 Reference Base  Wallows and wallow utilization of the Sumatran rhinoceros... |
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| Location: |
Asia - South East Asia - Malaysia - Peninsular |
| Subject: |
Behaviour - Daily Routine |
| Species: |
Sumatran Rhino |
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INTRODUCTION
Wallows are mud pools formed in poor drainage areas where the soil remains wet for long periods. They are widely distributed and are found in swamps and on mountain ridges. Wallows often exist individually or in a network of up to 10 pits. Wallowing, in which the animal covers itself with a layer of mud, is an important daily activity for a Sumatran rhinoceros. The layer protects the rhino against attacks from biting insects (Tabanidae) and keeps the animal's skin moist and cool.
Captive Sumatran rhinoceroses (Dicerorhinus sumatrensis) that were not provided with adequate bathing facilities developed broken and inflamed skins with suppurations, eye problems, inflamed nails and hair loss (Anderson, 1961; Coenraad-Uhlig,1933). Similarly, in the Melaka Zoo, pyoderma was observed in Sumatran rhinoceros caused by insufficient wallowing facilities (Zainal-Zahari et al. 1991). A young captive Sumatran rhinoceros that was not allowed to bathe for a week suffered a generalized cracked skin, and it died shortly
afterwards (Hubback, 1939). Although most facilities for captive rhinos now provide pools or constructed wallows, these are not enough. Problems of the integumentary system still recur.
Information on wallows and wallowing habits of the Sumatran rhinoceros is lacking, yet it is important for the health and survival of captive rhinos. This study looks at wallows in a natural enclosure and how Sumatran rhinoceros use and compares the information to that in previous reports.
MATERIALS AND METHODS
This study was carried out in a 10-acre natural. enclosure within the Sungai Dusun Wildlife Reserve, Selangor The area is forested and enclosed by electric fencing, The enclosure is moderately undulating and has both the characteristics of a lowland dipterocarp and peat swamp forest. It is built on swampy terrain with an altitude of 40 m.
Sungai Dusun is a prime habitat for the Sumatran rhinoceroses, and a pair was; released into the reserve. The width and length of each wallow was measured. Barriers including fallen trees, logs, trees, and Bertam palms (Eugeisonna triste) that were found surrounding the wallows were noted. The wallows were classified as active (used) or inactive (not used) and as shaded, partially shaded or unshaded. Activity periods of each wallow were recorded from March 1998 to October 1999. During this period, the rhino pair was observed from 1000 to 1600 for 38 days to determine wallowing periods. Observations were only carried out during these periods as they coincide with the keepers work schedule. In addition, the rhinos would come to the feeding area for foliage. Sampling throughout the study was by spot check except between 1300 and 1400, when a one-hour focal sampling was used.
RESULTS
The average length and width of wallows were 2.57 m (?0.61) and1.94 m (?0.68) respectively with an estimated area ranging from 2.5 to 14.8 m2 (Table 1). The length of active time for each wallow ranged from 2 to 122 weeks with an average of 5.85 weeks (Figure 1). Three active wallows were the maximum observed, these in the months of April and May, 1998 and September 1999. The rhinos made their wallows in two distinct periods, between March and July 1998 and between March and June 1999 (Figure 2).
The rhinos made all their wallows under open canopy, mostly in forest gaps. Half were completely shaded by Bertam palms, 25% were partially shaded and 25% were in the open. The barriers observed during the study were mainly Bertam palm, trees and logs. A total of 20 wallows were identified in three distinct networks, consisting of 4, 6 and 10 wallows. Network 1 was located in a swampy region while networks 2 and 3 were found at an elevation of 5 and 20 m respectively (Figure 3).
The animals customarily wallowed continuously for 2 or 3 hours before coming out to feed. Spot checks indicated that frequency of wallowing increased in the morning hours until 1130, decreased at midday before reaching a maximum at 130011 and gradually decreasing again from 1400H to 1600H (Figure 4).
