We have special treat today: some lovely photos and videos of peregrine falcons taken by reader Bruce Lyon. His notes are indented:
Jerry previously posted some of my peregrine falcon (Falco peregrinus) photos. This new batch illustrates the photographic fruits from a lucky discovery last year—the peregrines almost always take their prey back to one of two favorite plucking/eating sites near their nest. Finding the plucking sites allowed me to see what species they eat as well as how they eat their prey. I also initially imagined unlimited wonderful photography opportunities, but it turns out the birds are shy when they have prey and would not let me approach them while eating. J. A. Baker also noted in his book The Peregrine that his peregrines became shyer when they had food. Maybe it is general peregrine thing—perhaps a carcass is a valuable commodity worth stealing so the birds become warier. To get photos I initially I had to resort to a camouflaged camera connected by long cable to my laptop; this setup allowed me to hide from sight and take photos remotely. I also set up small video cameras to run continuously and record whatever prey items the birds bring in, and below I include a couple of segments from these videos. The birds continue to get tamer over time and, finally, this year they will now let me watch them while they dine.
Below: The female on the pairs’ current favorite plucking station, a tiny pinnacle jutting up from the cliff very close to the nest. The feathers build up over time, like a fossil record of the victims—looks like the result of a macabre pillow fight.
Below: I had hoped to get photos of the falcons with a nice variety of prey species but the falcons had other ideas. They are dove specialists and, in particular, they really love introduced Eurasian Collared-Doves [Streptopelia decaocto]. As a result, the menu at the plucking station has been disappointingly boring—doves, doves and more doves. Here is the female with a freshly killed collared-dove.
Below: The female flies by the cliffs with a collared-dove in her talons.
Below: The male with a collared dove. I include this blurry photo for a couple of reasons. First, it is a nice still life of predator and prey (literally still life for the dove). Second, about half of the days my camera will not simply not focus on the bird on the plucking stack. It is not a problem with the camera’s auto focus mechanism because manual focus will not work. On these days is almost a mirage-like quality to the air. I have wondered if the problem is the salty air or a swirling mixture of warm and cold air? If any readers know what might be going on I would love to hear some ideas. Whatever the explanation it is bloody frustrating to have an amazing opportunity to photograph the falcons and their prey and then not be able to get a single remotely sharp image on a given day.
Below: Finally, something other than a dove! The male with an embarrassment of riches: a male Black-headed Grosbeak and what I believe is a Tennessee Warbler (but possibly an Orange-crowned Warbler since Tennessee warblers are not very common here).
Below: The male’s beak has ‘tomial’ notches. Falcons generally use these notches to sever the spinal chord of their victims. The upper beak has a projecting “tooth”, and the lower beak has a corresponding notch, and these fit together to make a devastating cutting implement. According the online Birds of North America species description for peregrines, this biting the prey neck action is instinctive—captive raised young birds do it when presented with their first intact bird carcass. The tomial notches are also used to cut bones; I assume this is how they snip away at the breastbone, which my birds always eat. In fact, the birds eat everything and at the end of the meal all that remains are the plucked feathers.
Below: The video [JAC: videos also taken by Bruce] shows the female biting the neck of a collared-dove as soon as she arrives at the plucking spot. I watched her chase this dove and comparing her departure time with the time stamp on the video camera for her arrival revealed that the entire chase and return to the plucking site took 2 minutes! Note that the female starts by eating the head—they always do this.
The birds always pluck the all of the flight feathers on the wings and tail at some point during the meal, and they typically pluck many of the body feathers too. They pluck body feathers by yanking beakfuls of feathers and then spitting them out, as this photo shows for the female:
Below: The wing feathers are so aerodynamic that after the falcons spit them out they sometimes spin upwards in the wind currents like a wind dispersed seed (e.g. maple keys), sometimes spinning for several minutes. The video below, taken a couple of days ago, shows the male plucking wing feathers from a dove and some of the primary feathers twirl away in the wind:
The pair sometimes share a prey item (the first bird to eat leaves some of the prey for the other bird). In the two photos below, the female has just eaten her share of a dove while the male sat impatiently on the nearby cliff, whining frequently about wanting his share. Once the female was done and no longer holding the dove down to eat, the wind blew the half eaten dove to the edge of the stack where it threatened to topple over and disappear into the ocean below. The female watched teetering carcass inch towards the precipice but did nothing. At this point, the male couldn’t stand it any more and had to come in an rescue his meal:
Below: The birds really do eat everything. Often the prey’s feet are the last thing to go down the hatch. Kind of fitting—head first, feet last. Here a fledgling savors a dove foot.
Wow, utterly magnificent story and photos. I did not know they ate everything. The last picture of the dove’s foot going down the hatch is really neat. Thanks for sharing all this with us.
I don’t understand the focus problem you described, but I would doubt it has anything to do with the air itself. I rather suspect the lens gets condensation on it. This could happen especially after a cold night, if there are warm humid morning breezes.
