Camera Trap Photo Tricks 101

I've been fairly busy wrapping up the development of the next WildLog version (should be out in March) and haven't had much spare time for blogging. I've been wanting to do some blog posts about the "post processing" I do on the camera trap photos I post on this blog. So I'll try to do 2-3 posts about it over the next few weeks, starting today :)

The sad truth is that even the best digital cameras can struggle to capture a natural scene in it's full glory and most commercial camera traps don't use anything close to the best (and most expensive) camera lenses / sensors.

My goal is to "restore" the photographs, to get them as close to the real life environment as possible. I try to get more natural colours, not "fake enhanced nature", but it can be tricky at times to find the balance. I don't use the rubber stamp, paint brush, smudge or any other fancy tool to "fake" or edit the images.

Below are some examples of what a few simple processing steps can do to improve your camera trap photographs. I've included a list of the steps taken in every example.

Long time readers might recognise some of the examples photos from earlier posts :)

Common Duiker (Gewone Duiker - Sylvicapra grimmia) at Koeberg Nature Reserve

Even though the After photograph looks much better than the Before, the colour of the animal is still peculiar. I try to only use tools that affect the entire image. Usually you have to find a balance between the real colours and the quirks of the camera hardware/software.

Over the years I've found that the "auto" tools in Photoshop do a decent job and I don't need any crazy technical knowledge or hours of time to get a decent result.

A few years back I was fortunate enough to get Photoshop Elements from the Adobe online store for a crazy good price (something like 75% off). I have found that the Photoshop Elements edition is much cheaper and more user friendly than the full product. The functionality it provides is more than enough for my needs. (For those on a budget, there are many decent free, or cheaper, alternatives out there.)

Small Grey Mongoose (Kleingrysmuishond - Galerella pulverulenta) at Berg River Dam

The auto colour and level correction tools are usually able to find a more natural colour balance, but the brightness and contrast tools can also make a big difference.

My usual approach is to darken the highlights slightly and (sometimes) lighten the shadows very slightly. Then play around with auto levels and colour until I get a decent result. The order in which you apply the steps can sometimes make a huge difference (and can be different every time).

Caracal (Rooikat - Caracal caracal) at Tygerberg Nature Reserve

Be careful not to overdo the effects, especially when playing around with the shadows/highlights. The presence of shadows and highlights add to the overall image and overdoing it can make the image look awkward and unnatural. I hope I strike a good balance myself!

The photograph of the Caracal above is a good example where the grass might look more "fake green" in the after photo, but the fresh spring grass at Tygerberg really do look very bright green in real life, not that strange yellow green in the original photo.

The "after" image in the below example takes the adjustments a bit further that I would usually do, but it illustrates just how much of the natural colour can be recovered through post processing.

Small Grey Mongoose at Tygerberg Nature Reserve

Unfortunately, no matter how hard you try some images just can't be saved. If there is no colour information present in the saved pixels to work with, then there is nothing any photo editing tool can do.

Usually you can still recover from severely under exposed photos, because there is a greater likelihood of some colour information still being present in the very dark shades, but recovering from over exposed photos are mush harder, since most of the pixels will be pure white.

Helmeted Guineafowl (Tarentaal - Numida meleagris) at Koeberg Nature Reserve

Interestingly enough the IR (InfraRed) flash cameras can produce some unexpected colours at night. I think it is due to the extent to which some materials reflect InfraRed light.

Above: Daytime photo from phone camera; Below: Nightime photo from IR camera trap

The change in perceived colour is most remarkable for the green and grey shirt at the top-right. The colours on the shoulders and the body almost seem to have swapped around! The dark navy blue shirt at the top-left also reflects very brightly in the infrared light and looks almost white.

I haven't noticed such a dramatic colour change in my real world camera trap photos, but I'm sure it happens to some extent.

Meeting The Francolins

Some scenery from Koeberg Nature Reserve

The Cape Francolin is by far the most common animal camera trapped at Koeberg. Its range is mostly restricted to the Fynbos zone at the South-Western tip of Africa, but inside that range it is fairly common. Other similar Francolin species fill the gap throughout the rest of Southern Africa.

Cape Francolin (Kaapse Fisant - Pternistis capensis) also known as the Cape Spurfowl

Amongst the torrential flood of  Cape Francolin photographs at Koeberg hides another Francolin species: The Grey-Winged Francolin.

Grey-Winged Francolin (Bergpatrys - Scleroptila africanus) at Koeberg

Both of these species are part of the Phasianidae (Pheasant) family and shares that honour with the infamous Chicken (one of humanities primary food sources).

For those wondering: The Helmeted Guineafowl is not grouped in the same family, although apparently the American Ornithologists' Union don't agree with this.

We often forget that, as with almost any form of science, describing and grouping organisms into species isn't an exact science.

A little bit too close to the camera for good focus

As is often the case with common names, the Grey-Winged Francolin is another victim of having an odd common name.

