Abstract
Khatasa Protected Forest is one of the protected forests found in Awi Zone, Amhara Regional State that has been protected since 1994. The study on home range and habitat use of Colobus monkey (Colobus guereza) was carried out from January 2021 to August 2021. For this purpose, ranging data were collected from the focal animal group, and following for continuous periods at regular intervals of 10 min. This study was carried out in combination with feeding and habitat use of focal animal samples. During the observation of focal animals in each group, location of troops were recorded using GPS in every 10 min until the follow was concluded. The values from the map were calculated by using measuring tools in the GIS software ArcGIS 10.8. Data on habitat use and feeding were collected in using a scan sampling starting from early morning 7:00 to 12:00 h and in the afternoon from 14:00 to 18:00 h throughout study period. The ranging ecology of Colobus monkey in the study area was characterized by a mean daily range length of (207.13 m, SE ± 10.14) in the study. The highest mean daily range length was recorded during the dry season mainly in March (281 m, SE ± 16.33) while the lowest mean daily range length was recorded during the wet season mainly in July (147 m, SE ± 6.45). In regarding to habitat use/feeding, colobus consumed nearly 15 plant species in Khatasa Protected Forest. Among the plant species Albizia Schimeperiana and Apodytes dimidiate had contributed to high proportion of the diet of Colobus monkey, which were (33.25%) and (12.85%), respectively. The variation in type of plant species consumed in the study period showed a significance difference (χ2=49, df=1, p=0.05) between dry and wet seasons. Determine the ranging and feeding ecology of Colobus monkey in dry and wet seasons in this protected area would enable to take conservation actions.
Keywords: Colobus monkey, Forest, Home range, Habitat use, Seasonal variations
Introduction
Colobus monkeys are arboreal species, and they are mainly susceptible to deforestation activities [21, 23, 34]. Two of the eight subspecies of Colobus guereza are endemic to Ethiopia: C. g. gallarum and C. g. guereza [24]. However, the validity of the Ethiopian taxa is debated and observed morphological differences were attributed to clinal variation within C. g. guereza. Some of the population of the species, especially those belonging to the sub-species C. g. gallarum have a notably small habitat range [5, 24]. The foliverous species tend to have smaller home range every day than frugivorous primates do [43].
Colobus monkey can modify their ranging behavior in response to seasonal modifications in food availability as some primate species decrease the size of day by day tours when notable food is scarce [3, 22], whilst others show the opposite response, visiting in search of remarkable diet [4, 37]. Colobus monkeys are in a position to use a very small home range and adapt to food scarcity within energy conservation approach of growing rest while decreasing each day travel as a result the species can also alter their behavior to adapt to local environmental conditions (Dunham and Graw, 2014; [2]). Anderson,
Colobus monkeys are dominantly inhabit large contiguous rainforests, gallery forests, and fragmented forest patches [1, 7, 16]. They are predominantly folivorous, with a diet mostly consisting of young leaves [38, 39]. Habitat use of colobus monkey is notably influenced by fragmentation and different varieties of human disturbance to their natural habitats [23, 25, 26, 30]. In addition, the feeding ecology of the species has been significantly influenced by different ecological factors such as scarcity of essential nutrients [14]. Though this factor has also had been brought significant impacts on colobus monkey’s ecological behavior and ranging patterns [36, 40, 42, 43]. As far as the black and white Colobus monkey is concerned, few studies associated with behavior ecology and population status had been studied in different area of Ethiopia. However, studies on home range and habitat use had never been studied in the present area. Therefore, the main objectives of this study were to (1) estimate home range size of black-and-white colobus monkeys in Khatasa Forest, Awi Zone, Amhara; (2) determine habitat use of black-and white colobus monkeys; and (3) provide appropriate recommendations for the long-term protection of C. g. guereza and its habitats in the area.
