I think there has been great discussion about red-breasted merganser numbers.  While we know there has been a decline since the 1980's, I don't know that we can say at this time that there is immediate need for concern.  I have placed a graph I created from Christmas Bird Count data at the following site:

 

http://www.rarebird.org/forum/forum_posts.asp?TID=4435&PID=12829#12829

 

I used red-breasted merganser data from all of the United States from the first count until the most recent.  Ohio-only data would not be useful as most birds are gone by count time.  What this data appears to show are spikes in numbers in the 1940's and 1980's.  The graph away from thos spikes is pretty flat with just minor fluctuations.  There has been a gradual rise from before the first spike, between the two spikes, and since the last spike.  I think these increases are probably due to increased number of observers.  Are these "non-spike times" more typical of the species, and the the spike in the 1980's an anomoly.  It would be interesting to know what caused the huge population increases in the 40's and 80's.  I don't think we can make any firm statements from the Christmas Bird Count data.  The data is valuable, but there are a lot of variables in it such as observer numbers, population shifts to or from areas that may or may not be counted.  As Mark and others have stated there is a lot we don't know.  Most waterfowl surveys conducted by the government agencies lump the mergansers together.  Also, once they leave the Great Lakes they head to the coast and may be far out on the ocean where numbers are difficult to count.

 

Another brief note about the count of 250,000 birds counted in the 1980's.  There were several of us at Sherod Park west of Vermilion watching.  There was an endless flock of mergansers that passed by for over two hours.  It was not a trickle, but a dense flock for two hours.  It is something that should be experienced.  After the flight we talked with Ohio Division of Wildlife personnel that were a little skeptical.  they had reason to be skeptical.  In Bellrose's Ducks, Geese and Swans of North America he mentions that red-breasted mergansers travel in flocks of 5-15 birds.  He also mentioned an average winter population of 60,000 birds for the four flyways.  Wildlife personnel said that if we saw flocks that large the next year let them know and they would attempt an aerial survey.  The following year an aerial survey was conducted and their count was I believe 220,000 plus or minus 40,000 and they felt it was more on the plus side.  They also felt that Lake Erie was a staging area for the majority of the red-breasted merganser population in North America.  I can't remember the estimate, but I think it was above 70%.   

 

In any case, Lake Erie is one of the few areas where these kinds of numbers of red-breasted mergansers can be obseerved.  It is something that should be experienced.  After seeing the huge flocks in the 80's I had a lot better understanding of accounts of the huge passenger pigeon flocks.  We saw what happened with that species.  It is amazing how such an abundant species can disappear.  Let's keep an eye on the red-breasted merganser population levels.  If Lake Erie is still the main staging area for this species in North America then our counts are critical.  The count of 80,000 this past week is a pretty respectable number.  However, it is a large drop from numbers counted in the 1980's, but which numbers are more typical?  Maybe we should be watching this species more closely.

 

John Pogacnik
                                          
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