The "grey-winged" part seems to refer to the wing tips having a greyish look while the bird is in flight, which supposedly helps to tell it apart from the similar looking Red-Winged Francolin. There are much easier ways of telling the two species apart, but somebody decided to go with a feature only visible when in flight...

The Afrikaans name isn't much better either. At least they stayed away from the wing colour, but the "berg" part of the name indicates a mountain, and as you can clearly see Koeberg is not mountainous at all. The "berg" in the name refers to the fact that this species is most commonly found in mountain grassland 1800m above sea level. Unfortunately because of the common name one would not expect to find the species in coastal scrubland 1.8 m above sea level...

Keeping an eye on something to the left, outside the view of the camera trap

The above photograph was taken by an old Bushnell Trophy Cam. The Bushnell usually does OK with lighting a scene, but at this location it was placed in the shade of a tree and severely overexposed the backdrop which was being hammered by the summer sun. The bright and reflective sand / dead grass doesn't help much either.

The Cape Francolin photos (top and bottom) were taken by the Bridcam 2.0.

Is this that "Internet" thing they said I'm going to be on?

The Owner Of The Hole

I spotted the hole a few months ago but didn't have a camera trap at hand. Now, almost a season later I decided to return.

The hole at Koeberg is under a bush at the top of a small dune

I didn't have the exact GPS co-ordinates and at first had some trouble finding it again. When I eventually tracked it down a slight sinking feeling fell over me... It looked very much abandoned. But then again it looked fairly abandoned the first time I saw it as well.

I decided it can't hurt to try my luck, and slapped the camera trap into the sand next to the hole. Two weeks later when I collected the camera everything still looked more or less the same: abandoned.

But when I checked the SD card I was pleasantly surprised by a familiar face, although more often than not the face that greeted me back didn't look very pleasant at all.

Small Grey Mongoose (Kleingrysmuishond - Galerella pulverulenta) master of the stink-eye!

The Small Grey Mongoose was the only animal species photographed during the two weeks at the hole, but what was lacking in variety was made up for in reliability. On average the mongoose was photographed once every day, usually just before or after mid day.

Is this what a Small Grey Mongoose looks like when it is in a good mood?

I think it is safe to assume the mongoose uses the hole in some way, but I'm not sure how exactly...

Some of the books mention that although these mongooses are active during the middle of the day, on warm summer days they like to rest during the hottest parts. It looks like a decent spot to take a siesta?

Oi! You talkin' about me, punk? I dare yous to say it to my face!

Another possibility is that this is a potential den site. They are known to sometimes have their pups in holes in the ground and these photos where taken during the middle of the breeding season. I haven't camera trapped many animal den sites, and none for extended periods of time, but I would assume to see more than one visit per day if this was a den site? And won't the visits be closer to sunrise and sunset? Then again I was using a Cuddeback which is notorious for missing a lot (most) of the action...

I don't have plans to camera trap at Koeberg again this year and I have other plans for the first half of next year. So, at least for now the mystery remains.

Keeping Score

This post has been on my to-do list for a while but it was Codger's comment on my previous post that got me moving on it. I'll be using some of the new reports I've been working on for WildLog to share some of the my camera trapping data. The charts are still a work in progress so I hope everything goes well and that I haven't missed any glaring bugs... (Again the usual warning: this isn't "scientific" data, just some basic analysis of my own random data collection.)

For those not statistically inclined I've mixed in some bugs like this Corn Cricket (Koringkriek -  Hetrodus pupus) for your viewing pleasure

I've been camera trapping, off and on, for the past 6 years (since 2 March 2008). In this time I've recorded about 4430 camera trap observations using mostly Bushnell and Cuddeback cameras.

If the charts are hard to read, try clicking on the images to view the full size image

The first comparison I wanted to make was to see just how many of the camera trap observations are from mammals and how many from birds.

My primary focus is on mammals and I'm happy to see that the largest piece of the pie is for mammal observations. Camera traps really are great tools for monitoring animals, especially mammals. It would be virtually impossible to get a dataset like this without the help of camera traps.

Next I wanted to see how many species I've camera trapped in each creature category.

 

In total I have been able to camera trapped about 135 species. I say "about" because there are some species I'm not completely sure about. Some of the tiny mammals can by especially tricky to tell apart in photographs.

I've been fortunate enough to have a steady stream of new species through the 6 years of camera trapping. The chart below shows the rate of new mammal species captured over the years.



Species accumulation curve for mammals captured using camera traps

The species accumulation chart for birds looks more or less the same as the one above. Proving again what a big influence a new location and habitat niches can have on discovering new species, be it mammal , or bird.

Below is a breakdown of the number of camera trap observations for each mammal species.

There are 3 species that are very frequently camera trapped, but I'm pleased to see 10+ species that have a good number of observations and isn't really overshadowed by the dominant 3.



I guessing those red beads on this caterpillar are some form of parasite...

Because my camera traps are usually active for the entire day/night cycle the data can give a good idea of what animals are active at what times.