Methods
Description of the study area
This study was conducted in Khatasa Protected Forest Awi Zone of Amhara National Regional State, Ethiopia. Khatasa Protected Forest is geographically located between 10’58’ 34.5’’ to 10° 59‘02.1’’ N latitude and 36° 47‘03.9’’ to 36⁰ 48‘26.9‘‘E longitude with an area of 540.74 ha. The topography of the study area consists of areas with gentle to steep slopes. The landscape is composed of agricultural and grazing areas, settlements, rivers, hills, and small to medium-sized mountains. The topographic feature of the study area ranges between altitudes of 2,200–2,500 m.a.s.l [28]. As a result of this, the study area consist of different vegetation types such as Dry Afromontane forest, Riverine forest and plantation forest. It also harbors a diverse wildlife species such as mammals and birds. Among the large mammals: leopard, spotted hyena, African wolf, serval, Olive baboon, Grivet monkey, Blue monkey and Abyssinian hare were the most common wildlife species recorded during the study period (Fig. 1).
Fig. 1.
Map of the study area
The climate of the area is characterized by a moderate temperature [17]. However, the mean monthly temperature of the area ranges between 12 º C and 27 º C. The area has a unimodal rainfall pattern with precipitation mean ranges from 150 mm to 250 mm (Fig. 2).
Fig. 2.
Mean monthly rainfall (mm) and temperature (℃) of the study area
Data collection methods
Preliminary survey
Prior to the actual data collection, a reconnaissance survey of the study area was conducted in December 2020, and the survey showed the study area is heterogeneous in vegetation type and topography. Data collection was conducted in Khatasa Protected Forest from January 2021 to March 2021 in the dry season and from June 2021 to August 2021 in the wet season.
Range ecology
Ranging data were collected from the focal animal groups by following for continuous periods at regular intervals of 10 min. This study was carried out in conjunction with observation of feeding behavior and habitat use. During the focal animal follows, the location of the animals were recorded using GPS in every 10 min until the follow ended- either when the colobus monkeys’ entered their evening sleeping site/tree or when the researchers could no longer locate them [9, 36].
In addition, data were also collected even when activity data were not obtainable owing to poor visibility, as long as the focal individual’s location could be confirmed via signals such as distinctive tree movements or vocalizations [11, 12].The day range length was determined based on the shortest point-to-point movements of the focal individual colobus between consecutive GPS locations during full-day flow in sampling day (four days in each month) ([41]; Mekonnen et al., 2010). Each day range was plotted on a GIS-system generated map (Arc Map version 10.8) and Google earth pro by connecting the consecutive GPS location records and the total distances traveled per day.
The range sample size from all-day follow may be small for some months and larger on other days. So, we calculated seasonal rather than monthly mean day range lengths. Also home ranges were calculated using a program called kernel density estimation Geo processing tool from Arc GIs software for the purpose of drawing the home range area and different percentage of area usage in different season [27]. The GPS points from all of the observation periods were merged together to analyze the utilization of the habitats in dry and wet seasons.
Habitat use
To study the habitat use and characteristics of the focal animals, sample quadrates were made on the habitats of Colobus monkey. For vegetation description of the study sites, four 50 × 40 quadrates in each site were established, and in each quadrant, the type and number of plant species were recorded [18, 35].Behavioral data on Colobus monkey were collected using scan sampling. Feeding activity of focal individuals was recorded every 30 min from 7:00 AM to 6:30 PM or later if the group had not settled for the night. At the beginning of each scan, the first monkey seen was used, but we waited 5 s before recording its behavior to avoid biasing the data in favor of eye-catching behaviors. We then moved to the next individual to the right of the first, until the feeding activity of the group members was recorded [6, 37].
Data recorded were feeding habit (upper, middle, or lower third of tree crown); food tree species; plant part; and diameter at breast height (DBH). Diet was determined from these scan data. Diet tree species were defined as any tree consumed for > 1% of the feeding observations of any group [32]. Similarly, diet of the species were defined as any species–plant part combination consumed for > 1% of feeding observations of any group member; plant parts included mature leaves, young leaves, petioles, leaf buds, fruits, flowers, bark, and seeds. Using repeated standard observation and the scan sampling method, the feeding habit, food items, and seasonal dietary variations of the species were identified [6, 13]. Data such as the name of the plant species, the forms and parts consumed by the animal, the time spent foraging, and the number of observation times when they consume the plant types or parts were recorded [13, 29].
