Friday, 8 March 2019

What are the odds

Natural history photographers strive for that cutting-edge image that is unique and shows a phenomenon from the natural world most of us never see. Such an image sets that brief moment in time ... forever. To get such a unique image many elements have to come together at the same time. I want to illustrate how difficult this image consolidation is. 

I will use two images, interestingly taken about 50 metres but several years apart. One of the things I look for when walking and observing is potential nesting holes and clear perches. If these become active the chances of getting a good action shot increases but it must be remembered the welfare of the bird is always paramount and they should never be put at risk.

In the first image it is the time of the year when cavity-nesters looks for a suitable tree hole to raise a family, their principle mission in life. 

The players in Image 1

Laced Woodpecker

Lineated Barbet

I had noted several cavities at Air Hitam Dalam, a conserved nature park on mainland Penang and usually check them when I am there. On this occasion two different species, both cavity nesters, a Lineated Barbet and a Laced Woodpecker arrived at the same hole to check it as a potential nursery. What were the odds of capturing this moment?


The precise moment when two searches for accommodation coincide.

For the second image I had noted a cavity that faced the morning sun and could be easily seen from the track on the nearby bund. I had walked past it 20 times at least and checked it with binoculars and had seen no action. 

In mid to late February 2019 my persistence paid off. What is seen in the next image is a nest cavity claimed by a pair of Spotted Wood Owls. A Monitor lizard has invaded and is possibly raiding the owls eggs when the distraught parents (both took turns) are trying to dislodge the reptile. The owl has not landed but the instant is shown where the outstretched talons hit the lizard.

The Second Image
An adult Spotted Wood Owl attacks the monitor lizard that is robbing its nest

The next two images are taken 1/10 and 2/10s of a second, respectively after the image above. This illustrates the short time window to  is needed to capture a moment.

 Spotted Wood Owls

Spotted Wood-owls (Strix seloputo) belong to the genus Strix that includes relatively large owls which frequent forested habitats. There are three sub-species.

This species is 45-47cm in height with the male weighing just over 1 kilo.
The adult has brown upper parts with reddish-brown lower back. Head and upper neck are darker, almost black. Numerous lack-edged white spots cover the dorsal area, extending to the fore-crown. The upper wing-coverts are brown barred white, whereas scapulars are white with dark brown stripes.
On the under-parts, the chin is buff. The throat is white with brown-edged feathers. Neck sides are barred white. The remaining underparts are white with reddish-brown tinge on the breast, all heavily barred dark. On the head, the ear-tufts are absent. The facial disk is plain rusty. The bill is greenish-black. The eyes are dark brown. The tarsi are feathered white with dark barring. The toes are grey. Both sexes are similar.

The Spotted Wood-owl frequents the edges of evergreen forests and logged forests, plantations, wooded parks, orchards and open forest. It can be seen in rice-fields, cultivated areas and sometimes mangroves and open deforested areas. The species occur below 800 metres, but sometimes up to 1000 metres of elevation.
The species feeds mainly on small rodents, small birds and large insects. It may occasionally catch snakes and bats. It usually hunts from a perch, 2-3 metres above the ground. It uses the most basic hunting style ‘sit-and-wait’. Once the prey is detected, it drops or glides from the perch and attacks the prey on the ground. The prey is killed with talons and a bite to the back of the skull.
The breeding season takes place between January and June in the Malay Peninsular. Young fledglings are visible from March to August. The Spotted Wood-owl nests in tree-hollows between 2 and 18 metres above the ground. The female lays two white eggs, directly on the floor of the nest without any lining.

The distribution of Spotted Wood Owls

Monitor Lizards

Monitor Lizards (Varinidae) are large, muscular predators with strong jaws, sharp teeth and a long, forked tongue, which they use to taste the air when searching for prey. Many swim well, and nearly all can climb trees. Worldwide there are currently 79 species, which includes the Komodo Dragon, the largest lizard in the world. There are many monitors in the adjacent Sungai Jarak River which is adjacent to Air Hitam Dalam..

