The University of Alberta, Canada has been studying the 10 year "boon/bust cycle historically associated with Canada Lynx and their primary prey, the Snowshoe Hare............This study evaluates if either climate change or barriers to dispersal is the main biological mechanism behind the breakdown of southern lynx cycles......... If seasonality is the primary driver, the analysis will provide evidence of how climate change is altering essential population cycles............ If dispersal is the primary driver, habitat/dispersal maps identifying barriers to movement through key lynx habitats will be created

UNIVERSITY OF ALBERTA LYNX RESEARCH

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A bit about the project...

This research focuses on the biological mechanisms driving population cycles of the Canadian lynx (Lynx canadensis) with specific attention paid to habitat fragmentation and climate change hypotheses. Persistent and regular population cycles produced by specialist predators and their prey are a rarity in nature, but Canadian lynx and snowshoe hare (Lepus americanus) display such a pervasive 10-year cycle. A recent breakdown in southern lynx cycles and falling population numbers in the US highlight threats to the integrity of boreal forest habitats, and may portend more widespread consequences of continued boreal forest fragmentation. An alternative hypothesis is that global warming is eroding the seasonality that maintains the 10-year cycle.

Our research objectives are to 1) regionally document the 10-year cycle break down at southern latitudes, 2) evaluate if barriers to lynx gene flow (hence dispersal) exist on a latitudinal gradient using genetic data, 3) use a sample of radiocollared lynx to create a model of habitats that facilitate dispersal, and 4) examine timeseries dynamics relative to climate data to evaluate the seasonal-forcing hypothesis.

 

 

Understanding dispersal trends is essential for managing habitat fragmentation and protecting habitat connections in southern Alberta and British Columbia. Likewise, climate change might be rapidly dismantling population cycles in the boreal forest. The persistence of lynx near the Canada-US border may depend on either quality of dispersal connections with the core Canadian population or stemming the progression of climate change before it permanently alters the species' dynamics. This study will help wildlife managers maintain an important predator in southern Canada. This research will also be used to inform forestry and other resource extraction industries, the trapping industry, and the collective knowledge of population ecology.

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The location of radiocollar fieldwork is the Central Eastern Slopes area of the Rocky Mountains. This foothill and mountain forest region is in the area surrounding and west of Nordegg, Alberta at Latitude 52.29 N Longitude 116.05 W. The Central Eastern Slopes area is densely forested. However, the region is primarily provincial crown land and therefore supports natural resource use including forest production, trapping and outdoor recreation, and oil and gas well sites.

This temperate coniferous forest area contains a mix of white spruce (Picea glauca), trembling aspen (Populus tremuloides), and lodgepole pine (Pinus contorta) with paper birch (Betula papyrifera), balsam poplar (Populus balsamifera), and balsam fir (Abies balsamifera). Lodgepole pine dominates drier locations and black spruce (Picea mariana) occurs in wet locations. Higher elevations contain subalpine forests consisting of lodgpole pine, alpine fir (Abies lasiocarpa), and Engelmann spruce (Picea engelmannii). The vegetation is a mix between boreal and cordilleran sometimes described as the Montane Cordillera ecozone. The landscape contains steep slopes as well as rolling hills, typical of mountain foothill areas
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OBJECTIVES-
This proposal focuses on mechanisms driving population cycles of the Canadian lynx in southern portions of their range by evaluating the predator dispersal versus the seasonal-forcing hypothesis (see lynx ecology page). The objectives are to 1) regionally document the 10-year cycle break down at southern latitudes, 2) evaluate barriers to gene flow (hence dispersal) across a latitudinal gradient, 3) use radiocollared lynx to create a robust GIS-based model of habitats that facilitate dispersal into the southern portions of the species’ range, and 4) examine timeseries dynamics relative to climate data to evaluate the seasonal-forcing hypothesis.

METHODS-
To quantify the breakdown of the lynx cycle on a fine scale (objective one) trappers’ harvest data will be compiled for Alberta, BC, Yukon, and NWT from the Hudson’s Bay Company Archives prior to1950 and provincial registered fur management areas (traplines) between 1950 and 2006. We will aggregate harvest data among adjacent areas having similar dynamical patterns based on Moran’s I (Moran 1950) and analyze the north-south gradient using timeseries methods organized spatially in a geographical information system (GIS).

Evaluating dispersal barriers using genetics (objective two) will require gathering tissue samples during the 2007-08 Alberta and BC trapping seasons (small samples of skin removed harvested lynx pelts). We will use 20 microsatellite loci effective in genotyping lynx to quantify the geneflow across southern portions of the range (Campbell & Strobeck 2006, Schwartz et al. 2002, Rueness et al. 2003). Genetic structuring of the population will be characterized using STRUCTURE software. We will analyze isolation at the individual level using spatial autocorrelation procedures (Cushman et al. 2006).

 

 

The third step involves radiocollaring a sample of 20 lynx in the Central Eastern Slopes area of the Rocky Mountains in Alberta, collaborating with Washington Fish and Wildlife’s efforts to collar 5 lynx in Washington east of Ross Lake, and utilizing a lynx movement dataset collected previously by NWT Fish and Wildlife in the northern range. The Rocky Mountain sample constitutes the southernmost tip of the core population where we expect the greatest potential for dispersal through the Kettle River Mountains towards the BC-Washington border as well as down the Rocky Mountain foothills towards the Alberta-Montana border. We will characterize and map dispersal habitats by estimating a GIS-based step selection function (SSF) to characterize habitat selection by lynx in the three locations (Fortin et al. 2005). The SSF/dispersal map will identify movement barriers throughout the region (Chetkiewicz et al. 2006). Landscape-based movement barriers will be compared with gene-flow barriers for a holistic understanding of lynx movement in the region.

The final step (objective four) involves examining seasonality metrics calculated from the past 50+ years of data from Alberta, BC, Yukon, and NWT weather stations. One important trend to explore is the change in quasi-periodic atmospheric circulation patterns, such as positive Pacific Decadal Oscillation (PDO) trends associated with warmer winters, higher winter rain ratios, and early snowpack melt (Mantua et al. 1997, Kitzberger et al. 2007). We will be exploring which combination of climate metrics might be the key biological component(s) of seasonality for the lynx-hare cycle, including the winter PDO index, temperature, snow pack depth, snow water equivalent, and season length (Stenseth et al. 1999, Case & Peterson. 2007, Hurrell 1995, Hebblewhite 2005). Preliminary studies indicate that snow type might particularly influence lynx hunting efficiency (Stenseth et al. 1999). Once an adequate index is ascertained, we will estimate correlation between my a priori expectations of reduced seasonality and deterioration of southern lynx cycles.

SIGNIFICANCE-
Persistent and regular population cycles are a major force creating a periodic rhythm in boreal ecosystems (Krebs et al. 2001). Localized examples of a dampened southern lynx cycles in Alberta and British Columbia as well as declining populations in the US highlight threats to the integrity of forests in western Canada and adjacent Border States. These changes have direct implications for the consequences of increasing fragmentation and climate change in the boreal forest (Schneider 2002). This study evaluates if either climate change or barriers to dispersal is the main biological mechanism behind the breakdown of southern lynx cycles. If seasonality is the primary driver, my analysis will provide evidence of how climate change is altering essential population cycles. If dispersal is the primary driver, we will have habitat/dispersal maps identifying barriers to movement through key lynx habitats. This will allow me to model scenarios in which industry might modify their practices to maintain persistent lynx populations and dispersal connections throughout the range. The project results will inform the sustainable use of Canada’s forest habitats for functioning ecological processes and long-term economic viability in Alberta and British Columbia.