31 December 2016

The Owl Project

This Christmas season I decided to stay home, relax and maybe work on a few small projects around the house. Highest on my list was to make an owl box.

An owl nest box, hopefully for a Spotted Eagle-Owl (Gevlekte Ooruil - Bubo africanus)

I got a rough idea of the size and design from online sources, but didn't feel like following any specific plan. Instead I bought a couple of pieces of scrap wood, screws, varnish and a brush from my local hardware store and started putting it together as I went along. It isn't finished yet, but I think its turning out decently well.

The plan is to place the nest box at our family holiday home. I've seen Spotted Eagle-Owls in the area, but we'll have to wait and see what happens...

The Spotted Eagle-Owl is a common species throughout most of South Africa and I've even camera trapped them a few times.

Spotted Eagle-Owl camera trapped at Berg River Dam

Hopefully towards the end of 2017 I'll be able to do a follow-up blog post with some good news.

26 November 2016

Lizards Of The Pearly Mountain

I recently started camera trapping at Paarl Mountain Nature Reserve. The reserve is situated a short distance outside Cape Town, on the border of the town (of similar name) Paarl.

Like most of the small nature reserves I've been camera trapping at it borders partially on urban development and partially on rural / farming development. This nature reserve is unfenced, which is somewhat problematic (as I'll try to touch upon in future blog posts).

Paarl Mountain Nature Reserve in the Western Cape province of South Africa

When visiting the reserve you are bound to see many Southern Rock Agama basking on the boulders scattered over the landscape.

Southern Rock Agama (Suidelikke Rotskoggelmander - Agama atra) soaking up the rays

Their body color usually match very well with the rocks they live on, but when ready to mate they can become brightly colored. The males are larger than the females and develop a much brighter blue head and a yellow band on the sides of the body. They also usually have a white band running along the spine. These Agama lizards can also quickly change their body color, similar to chameleons (but not as dramatically). They can use this ability to subdue their bright mating colors when a predator is around.

I have a camera trap placed in a small natural shelter formed by the boulders. Like most boulders on the reserve it is home to some of these lizards.

Bushnell camera trap monitoring a grotto at Paarl Mountain

Having reptiles trigger a camera trap is very uncommon. In the past I've mostly managed to camera trap the odd tortoise walking past a camera trap. There have also been a few flukes when a lizard stopped in front of a camera trap, but this is the first spot where I'm getting a lizard repeatedly triggering the camera trap using its own body heat.

Southern Rock Agama triggering the camera trap in the grotto

The lizard usually triggers the camera trap in the afternoon. By then it must surely be hot enough from all the sunbathing.

The photos are in gray because the camera switches to IR flash mode, even during the day, due to the low light available in the shelter.

Southern Rock Agama running up a boulder

If all goes well I'll be camera trapping at Paarl Mountain for the next few months, so stay tuned for more about the wildlife at this nature reserve.

Three lizards basking in the sun

26 October 2016

Koeberg Data Summary - The Patterns

One of the benefits to using camera traps to monitor wildlife is that it can be active for 24 hours per day, day in and day out. This makes it possible to start examining the day-night cycles and even moon phase activity patterns of animals. Below are some of the theories I came up with. (As always please take all of these "statistics" with the appropriate grain of salt.)

The "dune cliff" at Koeberg Nature Reserve

One of my favorite things to compare between species is the difference in their day-night activity patterns.

The closer you get to the poles, the greater is the seasonal difference between sunrise and sunset times. As a result when working with more than a year of camera trapping data you can't simply compare the observations based on the time alone. Instead you have to compensate for the difference in the length of the day.


I like to group the observations into categories, for example sunrise, early morning, mid day, etc. The general distribution still looks the same, but in this way I can more reliably compare observations over a longer period of time.


The Eland (Eland - Tragelaphus oryx), Common Duiker (Duiker - Sylvicapra grimmia) and Steenbok (Steenbok - Raphicerus campestris) all showed more or less the same activity pattern. Showing peaks of activity during early morning and late afternoon as well as an increase in activity around midnight. But there are small differences between the species, for example the Duiker seem much more active at night and the Steenbok seem to be more active at mid day. The Eland was also the only one to be more active in the late afternoon compared to the early morning.


