Eagle maturation
Immature Bald Eagle _ Peekskill Bay
Nikon Z9 with Z 180-600 lens
1/2000 sec f/7.1 OSP 9000
Out once again to check and see if there were any new arrivals from the north today . The ice was a little more sparse than it was over the weekend, but currents and tides on the river will drive the ice in different directions and into different areas throughout the week and even throughout the day. For whatever reason, there was a little less ice and a bit fewer eagles at this location. One eagle that was sitting on the ice drew the attention of the folks who were looking for birds or just happened to be walking by. It was the young eagle seen above. A couple who were walking by wanted to know if both sexes of Bald eagles have white heads which lead to a discussion of how eagles plumage changes over the course of the first 5 years of their lives.
Bald eagle plumage is characterized by its striking contrast and distinct coloration, which plays a crucial role in the bird's identity and visibility. Adults feature a white head and tail, which stand out prominently against their dark brown body and wings. In an earlier post (1/6/25), I talked about how in certain species, the males and females have markedly different color patterns in their plumage. In Bald eagles, however, the only real difference in appearance is in size. The female eagle is actually a bit larger than the male. The feathers of both are dense and provide insulation, allowing them to thrive in varying temperatures. During mating season, the brilliance of the plumage is particularly highlighted, as these eagles engage in aerial displays to attract partners. Immature bald eagles like the one in the image above, however, have a more mottled appearance, displaying a mix of brown and white that gradually transforms into the iconic adult coloration as they mature, typically between four to five years of age.
An adult eagle with its iconic look of a pure white head and tail. Nikon Z9 with Z 180-600 mm 1/2000sec f/7.1 ISO 125
Tech Tip - ISO is a setting used to increase of decrease the sensitity of the sensor of a camera. A higher ISO setting on your camera will allow you to take pictures in lower light conditions while a lower reading will cut down on the sensitivity and allow you to shoot at higher speeds. Notice in the images above, both images were shot at 1/2000 sec and an aperture of 7.1. The first shot (the immature bird) was taken in overcast conditions where I needed to have a more sensitive sensor and therefore required a relatively higher setting of 900. The lower image was taken in bright sunlight and did not require as much sensitivity - hence a lower setting of 125. There is a negative trade-off in using higher ISO numbers. The higher the ISO, the “noisier” the image (what we used to call “grain” in the days of film). Lower settings give you a “cleaner” image. You may be able to see the difference in clarity of the two images above.
One easy solution to this “problem” is to set your camera to “AUTO ISO”. You set the shutter speed and the aperture and the camera will set the ISO to the correct setting to give you the proper exposure. I use AUTO ISO 90% of the time for wildlife photography. For a more in-depth explanation of using Auto ISO, Google Nikon Learn and Explore Understanding Auto ISO.
