Charlie’s Photo of the Week is a Case of Empty Nest Syndrome

This article was originally intended to be my early “Spring is Here” message, showing the Great Blue Herons in their annual nesting grounds, preparing to bring in this year’s NEW GENERATION!! However, it has turned out to be a notification that this nest site is now abandoned!! The following message is my report and observations to friends at the New Jersey Division of Fish & Wildlife – Endangered & Non-game Species Program, followed by their responses.

My message*:

April 7, 2019, I visited the Pequest Great Blue Heron Rookery in Independence Township, which is a short distance from my home in Allamuchy. Throughout my visit I did not see one Blue Heron, in the air, on a branch or in a nest!! My visits in other years were always limited to a peripheral view, as I did not want to disturb the rookery!! On those visits, there were always quite a few circling above or coming and going. There was always a lot of action in the trees with the birds landing on branches or nests!! In these earlier years, I would always notice the herons flying back and forth from the rookery by looking out my front window, where my computer is, but this year I maybe saw one or two!! Yesterday, during my visit, because there were no birds, I walked around and noticed several new trees in the rookery area, each loaded with empty nests! The only thing I did notice was (I think) white bird scat under several of the trees, but not sure. Just as I was getting ready to leave, I heard a croak, looked up, and observed one heron land on a branch and then immediately fly away!!

My other visits, in earlier years, were in early March through April, both with no leaves and with leaves on the trees, this area was always busy with birds no matter what time of day! I attempted to visit this site about two weeks ago but opted not to go off the road without marking my in for an easy-to-find way out!! From the road it is only a little over a quarter mile in and I didn’t observe or hear one Heron, which I thought was strange!!

I am puzzled as to why this site would be completely abandoned, the rookery area itself seems perfect and intact, with no intrusion from man, as this is posted private property and out of sight and mind. My only concern might be airplane spraying of mosquitoes over the years, which is done pretty close to this site as I can watch the planes from my computer window just like I used to observe the Herons!

I believe at one time this was the largest Blue Heron Rookery in New Jersey!!??

Response from Principal Zoologist Kris Schantz:

That is puzzling! I was at this rookery MANY years ago and, yes, it always was quite productive. I’m looping in Christina Davis, our biologist responsible for this species. She may have some insight into what’s happening.

Response from Christina Davis:

Thanks for the message. This is something that happens with Great Blue Herons with some regularity — and with a lot of mystery! We have colonies all over the state that will abandon for reasons we do not really understand. What happens most of the time is that they simply move to a nearby locale, it does not seem to be a total abandonment of the general area. We aren’t sure why — maybe there is a predator we aren’t aware of or maybe foraging conditions declined. Or something else we haven’t detected! It is often hard to find the new spot because they like to be away from human disturbance. But if you look at an aerial and see bodies of water, that can be a good indication they will be nearby. When you do see foraging birds in the same general area as abandoned colony, you can watch and note which direction they fly to give you clues. If you want to take a really deep dive, some “heron detectives” have used tools like Google maps or Bing maps. If the aerials were taken in the winter, you can sometimes see nests in the trees! We have actually found new heronry sites this way!

The nests can persist for quite a few years, so that is why you are still seeing nests in places where there are no birds. By this time of year, the colonies should definitely be active so no herons is not a good sign… but it is possible it is just getting started really late (seems unlikely to me).

Mosquito spraying has potential impacts to a lot of wildlife, but not sure there is enough evidence to state that is the problem here, especially because Great Blue Herons do tend to move around. But maybe lack of mosquitos meant less fish in a nearby pond/water feature and they didn’t like that. Or ???

Thanks for your observations and let us know if you uncover anything new!

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For now, the site remains unused, but these Flickr links show the rookery site in past years: