An animal killed by a vehicle remains visible to observation for a period of time. This could be for as short as a few hours or as long as a month.
This means that where the observer is unable to be at the site of the roadkill event before it is no longer observable then such events will not get recorded.
The frequency of coverage by the observer therefore impacts on the accuracy of the total number of animals recorded as killed by a vehicle. Obviously, the more a specific road is monitored by an observer then the more likely it is that all animals killed on that road will be observed and recorded.
Therefore, only a minimum rather than actual number of animals killed by traffic within the principle observation zone(s) can be calculated.
During 2014, the frequency of observation across most of the principle observation zone was less than that required (the specific requirement has to be worked out). As a result of this the total number of animals killed within the principle observation zone will be less than those that were actually killed.
Before the end of 2014, this challenge will be addressed, with a view to understanding the specific requirement and to meeting that requirement for observations that will be undertaken within the principle observation zone(s) during 2015 and beyond.