However, the Springbok (Springbok - Antidorcas marsupialis) showed a different pattern compared to the other herbivores mentioned above. It lacked the spikes in activity around late afternoon and at mid night. Why this is I'm not sure. Maybe during the later part of the day the herd moved out of the areas where the cameras were placed, or maybe it is a reflection of seasonal changes in behavior. Most of my camera trapping in the area where the Springbok hang out happened in the autumn months.


The above species all showed both diurnal and nocturnal activity, but some species are very strict about their preference. As alwys the Porcupine (Ysterverk - Hystrix africaeaustralis) at Koeberg are strictly nocturnal.


The Porcupine even seem to go as far as to avoid the moon. The number of observations are heavily skewed towards times when the moon is not shining. This trend at Koeberg is consistent with my observations at Tygerberg were the Porcupine showed an almost identical pattern, being highly active during new moon and less active during full moon. Both locations also show far more observations during periods the no moon visible, but this latter effect is less pronounced in the Koeberg data compared to Tygerberg. My guess would be that because Koeberg is more remote and has less human activity at night, compared to Tygerberg, the animals are a little more comfortable to go about their nightly routine.


The polar opposite of the Porcupine must be the Small Grey Mongoose (Kleingrysmuishond - Herpestes pulverulentus) which is only active during the day.


The Small Grey Mongoose and Caracal (Rooikat - Caracal caracal) both prey on rodents, but it seems fairly safe to assume that they prey on different species, for the most part. The chart below is fairly busy, but I wanted to show how the activity periods of the predators at Koeberg overlap with their prey. The two Gerbil species are mostly exposed to predation from Caracal and Small-Spotted Genet (Kleinkolmuskeljaatkat - Genetta genetta), while the Four-Striped Grass Mouse (Streepmuis - Rhabdomys pumilio) primarily has to deal with the Small Grey Mongoose and a small amount of pressure in the late afternoon from the Caracal.


By far the majority of observations were of single animals, but there are some interesting exceptions. Porcupine families tend to travel together fairly regularly and as a result they have a much larger percentage of observations with two or more individuals.


For some species it is also possible to differentiate between the sexes. For both Steenbok and Duiker the males seem to get photographed more frequently. Maybe they patrol their territories more actively, or walk around more while looking for females? Interestingly the male-female sex ratio seems to be even more exaggerated for Duiker compared to the Steenbok.


The last theory I want to touch upon is one that originated from way back in March 2014 when I did a blog post about it, over here. I had a theory that the Duiker at Koeberg seem to adjust their activity pattern based on the season. The data seems to support the idea, showing that the Duiker are very active late at night during the warm summer months and much more active early in the morning during the cool winter months.


This past couple of posts analyzing the camera trap data from Koeberg is just the tip of the iceberg. I'm sure there are many more discoveries to be made in the future, but in the next couple of posts it is time to share some more camera trap photos and a new nature reserve.

19 October 2016

Koeberg Data Summary - The Maps

When I started camera trapping at Koeberg Nature Reserve I decided to try and cover as much area with my few (4-5) camera traps as possible.

Some scenery at Koeberg Nature Reserve

I decided to try and move each camera trap to a new location after 2 weeks.



With over a year of camera trapping data it is time to look at the maps.

First up is a heat map showing all observations plotted on the map. Just looking at this map the data may seem a little disappointing, with some areas clearly dominating the others in term of the number of observation records.


The map above can be misleading, especially when some camera trap locations were spaced close together or one camera trap recorded very high animal activity.

What if instead of just plotting each observation on the map, we try to compensate for the length of time the camera was active. The map below shows the areas on the map with the highest frequency of observations during each camera trap period. (The number of observations divided by the number of days the camera trap was active.)


