There is renewed interest in the nesting success of Common Loons (photos by Mark Peck).

The Canadian Lakes Loon Survey conducted by Birds Canada has analyzed information about a remarkable 35,000 nesting attempts by Common Loon pairs across southern Canada, collected by more than 4,000 volunteer birders. Data collection started in 1981 in Ontario and spread across the rest of southern Canada in the mid-1990s. The huge amount of information provided biologists with an opportunity to test the influence of more than a dozen different factors on Common Loon productivity over an extended period.

The factors included the effect of acid rain, mercury contamination in fish, shoreline development, boating activity, risk of predation by Bald Eagles, competition for forage fish by Double-crested Cormorants, and a suite of weather variables based on temperature and precipitation.

Researchers ruled out shoreline development, human disturbance, eagles, and cormorants as strong factors for the declines in Common Loon productivity across all of Ontario or southern Canada; however, some of those factors certainly play a role on particular lakes. Their analysis suggests that a complex interplay between the effect of acid rain, mercury pollution, and on-going climate heating may be at least partly responsible for productivity declines of Common Loons across southern Canada. Dubbing this the “acid-mercury-climate hypothesis,” biologists are pursuing additional research to test its merits, which will provide much needed guidance about what can be done to best conserve the Common Loon, an impressive symbol of pristine wilderness.

Learn more about the information provided in the Birds Canada report at https://www.birdscanada.org/canadian-lakes-loon-survey-new-report-helps-explain-mysterious-declines/ and view an enjoyable introduction to the Common Loon report on YouTube at https://www.youtube.com/watch?v=hFEjkiy_IT4

The study of West Nile virus in ruffed grouse will resume this fall in Michigan, after a one-year pause due to the COVID-19 pandemic. In partnership with Minnesota and Wisconsin natural resources departments, the Michigan Department of Natural Resources began this multiyear study in 2018 to better understand the prevalence and distribution of the virus in ruffed grouse in the Upper Great Lakes region.

Results from previous study years suggest that while the virus is present in the Great Lakes region, grouse exposed to the virus can survive and develop antibodies as an immune response. In 2019, 20 of the 281 samples collected tested positive for exposure to the virus. Viral antibodies were confirmed in seven birds and likely in 13 additional birds. Only one juvenile male tested positive for the virus. In 2018, 28 of 213 samples were positive for exposure to the virus, with viral antibodies confirmed in nine birds and likely in 19. Four samples were positive for the virus.

“Though the virus can impact the ruffed grouse population, the impact appears to be minimal in Michigan,” said Julie Melotti, a laboratory technician at the DNR Wildlife Disease Laboratory. “In the Upper Peninsula, the overall health of the grouse population is more dependent on high-quality habitat, such as areas of regenerating aspen stands near stands of mature timber. In these areas, grouse are more likely to be healthier and have stronger immune responses to disease, inclement weather and other limiting factors.”

Sample kits have been distributed to grouse hunters in key West Nile virus surveillance areas to collect samples for viral analysis. The samples will be analyzed for antibodies, which indicate exposure to the virus, and heart tissue will be examined to screen for current presence of it. Sample kits were not distributed in 2020 due to the ongoing COVID-19 pandemic, but recently have been distributed to Michigan hunters for data collection during the 2021 season. Hunters who have kits remaining from past seasons are welcome to use them and submit additional samples. Hunters who provide email contact information with their samples will be notified of their results next fall.

West Nile virus was first detected in ruffed grouse in Michigan in 2002. Transmitted by mosquitoes, the virus can cause inflammation of the brain, brain lining, and spinal cord and heart lesions in infected birds. Grouse that have contracted the virus may fly erratically, act abnormally, or appear sick, thin and in poor condition. However, these symptoms are not always present in infected grouse. If you find a bird that appears thin or sick, please report your observations to the Wildlife Disease Lab at 517-336-5030 or through the online reporting system Eyes in the Field. Read more