Tuesday, 9 September 2014

Re: [cobirds] Black-crowned Night Heron seen floating on water, Wash Park, Denver. Who knew?

This may not be exactly the same, but a couple of years ago, I had a great blue heron walk into the pond where I live, wade out and then float in the water for 15 minutes or so. His wings for outstretched over the water. 
     I had some concerns that this was a suicidal gesture on the heron's part, but it proved to be unsuccessful, if that's what it was! It was a very odd sight to see and was really concerning to me. When I posted on Co birds about it, someone suggested that he was trying to drowned insects in his feathers… seemed reasonable to me.
      Deb Carstensen, Littleton, Arapahoe County.

Sent from my iPhone

On Sep 7, 2014, at 12:53 PM, Joe Roller <jroller9@gmail.com> wrote:

 I have been stopping by Grasmere Lake, the southern water body in Washington Park, at Downing and Louisiana, almost daily for a couple of weeks, counting American White Pelicans as their numbers grow - from 4 to 21, now plateauing around 19-21.

While there this morning I saw an adult Black-crowned Night Heron (hereafter BCNH) floating on the water!

It took me a while to figure out what family this bird was in, let alone species. It was somewhat loon-like, but the thick dagger bill, black crown and gray wings convinced me otherwise. The body was held horizontally, the bill parallel to the water.  I watched it for a minute, as it floated, not fishing or swimming. I ran around the south end to get a better look, and by that time it had resumed its normal vertical or hunched position on branches at the water's edge near it's 3 or 4 off-spring. I looked it up:

This from the Florida Natualist, Fall, 1973, James Kushlan:

Five feeding methods have been previously described for the species: 

Stand and Wait* &

Walk Slowly being the most common; 

Bill-vibrating, standing in shallow water while rapidly vibrating the bill at the surface, (Stone, 1937; Drinkwater, 1958); 

Hovering, flying in place above the surface and catching prey without settling into the water (Meyerriecks. 1960); and 

 Swimming- feeding, alighting on the water and catching prey while afloat (Wetmore, 1920). 

In this article, Kushlan describes "plunge-diving" from the air as a 6th feeding behavior.

Has anyone observed the floating or swimming behavior of Night-Herons?

Intriguing,  I thought.


* Milton - "They also serve who only stand and wait." 


Joe Roller,

Denver



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