I was still not happy with the two maps above and decided to make another map that to more accurately show the amount of effort (time) I put into camera trapping at a specific area. The map below ignores the observations, and instead just uses the number of days the camera trap was placed at a given location. (Using just the number of days the camera trap was active.)


I think it gives a much better indication of what areas were covered and what areas weren't.

I then wanted to see in what areas I recorded the highest species richness. The map below shows the number of species observed during the camera trap's active period. (The number of species divided by number of days the camera trap was active.)


I'm really pleased with how each of these maps highlight different areas of the reserve and tells a different story.

Another thing I wanted to try at Koeberg was to compare the maps of different species to determine whether some sort of rudimentary distribution map for the reserve can be created. Below are the distribution maps of common herbivores on the reserve. I'm very pleased with the results.

The Steenbok (Steenbok - Raphicerus campestris) were mostly found in the sandy dunes to the North.



The Common Duiker (Duiker - Sylvicapra grimmia) seldom ventured onto the open dunes and preferred the somewhat denser vegetation to the East and South.



The Eland (Eland - Tragelaphus oryx) ventured throughout the reserve, but had a preference for drinking at the dam in the North-West and the grassy area around the offices (which also has a small dam and is where they are fed once a week).



The Porcupine (Ystervark - Hystrix africaeaustralis) avoided the open sandy dunes all together and focused its attention on the thicker vegetation towards the East and South.



The other species listed above are natural to the area, but the Plains Zebra (Bontsebra - Equus quagga) are usually found much further to the North and East of the country. Interestingly they also have a very small distribution inside the reserve, preferring to stay on the grassy area around the offices. The extinct Quagga was closely related to the Plains Zebra and was historically found throughout the greater Western Cape province. The Plains Zebra at the reserve don't seem to move around much. Based on the behavior of these animals at Koeberg I think that either the Quagga would have specifically adapted to the region's conditions or it didn't occur in the reserve, instead preferring more grassy areas outside the reserve.



It really is amazing what can be done with only a hand full of camera traps on a small nature reserve if you are willing to persevere, keep the cameras in the field as much as possible and record the data in a structured manor. (I use WildLog, but any structured database or spreadsheet can do.)

Note: All these maps use Google Earth as the base layer. I cropped the images to make it easier to compare the different maps. Hopefully I won't get into too much trouble. :)

12 October 2016

Koeberg Data Summary - The Numbers

In the next three posts I'll be summarizing my camera trapping results form my time at Koeberg Nature Reserve. (You can click on the images to enlarge the charts.)

The white sand dunes at Koeberg Nature Reserve with Table Mountain in the background

I started camera trapping at the reserve during September 2013 until around November 2014. Earlier this year I returned to try and photograph the Leopard from May 2016 to June 2016.



A good balance of mammal and bird species showed up at the camera traps. The reptile and amphibian species were a pleasant surprise. I saw more snakes at Koeberg than any previous reserve I camera trapped at, but it seems that snakes are not easily camera trapped. The reptile species that showed up on the photographs were of Red-Sided Skink, Cape Skink and Angulate Tortoise.


Looking at the number of observations the mammals have slightly more total observations than the birds. Breaking it down and looking at the number of observations per species, we see that the mammals have a fairly good spread, but for the birds almost half of the camera trap observations were of Cape Francolin, and another quarter was of Cape Robin-Chat.


The species accumulation curve shows the usual trend: An initial ramp as new species are camera trapped for the first time, and then a steady decline as more time passes before encountering the next new species. The smaller "jumps" on the curve are usually due to one or more cameras being moved into a new "micro-habitat" such as a small pond or rodent nest. I'm surprised to see the strong leap in new species during 2016, after my long absence from the reserve. It seems like the reserve still has a lot to offer and new discoveries to be made. A new university study is currently underway and it would be very interesting to compare our results.


Not all camera trap locations are equal and some have a much higher species richness than others. Yet both the number of species per camera trap location and the total number of observations per camera trap location show the expected pattern: A few locations with lots of species / observations and many locations with fairly low amount of species / observations.


