July 05, 2015

Journey to a Rare Harpy Eagle Nest


Timing is everything in the Amazon rainforest. So when Jeff and I heard that there was a harpy eagle nest near the Refugio Amazonas Jungle Lodge, we knew that we had a narrow window of opportunity to see these rare birds caring for their young.

 Biologist Aaron Pomerantz and Wildlife Photographer Jeff Cremer visit a rare harpy eagle nest in Tambopata, Peru

Why are harpy eagles so cool? For one, they are the largest eagle in the Americas and are considered the most powerful bird of prey in the entire world. With tarsal claws 5 inches long and a wingspan of up to six and a half feet, these beautiful and formidable predators make quick meals out of monkeys and sloths.

An adult harpy eagle brings back a howler monkey for breakfast. Image by Chris A. Johns

Harpy eagle nests are extremely rare and difficult to find. One researcher I spoke with in Peru described searching for harpy eagle nests like "searching for a needle in a haystack!" There are several reasons for their elusiveness:

  • Harpy eagle nests are sparsely distributed throughout the vast rainforest
  • The adults have slow reproductive rates, producing one chick every two to three years
  • They tend to nest in massive trees, like the Brazil nut, making them difficult to spot from the ground

This last reason made things tricky. If we wanted to film this nest, we were going to need to be high up. So we grabbed our camera equipment, ropes and harnesses, then climbed up 100 feet into the canopy to observe this rare harpy eagle chick.

The harpy eagle nest is constructed in a massive tree in the Amazon rainforest

The view from the canopy was pretty incredible. We could overlook the seemingly limitless green rainforest and were eye-level with the nest. Jeff's camera equipment came in handy - although we were around 30 meters away from the nest, the 600mm and 800mm lenses caught some really sharp footage of the chick.

The chick calls out to the adults for food, mainly eating monkeys and sloths

The harpy eagle chick is about 6 months old and looks strong and healthy. The adults have been visiting the nest less frequently and the chick is becoming more active, which indicates it may fledge soon.

The adult harpy eagle shreds a freshly caught monkey for the chick

All in all, the journey was well worth it. Everyone was safe getting up and down from the canopy and the eagles were not disturbed. We feel very fortunate to have seen such an incredible animal in its natural environment and hope to see the chick return someday as a full grown adult with a wild mate of its own.

The harpy eagle chick will one day be the top aerial predator in this jungle

You can follow us on Twitter @AaronPomerantz and @JCremerPhoto!

Check out more awesome images by wildlife photographer Jeff Cremer and visit www.PeruNature.com!

June 17, 2015

Photographing A Harpy Eagle + Canon 800mm f/5.6 lens review and Live View Focusing Technique


Harpy Eagles are the AH-64 Apache gunship helicopters of the jungle:

  • Stalking the Shadows - Harpy eagles fly below the canopy in the dense shadowy forest hunting for sloths and monkeys.
  • High Speed Flight - A harpy eagle can reach speeds of over 50mph while attacking prey in a dive.
  • Vertical Flight Capabilities - They have short, broad wings and can fly almost straight up, too, so it can attack prey from below as well as above.
  • Advanced Target Acquisition - A Harpy eagle can turn its head upside down to get a better look at its potential meal. They also have excellent vision and can see something less than 1 inch (2 centimeters) in size from almost 220 yards (200 meters) away.
  • Serious Weapons – Harpy Eagles have huge talons. Their rear talons can reach over 5 inches long – the same size as a grizzly bear’s claws!
  • How rare are harpy eagles? I don't really know but they are pretty damn rare and seeing a chick in the wild is almost impossible.

Canon 800mm f/5.6 IS USM Super Telephoto Lens

I have a Canon 800mm f/5.6 and take it everywhere with me. The lens weights almost 10lbs so it can be a little difficult hiking with it in the jungle but it’s totally worth it when I get a good shot. 

Here is why I love my 800:

  • Largest Lens That Canon Makes: Thats cool.
  • Fluorite Lens Elements: This lens is really really sharp. I think that it could be the sharpest lens that I have ever used. The reason for this is two fluorite lens elements, one UD element, and one Super-UD-glass element.  This makes for outstanding correction of chromatic aberrations and extreme contrast and sharpness.
  • Magnesium Alloy Construction – I constantly bang my cameras and lenses into trees while walking in the jungle. This lens takes all the punishment and keeps on going. One time I slipped and fell and slammed the lens onto some rocks and it didn't break. It also has weather-resistant gaskets that really come in handy in the rain.

    • Image Stabilization: The lens is image stabilized, providing up to 4 stops of correction for camera shake. Now, even though I shoot from a tripod the image stabilization help steady the image when shooting at extreme high magnifications like when I shoot with a crop sensor (1280mm) or with a 2x Teleconverter (2560mm)
    • Photographing The Rings On Saturn: This lens is so awesome you can take a picture of the rings on Saturn with it. Also, on a clear night you can see the banded clouds on Jupiter and some of its moons.  

