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Pick a Bird Brain Series 2023

Periodic Invasions of Northern Goshawks

Ordinarily, hawk count sites do not see large numbers of Northern Goshawks during fall counts because migration is unnecessary with prey species available year round in their home ranges. Juvenile males make up the majority of the goshawks annually seen at hawk watches in most years. However, about every ten years, the normal patterns change in significant ways, and there is over one hundred years of data demonstrating this obvious change which is called an invasion. What does an invasion entail, and what might be responsible for this dramatic change? There is a story here, but even that predictable story is changing as there has not been an invasion observed since the early 2000’s.

Dr. Dick Green will look at historical observations made at three hawk watch sites: Hawk Ridge in Duluth, Minnesota, Cedar Grove in Wisconsin, and Hawk Mountain in Pennsylvania. He will puzzle out the pieces of the story that we know, and also attempt to understand the invasions by looking at the boreal forest community where Northern Goshawks live. Join us to take a look at this fascinating bird mystery!

Registration is required for this event.

Dr. Richard Green is a Professor Emeritus from the Swenson College of Science and Engineering, at University of Minnesota, Duluth. His research interests are mathematical models in animal behavior and ecology. He also serves as a member of the Hawk Ridge Bird Observatory Research Committee.

Mar 21, 2023 07:00 PM in Central Time (US and Canada)