Data analysis
Range data was calculated by using ArcGIS 10.8. It was also calculated using a program called Kernel Density estimation Geo processing tool from Arc GIs software for the purpose of drawing their home range areas with percentage area of using in dry and wet seasons. Feeding activity and dietary composition of Colobus monkey were analyzed using a combination of descriptive and inferential statistical tests. Differences in feeding activity between seasons were tested using, post hoc pairwise comparisons were conducted using Tukey’s HSD test. While the dietary composition of consumed plant species was quantified as proportions of total feeding records. Differences in the contribution of plant species, plant parts, or food categories were analyzed using chi-square tests of independence. Spearman’s rank correlation was used to examine relationships between feeding activity and environmental variables. All statistical tests were conducted at a significance level of p < 0.05. Dietary composition was measured by calculating the proportion of various dietary items and plant species consumed by focal groups based on the total amount of feeding time spent [15, 29].
Results
Daily range lengths
The ranging ecology of Colobus monkey in the study area was characterized by a mean daily range length of (232 m, SE ± 12.930) in the dry season and (181.6 m, SE ± 12.09) in the wet season. The focal animal group was followed 3 days in a week for 3 months in dry season with 396 h of behavioral observation, and similar behavioral observation was also done in wet season for 3 months with 278 h of behavioral observation. However, daily traveling range also varies from one habitat to other habitat type in both dry and wet seasons. The highest daily range length was observed in plantation forest (315 and 290 m) in both seasons. So that One-way ANOVA shows that there was significant difference between mean daily range length of colobus monkey in different habitat type (χ2=10018.7, f=5.7, p=0.010) (Table 1).
Table 1.
Daily range length of Colobus monkey in different habitat
| Daily rang lengths of C. monkey in dry and wet seasons | ||||
|---|---|---|---|---|
| Seasons | Habitat type | Total distance in (m) | Std. Error | Mean(m) |
| Dry season | DAF | 1781 | 11.41 | 222.63 |
| RF | 694 | 34.59 | 231.33 | |
| PF | 315 | 315 | ||
| Total | 2790 | 12.93 | 232 | |
| Wet season | DAF | 1226 | 8.221 | 175.4 |
| RF | 665 | 17.021 | 166.3 | |
| PF | 290 | 290 | ||
| Total | 2181 | 12.091 | 181.6 | |
NB:-DAF: dry afromontane forest, RF: riverine forest, PF: plantation forest
Multiple compression of Post hock test was also conducted to show which habitat has really significant effect on the daily range length of colobus monkey in the study area. It showed that there was a significant difference in the distribution of the species, particularly Dry afromontane Forest (DAF) with, Plantation Forest (PF) and Riverine Forest (RF) with Plantation Forest (PF) (Table 2).
Table 2.
Tukey HSD multiple compression of effect of study habitat on the daily Rang length of Colobus monkey
| (I)habitat | (j)habitat | Mean difference | Std. error | sig | 95% confidence interval | |
|---|---|---|---|---|---|---|
| DAF | RF | 6.324 | 19.158 | 0.942 | -41.96 | 54.61 |
| PF | -102.033* | 31.506 | 0.011 | -181.45 | -22.62 | |
| RF | DAF | -6.324 | 19.158 | 0.942 | -54.61 | 41.96 |
| PF | -108.357* | 33.557 | 0.011 | -192.94 | -23.77 | |
| PF | DAF | 102.033* | 31.506 | 0.011 | 22.62 | 181.45 |
| RF | 108.357* | 33.557 | 0.011 | 23.77 | 192.94 | |
*. The mean difference is significant at the 0.05 level
In overall, the ranging ecology of Colobus monkey in the study area was characterized by a mean daily range length, of (207.13 m, SE ± 10.14) in the study period. The highest mean daily range length was observed during the dry season mainly in March (281 m, SE ± 16.33)while the lowest mean daily rang length was observed during the wet season mainly in July (147 m, SE ± 6.45) it might be associated with different factor. However, the independent sample t test shows that there was a significant difference in the mean daily range length of colobus monkey in dry and wet seasons (t = 2.86, df=22, p=0.009) (Table 3).
