Impending Tragedy: Cormorants in the Great Blue Heron Rookery

I've always liked Cormorants very much I don't think they are ugly or funny looking, and I like how recognizable they are when flying.

According to the first Massachusetts Breeding Bird Atlas, Double-crested Cormorants don't breed in Middlesex County at all, never mind in the middle of Framingham.

This is the Great Blue Heron Rookery in the middle oft he Foss Reservoir between Route 9 and the Mass Pike. It is hard to get decent pictures from the shore, but you can see that there are quite a few Great Blues in the nests. (Click on the image for a larger view.)

There are fewer herons in the rookery than there were a year ago. There are many more Double-crested Cormorants than last year - and they are definitely breeding. It is hard to tell from so far away, but there are quite a few cormorant chicks among all those cormorants. Studies suggest when cormorants move into a GBH rookery, the herons will abandon it. (Click on the image to see the cormorants nesting.)

If I am going to lose my beloved Great Blue Herons to a bunch of cormorants, I will heartbroken and resentful. Just the possibility fills me with horror. I don't know why the Great Blue Herons give up their ancestral homes so easily, but the sheer volume of cormorants that appeared this year suggest they are simply outnumbered.