    Photography Technique: 

    A lot of people ask me about the camera settings that I use.  Here is what I do:
    • Aperture Priority: Aperture priority, often abbreviated A or Av (for aperture value) on a camera mode dial, is a setting on some cameras that allows the user to choose a specific aperture value while the camera selects a shutter speed to match, thereby ensuring proper exposure.
    • Aperture - I use the camera in Aperture Priority mode. I set and leave the aperture value. I set the Av to f/5.6 and never move it. I do this because I want to get as much light as possible into the camera. The more light the camera gets the quicker the shutter speed can be. The quicker the shutter speed is, the less chance of a blurry image.
    • ISO - I set and leave the ISO – I normally set the ISO to 800 when I start shooting. In very basic terms, ISO is the level of sensitivity of your camera to available light. The lower the ISO number, the less sensitive it is to the light, while a higher ISO number increases the sensitivity of your camera. I increase the ISO in order to reduce the shutter speed. Again, the quicker the shutter speed is, the less chance of a blurry image.
    • Shutter Speed – When you are shooting in Aperture priority the camera automatically chooses the shutter speed. To make sure that the settings are correct I use something called the reciprocal rule. The basics of this rule states that if you’re hand holding your camera, your shutter speed should not be slower than the reciprocal of your effective focal length in order to avoid “camera shake,” i.e. the blur that results from any slight movement of the camera during the capture of the image. I shoot of a tripod but I use long focal length lenses that are susceptible to any little shake or vibration so I still think that this is a pretty good rule of thumb.

    Live View Focusing
    We saw this adult harpy eagle in a tree the week before.

    I also use something called “Live View Focusing” to get perfect focus and sharp images:
    • Live View and Zoom: I set the lens to manual focus and switch the camera into live view mode. I then zoom into the image and manually focus on the eye or beak of the bird.
    • Focus on the catch light: For super sharp focus I focus on the reflection (sometimes called “Catch light”) in the eye of the bird.
    • Timer Mode: I switch the cameras shutter release mode into two second timer.  This way I won’t be touching the camera when the photo is taken. This reduces camera shake and vibration. You can also use a cable release to take the photo as well. Using this technique can make the images a lot sharper. It’s good to note that this focusing technique can also be used for macro photography. I use it all the time when I’m taking pictures of bugs.

    So that's how it’s done folks. I hope that this article and video helped a little bit and gave you some ideas to try out and let me know how you like using the Live View Focusing Technique.  I think that its pretty cool. I’m going to start making more videos and writing more articles so stay tuned. I put some more pictures that I took on the trip below. – Jeff



    Slug Moth Caterpillar

    Hunting Spider

    Juvenile Cara Cara

    Titi Monkey

    Giant River Otter

    Stink Bug


    Yellow-crowned Parrot

    Spectacled Caiman


    April 26, 2015

    We Found (and yelled at) a Crazy Tentacled Caterpillar

    On my recent travels through the Peruvian Amazon, I came upon the craziest caterpillar that I have ever seen, and subsequently yelled at it for hours.  

    Why did I yell at it? Well, its strange behavior towards sound was why I noticed it in the first place. I had just climbed to the top of a canopy tower overlooking the rainforest when I called to my group below me - suddenly a flash of movement at eye-level caught my attention.

    On a nearby tree branch hung a caterpillar with four strange tentacle-like appendages protruding from its abdomen. I might never have noticed this small brown insect had it not been for its unusual movement: noises would cause it to fire its tentacles in randomized directions, then slowly twirl back into a spring-like "ready" position to await its next alarm. This reaction to noise was so peculiar that once my group joined me around the creature, we proceeded to take turns yelling at it and filming its contorting reactions for over an hour.

    After a little research, I found that this caterpillar is in the moth family Geometridae and is in the genus Nematocampa. Also referred to as ‘horned-spanworms’ or ‘filament bearers’, these peculiar caterpillars can be found in North America and the Neotropics.

    David Wagner, in his field guide ‘Caterpillars of Eastern North America,’ notes: 

    “It is difficult to imagine what the [Nematocampa] larva is mimicking, but the overall effect is not unlike a fallen brown flower with exerted stamens. Alarmed caterpillars shunt hemolymph into filaments, enlarging them by as much as twice their resting length.” [1]

    What Wagner seems to be proposing is that the larva movement is similar to the way flowers or other plant matter move in the wind: the behavior more effectively blends the caterpillar into its surroundings. 

    Other potential purposes this behavior may serve include:

    1.     The tentacles extend when the caterpillar is alarmed so that an attacking predator (such as a bird) has a higher probability of snagging a tentacle, as opposed to the main body, so that the caterpillar may drop away and escape with its life (similar to how some lizards are able to lose their tails). 
    2.     The setae, or "hairs," located at the tip of a long tentacle could be highly sensitive vibration detectors that are able to sense predacious birds or insects that make nearby sounds [2].

    What do you think? Screaming at caterpillars doesn’t fall into most people’s job descriptions. But that’s exactly what I found myself doing a couple weeks ago in the Peruvian Amazon, all to bring the story of this bizarre organism to you! Leave a comment below and let us know how you feel about this peculiar caterpillar found in Tambopata, Peru.

    -Aaron Pomerantz, Entomologist

    You can follow me on Twitter @AaronPomerantz

    Thanks to contributing footage by Steven Senisi of EdTechLens and Dr. Andrew Warren (@AndyBugGuy) for pointing out additional Nematocampa references.


    [1] Wagner DL (2005) Caterpillars of Eastern North America. A Guide to Identification and Natural History. Princeton University Press, Princeton. 512 pp
    [2] Sourakov A, Stubina M (2012) Scientific note: functional morphology of masquerading larva of Ceratonyx satanaria with notes on horned spanworm, Nematocampa resistaria (Geometridae: Ennominae). Tropical Lepidoptera Research. 22:53-59

    Additional Reading

    Gerguson DC (1993) A revision of the species of Nematocampa (Geometridae: Ennominae) occurring in the United States and Canada. Journal of the Lepidopterists’ Society 47:60-77

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