Readers’ wildlife photos

Today we have another batch of fantastic photos of peregrine falcons taken by Bruce Lyon. It even has a title! His text is indented.

Peregrines during Jerry’s peregrinations

Jerry’s put up previous posts on these bird s(see here, here, here, here, and here), and it’s nesting season again for the pair of peregrine falcons (Falco peregrinus) I have been observing for the past four years along the California coast between Santa Cruz and San Francisco. Every year the pair has nested in a small cave in a cliff above the ocean. This year I was lucky enough to watch the female lay her first egg in mid-March. This post, however, is about last year’s nest, but I include a photo of the normal cave nest site to put last year’s turn of events into perspective.

Below: March of this year—the female walks to the nest with three eggs at the back of the small cave; the next day she laid a fourth egg and the both adults have since shared in incubation. When walking to the eggs the falcons resemble parrots which is not that surprising since we have learned in the past decade that the falcons are close to parrots on the avian family tree (and not related to hawks and eagles).

Last year, the birds nested in the same cave they used in the two previous years, but that nest was not successful, for unknown reasons (the eggs disappeared between my weekly visits). Previous studies of peregrines in central California found that they will often have a second nesting attempt after a failed first nest. My birds did eventually re-nest but they shocked me by their choice of nest site. The second nest was a tiny open shelf at the top of the cliff, at eye level and very close to where I always sit to observe the birds! It does not get better than this from a natural history perspective—tame falcons nesting at eye level in an open photogenic spot.

Below: The male settling in to incubate the three chestnut eggs. I find the egg color quite beautiful.

Below: A close-up of the male turning the eggs.

Below:  The female was snoozing when the male showed up to take a turn at incubation. The fact that she was snoozing while I sat 40 feet away shows how comfortable the birds had become with me. Perhaps they see me as just another dumb cow on the landscape.

Below: The male’s sudden arrival startled the sleeping female; she started to fall over and had to spread her wings to maintain balance.

Below: The female with two fairly recent hatchlings.

Below: Ten days later the male checks out the one surviving chick. The brood was quickly reduced to one chick, presumably due to limited food. Some starvation is normal in falcons, and peregrines and many other birds have a mechanism to efficiently cull the brood size (“brood reduction”) if it turns out they laid an overly optimistic number of eggs. They create an asynchronous hatch by starting incubating the eggs before all have been laid. This gives the early eggs a head start and a competitive advantage should food be limiting.

The adults each have their roles and the female seems to be the one who controls food at the nest. Whenever the male brought food directly to the nest she would rush to the nest to get the food from him. The sequence of photos below shows such an encounter. The male showed up with a freshly killed female red-winged blackbird and perched for a bit on a nearby rock before flying to the nest. As soon as he went to the nest the female showed up within seconds. The male then took off with the prey item, with the female following in hot pursuit. She eventually got the blackbird from him in an aerial transfer and then returned to the nest with it. Amusingly, the chick then stole the prey item from her and it took her a few minutes to get it back from the chick.

Below: The male perched next to the nest with a female red-winged blackbird.

Below: Before the male could even land at the nest with the prey the female showed up, causing him to take off with the meal.

Below: As the chick got older it started to harass the parents, perhaps telling them it was hungry and that they should go at get some dinner for it. Here the chick has rushed the female who was perched at the nest and she complains and decides to leave.

Below: Another example where the male showed up at the nest with prey, only to have the female arrive within seconds and cause the male to leave. In this particular encounter, I had watched the pair kill the prey item about half an hour earlier. The male and female went after a mourning dove that they had watched go in and roost in a bush on a hillside several hundred yards (meters) away from the nest. The female flushed the dove from the bush and the male then nailed it. This photo was taken in the evening and had lovely backlighting, an effect I am very fond of.

Below: The chick five days before fledgling. It is hanging onto a branch while flapping furiously, presumably to strengthen its flight muscles in preparation for real flight.

16 Comments

  1. Stephen Barnard
    Posted April 19, 2017 at 8:18 am | Permalink

    Fantastic photos

  2. Debbie Coplan
    Posted April 19, 2017 at 8:43 am | Permalink

    Great post! I love the details of the story and seeing these incredible photos.
    Thanks!

