Phase Two of the roadkill project is well underway with the following schedule (from 02/10/2011 to 10/11/2011) ….. ’40 days and nights in the wilderness’.
There is one main transect of 100km driven each morning on the tar road. In addition, there are also three sub-sample-transects, all of 20km in length.
- Dirt road (this will give me a sub-comparision of the differences in roadkill rates between gravel and tar roads)
- Post-dusk (1 ½ hours after sunset)
- Pre-dawn ( 1 ½ hours before sunrise)
The latter two are providing information about ‘what’ is ‘hit’, and when, in relation to night and day. Whilst it may seem obvious that nocturnal species are only hit at night and vice versa for diurnal, data are showing that this isn’t always the case. I saw a cheetah running down the road at 04:00 on one of my morning transects, and whilst it was not a roadkill, it indicates that the ‘diurnal’ species are not strictly diurnal (as we all know). I have found other ‘diurnal’ species as roadkill on my night-time transects.
Additionally, many of the roadkill species I find dead on the road at 04:00, have then ‘disappeared’ from the road when I complete my main transect, 4 hours later, which suggests either scavenging by natural means or removal by man.
I am just over half-way through the transects and the data are already extremely interesting. The 30-day transect that I completed in March, showed 374 roadkill over that period, with over 50% of the carcasses having disappeared by the next day.
Whilst the roadkill figures for October are lower than the March data, it is only marginally so, with almost 300 recorded roadkill over 25 days. There is also quite a large variation in Taxon detected between the March and October data. Birds do not figure as highly on the October transects as they did in March, despite many migrants having appeared in the area. This may be due to the small amount of insects on the roads at this current stage, which should increase once the rains appear.
Figure 1: Roadkill data collected across two ecological seasons.(Data for October, 2011, shows a 22-day period, whilst March, 2011, shows a 30-day period).
We are recording roadkill across the three ecological seasons:
There have been slight early rains on this first season’s transect, which will be noted during the analysis.
Vegetation / surrounding habitat, mean grass-verge height, grass-verge thickness, fence type are all being recorded at each roadkill sighting.
The Picocount 2500 roadtube has been assembled on two of the roads of the transect; the R572 and the R521, both of which border the De Beers Venetia Limpopo Nature Reserve. The R572 also passes Mapungubwe National Park, and the Vele coalmine section.
The data being recorded is;
- Traffic volume
- Vehicle speed
- Vehicle weight
Already the data are showing that many vehicles exceeding 12tonnes are using the R572.
Figure 2: Preliminary traffic data on the R572 for a two-week period. (Speeds are in MPH.)
Laying the road tube
Affixing the roadtube counter
Claire Patterson-Abrolat (EWT – Airport Wildlife Programme), Derek van de Merwe (EWT / AWP), Rox Brummer (EWT – Wildlife Mitigation and Conflict Programme) and three staff from Durban Airport joined the evening transect.
Rhombic egg eater (Rox Brummer demonstrating the lack of fangs to Derek vd Merwe)
Rox Brummer and Wendy Collinson discuss …. ‘is it a Rhombic Night Adder’ or a Rhombic Egg Eater’?
Pearl-spotted Owlet (despite being roadkill, this was my first opportunity to examine this owl up-close …. It is a really beautiful species!)
Domestic Cat Large-Spotted Genet Peter’s Ground Agama
Bushveld Jellyfish (What you start to see after 40 days and 40 nights of early-morning transects …….. hallucinating!)
Other roadside problems
Thanks to Dan Parker, Ric Bernard, Duncan MacFadyen, Ian Little, Andrew Rae, Sean Thomas, Jeanne Tarrant, Michael Cunningham, and Chutney for identification.