The duration of camera trap observations also reflects the expected trend. With a very high number of observations shorter than 10 seconds and then a steady decline. I suspect the small bump around the 1 minute mark is mostly due to the long delay between photographs on the Cuddeback cameras (also the odd time when I set the interval to more than 30 seconds on the Bushnell cameras). At the end of the chart I group all very long (7 minutes or more) observations together, which all add up to more or less the same amount of observations as the 10-20 seconds group.


I always enjoy interpreting the charts below. When a species visits a camera trap, what is the chance of that same species showing up again during the same day-night cycle?



These charts also nicely show the danger of interpreting data in this manner. From the charts the Honey Badger seems to be almost guaranteed to visit a camera trap more than once per day-night cycle, but this was only true for the 3 observations I recorded, and that is far too small a sample size to establish any meaningful trend. Another thing to note is that the Honey Badger observations were in fact "baited" by the presence of a carcass and does not reflect normal foraging behavior. In contrast a species such as the Duiker or Steenbok, with much larger sample sizes, will provide a much more accurate reflection of reality.

The rodent species usually top these charts, but there can be meaningful differences even for larger species like the Steenbok and Duiker.


The Bush Karoo Rat construct and live in large wooden lodges and thus its data pattern is very different to most other species.

One of the Bush Karoo Rat lodges at Koeberg Nature Reserve

As you'll see in the posts to come Steenbok and Duiker, in particular, provided a very good comparison - as both species have decently large sample sizes, but showcase very different behavior.

20 September 2016

The Missing Mustelidae

During my initial camera trapping stint at Koeberg Nature Reserve I didn't manage to photograph any of the species that form part of the Mustelidae (weasel) family. On a few occasions I saw Honey Badger paw prints, but I never got a photograph.

Even though the focus of my recent camera trapping was to capture evidence of the Leopard, I still hoped to add some new species to the list.

I was very glad when I learnt from the reserve staff that a Honey Badger walked past one of the camera traps.


Honey Badger (Ratel - Mellivora capensis) snacking on a Springbok carcass

Apparently one of the Springbok got hit by a car and the reserve staff decided to put some of the carcass out in front of the camera trap to possibly lure the Leopard. The Leopard didn't show up. The Honey Badger did, but only after the local Pied Crow(s) and Small Grey Mongoose cleaned off most of the meat.

Honey Badger carrying off what remained of the carcass

Unfortunately this luck didn't last.

There are two more members of the Mustelidae family which I know are present on the reserve, but I still don't have any camera trap evidence to back it up.

First up is the Cape Clawless Otter. I didn't see many signs of them on my previous visit, but this time around the one dam was crawling with footprints.

Otter tracks at the dam

I placed a camera at the dam, but didn't catch the otter in action. I'll have to come back someday to settle the score.

The other missing member is the African Striped Polecat. I found one that was killed by a car on the road just outside the reserve, so I know they are in the area, but I didn't photograph any on my camera traps.

A dead Striped Polecat (Stinkmuishond - Ictonyx striatus) found just outside the reserve

The polecat was in fairly good condition when I found it, so I decided to take it home and try to clean the skull.

The skull is now part of my collection

25 August 2016

Them Spots

Some of you might be surprised to hear that I have never camera trapped a Leopard before. Well, technically speaking, until very recently.

Leopard (Luiperd - Panthera pardus) at Koeberg Nature Reserve

The reason these big cats stayed off my list isn't because they aren't around, but rather that I tend to be drawn to the smaller creatures. I also feel like every second camera trap research project is targeting Leopards of one form or another. I'm not saying the Leopard work isn't important, because it is valuable. It just feels like many of the smaller species often fall by the wayside.

But to get back on track, it all started while I was still away on holiday, at the end of May.

I'm not a huge fan of constantly checking my emails or other "social media" from a mobile phone, especially when I'm on holiday. However, since I was away form home for 2 weeks I decided to check my personal email after about a week went by. Just in case there where any emergencies. I scanned thought my inbox and an email from the reserve manager at Koeberg Nature Reserve caught my eye.