Table 3.
Mean daily range length of Colobus monkey during dry and wet season
| Monthly recorded | Session | Total travel distance in(m) | Std. error | Mean(m) |
|---|---|---|---|---|
| Dry season | 1 | 892 | 14.15 | 223 |
| 2 | 773 | 6.09 | 193.25 | |
| 3 | 1125 | 16.33 | 281.25 | |
| total | 2,790 | 36.57 | 232.5 | |
| 4 | 782 | 10.14 | 195.5 | |
| Wet season | 5 | 588 | 6.45 | 147 |
| 6 | 811 | 29.17 | 202.75 | |
| total | 2,181 | 45.76 | 181.75 |
NB:- session 1: January, session 2: February, session 3: March, Session 4:Jun, session 5: July, session 6: August
Habitat use
The home range of an animal is the area that inhabited and used for the daily activities. In present study, Kernel Density Estimates showed evidence of well-defined home range use and the total area covered by individuals of the species. KDE approach calculates density fields that can be transformed and/or rescaled into probabilistic utilization surfaces. To derive volume contours from the utilization density surfaces—or polygons that are formed, so from the current study result, area usage of home range was classified into three main classes as highly, moderately and low used areas based on the Kernel Density value per unit area for density of point location that colobus monkey exist related to their forging utilization activity (Fig. 3) so, the result shows that highly used area which is represented by blue black and white color is more intense use, moderately used area which is represented by red color while this is denser than low used area which is represented white and green in dry and wet season, respectively. The usage proportion might be related to the resource availability and other factor such as presence and absence of disturbance and suitability for other courtship display is cause for denser or scatter point existence of colobus monkey (Fig. 3).
Fig. 3.
KDE home range usage of colobus monkey in Khatasa Forest during dry and wet seasons
As the date in (Table 4) shows the utilized area based on the percent of data point, and hence the average home range size of colobus monkey in Khatasa Forest is much different so low used area comprising (0.00214 and 0.00034 km2) and highly used area comprising (0.0059 and 0.00031 km2) in both dry and wet seasons, respectively, so there was significance difference between home range size colobus monkey in dry and wet season (t = 3.009, df = 4, p = 0.048).Habitat types inhabited by colobus monkey at Khatasa forest is a might be related to resource availability, suitability as well as rivers and small streams that surround the forest, giving it more highly used (Table 4).
Table 4.
Estimated home range size in (km2) of Khatasa forest
| Method | % Data point | Area estimated(km2) | ||
|---|---|---|---|---|
| Kernel density | Dry season | Wet season | Dry season | Wet season |
| 14 | 23 | 0.00214 | 0.00034 | |
| 39 | 21 | 0.00718 | 0.00083 | |
| 47 | 56 | 0.0059 | 0.00031 | |
In the present study, colobus consumed nearly 15 plant species in Khatasa Protect Forest. The plant species were predominantly trees. From these plant species that contributed to high proportion of the diet of Colobus monkey was Albizia Schimeperiana, (33.2%), Apodytes dimidiate(12.8%), Dodonaea Angustifolia(11.1%) and Schefflera abyssinica (8.4%),these contributed a total of 77% of their diet, However, the variation in the types of plant species consumed in the study period showed a significance difference (χ2=49 ,df=1, p=0.05) between dry and wet seasons (Table 5).
Table 5.