  3. darrelle
    Posted April 19, 2017 at 9:11 am | Permalink

    Beautiful pics! I also appreciate the narrative.

    The second picture, the one with the Peregrine staring right at you, if that had been me behind the camera I would have been a bit alarmed. That is a fierce look!

    • eric
      Posted April 19, 2017 at 9:34 am | Permalink

      Yes. The talons showing in the second to last shot are also very impressive. Great nature pics.

  4. Mark Sturtevant
    Posted April 19, 2017 at 9:48 am | Permalink

    Great pictures, and a fascinating narrative! I really enjoyed it.

  5. rickflick
    Posted April 19, 2017 at 11:04 am | Permalink

    Peregrines are my favorite hunting birds. Fast and beautiful. Thanks for the wonderful close view of their fascinating behavior.

  6. Heather Hastie
    Posted April 19, 2017 at 12:17 pm | Permalink

    Wow! What fabulous photos and a great narrative! Most enjoyable.

    I’ve loved previous photos of this pair, and can’t wait for more.

  7. revelator60
    Posted April 19, 2017 at 12:44 pm | Permalink

    Superb photos and very informative text. I must say, falcon family life does not seem especially warm…

  8. ploubere
    Posted April 19, 2017 at 12:52 pm | Permalink

    Excellent photos and story. Between Bruce and Stephen, I’m too abashed to ever submit photos again.

  9. Reggie Cormack
    Posted April 19, 2017 at 2:19 pm | Permalink

    Thanks for sharing.

  10. Mark R.
    Posted April 19, 2017 at 2:21 pm | Permalink

    I’ve been missing the RWP, but this excellent batch makes up for the lapse.

  11. Posted April 19, 2017 at 5:10 pm | Permalink

    Congratulations to Bruce Lyon for the photos and the narrative!

    Does anyone know an explanation why brood size is culled? I mean, a bird egg is a huge investment – how does it pay to lay several eggs just to reduce them to one later? (To me, this resembles the strategy of United Airlines to overbook flights and then to drag passengers off planes.)

    • Jonathan Wallace
      Posted April 20, 2017 at 9:39 am | Permalink

      I think there are several different hypotheses for why hatching asynchrony occurs. The idea suggested by David Lack and others is that it provides a mechanism for adjusting the number of chicks raised to the available food supply. If there is plenty of food all of the eggs will result in fledged chicks but if they are poor then at least some of the chicks should survive because the larger chick(s) will be able to monopolize what food there is (if all the chicks are equal in size and strength then it may be that none of them get enough and all starve). A related benefit is that if food supply is short the smaller, weaker chicks will die quickly thereby minimizing the amount of wasted parental investment.

      In eagles and some other large species this cannot be the explanation though because the first hatched chick always (or virtually always) kills its sibling even when food is very plentiful _ ‘obligate siblicide’. In this case it is suggested that the second egg is laid as an insurance against infertility (or accidental harm) in the first egg.

      Hatching asynchrony is set up by the parent bird incubating the eggs from the moment they are laid (normally at daily intervals) rather than waiting for the full clutch to be laid before starting to incubate. A third explanation is that the brood hierarchy set up as a result of asynchronous hatching is simply a by-product and the reason for asynchronous hatching is that it reduces the amount of time before at least one chick is safely fledged and hence the length of exposure to predation. The end result is the same – ‘at least one chick raised to fledging’ – but the mechanism is avoided-predation rather than avoided-starvation. The reduced time-to-fledging of the first chick may also be beneficial in species that exploit a food resource that is available only during a narrow time band as it will help ensure that at least one chick is fledged before the food supply dries up.

      Hatching asynchrony and the associated ‘culling’ of part of the brood of chicks therefore is likely to have different explanations in different species depending on the ecology of the species and the key mortality factors affecting the probability of chic survival.

  12. Tracy H
    Posted April 19, 2017 at 6:15 pm | Permalink

    Oh, thank you thank you for that wonderful photo essay!

  13. Michael Waterhouse
    Posted April 20, 2017 at 12:35 am | Permalink

    Great pictures and story.

    Is there something about apex predators that makes them extra special?

  14. Posted April 20, 2017 at 9:55 am | Permalink

    Great photos! Wow! Thanks for sharing them!


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