I stopped camera trapping at Koeberg a while back and wondered what the email might be about. She was asking whether I might have a few camera traps to spare because they might have found Leopard tracks on the reserve.

My cameras where at home gathering dust, so I told her I'll drop by the reserve when I get back home.


The reserve manager sent me this photo of a Leopard track (photo taken by a staff members)

We placed some cameras in areas she thought the Leopard might move through. Some interesting things have been happening on the reserve since I stopped camera trapping there. There has been a fire, and apparently the Springbok numbers have been dropping faster than usual.

The plot thickened a few days later with more reports of Leopard tracks. Then a dead Eland was found. The Eland was seemingly pulled into some vegetation for cover and might have been fed on.

I doubt that a Leopard would want to take on a healthy adult Eland, but maybe this individual was very old or sick and possibly died from natural causes when the Leopard happened upon it. Who knows, but things were getting interesting.


Video: What remained of the Eland carcass by the time I got there...

And then, a few days later the news came in that the Leopard was photographed on one of my camera traps!

What makes this Leopard interesting is that it appeared out of nowhere, in habitat that isn't what we would normally expect from the local "Cape Leopards" - which are usually associate with the mountainous areas in the Western Cape province.

As a species Leopards can be found in an incredibly wide range of habitats over most of Africa and into Asia. The dunes at Koeberg is definitely not outside the realm of possibilities. From my camera trapping results we know that there is a fair amount of small to medium-ish mammals on the reserve - such as Steenbok, Duiker and Springbok.

One theory is that this might not be a "Cape Leopard" from the mountains, but rather a "Namibian Leopard" more at home along the western coast of Southern Africa. There are some scarce reports of other Leopard sightings some distance higher up the coast, in the vicinity of the West Coast National Park.

I don't know if we will ever be able to know where it came from, or for how long it will stay, but my guess is that it might be sticking around in the area, at least for the time being.

Now, since Koeberg is open to the public to visit and have staff working at the power plant on a daily basis I have to just remind people not to get over excited and scared of being eaten alive. This cat has been in the area for a while before the reserve staff even became aware of it. It is very reclusive and direct conflict is incredibly unlikely. Leopards in general are also more active at night, so normal daytime visitors really don't have anything to fear.

My time back at Koeberg had a few more surprises in store (and as always also the one that got away). But more about that in the next posts.

31 May 2016

Sunrises And Sunsets

Sunrises

I often find myself wishing that I could experience more sunrises and sunsets in my daily routine. Living a busy life in a large city makes it difficult, but there are times when it becomes a little bit easier. For example, during the winter months the sun rises later and sets earlier, making it much easier to overlap with my daily routine.

A friendly Bearded Scrub Robin (Baardwipstert - Cercotrichas quadrivirgata)

Maybe the most common way we all appreciate sunsets, in particular, is while we are away on holiday. I was fortunate enough to be away from April-May and got to see some great sunrises and sunsets.

I really enjoyed the trip and will try to share some of the experiences in this post. I'm not a very good photographer and when I'm in nature I tend to prefer taking "for the record" photographs instead of "for the album", so please don't expect too much. :)

Large unspoiled sceneries like this are becoming a rare thing on this planet

The trip was a form of "volunteer tourism" and I wasn't sure what to expect. It was mostly focused around tagging along with a wildlife monitor as he goes about his daily routine, to keep an eye on the nature reserve's Wild Dog pack(s). The dogs tend to get into all sorts of trouble with snares, etc. and monitoring them contributes to their survival. With only a few hundred left in the country (and a much smaller number if you count in terms of breeding packs, not individuals) any conservation effort going towards them is valuable.

One of my favorite African mammals, the Wild Dog (Wildehond - Lycaon pictus)

I won't go into much details about the "monitoring" or "volunteer" part of the trip, but in short it is a form of tourism aimed at generating income. The money is then, for the most part, used to fund the radio collars, veterinary services, relocations, etc. of the dogs. Its not a perfect system, but seems to strike a decent enough balance. I must admit that I was expecting more "scientific" or "working" activities to be part of the trip, but it soon became clear that it was basically a special kind of "safari" holiday aimed at overseas tourist and not "honorary ranger" type of work. Regardless it was still a lot of fun and a great experience.

