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. :)

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