Santiapillai et al. (1993) report tracks only in Lam Dong province and an animal which crossed the river into Song Be province. By that time the rhinos of Dong Nai province may have permanently retreated into Lam Dong province, ranging throughout the 35,000 ha Cat Loc area.
In 1988 a hunter shot a female rhino near the Dong Nai River in Cat Tien District. Rhinos were a protected species by Vietnamese law already at that time and thus the hunter was arrested after he tried to sell the horn and skin on the market (Schaller et al., 1990). This incident renewed the attention of the Vietnamese and international scientific and conservation communities for the rhinos of Vietnam. Moreover, the incident proved that rhinos were still surviving in Vietnam. Schaller et al. (1990) provide an overview of rhino sightings and killings during the late 1970s and 1980s. These are all from the Dong Nai river area, where Dong Nai, Lam Dong, Song Be (now divided in Song Be and Binh Phuoc) and Dac Lac province border one another.
Map
Vietnamese Rhinoceros
Vietnam. Griffiths (1992) recognising 31 individual Javan rhinos in Ujong Kulon, 60% of which the sex was known, notes that all individuals confirmed to be male have a horn, while all individiials confirmed to be female have no horn. Amman (1985) concludes that female Javan rhinos in Ujong Kulon have at most a small 'hump' and exceptionally a 'small horn'. Schenkel and Schenkel-Hulliger (in Amman, 1985), however, observed that all the rhinos they saw in Ujong Kulon had a distinctive horn and assumed that at least some of them must have been female. Whether or not female Javan rhinos from Ujong Kulon have a small horn or a hump remains unclear. The horn in the pictures of the rhinos from Cat Tien National Park are not large but seem to be too large to be, subjectively, classified as 'hump' or 'small horn'.
The rhino on Photo 4 (rhino 4) has its mouth wide open. A large incisor in the lower jaw is clearly visible. Van Strien (pers. comm.) believes that having large incisors is typical for male Javan rhinos.
Vietnam. Griffiths (1992) recognising 31 individual Javan rhinos in Ujong Kulon, 60% of which the sex was known, notes that all individuals confirmed to be male have a horn, while all individiials confirmed to be female have no horn. Amman (1985) concludes that female Javan rhinos in Ujong Kulon have at most a small 'hump' and exceptionally a 'small horn'. Schenkel and Schenkel-Hulliger (in Amman, 1985), however, observed that all the rhinos they saw in Ujong Kulon had a distinctive horn and assumed that at least some of them must have been female. Whether or not female Javan rhinos from Ujong Kulon have a small horn or a hump remains unclear. The horn in the pictures of the rhinos from Cat Tien National Park are not large but seem to be too large to be, subjectively, classified as 'hump' or 'small horn'.
The rhino on Photo 4 (rhino 4) has its mouth wide open. A large incisor in the lower jaw is clearly visible. Van Strien (pers. comm.) believes that having large incisors is typical for male Javan rhinos.
Vietnam. The results of the analysis of dimensions and forms of plaster casts and field measurements are summarised in Table 3. Here it is noted that in general that the widths of the feet measured from casts and in the field are comparable, but the lengths of the feet measured in the field are generally one cm larger than those measured from casts. The analysis of differences and dimensions and the form of plaster casts made of full prints and front hooves, suggests that there are six individual rhinos. However, the analysis and comparison of the dimensions of 241 footprint sizes measured in the field shows that the range of variation is rather large. From 157 mm to 240 mm wide, and 187 mm to 258 mm long. The smallest footprint is 157 mm wide and 197 mm long, and the largest footprint is 240 mm wide and 248 mm long. It is concluded that these are the footprints of many different individuals. 90% (217 measurements) of the footprints' widths are within the range from 176 mm to 215 mm. There are 19 footprints shorter than 176 mm and five wider than 215 mm. Among the footprints which are wider than 216 mm, there are three particularly large, of' which measurements were taken at three different locations. There is also a very large plaster cast of 135 mm wide and 246 mm long. All the other casts are less than 120 mm wide. Obviously, this is the footprint of a rhino different from the six rhinos that were recognised above. Based on the above analysis, the minimum number of rhinos in Cat Tien National Park is estimated to be seven. Besides these seven individuals, there are a number of footprints of which the widths are beyond the above seven rhinos' range of dimensions. In addition, in the process of investigation there were many footprints recognised at different locations, but their plaster casts could not