The chart bellows takes the 3 most frequently photographed mammals and compares the time at which the animal visited the camera trap.

It is quite interesting to see the distinctly different activity patterns. The Porcupine is clearly nocturnal, the Four-Striped Grass Mouse clearly diurnal and the Bushbuck likes to be active during early mornings and late afternoons.

There is also the obvious difference in activity patterns between mammals and birds, but it is nice to see it reflected in the data. The first chart is for the birds only, and the second chart for mammals only.

The active time of all bird observations



The active time of all mammal observations

The problem with comparing the times directly is that sunrise, sunset, etc. can differ remarkably between two sites that are far apart, or even at the same site during different seasons. With WildLog I try to auto-magically assign a "time of day category" to each time based on the estimated sunrise and sunset times at that location. Below is a chart using this time of day category for all bird observations.

Time of day categories for bird observations using camera traps

From the chart it can be seen that birds are much more frequently camera trapped during the middle of the day (mid morning to mid afternoon), with over 50% of captures being during this period. There is also a higher activity pattern in the mornings, compared to the afternoon. Again, no new news, but still good to see represented in the data. (This dataset is dominated by Francolin and Guineafowl records.)

As can be seen from the chart below the mammals have a much more even spread of activity, with an almost even split between diurnal and nocturnal activity.

Time of day categories for mammal observations using camera traps

The mammals, similar to the birds, also have a slight decrease in activity in the afternoon, before the night shift swings into action. (In this dataset the diurnal Four-Striped Filed Mouse and nocturnal Porcupine nicely balance each other out.)

Seeing these differences between mammals as a group and birds, bring the question to mind: "Why are they different?".



A species of Handmaiden next to a small body of water

On average I have camera trapped 4.09 species per camera trap set, with the lowest number being 1 and the highest 24. (Well, actually I sometimes don't get any species as a set, for various reasons, but I don't record those.)

Lastly, I've also tried to get some idea of how long the average camera trap visit lasts using the time between subsequent photographs. (By default when importing the photographs into WildLog the application will group all photographs together into one observation until there is 2 minute, or greater, period without any activity.)

As can be seen from the chart below by far the most of the visits to the camera traps are less than 10 seconds, in other words the animal is simply walking past the camera trap. The vast majority of my camera trap sets don't use any scents or baits.

Duration of a mammal's visit to a camera trap

At the 1 minute mark there is a peculiar "bump". My theory is that it is, at least partially, the result of the slow response time of the Cuddeback camera traps. The Cuddebacks take 30+ seconds to re-arm before the next photo can be taken. The Bushnells can take 3 photographs and re-arm in under 10 seconds, making them much more accurate at estimating the duration of a visit.

The couple of visits with a duration of 7+ minutes are mostly when an animal decides to rest or eat in front of the camera trap, for example it often happens on hot days if the camera is placed next to a good source of shade, etc.

This Monkey Beetle on a flower seems fitting to wrap up this monkey business :)

I hope that most of the charts made sense. I enjoy playing with these charts and "interpreting" the data. I'm sure I'm making a lot of mistakes. But I'm also sure there is a lot more to that can be learnt from charts like these.

The Elusive Fox

There is one species that has been on my camera trap wish list for years, the Cape Fox.

Wherever I went I'll heard stories about Cape Foxes being seen in the area "only a year or two ago". I would get my hopes up, but nothing ever showed up on the camera traps. The closest I ever got was this photograph from years back at Tygerberg.

Possible Cape Fox (Silwervos - Vulpes chama) at Tygerberg Nature Reserve

Unfortunately this was the only photograph I got and I'm not confident enough to be 100% sure whether it is a Cape Fox or not. Initially I leaned towards Bat-Eared Fox (which is in fact not a true fox). I did a blog post about it which can be seen over here. Since then I've changed my mind and am now leaning towards it being a Cape Fox, but I just can't be sure.

When I got to Koeberg the reserve manager mentioned that she saw a small fox-like animal recently. I've heard this sort of story before and didn't get my hopes up too much, but at least there was a chance.

Then, a few months later it happened!

Cape Fox at Koeberg Nature Reserve

Finally!

It isn't the most awesome photo ever, but at least this time I can be sure it is a Cape Fox. I really wanted a better photograph. Over the next few months I kept an eye open for signs, and saw plenty of tracks, sometimes even fairly close to where I had a camera trap. However, after a year of camera trapping at Koeberg I only camera trapped the Cape Fox this one time.

The Bushnell Trophy Cam was set to take three photos per trigger. Below is a cropped version of the last photograph in the series.

Heading straight towards the camera trap

What makes the Cape Fox interesting is that it is the only true Fox (genus Vulpes) found in Southern Africa.

The Cape Fox is on the smallish side, measuring only 30cm at the shoulders and weighing about 3kg. Like most members of the dog family they tend to mate for life.

They will usually forage alone and both parents care for the young. The male will bring food to the female as well for the first few weeks after the pups are born.

Although the fox is still elusive, at least I now know it can be done :)