During the summer months I visit four bald eagle nests on Lac LaRonge, a large lake in the precambrian shield region of Northern Saskatchewan. The three birds in this article are members of the same family. The photos of the pair of mature breeding eagles were taken at a nest site in June 2012. The nest is on the island that is barely visible behind the flag on the right side of the photograph below. The photo of the three year old juvenile bird was taken in July 2012 at an island three kilometers away. The parents now have nothing to do with the son. They kicked him out when he was 14 weeks old.
Figure 1 – August 16, 2011
All my photographs are taken from a 20-foot Lund Alaskan boat with a 90 HP Honda outboard. The flat bottom of the boat makes for a stable platform. Holding the boat is the ‘Admiral’, my wife CL.
The photos were taken with a Pentax K-5. All but one of the photos were taken with an smc Pentax-DA* 300mm F4 IF SDM lens. The exception is the photo of the female who is in a spread eagle position with her back to the camera. That photo was taken using a Tamron AF 18-250mm F3.5-6.3 Di LD Aspherical IF Macro.
The photograph below was taken on an overcast day using center-weighted auto focus. A day with diffuse light, as in cloudy or overcast conditions, is better than a bright day. A bright and sunny day makes for difficult metering and an increased risk of chromatic aberration.vAnother problem with a bright day is that, for some reason, the birds like to fly with the sun behind them. June 4, 2012 was overcast and without wind, a perfect day.
Figure 2 – June 4, 2012 – 1/3000 sec, F/6.7 ISO 400
To take the photograph I take a position at the stern of the boat near the motor. A small sand bag on top of the motor is my preferred method to take photos of stationary birds. Center weighted auto focus works best for a photograph of the juvenile bird seen below. This bald eagle is the son of the adult birds that are depicted in this article. The yellow cere, light skullcap, heavy mottling and fully developed flight feathers confirm that he was half way through his second molt in his third summer. The shape of the beak is clearly that of a male.
Figure 3 - July 12, 2012 - 1/750 sec, F/8, ISO 400
I use manual focus to capture birds that are among trees or against a busy background. The pair of mature mating eagles was guarding the nest with newly hatched young. The gender can be determined by the relative size of the birds, (the female on the left is 25% larger than the male) and the shape of the beak. A female’s beak is deeper and larger, more like that of a parrot.
Figure 4 - July 12, 2012 - 1/750 sec, F/8, ISO 400
The other way to distinguish a male from a female is by the length of the hallux talon (located at the rear of the foot). The male’s hallux talon measures just over 1 inch in length while the female’s measures over 2 inches. I chose to use the manual focus to take this photograph of the male even though he was stationary when he came into view. The small window in the foliage made me unsure about whether I could take the shot quickly enough while using auto focus to avoid a poor result. Notice the length of the hallux talon.
Figure 5 - June 19, 2012 - 1/1000 sec, F/8, ISO 400
I also use manual focus if I can anticipate the landing spot. I focus on the target branch and lock the focus while I follow the bird to the branch. The long hallux talon and the deep ‘parrot’ beak clearly identify this bird as female.
Figure 6 – June 19, 2012 - 1/1000 sec, F/8, ISO 400
The photo of the female below illustrates term ‘spread eagle’. She flew in very low and directly over me so I couldn’t follow her in the viewfinder. She landed near the nest that is situated at the lower right of the frame. I was able to guess the landing spot so I used the nest as the focal point and then moved the focal point to fill the frame with the bird just before she landed. This photo was taken with the Tamron lens at 230 mm and suffers from chromatic aberration. One cause for this was the was a sharp contrast between the dark bird and the sky despite the diffuse light of an overcast day. Another cause was that at a setting of 230 mm the 18-250 mm telephoto lens was outside it’s optimum focal length. I could fix most, but not all, of the chromatic aberration in Lightroom. The problem would have been considerably less if I had used the fixed focal length 300 mm lens.
Figure 7 - June 4, 2012 - Tamron (18-250 mm) at 230 mm, 1/3000 sec, F/6.3, ISO 400
For birds on the wing, I mount the camera on a modified monopod that is cut down to 2 ½ feet. It is positioned in a homemade base that inserts into the floor of the boat. The monopod, with the camera on it, is stable and can stand unsupported in the boat to free my hands to maneuver the boat. I start by sitting on the floor but can easily make a quick transition to standing by releasing the monopod and camera from the base. In the standing position, I use the monopod as a camera support by holding it tightly against my body. This method of camera stabilization reduces camera shake by at least 50% compared to holding the camera freehand fashion. I used center-weighted auto focus because the bird was against a neutral background. This female was vigorously defending her nest on June 4, 2012 while her mate was out hunting.
Figure 8 - June 4, 2012 - 1/3000 sec, F/6.7, ISO 400
The same bird was just as diligent a protector two weeks later. Not only is she good mother, she is an excellent subject.
Figure 9 - June 19, 2012 - 1/1500 sec, F5.6, ISO 400
There is another nest in a more sheltered spot four kilometers from this nest. That site is more suitable for regular visits so I was able to follow the hatchling from June when it was three weeks old until after it had fledged in late September. I’m always surprised by how quickly hatchlings grow. Even more impressive is the amount of food that the parents must deliver to it.
Each year I improve my methods. This winter I’ll modify the monopod setup for more stability, quicker release from the boat and switch a quick release swivel head. Next year I’ll, once again, experiment with the continuous shooting mode.
Getting ready to go. Sometimes I use my other boat, a 16 foot Lund SST with a 40 HP Mercury outboard. It is more fun than using the bigger boat but it is less stable and the motor does not have electric start. I can barely move my arm after a long day.
Also see Dr. Dale Mierau's previous article for Canadian Nature Photographer
1. Berdan R. Birds in Flight; at: http://www.canadiannaturephotographer.com/birdsinflight/ZAB1008-RobsArticle.pdf
2. Gerrard JM, Gerrard P, Gerrard PN, Bortolotti GR, Elston HGR, Dzus R. 1992a. A 24-year study of bald eagles on Besnard Lake, Saskatchewan. Raptor Res. 26(3):159-166.
3. Gerrard, JM, Harmata AR, Gerrard PN. 1992b. Home range and activity of a pair of bald eagles breeding in northern Saskatchewan. Journal of Raptor Research 26:229-234.
4. Linthicum JL, Jackman RE, Latta BL., Koshear J, Smith M, 2007. Annual migrations of bald eagles to and from California. Journal of Raptor Research, v.33 n.2: 106-112.
5. Mahaffy, M.S., and L.D. Frenzel. 1987. Elicited territorial responses of northern bald eagles near active nest sites. Journal of Wildlife Management 51:551-554.