be made because they were not clear. There were also a number of locations in which there might be rhinos' footprints but the survey team could not reach them despite the fact that this survey has been the most intensive one ever. It is possible that several rhinos were not counted in this survey. Therefore, the maximum number of rhinos in Cat Tien National Park is estimated to be at least eight. Table 3. Comparison of rhino footprint characteristics for identification of individuals: average dimensions of footprint plaster casts and measurements in the field. Characteristics Foot plaster casts Footprints Front hoof N = 111 N = 241 plaster casts Width Length Width Length Width Length [mm] [mm] [mm] Rhino 1 (n=21) 191.2 217.9 191.1 228.3 106.0 46.9 Front hoof regularly round, wide, high Rhino 2 (n=19) 202.1 222.9 195.8 234.7 111.9 33.7 Front hoof regularly round, wide Rhino 3 (n=10) 196.6 219.7 194.6 232.0 107.6 47.4 Front hoof slanting, wide, high Rhino 4 (n=29) 185.8 220.8 190.0 228.9 101.1 33.4 Front hoof regularly round, low, narrow Rhino 5 (n=17) 187.0 207.4 190.0 218.6 93.4 47.1 Front hoof slanting on the right,high, narrow, hoof rim sharp Rhino 6 (n=15) 191.1 210.1 187.5 218.5 96.4 44.4 Front hoof slanting on the left, high, narrow, hoof rim sharp
Vietnam. Sung et al. (1998) estimate that the R. s. annamiticus is about 75 to 80% of the size of a R. s. sondaicus. They base this estimate on the ratio of the width of the hind feet measured in Cat Loc (20-23 cm) versus those recorded in Ujong Kulon (25-28 cm). Using this relation in size and estimating the weight of a R. s. sondaicus to be 1,600 kg, it may be estimated that a R. s. annamiticus weighs about 650 to 800 kg (1,600 kg x 0.753 to 0.83).
Photo 1 shows a rhino (rhino 1) where a height-marker is visible behind the animal, just in front of its ears. The height of the marker is one meter (32 mm on the picture, about 40 mm at rhino's shoulder when accounted for perspective). The height at the shoulder of this individual is estimated to be 130 cm (52 mm on the picture/40 mm) which is slightly larger than the estimate presented (110- 120 em) by Sung et al. (1 998). Sung et al. (1998) estimate that the R. s. annamiticus is about 75 to 80% of the size of a R. s. sondaicus. They base this estimate on the ratio of the width of the hind feet measured in Cat Loc (20-23 cm) versus those recorded in Ujong Kulon (25-28 cm). Using this relation in size and estimating the weight of a R. s. sondaicus to be 1,600 kg, it may be estimated that a R. s. annaniiticus weighs about 650 to 800 kg (1,600 kg x 0.753 to 0.83).
Photo 1 shows a rhino (rhino 1) where a height-marker is visible behind the animal, just in front of its ears. The height of the marker is one meter (32 mm on the picture, about 40 mm at rhino's shoulder when accounted for perspective). The height at the shoulder of this individual is estimated to be 130 cm (52 mm on the picture/40 mm) which is slightly larger than the estimate presented (110- 120 em) by Sung et al. (1 998). Sung et al. (1998) estimate that the R. s. annamiticus is about 75 to 80% of the size of a R. s. sondaicus. They base this estimate on the ratio of the width of the hind feet measured in Cat Loc (20-23 cm) versus those recorded in Ujong Kulon (25-28 cm). Using this relation in size and estimating the weight of a R. s. sondaicus to be 1,600 kg, it may be estimated that a R. s. annaniiticus weighs about 650 to 800 kg (1,600 kg x 0.753 to 0.83). The small size of the footprints from Cat Loc is more in accordance with the size of footprints of Sumatran rhinos (Dicerorhinus sumatraensis) or with sub-adult R.s. sondaicus (Sung et al., 1998). Since all footprints from Cat Loc are between 20 and 23 cm in width, it would be hard to conclude that the Cat Loc population consists only of subadults. From the pictures presented in this article it is beyond doubt that the Cat Loc rhinos are Javan and not Sumatran rhinos. Sung et al. (1998) argue that the poor quality of the habitat in Cat Loc may have contributed to the smallness of R.s. annamiticus and that the Ujung Kulon and Cat Loc populations belong to clearly distinct gene pools. To stress this point, they also suggest for R.s. annamiticus the vernacular name 'Vietnamese rhino' instead of using the tenn 'Javan rhino' in Vietnam. Looking at the locations, dates and times that the pictures were taken, combined with the fact that adult Javan rhinos are generally regarded as solitary animals, an attempt can be made to deduct whether the pictures are all of the same or of different individuals. The rhinos on photos 1 and 2, 3 and 4, 6 and 7 are almost certainly of the same individual (each pair of pictures has been taken at the same place and very shortly after each other). Hence it is deducted that all pictures are of at most four different individuals (including the possibility that all pictures are of the same individual).
