Monday, May 13, 2013

Immature Black-crowned Night-Heron

As I was taking a quick drive around the Provo Airport Dike (Provo, Utah) last Saturday, just before the sun rose from behind the Wasatch Mountain range, I came across about five Black-crowned Night-Herons in varying phases of plumage. I saw one adult, one 1st-summer bird (showing both adult and juvenile feathers), and several still in juvenile plumage. One of the young birds perched on a snag and allowed nice views. A little sunshine would have revealed much more detail, but I like how well the images turned out in such low light. It seems like a more typical light condition for seeing these birds since they are more active in open space during evenings and early mornings. Seeing this plumage in the middle of May seems late for what most field guides show for juvenile plumage. Sibley, for example, indicates juvenile plumage falls in the approximate range of July to January. First-summer plumage ranges from February to August.

Immature Black-crowned Night-Heron on Provo Airport Dike--Provo, UT (Photo by Jeff Cooper)
You can see the start of the birds white plume coming from the nape and running just past the shoulder in the image below. An adult bird's white plume will reach to about the middle of the back.

Black-crowned Night-Herons show a heavy and sharply pointed bill. While the adult has a dark bill, the bill of a juvenile shows extensive yellow, especially on the lower mandible. The throat and chest of young birds show broad and blurry streaks. A younger juvenile bird will show many more large white spots on wings than seen on this bird because this one has lost some juvenile feathers. This bird's white spots are fewer and smaller than a full juvenile plumage. Juveniles show more of an orange-red iris while adults show a very red iris.

Here is a true juvenile from two summers ago. It is perched in a pose not often seen for with Night-Herons, a fully extended neck. You can see much more spotting on the wings and back of this one.

I don't have very many images of adult Black-crowned Night-Herons, but here is one as a comparison to the immature plumage. The black bill, black crown, dark back and gray wings and tail can be seen. The feet barely extend beyond the tail in flight.

Adult Black-crowned Night-Heron in Flight on Deseret Ranch in Rich County, UT (Photo by Jeff Cooper)
And below is a view from the front of an adult bird. This one was seen during the summer of 2011 on the Provo Airport Dike. A careful look will reveal the long white plume from the crown to the back.

It's not a detailed imaged (probably a good thing considering the subject), but this final image shows a Night-Heron emptying its bowels mid-flight. That rope of stuff seemed to stretch for about 20 feet at one point as it fell from the sky.

Adult Black-crowned Night-Heron Lightening The Load Over Warm Springs WMA Utah County, Utah
(Photo by Jeff Cooper)

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