Cormorant Menace?

I just sent the following email to the most excellent IslandWalk Lakes Committee.

When I posted my 2021-2022 IslandWalk Birds report, I noted a lot more double-crested cormorants than what I remembered as being usual.

A month or so ago, I read an article about how 10s of 1000s of cormorants were wreaking havoc on the salmon population in the pacific northwest. I couldn't find that article again, but if you google DuckDuckGo "cormorant problems", there are dozens of articles.

Then a couple of weeks ago, my wife & I vacationed in Ottawa, Canada. On the way there we spent a night in Clayton, NY, and took a 5 hour boat tour of the Thousand Islands - the area where the St. Lawrence River leaves Lake Ontario.

We learned an island is defined as: 1) above a minimum size; 2) always above water; 3) has at least 1 tree. We were shown 1 ~30-40' island that had no tree, but instead dozens of cormorants. The cormorants had started roosting there, and their acidic droppings had killed all the trees on the island.

I wanted to get at least 1 more data point, so I compiled my 2020-2021 IslandWalk bird data:

http://portraitofthedumbass.blogspot.com/2022/08/islandwalk-birds-2020-2021-season.html

Between the 2 sets of data, there was indeed a large increase in cormorant #s. 2020-2021, I counted at least 1 cormorant 100% of the time, the average was 3.2 birds, with a max of 10. 2021-2022, it was 95% of the time, but the average was 7.9, with a max of 25. That is around a 2.5x increase.

Hopefully I will be counting again this year, and hopefully this trend will not continue. And, of course, 2 data points is not nearly enough from which to extract a trend line.

But I wanted to bring it to your attention as something that needs to be watched. Does our lake management company also monitor the wildlife? If so, maybe pass this on to them? Maybe this is something that could be nipped in the bud before it becomes a problem?

It's too bad, I have enjoyed watching the cormorants fish on Lake #1, and I like how an aid to identifying them is how they always, whether swimming, standing on the bank, or roosting in a tree, keep their head at the same 20 degree angle.

And, of course, cormorants are protected by the Migratory Bird Treaty.

Best regards,
Chris Heinz