DISCUSSION
Wallow shape varied from elongate to irregular ovoid, often conforming to the shape of the rhinoceros. Wallows increased in size as the rhinoceros continued to use them, because the animal would scrape mud from the wall of a wallow to reconstitute the contents. The Sumatran rhinoceros prefers mud that is thick and viscous enough to stick to the skin after it wallows. The dimension of wallows varies from location and within a network.. The length and width observed were within previously reported dimensions of 2 to 4 m by 1 to 2.1 m (Talbot, 1960; van Strien, 1985). However, wallows of up to 8 m in diameter have been recorded (Kurt, 1970). Of the three networks off wallows identified during the study, two were located near the main trail (at 5 and 20 m altitude) and one near a swamp. Each network consisted of 4 to 10 wallows. Studies in Gunung Leuser indicated 10 wallows within a network located along the main rhinoceros trails. Within the network of wallows, only one or two were active. These findings are similar to those from previous studies (van Strien, 1975; 1985). Wallows are more frequented than salt leeks and are often found near streams and low saddles on ridges (Foenander, 1944). In Sungai Dusun, the wallows were located under open canopy, 75% of them completely or partially shaded by Bertam palms. The barriers surrounding the wallows include Bertampalms, fallen logs and trees. However, in Gunung Leuser, wallows often bordered fallen tree trunks and cavities left by uprooted trees (van Strien, 1985). The areas surrounding the wallows were intact except for the trails that led into them, which ranged from 1 to 4 in number.
These trails were clear of vegetation. Previous studies have shown that surrounding areas of 10 to 35 m around the wallows were cleared of vegetation (Kurt, 1970).
There is no past study that shows the length of active time for a wallow. However, van Strien (1985) found wallows reopened that had not been used for many years. Inactive wallows are watery, clear and usually filled with, algae, dead branches, twigs and feces, unlike the soft, rich, creamy-looking mud in active wallows. This is similar to studies carried out in Gunung Leuser (van Strien 1985). Of the 20 wallows, wallows 3, 16 and 18 were active for a maximum period of 12 weeks each (n = 20; ? = 5.85 weeks). The physical size, shape and type of barrier are not correlated to the length of time a Sumatran rhinoceros uses a wallow. Some possible factors influencing the usage time are the consistency of mud and the chemical composition.
During the study, a season when wallowing increased was distinctly marked. Three active wallows were observed in April 1998, May 1998 and September 1999 as compared with an average of 1.63 per month throughout most of the study period. Two distinct periods when the rhinos increased their wallow making were during March to July 98 and March to June 1999. These periods coincide with the dry season. This is similar to previous findings that wallowing frequency increased during the dry period (Borer, 1979; Richard et at. 1990). In Gunung Leuser, Sumatran rhinoceros were observed wallowing in both dry and wet periods.
Wallowing occurred throughout the observation period, with a peak time between 1100 and 1130; it then decreased gradually towardsevening. Similarly, in Zoo Melaka, wallowing was observed between 1100 and 1500 with increased frequency during hot weather. In these artificially made wallows or concrete pools at Zoo Melaka, the duration of wallowing ranged from 3 to 4 minutes on a cool day and 45 minutes during hot weather (Richard et at. 1990). In contrast, the study in Sungai Dusun indicated that the rhinoceros spends between 80 and 300 minutes daily (an average of 166.32 minutes) in wallowing. This is similar to the observations in Gunung Leuser, where the Sumatran rhinoceros spends hours wallowing (van Strien, 1985).
CONCLUSION
Wallows are essential in any management of the captive Sumatran rhinoceros. Whenever possible, the wallow or its contents should be changed every 3 months, according to the length of time a wallow was used as observed during the study. Although artificial wallows or pools cannot substitute for natural wallows, their quality can be improved by selecting good-quality mud or clay with a thick, creamy consistency.
The wallows observed were made where there were natural barriers like palm trees or logs. The enclosure for the captive animals should therefore simulate such things. During the dry season, the agement of the facility should ensure that the wallows for the rhinoceroses are sufficient in number
Further studies should be carried out to find out why the animals abandon a wallow and what the chemical elements in a wallow are.
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