Thanks Lou. No, it is not the standard condensation problem at (I am familiar with that one issue). The camera and lens work just fine if I quickly turn and focus on something away from the pinnacle and I have also tried every combination of lens and body and problem persists. It really is something about the very specific location. Two days ago I had the problem and looking through the view finder the image through the view finder was shimmering, like a mirage—that is why I wondered if it might actually be something to do with the air and light. Perhaps I need to chat with some astronomer folks here at the University of California, Santa Cruz—they deal with ‘adaptive optics’ to remove distortions to images of space caused by our atmosphere (I think)so perhaps they might have some ideas.
I’m at a loss for an explanation then. I’ve never experienced that, but I guess if your lens is far enough away from the pinnacle, heat-shimmers might be a factor, like the shimmers that appear in the distance in deserts in the summer. Hope you figure it.
This sounds like a turbulent air flow effect, this article covers it
http://www.the-digital-picture.com/Photography-Tips/heat-waves-and-photography.aspx
Bingo! Thanks so much for finding this article. The photo of the bridge in the article your found looks just like all of my out-of-focus shots of the birds. Unfortunately it seems there is nothing that can be done except waiting for a different day and hoping that the birds do not bring in that extra charismatic prey item on a day with crappy shooting conditions.
I was thinking “heat haze” might be a problem too. It’s not that uncommon in sunny mountainous area.
It’s also well known in diving, from both thermoclines (temperature variations) and haloclines (salinity variations). In some dive environments, it’s bad enough to hamper vision, though rarely bad enough to be “unable to see a hand in front of your face.” Unless you’re on a cave dive – see Bahamas “Blue Hole” expedition reports ad nauseam.
Wow! Great pics and videos. Lots of work but well worth it. Fairly gruesome!
Could the focus issue be condensation forming on or within the optics? This can be a problem with telescopes in some environmental conditions and causes issues similar to what you describe. SOP is to let your scope acclimate to the conditions you will be using it in for a good while before using it. A dew shield can be helpful too.
What a great set of photos and some very interesting behaviour too!
Fascinating that the birds are specialising to such a great extent on a single prey species. Since I presume other potential prey species are present in the area this must represent a clear choice on the part of the peregrines. I guess that the doves are pretty abundant but also provide the right combination of behaviour, body size and possibly other attributes to make them the ideal prey.
Doves, like the other favorite Peregrine prey, ducks, have a lot of meat on them compared to most birds of their size. I think that is at least part of the attraction.
Beautiful stuff, but also.. yeesh these lovely birds are lethal. I especially like the last one with the foot going down the hatch.
Dinosaurs are beautiful. And grizzly.
Terrific photos Bruce! Wow!
Lucky you! More or less where do you live?
Cheers!
Santa Cruz California. The birds are on the coast between Santa Cruz and San Francisco.
Nice! And good work going “out there” and finding them.
That pile of feathers around the plucking site is impressive!
How wonderful to see Eurasian Collard-Doves performing a useful purpose! I wish we had a LOT more peregrines.
Being a dove must be like being in the Jurassic Park kitchen scene. Plucking seems like a lot of work for the falcon. I would guess that eating too many feathers could be hard on the digestion, but bones and feet are probably not that helpful either. It’s clear though, that feathers would cause a full feeling, like eating pillows, while not producing enough energy. Plucking makes sense for humans too, come to think of it.
Stupendous photography.
The last photo reminds me of Wilhelm Busch:
Und vom ganzen Hühnerschmaus
Guckt nur noch ein Bein heraus.
(And of that great hen-feast now
Each has but a leg to show.)
If you want to read the whole slightly gruesome story:
Max und Moritz. A Rascals History in Seven Tricks.
http://www.davidgorman.com/maxundmoritz.htm
Wow! Fantastic photos and a great story! I enjoyed this series immensely. Thanks so much. 🙂
We could use some of those Peregrines around here. The Eurasian Collared Doves have taken over and displaced the native Mourning Doves.
Beautiful photography. I have no idea what’s going on with your camera.
Fantastic photos and descriptions! Thanks.
That’s enough birdy drama for me today I enjoyed your labour and efforts thanks for the post.
Amazing birds that’s for sure.
After reading Sean B Carroll, The Serengeti Rules early this year I can’t help thinking that switching to Eurasian Collared-Doves must have had an effect on their natural prey such as a slight/heavy increase in numbers, the knock on effect on what they (the prey) feed on and possibly their habitat.
I guess it would depend on how many of the Peregrines are working the area and taking advantage of the food supply. It makes it all the more interesting anyhow.
I get a little concerned about our natives and endemics with invasive species moving in (mainly pigeons) but so far, so good as far as I can tell.
Nothing is as it seems in nature.
That’s one dove, doubly collared… boohoo…
Thanks for the spectacular photos, Bruce!