Readers’ wildlife photos

Posting will be light today, but I’ve prepared this in advance for Grania to post when I’m downtown. It’s another great series of photos and stories from Bruce Lyon, documenting the lives of his local peregrine falcons. Bruce’s notes are indented.

Here is another installment of photos of the nesting  peregrine falcons (Falco peregrinus) I have been following for the past several years (most recent post here). Just like people, peregrine falcons sometimes have rodent problems in their attic. This year, the rodents in question—California ground squirrels (Otospermophilus beecheyi)—created such a mess in the small cave the peregrines normally use for nesting that the birds had to switch to a new site. The squirrels were tunneling in the roof of the cave, which caused a cascade of of dirt and rocks, making the cave unsuitable. This turned out to be a lucky break for me because the falcons ended up nesting in a much more photogenic spot near the top of the cliffs, a mere 15 feet from where I often sit to observe them. They nested at this site once before. In that year the nest was fully visible but cliff erosion did that specific dirt ledge in and they nested around a tiny corner just out of sight. I was still able to photograph them coming to the nest or landing on the branch near the nest.

Below: Guilty looking, or what? A California ground squirrel, but probably not the actual home-wrecker. In fact this one looks like it is lining its own home with soft materials.

In early March, a couple of weeks before the female laid the eggs, the pair began giving me clues that they would use the new site: they started spending way more time perching on the branch adjacent to the future nest site and they started bringing prey items to the branch and future nest site. Below the female flies in to perch on the favorite branch perch.

Below, the male brings a half-consumed Eurasian Collared-Dove to the same branch perch, with the female in hot pursuit just out of view. A split second after he landed, she landed beside him and snatched the dove from him. I do not interpret this as food stealing because the male often brings food to his mate. Sometimes the prey item is transferred in the air and sometimes the female grabs it from the male after he lands.

Below: Some photos of the other way the female receives prey from the male, with an aerial transfer. Sometimes the male holds the prey in his feet for the transfer, as shown below in the transfer of just captured European starling. All of these photos of prey transfers were taken from quite a distance so I had to crop them a ton.

Below: Less often the male holds the prey item to be transferred in his beak. This is actually the same starling as above. After it was half-eaten it got cached in a crevice in the cliff and the male later retrieved it and again offered it to the female.

More shots of same prey transfer but with pure sky background. After seeing the photos below a friend asked if I had done something funky in Photoshop to get the white background. The white background is simply just sky as it was overcast sky. Shooting birds against an overcast sky can be a tricky so I usually use a manual setting for the lighting: I check the light on the rocks on the cliff or the sandy beach below, lock in that exposure and it works pretty well. This accounts for the white sky, which I don’t mind and it did result in the lighting on the birds being properly exposed. On an automatic light meter setting, the birds would have been silhouettes. One can fiddle with exposure compensation but I find that manual control works better.

Below. Three shots of the female coming in to land at the favorite branch perch. These are taken with a new high-end Canon body (1DX Mark II). Given that the the nest location, this year was ideal for flight shots, and since the birds are now ridiculously tame around me, I decided to splurge and go for a body that can do real justice to flight shots. The new camera has not disappointed and I have been able to get lots of photographs that just were not possible in previous years.

Note in the photo below the female’s alulae are extended— the alula is the part half way along the wing that sticks up like a mini wing in the photo.  The alula, also known as bastard wing, is connected to the bird’s first digit (thumb), and the bird can move these feathers independently from the rest of the wing. Lift depends on smooth (laminar) flow of air over the wing and the alula plays a very important role in maintaining that smooth air flow at slow speeds, which prevents stalling. Looking through all of my photos shows that the birds often use the alula just before landing, presumably because they have slowed down. Lift increases as a square of airspeed so lift can drop dramatically at slow speeds and devices like the alula are useful in preventing stalling and crashing.

Another photo of the female flying by the branch perch. I like taking photos from this particular spot and angle because the wet sand beach in the background provides a nice mood, particularly when the bird is backlit. New camera aside, I was not previously able to get photos from this angle because I have to be really close (15 feet) to get a clear view of the perch without vegetation in the way. In the past, the birds would never have come in when I was this close but they now seem fine with it — I am just part of the scenery. Once in a while it hits me just how lucky I am to be able to watch these birds up so close, all while they go about their business normally.

I like the photo below because it shows the complicated arrangement that the wings and feathers sometimes take during a landing.

 

20 Comments

  1. Stephen Barnard
    Posted June 12, 2019 at 8:08 am | Permalink

    Spectacular photos

  2. Michael Fisher
    Posted June 12, 2019 at 8:20 am | Permalink

    Amazing birds & photos both! I especially like the last pic of the falcon in landing configuration.

