Camera Trap Surveys
Video Trap for Monitoring the birth of Javan Rhino in Ujung Kulon National Park
Adhi Rachmat Sudrajat Hariyadi, WWF – Indonesia.
One of the most important aspects of wildlife monitoring is to determine the birth rate within a population to further assess if the population is increasing, stagnant, or declining. Similarly for the javan rhinoceros (Rhinoceros sondaicus) population in Ujung Kulon, the birth rate is an important indicator that shows the capability of this small population to replenish. Unfortunately, monitoring such aspect for javan rhinoceros is not an easy task, as the animals spend most of their time hiding and avoiding encounters with humans. After identifyingthis challenge, a team consisting of Ujung Kulon National Park authority and WWF Indonesia sets out a special procedure for monitoring the birth of rhino in this National Park.
Based on previous experiences, it is generally agreed that the newborn rhino calf will have a foot print size in the range of approximately 14-17 cm wide that is usually accompanied by the mother’s foot print, while foot print larger than 17 cm is normally considered as young or juvenile rhino that has been separated from the mother. Therefore, finding a new small footprint size always gives excitement for the rhino observation and monitoring team (ROAM team), as it indicates that a new member in the rhino population has just been born. This was the case from the previous rhino survey activity conducted last year where the team detected a foot print size of 14cm wide, but the automatic cameras used in that activity did not manage to record the presence of this newly born rhino.
This finding was followed up by designing video trap camera placement specifically for monitoring the newborn rhino. This required special modification to the existing video trap monitoring method to allow detection of the mother and calf pair without creating unnecessary disturbances to them. This was achieved by carefully identifying the blocks where the footprints are detected and placing video trap equipments such that these devices were concealed from possible detection by the rhinos. The video trap devices were placed at the height of 2.5 meters with a down angle so that the rhino path would be covered within the field of vision of these video camera units. The angle was checked using digital pocket camera to ensure that this was an appropriate angle for recording the rhinos, as well as ensuring that this angle would allow identification of the individual rhinos.
Sixteen video trap units were used to identify the newborn rhinos, and the survey area covered an area in the south coast of Ujung Kulon national Park (Cibunar to Citadahan blocks) where the footprint was first detected. These video trap cameras were placed for 30 days and the data was collected afterwards. Using this method the team managed to record two mother-calf pairs, as well as identifies the sex of the newborn calves. This finding confirms that with minor modifications on camera placing and sample site selection these equipments can be used for detecting and identifying the newborn rhinos in the wild. Advance sampling methodology is being discussed in order to allow long term monitoring of the calves that will yield information on the population growth, as well as the growth rate of the individual calf. Current data shows that the calf can grow from 13-cm foot print size to 18-cm size in a period of 18 months.