Mortality Data as an Indicator of Ecological Trends

The information collected at operational wind turbines provides a unique opportunity to assess general population and behavior trends of a wide variety of bird and bat species, including some species that are otherwise... [ view full abstract ]

The information collected at operational wind turbines provides a unique opportunity to assess general population and behavior trends of a wide variety of bird and bat species, including some species that are otherwise difficult to study.

Using a dataset collected at more than 30 operational projects in Ontario over the last 6 years (2009-2015), a unique opportunity exists to analyze the dataset as a whole to assess larger ecological trends, such as migration timing, or even to assess the relative population dynamics over time to assess whether the species is showing signs of population decline.

Using Little Brown Myotis as a case study, an analysis of the mortality data indicate a steady and continuous decline in observed mortalities from 5.33 Little Brown Myotis/turbine in 2009 to 0.06 Little Brown Myotis/turbine in 2015. Although this decline in observed Little Brown Myotis observations is due to the spread of white-nose syndrome in Ontario during those years, the decline in observed mortality is nonetheless linked to the population dynamics as a whole.

Using this link between observed mortalities and known populations declines of Little Brown Myotis during this time period, this presentation will use a similar comparison of data to assess whether any other species appear to be showing population declines. Preliminary information indicates that although annual fluctuation is observed in each of Eastern Red Bat, Hoary Bat, Silver-haired Bat, and Big Brown Bat, most results show no indications of a decline in per turbine interactions which can be very loosely attributed to confirmation that populations are not undergoing dramatic population declines.

This presentation will provide a detailed look at the preliminary assessment made in this review of annual per turbine mortality rates and will provide further insight into the current status of other Ontario bat species in the context of general population, seasonal behaviour, and migratory activity. This comparison is particularly important for many of the bat species, where little is known about population numbers and therefore cumulative effects are difficult to assess.