Field of Science

Heron rookery in early spring

The Phactors, other guests, and our country-living hosts all took a pre-dinner nature walk to work up an appetite. The destination was the banks of a nearby river where the great blue herons had returned to their rookery high in a sycamore. For those of you who have never seen a great blue heron please understand that they are a big bird about 1.2-1.4 m tall and 2-4 kg in mass. This shows the top of the tree and less than half of the nests in the rookery. There were 20-30 herons present at the time; it was difficult to get a good count because of comings and goings, and our distance (and somebody didn't bring their spotting scope).  In the summer, the rookery is rather hard to see because of the leaves, but you can hear the birds from some distance especially after the eggs hatch. 


Anonymous said...

The rookeries I've seen have led to defoliation of the trees and breakage of limbs. Are these common effects - is the rookery you watched affected? Also, do you notice a smell? Or maybe the weather is still too cool and the residents too recently arrived.

The Phytophactor said...

No question some damage occurs to the tree, but it's crown was quite leafy last season. Probably is smelly under the tree, but never been there.