FIELD OBSERVATIONS
Feeding on soil by moustached tamarins was observed on three different occasions. The first observation took place on September 1, 1990. At 10:14, an adult moustached tamarin went down to the forest floor, took a piece of soil from a broken and abandoned mound of leaf-cutting ants (Atta sp.; Formicidae: Myrmicinae: Attini), returned to a tree trunk, and started to ingest the soil. Feeding lasted for about 30 sec.
A second instant of soil feeding was observed on September 4, 1990. At 13:46, an adult moustached tamarin fed for about 20 sec, picking up soil with the mouth directly from the forest floor. After this animal had stopped feeding, the group's juvenile fed for about 20 sec, too, at the same site. No scratching or digging was observed. The soil feeding place was bare of vegetation or leaf litter and had a diameter of about 10 cm.
On the third occasion, on September 5, 1990, soil feeding was not directly observed, but was obvious from the circumstances. At 14:06, an adult moustached tamarin went down to the forest floor, and at 14:07, two other adults followed. They stayed there for about I min. When the site was inspected where the tamarins had stayed, a spot of bare soil was detected. Generally, moustached tamarins were observed to descend to the forest floor only to feed on fruits [mainly pods of Parkia nitida, (pers. obs.)]. Foraging on the forest floor for insects or small vertebrates has not been observed in moustached tamarins. Thus, although soil feeding was not directly observed on September 5, the lack of fruits on the forest floor and the presence of a spot of bare soil support the assumption that soil feeding took place on this occasion, too.
After these observations had been made, it was tried to find spots of bare soil in the study area. However, it turned out that bare soil is extremely rare. When removing the leaf litter, one finds a very dense mat of roots that makes access to the soil difficult if not impossible.
No other instances of soil feeding were observed during this field study nor during a previous 13-month field study at the same site in 1985/86, nor was it observed in the saddleback tamarin group (Saguinus fuscicollis) that was living in permanent association with the moustached tamarin study group (HEYMANN, 1990).
CHEMICAL COMPOSITION
Table 1. Chemical composition of soils consumed by Saguinus mystax.
|
Sample A1)
|
Sample B
|
Sample C
|
|
| SiO2 |
68.190 weight %
|
91.000 weight %
|
94.150 weight %
|
| TiO2 |
1.52
|
0.535
|
0.793
|
| Al2O3 |
18.24
|
2.29
|
1.54
|
| Fe2O3 |
3.39
|
0.56
|
0.58
|
| MnO |
0.009
|
0.005
|
0.005
|
| MgO |
0.18
|
0.02
|
0
|
| CaO |
0.02
|
0.02
|
0.02
|
| Na2O |
0.02
|
0.07
|
0.03
|
| K2O |
0.243
|
0.046
|
0.027
|
| P2O5 |
0.041
|
0.029
|
0.024
|
| .................... | .................................................. | .................................................. | ................................................... |
| Sc |
9 ppm
|
4 ppm
|
4 ppm
|
| V |
168
|
27
|
29
|
| Cr |
87
|
17
|
15
|
| Co |
< 5
|
< 5
|
< 5
|
| Ni |
8
|
< 5
|
< 5
|
| Zn |
38
|
9
|
4
|
| Ga |
26
|
4
|
4
|
| Se |
< 5
|
< 5
|
<5
|
| Rb |
14
|
4
|
5
|
| Sr |
52
|
14
|
19
|
| Y |
33
|
15
|
21
|
| Zr |
645
|
394
|
588
|
| Nb |
25
|
11
|
15
|
| Ba |
59
|
10
|
13
|
| Pb |
13
|
10
|
8
|
1) From mound of Atta sp. ants.
Sample A (from the ant mound; September 1) is a reddish brown,
fine-grained soil, sample B (September 4) a very light brown sand, and sample
C (September 5) a light brown sand. All samples were tasted by the observer
immediately after collection. No special taste was apparent, except that sample
B had a very light salty taste.
The chemical composition of the soils consumed by the moustached tamarins is presented in Table 1. Samples B and C are very similar in their composition, but sample A (ant mound) exhibits elevated concentrations of several elements.