Percentage of plant species consumed by Colobus monkey in dry and wet seasons
| Local name | Species name | Family | Life form | Part consumed | % of contribution | ||
|---|---|---|---|---|---|---|---|
| Dry season | Wet season | Mean | |||||
| Dong | Apodytes dimidiate | Icacinaceae | Tree | YL, ML, FR | 13.1 | 12.6 | 12.8 |
| Lol | Ekebergia capensis | Meliaceae | Tree | YL, ML, SH | 12.1 | 10.1 | 11.1 |
| Shola | Ficus sur croton | Moraceae | Tree | YL, FR | 6.9 | 0 | 3.45 |
| Besana | Macro stachus | Euphorbiaceae | Tree | FR | 2.7 | 4.3 | 3.5 |
| Tid | Juniperus procera | Cupressaceae | Tree | FR, BR | 0.5 | 0 | 0.25 |
| Sesa | Albizia Schimeperi | Fabaceae | Tree | YL, SH, FR | 30.7 | 35.8 | 33.2 |
| Keteketa | Dodonaea angustif | Sapindaceae | Tree | YL, FR | 11.1 | 11.1 | 11.1 |
| Kimo | Rhus glutinosa | anacardiaceae | Tree | YL, FR | 6.1 | 8.6 | 7.35 |
| Welekefa | Dombeya torrida | Sterculiaceae | Tree | BR | 0.4 | 0 | 0.2 |
| Shenbko | Arundo donax | Poaceae | Tree | YL | 2.2 | 4 | 3.1 |
| Avalo | Brucea antidysenterica | simaroubaceae | Tree | YL | 0.5 | 0 | 0.25 |
| Gitem | Schefflera abyssinica | Araliaceae | Tree | YL, FR | 8.5 | 8.3 | 8.4 |
| Kulkual | Opuntia ficusindica | Cactaceae | Tree | FR | 0.8 | 0 | 0.4 |
| Cheba | Acacia nilotica | Fabaceae | Tree | YL, FR | 0.7 | 0.5 | 0.6 |
| Atete | Maytenus gracilipes | Celasteraceae | Shr | YL | 0.7 | 0 | 0.35 |
NB: - YL: young leaves, ML: mature leaves, SH: shoot, FR: fruit, FL: flower, BK: bark, RT: root
Discussion
The ranging ecology of Colobus monkey in the study area was characterized by the daily travel distance of the species. In the study period, the daily travel distance of Colobus monkey was vary from season to season. The highest daily range length was 232 m in the dry season while the shortest range length was 181 m in the wet season. The shortest range length in wet season might be associated with high amount of rainfall and excess food availability in the area. However, high range length in the dry season might be associated with in search of food as compared to the wet season. Similarly, Petros et al., [31] had reported that daily range length of colobus in dry season was 248.7 m in Bale Mountains National Park, which was almost similar to the present study in Khatasa Forest. In addition, he had also reported that Colobus monkey day-range length was strongly associated with the availability of food resources.
In the present study, daily travel range was not only varied among seasons but also vary from one habitat to another habitat type in both dry and wet seasons. The highest daily range length was observed in plantation forest (315 m and 290 m) in dry and wet season, respectively. This could be related with the homogeneity of the habitat type in species diversity; i.e. feed-in variability pushes them to cover relatively highest range length than another habitat types. In addition, Petros et al., [31] had reported a similar daily range length of colobus monkey in Bale Mountains National Park that was associated with food resources availability of the species.
In this study, total estimated home range size of colobus monkey in Khatasa Forest was significantly varied from season to season (0.0152 km2) and (0.00148 km2) in dry and wet seasons, respectively. The variation might be related to the availability of food resource and different climatic factor such as high rain fall and perception push them to forging in small area and restricted around the area where the major plant species is presented. Similarly, Dunham [9] and Bocian [4] had reported that forest composition and food availability differed greatly among the home ranges of the colobus monkey, so, home range of the species was determined by the proportion of density of food species, i.e. the lower tree species and lower food availability. Moreover, Dunbar, [8] had also reported that the home range area usage of colobus monkey in the forests of Diani Beach, Kenya was different in both dry and wet seasons. This was correlated with the variations in weather conditions as a determinant factor for their activity pattern and home range. In contrary, Fashing [14] and [19] had reported that Colobus monkey at both Kibale and Kakamega, variability in ranging patterns over time appears to be more related to the distribution of infrequently eaten food items that are spatially rare yet nutritionally important, like sodium-rich swamp plants or Eucalyptus bark. Similarly, Colobus monkey at Kakamega Forest covered relatively longer range and travelled more than 600 m and ventured far beyond the ‘normal’ boundaries of their home range on excursions through intensely-defended areas of the ranges from other groups to reach their territory.