  3. Julian C
    Posted June 12, 2019 at 8:21 am | Permalink

    Amazing. For looking at again and again

  4. Mark Jones
    Posted June 12, 2019 at 8:21 am | Permalink

    Blimey!

  5. rickflick
    Posted June 12, 2019 at 8:38 am | Permalink

    Great photos. Great birds.
    Note that the alula, which provide laminar flow over the wing is similar to vortex generators on aircraft. Vortex generators are small tabs or airfoils on the top of the wing that serve the same purpose of preventing stall at low speeds. In aircraft they are not retractable as they are in birds.

    • Michael Fisher
      Posted June 12, 2019 at 9:02 am | Permalink

      There was an argument among birdologists, aerologists & others as to the function of the alulae – is it a classical high-lift device or a boundary layer fence? The latter being to decouple the detached flow on the hand wing from the attached flow on the arm wing. Well it’s come down on your side.

      I notice that the Wiki for “leading-edge slat” still references the alula as a slat type device.

      • rickflick
        Posted June 12, 2019 at 12:08 pm | Permalink

        Interesting science. I used to fly a Cessna Cardinal (177B) which had a fixed slot along the leading edge of the horizontal stabilizer.

      • Posted June 12, 2019 at 1:48 pm | Permalink

        Since it is very short relative to the overall length of the wing, it very likely sets up a tip vortex as well, helping to prevent the spread of flow separation over the wing.

        Is the alula present in all (flying) birds?

        Seems to me it is in every one I can think of. Seems like it (the alula) must provide some useful service or it would have gone by disuse.

        The Wikiness:

        When flying at slow speeds or landing, the bird moves its alula slightly upwards and forward, which creates a small slot on the wing’s leading edge. This functions in the same way as the slats on the wing of an aircraft, allowing the wing to achieve a higher than normal angle of attack – and thus lift – without resulting in a stall.[1] The tip of the alula forms a tiny vortex that forces the airflow over the wing to better bind to it.[2][3]

        • Michael Fisher
          Posted June 12, 2019 at 2:26 pm | Permalink

          I can’t think of a flight ready avian without.

          The slot theory [analogy to airplane fixed or moveable leading edge slat] is not favoured these days as per my earlier comment. The alula is at the transition between the hand surface [turbulent airflow] & the arm surface [laminar attached airflow] & it is claimed the alula sets up a vortex that fences off the laminar flow of the inner wing from the turbulent flow of the outer wing – prevents the turbulence spreading inboard across the wing.

          Read this BASTARD WING post & comments below – excellent photos. The OP gives the slat argument while there’s comments below re vortex as an alternative. I think there will still be a to & fro on this in the next century!

  6. Terry Sheldon
    Posted June 12, 2019 at 8:45 am | Permalink

    Everyone else used all my superlatives, so I’ll just say thanks!!

  7. Posted June 12, 2019 at 8:45 am | Permalink

    As everyone else has said, these are spectacular photos of a spectacular bird. Great work.

  8. Debbie Coplan
    Posted June 12, 2019 at 8:51 am | Permalink

    Just gorgeous! What a wonderful post!
    Thank you-

  9. Robert
    Posted June 12, 2019 at 9:03 am | Permalink

    Amazing pictures and information. Thank you for sharing this.

  10. DrBrydon
    Posted June 12, 2019 at 9:04 am | Permalink

    Awesome pix! It’s all I can do to get people standing still in frame.

  11. Charles Sawicki
    Posted June 12, 2019 at 10:20 am | Permalink

    Beautiful peregrine photos, particularly of prey exchange. Interesting info on their wings.

  12. Posted June 12, 2019 at 12:19 pm | Permalink

    Beautiful photos Bruce! Thanks for sharing these and the stories with us!

    Excellent explanation of the “white sky” phenomenon in some of the shots. I used to be an all-manual guy. I didn’t even use the light meter in my cameras. When you now your film and are sensitive to the lighting conditions, you hardly need them. Shooting against the sky is particularly difficult (for light meters). You system is working well. Rocks make pretty good grey cards!

  13. Kenneth Averill
    Posted June 12, 2019 at 12:35 pm | Permalink

    Magnificent photos. Thank you!

  14. ThyroidPlanet
    Posted June 12, 2019 at 1:43 pm | Permalink

    Excellent set!

  15. Posted June 12, 2019 at 10:05 pm | Permalink

    Fantastic pics…

  16. Posted June 13, 2019 at 4:45 pm | Permalink

    Wha?! These are damn good!!


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