Features of the featured images
Both of the featured images possibly had odds of thousands to 1 to align all the elements together

I have divided the required factors into four sub-sections illustrating what I believe is required to get a good action or behavioural image. It is summarised by I.L.E.T... which are; Image, Light, Equipment, and Timing.

A good nature image should have the following characteristics;
1. Sharp.....the essential elements should be in focus (correct speed, aperture and focusing)
2. Good light....the image must be lit well
3. Good cut-off appendages and a good flow to the image.
4. No distractions (no clutter around the main subject, holes in the background or too many objects not in focus)
5. The main subject needs to be doing something (showing behaviour)
6. The picture should tell a story

A good image must be lit in the best possible way with strong lighting allowing for high speeds that are necessary to freeze action. 
1.  Sun from in front and at a low angle
2. Clear view of subject without branches etc in the way
3. Background should be non-distracting. Blue sky is very good, white clouds are awful. Vegetation in the background should be well out of focus.

1. A 600-800mm lens is shoot through holes in the foliage (the owls nest cavity is in the middle of the picture below taken with a 50mm lens). There are restricted positions that give a good view of the cavity.

2. With a heavy lens a sturdy tripod is also needed
3. The camera should allow speeds set at least to ISO 2000.
4. Action shots require speeds of at least 1/3200
5. Aperture should be set around f8 to give sufficient depth of field without compromising speed.
6. Rapid shooting should reliably give 10-15 frames a second because some action is over in less than a second

This is the magic component where you, being prepared, and your subject, about to do something interesting, intersect in time and space. This can be quite serendipitous. You can minimize serendipity if you know something is going to happen at a certain place and wait Wildebeest crossing the Mara River, where you may wait weeks but they only cross at certain points. The BBC staked out all the known crossings to get good video recordings.

In neither of the featured images did I know anything would happen at the particular time and I wasn’t prepared to wait for weeks so each relied on 'prepared serendipity'.
In the Barbet/Woodpecker image the two birds were only in the same alignment for 1/10th second....the surrounding foliage and branches could not be eliminated entirely  as there was only a narrow exposure window. The chances of these two exploring the same crevice at the precise same time when everything else was in place ( ie. the prepared photographer and the sun position) are likely to be thousands to one.

In the Owl/lizard image. I had never seen any action around this hole but I was ready to shoot within a split second of getting a clear sight. I first saw what I thought was a Crested Serpent Eagle near the was in fact a Spotted Wood Owl, which I had not seen so far in 2019. Initially the owl obscured the hole and the monitor lizard. 
I fired two rapid shots (lasting 2/10th second in total) and the owl was gone. 

I then saw movement in the crevice and identified it as a monitor lizard. 

Both owls were quietly upset with the situation and as soon as the lizard protruded from the hole one of them would come in on a strafing attack. They did not land but hit the lizard with their talons. In most of  the attacks the owl flew wide of the enemy...but in all of the 4 attacks my window of action lasted only 3/10ths of second. The contact with the lizard that is shown would have lasted perhaps 1/50th  to 1/100th of a second .....and only happened once until the sun was overhead and cast an unworkable shadow of the tree trunk.

Another pass with no contact

Another fly-past with no contact

The owls were not present in 2018 and I had seen them for three seasons before that but nobody I knew had seen where they everything was unexpected. They pair usually roosted in an adjacent tree and they are only there for around 3-4 months.

The odds of capturing an image of a Spotted Wood Owl attacking a large monitor lizard with armed talons would be at odds of thousands to one. The photographer has to have the equipment, fieldcraft and the luck for these elements to coincide in an image.

Close-up of the moment of impact

The point that I am making is that a good natural history image has a number of components to consider and a major consideration should be assessing the rarity value..... what are the odds that enabled this image to be acquired? Books are filled with images of perching birds or resting animals...the key to add impact is to catch them doing something interesting that the eye cannot perceive.


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