Colobus monkey consumed nearly15 different plant species throughout the study period. In the study area, the species spent more time in feeding. Among the plant species, Albizia Schimeperiana, Ekebergia capensis, Apodytes dimidiata, Dodonaea Angustifolia and Schefflera abyssinica had contributed a total of 77% of their diet. Similarly, Ibrahim et al., [20] had reported the highest proportion of the diet by these plant species in Borena Sayent National Park. In addition, Dwyer [10] had also reported that 72 tree species identified as a sources of food in Diani Forest, Kenya. However, Sefi and Mastewal [33] had reported only 5 species of plant that were the highly consumed by colobus monkey out of the total of 19 plant species in Harenna Forest. Similarly, Fashing, [13] had reported that colobus monkeys spending more time in feeding on a few species such as Ficus exasperata from 32 tree species in Kakamega Forest, Kenya.
In the present study, Albizia Schimeperiana accounted the highest percentage contribution of the plant food items that followed by Apodytes dimidiate, Dodonaea Angustifolia, respectively. On average, Colobus monkeys feed on low plant species diversity as compared to other sites in Africa. However, Albizia Schimeperiana, Apodytes dimidiata, Dodonaea angustifolia were the most frequently consumed food item during the present study in Khatasa Forest. Similarly, Fashing [13] had reported that Colobus monkey appear to be adapted to feed on relatively few food species and to maintain a low dietary species diversity even in species-rich rain forest environments in the Kakamega Forest, Kenya.
Conclusions
The study of home range and habitat use of the Black-and-White Colobus Monkey (Colobus guereza guereza) demonstrates that the species exhibits flexible in habitat use that strongly influenced by niche quality, food availability, and human disturbance. Home range size is generally shaped by the distribution of preferred food resources particularly young leaves and the structural composition of the forest. Areas with higher tree diversity and continuous canopy tend to support significant population size of the species with more stable home ranges, while fragmented or disturbed habitats often require larger ranges to meet nutritional needs.
Habitat use patterns of colobus monkey showed that there is a strong preference for mature and secondary forests with abundant folivorous resources, emphasizing the importance of canopy connectivity for movement, foraging, and predator avoidance. Seasonal variation also plays a role, with shifts in space use corresponding to changes in food availability. Overall, these findings highlight the ecological sensitivity of Colobus guereza guereza to habitat alteration and fragmentation. Effective conservation strategies should prioritize the protection and restoration of forest habitats, maintenance of canopy continuity, and minimization of anthropogenic pressures to ensure the long-term survival of the species. Understanding home range dynamics and habitat preferences is therefore critical for informed management and conservation of the species in the area.
Acknowledgements
I am grateful to the Department of Wildlife Conservation and Ecotourism Management, Bahir Dar University, Ethiopia for logistical support during the research work. I would like to acknowledge the Primate Conservation Inc. (PCI) for its support this research project. I would also like to acknowledge Khatasa Protected Forest Authority for giving support and permission to carry out this research work in the protected forest.
Author contributions
SM conceived and wrote the proposal. Field data collection and analysis were completed by SM. EM contributed to the data analysis, organization and GIS mapping. The manuscript was drafted by SM and revised and polished by EM. All authors read and approved the final version of the manuscript.
Funding
This research was granted by the Primate Conservation Inc. (PCI).
Data availability
The data associated with the paper can be accessed under the consent of the corresponding author (s) on reasonable request.
Declarations
Ethics approval and consent to participate
Not applicable.
Consent for publication
Not applicable.
Competing interests
The authors declare no competing interests.
Footnotes
Publisher’s note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
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