Readers’ wildlife photos

Reader Tom Carrolan, who works on raptors, sent us a post about eagles. His notes are indented:

The Bald Eagle (Haliaeetus leucocephalus) was an early bird on our Endangered Species List due to DDT use. At the first Earth Day, Syracuse NY’s Onondaga Lake was dead. In addition to a chemical plant, the city dumped raw sewage into the lake. In the early 20th century, bath houses and a full-blown amusement park atmosphere was present. Earlier, as Onondaga Lake is a salt lake, this industry was also present. Nowadays the Bald Eagle wintering population on the lake is fairly large . . .not Alaska or Mississippi River large, but forty wintering eagles is quite a sight! These are Canadian Bald Eagles moving in mid-winter as rivers and lakes freeze over farther north. Obviously, fish have repopulated the lake since the 70s.

This image of eagles landing on a slushy ice mix triggered Sean Kirst’s original Syracuse Post Standard article referenced above. Also we see a partial view of Bald Eagles of various ages in a tree right on the lake shore (it takes this species three years to develop the full white head and tail).

Adult Bald Eagles of the northern subspecies migrate in late winter through early spring. By the end of April into June, the southern population eagles (Florida and Gulf Coast) disperse north, all the way to the Canadian Maritimes. In August, mid-Atlantic and Ohio River Valley. Balds disperse through upstate New York state. September sightings of this species consist almost entirely of southern Balds heading back south for their December nesting. Satellite tracking of the northern birds shows even the youngest ones don’t move south until November. Northern adult migration continues well into December.
This pair was photographed near Onondaga Lake in late February. The female on the left is larger than her mate. Reverse sexual dimorphism is common in our hawks and owls,  and has been studied throughout the later 20th Century. . . looking for rhyme or reason.

This is also a bonded pair sitting not far from Onondaga Lake in winter. Like an old married couple on a long sofa, they are sitting like the image above—but not shoulder to shoulder.

In flight, the adult bird is iconic with a white head and tail. Before Brian Wheeler’s latest volumes, it was “common knowledge” that it took five years to reach this plumage, now we know it develops faster.

One last adult bird, photographed in winter at Onondaga Lake, Syracuse NY. Adults are difficult to photograph as the white head contrasts strongly with the body, making exposure allowances for a bright background difficult. All my in-flight raptor images have a plus overexposure setting to compensate for the bright sky (otherwise you get a nice silhouette… a cardboard cutout of a bird)! For adult Balds and also Osprey, I quickly change that setting as the bird approaches.

Immature bald eagles are all dark brown in their first year’s plumage and various changes occur over the next three years. This is a juvenile eagle showing a feature thought to be diagnostic for this species: note that the underwing coverts are white (leading half of the underwing). The all-brown fuselage varies a bit, and some young birds have white on the lower body toward the tail.

Some first year birds are much darker. The underwing coverts on this juvenile bird are quite dark brown. In September at a hawk watch that doesn’t see many Golden Eagles, this individual might get misidentified. But remember, September Florida Balds are abundant as they migrate south.

Here we see a white tail and a bit of an adult white head on the older immature bird, which also has a black facial mask (like an Osprey). Note the one long, pointed, pale feather at the mid-wing: a retained unmolted feather.

It is easier to see the longer retained feathers here, as there are several. The shorter, blunt feathers are the adult feathers. The pale translucent feathers in the outer wings are also unmolted younger feathers wearing out with age. The tail is still dark, but the head is getting white.

And last, in late April, we have a Florida Bald Eagle dispersing north along Lake Ontario on a warm hazy day. This one probably hatched in late December or early January.

 

17 Comments

  1. ThyroidPlanet
    Posted December 22, 2018 at 8:12 am | Permalink

    Thise are some perfect bald eagle photos!

    • ThyroidPlanet
      Posted December 22, 2018 at 8:12 am | Permalink

      Those

  2. rickflick
    Posted December 22, 2018 at 8:20 am | Permalink

    Bald eagles are a glorious bird. I’m glad the turkey was not chosen as the Nation’s symbol. We have seen several eagles in (south western) Idaho lately. I’m not sure if they are migrating or residence.

    • Posted December 22, 2018 at 10:46 am | Permalink

      Yes, a beautiful bird and definitely better-looking (to most of us) than the turkey.

      • gravelinspector-Aidan
        Posted December 22, 2018 at 3:40 pm | Permalink

        But in the spirit of utilitarianism, which tastes better?

  3. Randall Schenck
    Posted December 22, 2018 at 8:49 am | Permalink

    It is good to know why the photos I use to take don’t always come out so good. I wonder if the eagles will become over populated in some areas. When still living in southwest Iowa I would see as many as 100 eagles on a 25 acre lake during the spring thaw. There were a few golden eagles but primarily bald eagles.

    • rickflick
      Posted December 22, 2018 at 10:26 am | Permalink

      Once you spread 100 Eagles across North America they won’t seem so crowded.

      “At the lowest recorded point (in 1963), there were only 417 nesting pairs of Bald Eagles in the lower 48 states. By 2007 that number had grown to 10,000, which prompted the removal of the Bald Eagle from the Endangered Species list. Estimates for the current number of Bald Eagle nesting pairs in the lower 48 states are now at 14,000 – 15,000.”

      • Randall Schenck
        Posted December 22, 2018 at 11:04 am | Permalink

        30 thousand seems like almost nothing across the entire country. In the 60s it was rare to see a bald eagle. Seeing that convention on the lake just a few years ago provides a false sense of the real population.

  4. Mark Sturtevant
    Posted December 22, 2018 at 9:50 am | Permalink

    Very good! I expect that reverse sexual dimorphism is suspected to be the result of selection for fecundity. But that may not be demonstrated.

  5. SnowyOwl
    Posted December 22, 2018 at 10:36 am | Permalink

    Mark:
    Here are three PDFs on RSD in hawks and owls.

    The evolution of it:
    https://www.hawksaloft.com/Kruger2005a.pdf

    Dean Amadon’s naturalist approach to reason for, so unscientific:
    https://www.hawksaloft.com/Amadon1975-RSD.pdf
    https://www.hawksaloft.com/Amadon1977-RSD.pdf

    • rickflick
      Posted December 22, 2018 at 12:15 pm | Permalink

      From the Kruger abstract, “These results suggest that RSD in hawks, falcons and owls evolved due to natural-selection pressures rather than sexual-selection pressures.”
      Sounds right. Thanks for the links.

  6. Posted December 22, 2018 at 12:19 pm | Permalink

    Lovely pictures. I also laugh at some of the language, such as “working on raptors” and “fuselage”. It sounds like we’re talking about servicing fighter planes. They are certainly high-performance birds after all.

  7. Posted December 22, 2018 at 1:24 pm | Permalink

    It is wonderful that many of the raptor species that were so badly hit by DDT have managed to build up their numbers again. In many places and in many ways biodiversity has taken a tremendous battering so it is good to note the success stories that buck this trend.

    Great set of photos. Thank you.

  8. jpetts
    Posted December 22, 2018 at 7:39 pm | Permalink

    They are everywhere in coastal WA – we even have five breeding pairs in downtown Redmond.

  9. Mark R.
    Posted December 22, 2018 at 8:30 pm | Permalink

    These are the type of photos that make me wish I were a bird…

    • Mark R.
      Posted December 22, 2018 at 8:31 pm | Permalink

      I were…? maybe I was. 🙂


%d bloggers like this: