Population size
The average numbers of Boutourlini’s blue monkeys counted in the Apini and Dokuma forests were 71 and 111, respectively. The mean number of individuals counted in block 1, block 2, and block 3 in Apini forest were 19.5 ± SD 2.12, 22 ± SD 4.24, and 29.5 ± SD 2.12, respectively. The mean number of Boutourolini’s blue monkey among the three blocks did not show significant difference (2=2.73, df=2, P>0.05).
The total number of individuals counted in the Apini forest during the wet and dry seasons were (n=74), and (n=68), respectively. This showed there is no significant difference in population size estimate between the wet and dry seasons (2=0.25, df=1, P>0.05). The individual numbers of Boutourolini’s blue monkey counted in the three blocks in Apini forest is showed below (Fig. 1).
The total numbers of individuals in Dokuma forest during the wet and dry seasons were (n=118), and (n=104), respectively. The highest number of individuals was counted in block 2, while the lowest was counted in block 1. The total number of individuals counted during the wet and dry seasons among the four blocks did not show significant difference (2=0.88, df=1, P>0.05). The mean number of individuals counted in block 1, block 2, block 3, and block 4 in Dokuma forest were 12±SD 2.83, 57.5±SD 6.36, 22 ± SD 2.82, and 19.5 ± SD 3.54, respectively. The variations in the mean number of individuals counted between blocks 1 and 2 were statistically significant (2=30.22, df=1, P<0.05), and the same was true in blocks 2 and 4 (2=18.51, df=1, P<0.05). However, there was no significant difference in the mean number of individuals counted between blocks 3 and 4 (2=0.09, df=1, P>0.05), and blocks 1 and 3 (2=2.94, df=1, P>0.05). The individual numbers of Boutourolini’s blue monkey counted in blocks during the wet and dry seasons among the four blocks are shown below (Fig. 2).
In general, the populations size of Boutourlini’s blue monkeys in the Apini and Dokuma forests showed a relatively more mean number of individuals in Dokuma forest than in Apini forest, and the difference was significant (2=8.79, df=1, P<0.05).
Activity budget
A total of n=2436 individual observations were recorded from 773 scans for the Apini group, and n=2512 individual observations were recorded from 822 scans for the Dokuma group. The Apini group spent 47.5% time feeding, 14.1% resting, 20.2% moving, 12.3% different social activities, and 6.0% other activities including vocalization, defecation, urination, and looking to the observer. Whereas, the Dokuma group spent 48.6% of their time feeding, 13.5% resting, 18.6% moving, 14.3% different social activities, and 5.0% other activities (Fig. 3).
There was no significant difference in time spent on diurnal activity budgets between the Apini and Dokuma groups ( 2=1.17, df=1, P>0.05).
Boutourlini’s blue monkey of the Apini group on average spent 48.1% of the time feeding and 17.9% of the time resting during the wet season, and 46.8% feeding and 9.8% resting during the dry season. However, they spent relatively more time 25.6% moving and 7.0% for other activities during the dry season than the wet season which were 15.4% moving, and 5.0% other activities. There were statistically significant differences in time spent feeding (2=5.12, df=1, P<0.05), resting (2=39.91, df=1, P<0.05), moving (2=20.24, df=1, P<0.05), and grooming (2=7.47, df=1, P<0.05) in the Apini group between the wet and dry seasons.
The Dokuma group on average spent relatively more time feeding (51.5%) during the wet season than during the dry season (45.4%). They also spent relatively more time moving (21.9%) during the dry season than the wet season (15.6%) (Table 1).
There were significant difference in time spent feeding (2=19.40, df=1, P<0.05), resting (2=7.39, df=1, P<0.05), and moving (2=5.14, df=1, P<0.05) for the Dokuma group between the wet and dry seasons.