Wild Dogs being dogs

In recent years I've started to record every mammal sighting I see when visiting a nature reserve. This trip was no exception. Below is a summary of what I saw during my 2 weeks at the reserve.

Trip sighting count

I managed to see 29 mammal species. I usually have good luck with Leopards, but during this trip they eluded me. I heard a male calling one night in our camp, but I didn't manage to see it so it didn't make the list. I would have liked to end on a nice round 30, but the Suni also eluded me.

Kudu (Koedoe - Tragelaphus strepsiceros) might not be super flashy, but they do have a certain charm

I don't know why I enjoy to record all the sightings, I just do. Maybe part of it is to compare the results of each trip should I ever visit the park again. I also like to record the GPS location of each sighting to get an idea on which roads the animals were seen. Below is a heat map of all sightings. The two red dots are the camp and a nice bird hide situated next to a waterhole.

Each day we would crisscross the reserve on the trail of the Wild Dogs

Some of the highlights for me where the frequent Wild Dog sightings, a couple of new "life list" species (Thick Tailed Greater Bushbaby, Natal Red Duiker, Side-Striped Jackal) and the Reedbuck herd at the dam.

This herd of Reedbuck (Rietbok - Redunca arundinum) was a pleasant surprise

I found it frustrating at times to be in the back of a "safari vehicle", because I'm used to driving myself when visiting game reserves. I would have loved to stop at more of the smal things. The monitor was usually willing to stop when asked, but I feel bad asking to stop at each small thing, especially when there are other people in the car. The positive side of all the driving was that we followed the dogs all over the park and got to see lots of unique landscapes and corners of the park which would otherwise be hidden to normal visitors that have to stick to the main tourist roads.

Beautiful Fever Tree (Koorsboom - Vachellia xanthophloea) forest

Getting to see the Wild Dogs from up close was amazing. They are such amazing animals. It baffles my mind how, even today, they remain a fairly "unpopular" species.

They all have huge ears, black noses and white tails, but the body color differs

On our first morning we found the pack just as they spotted a herd of Wildebeest. The dogs ran closer, but the herd stood it's ground. The dogs lost interest fairly quickly and some started playing with the branches in the area. The rest of the pack trotted off to the left and soon after made a kill. I'm not sure what they ended up killing since it happened some distance away from the vehicle.

Video: Wild Dog pack harassing a Blue Wildebeest herd

Some of my favorite moments where seeing the dogs play, or just to watch them do "dog things".

Dogs jumping and chasing each other in the long grass

Below are some video clips (put together) of the dogs interacting and playing. The clips at the end of the video are my favorite. It was amazing seeing the adolescent dogs play in the long grass (after they had their breakfast).

Video: Wild Dogs playing

Before I wrap things up, below are a few more photographs from the trip.

Lappet-Faced Vulture (Swartaasvoƫl - Torgos tracheliotus), I always enjoy seeing vultures

Cheetah (Jagluiperd - Acinonyx jubatus) doing cat things
 
Njala (Njala - Tragelaphus angasii) keeping an eye and ear on me

Blue Wildebeest (Blouwildebees - Connochaetes taurinus) drinking at the bird hide

Plains Zebra (Bontsebra - Equus quagga) also drinking at the bird hide
 
More landscapes

Most of us are familiar with the standard variety of Guineafowl, but these Crested Guineafowl (Kuifkoptarentaal - Guttera pucherani) look much more fancy
 
These strange Giant Stapelia (Stapelia gigantea) plants grew in the camp

What lizard? Seriously, where?
 
Another landscape in the late afternoon

Baby Elephant (Olifant - Loxodonta africana) enjoying the water

Too cool for school
 
I enjoyed my visit, but I must admit, it felt good to be back home. Nothing beats having a dog curled up under each arm.
 
When I got back I dusted off my camera traps and got them out into the field again. So hopefully there will be some good photos to share soon.

and Sunsets