Nest Viability, Performance Indicator, Rainy Lake, Rule Curves, Water Level
JOURNAL NAME:
Natural Resources,
Vol.9 No.1,
January
24,
2018
ABSTRACT: Rule curves dictating target water levels for management
have been implemented in several water bodies in North America over the last 70
years or more. Anthropogenic alterations of water levels are known to affect
several components of wetland ecosystems. Evaluating the influence of rule
curves on biological components with simple performance indicators could help
harmonize water level management with wetland integrity. We assessed the
potential of using the probability of common loon nest viability as a
performance indicator of long-term impacts of rule curves on nesting wetland
birds. We analyzed the outcome of rule curves on the probability of loon nest
viability in Rainy Lake and Namakan Reservoir, 2 regulated water bodies located
along the Ontario-Minnesota border. The
analysis was focused on 4 hydrological time series between 1950 and 2013: 2
sets of time series simulating rule curves used to manage the water bodies in
the past decades (referred to as the 1970RC and 2000RC), one of the historical
measured water levels, and one of computed natural water levels. The
probability of loon nest viability under the 1970RC was 2× higher than under
natural conditions in both water bodies. The probability was also 2× higher
under the 2000RC than under the 1970RC in the Namakan Reservoir but not in
Rainy Lake. The rule curves generally improved conditions for nesting loons in
both water bodies. The presented performance indicator can be used to evaluate
future rule curves before they are implemented in the Rainy-Namakan or other
similar systems.