Dietary ecology
A total of n=1157 feeding observations were recorded from 381 scan samplings in the Apini group, and n=1222 feeding observations were recorded from 400 scan samplings in the Dokuma group. For the Apini group, young leaves contributed 52.8% of food items of blue monkey which was the highest proportion of food items foraged. Fruits and mature leaves made the second and third largest contributions of its diet with 30.2% and 6.6%, respectively. Flowers (3.3%) and tree buds (2.5%) made the least contributions of the diet (Fig. 4).
The most frequently consumed food item in Dokuma group was the fruit which contributed 42.3% of the diet. Young leaves were the second most frequently consumed food items which accounted for 39.8% of the diet. Mature leaves and tree buds were the third and the fourth most consumed food items which made 8.3% and 4.6%, respectively, of its diet. Other food items consumed were stems, flowers, seed and animal preys which accounted for 0.5%, 1.2%, 1.8% and 1.6%, respectively, of the diet. There was significant difference in time spent feeding young leaves (2=14.24, df=1, P<0.05), fruit (2=32.59, df=1, P<0.05), tree buds (2=8.57, df=1, P<0.05), stem (2=11.64, df=1, P<0.05), and flowers (2=9.98, df=1, P<0.05) between the Apini and Dokuma groups.
Boutourlini’s blue monkeys in the Apini forest spent 62.7% of time feeding on young leaves, and 7.5% of mature leaves during the wet season than the dry season which accounts 41.5%, and 5.6%, respectively. However, they spent 39.3% of time feeding on fruits, and 5.1% on flowers during the dry season than the wet season 22.2%, and 1.1%, respectively. There was significant difference in time spent feeding on young leaves (2=43.48, df=1, P<0.05), fruits (2=16.11, df=1, P<0.05), tree buds ( 2=7.75, df=1, P<0.05), and flowers (2=15.15, df=1, P<0.05) between the wet and dry seasons in the Apini group.
In the Dokuma forest, they spent 44.9% of time feeding on young leaves, 9.2% on mature leaves, and 4.9% on tree buds during the wet season than the dry season which were 33.1%, 7.1%, and 4.1%, respectively. However, they spent 49.1% of time feeding on fruits, and 2.4% on flowers during the dry season than the wet season which was 37.1%, and 0.3%, respectively (Table 2).
There was a significant difference in time spent feeding young leaves (2=35.85, df=1, P<0.05), mature leaves (2=6.18, df=1, P<0.05) and flowers (2=8.06, df=1, P<0.05) between the wet and dry seasons in the Dokuma group.
Boutourolini’s blue monkey of the Apini and Dokuma groups consumed a total of 14 plant species in their overall diet during the study period (Tables 3 and 4). In the Apini forest, the highest contribution of the diet was from the Albizia gummifera (33.7%), and Hyppocratea spp. (29.1%), while in the Dokuma forest, the most consumed plant species in the percentage contribution was Hyppocreatea spp. which accounted (35.1%), and Albizia gummifera (24.7%).
Ranging ecology
Ranging ecology of Boutourlini’s blue monkeys in the Apini group during the wet and the dry seasons were 44.4 ha and 78.3 ha, respectively (Fig. 5) whereas the ranging ecology of Boutourlini’s blue monkeys in the Dokuma group during the wet and the dry seasons were 51 ha and 56.9 ha, respectively (Fig. 6).
There was a significant difference between the wet and dry seasons in the home range size of blue monkeys in the Apini group (2=9.47, df=1, P<0.05). However, there was no significant difference between seasons in the home range size of the Dokuma group (2=0.33, df=1, P>0.05).
The mean daily range distance for the Apini group during the wet and the dry seasons were 648 m, and 732 m, respectively whereas for the Dokuma group the mean day range distance during the wet and the dry seasons were 715 m and 774 m, respectively. There was significant difference in the daily range lengths of blue monkeys of the Apini group between the wet and dry seasons (2 =5.11, df=1, P<0.05). However, in the Dokuma group, the difference did not show significant difference between the two seasons ( 2 =2.33, df=1, P>0.05).