Diet and microhabitat use of the woodland dormouse Graphiurus murinus at the Great Fish River Reserve, Eastern Cape, South Africa
- Authors: Lamani, Siviwe
- Date: 2014
- Language: English
- Type: Thesis , Masters , MSc (Zoology)
- Identifier: vital:11797 , http://hdl.handle.net/10353/d1019854
- Description: The diet of the woodland dormouse Graphiurus murinus was studied in a riverine Combretum forest at the Great Fish River Reserve (Eastern Cape, South Africa). Food remains were collected seasonally from a maximum of 45 different nest boxes between December 2010 and November 2011. An overall mean of 1.32 ± 0.51 food categories (range 1–4) were identified in each nest box used as “larder” during the year. Dietary diversity and standardized diet breadth were low to intermediate, with a peak in summer and a nadir in winter. In terms of percentage occurrence, arthropods were dominant (99%) in all seasons, followed by molluscs (16%) and fruits (14%). When relative percentage occurrence and percentage weight were considered, arthropods were still dominant, but a slight decrease was observed in summer. Besides spiders (order Araneae), nine arthropod families were found in the diet of the woodland dormouse; Tenebrionidae (40%), Spirostreptidae (30%), Carabidae (15%) and Blattidae (14%) were the most dominant families in terms of percentage weight. Grewia robusta and Ziziphus mucronata were the only fruit species present in the diet. Pianka’s diet overlap indices were very high (>0.93), indicating that the diet of the woodland dormouse was similar between pairs of seasons. This study also investigated whether woodland dormice Graphiurus murinus positively select or avoid specific microhabitat types or structures, and whether a set of predictor variables related to microhabitat characteristics can explain the presence and rates of visits to specific trapping stations. Trapping was conducted seasonally, over 5 days, between June 2011 and April 2012. A grid of 96 stations (16 rows × 6 lines) was established. Trap stations were set at 10-m intervals. At each station two Sherman traps were placed. The 192 traps were distributed relatively equitably among four height categories (0–0.5 m, 0.51–1 m, 1.01–1.5 m, and 1.51–2.5 m). On average, trapping success was 4.70 ± 4.17 dormice per 100 traps. Dormice were trapped at an average height of 136 ± 64 cm, which was significantly higher than the average height at which traps were set (99 ± 75 cm). Bonferroni Z tests indicated that dormice positively selected areas with high canopy cover and connectivity, possibly to decrease predation risk. Generalized Linear Models showed that trap use and numbers of visits and different animals caught were positively associated with a high arboreal connectivity, hence supporting the hypothesis that woodland dormice may depend on wooden “corridors” for their movements.
- Full Text:
- Authors: Lamani, Siviwe
- Date: 2014
- Language: English
- Type: Thesis , Masters , MSc (Zoology)
- Identifier: vital:11797 , http://hdl.handle.net/10353/d1019854
- Description: The diet of the woodland dormouse Graphiurus murinus was studied in a riverine Combretum forest at the Great Fish River Reserve (Eastern Cape, South Africa). Food remains were collected seasonally from a maximum of 45 different nest boxes between December 2010 and November 2011. An overall mean of 1.32 ± 0.51 food categories (range 1–4) were identified in each nest box used as “larder” during the year. Dietary diversity and standardized diet breadth were low to intermediate, with a peak in summer and a nadir in winter. In terms of percentage occurrence, arthropods were dominant (99%) in all seasons, followed by molluscs (16%) and fruits (14%). When relative percentage occurrence and percentage weight were considered, arthropods were still dominant, but a slight decrease was observed in summer. Besides spiders (order Araneae), nine arthropod families were found in the diet of the woodland dormouse; Tenebrionidae (40%), Spirostreptidae (30%), Carabidae (15%) and Blattidae (14%) were the most dominant families in terms of percentage weight. Grewia robusta and Ziziphus mucronata were the only fruit species present in the diet. Pianka’s diet overlap indices were very high (>0.93), indicating that the diet of the woodland dormouse was similar between pairs of seasons. This study also investigated whether woodland dormice Graphiurus murinus positively select or avoid specific microhabitat types or structures, and whether a set of predictor variables related to microhabitat characteristics can explain the presence and rates of visits to specific trapping stations. Trapping was conducted seasonally, over 5 days, between June 2011 and April 2012. A grid of 96 stations (16 rows × 6 lines) was established. Trap stations were set at 10-m intervals. At each station two Sherman traps were placed. The 192 traps were distributed relatively equitably among four height categories (0–0.5 m, 0.51–1 m, 1.01–1.5 m, and 1.51–2.5 m). On average, trapping success was 4.70 ± 4.17 dormice per 100 traps. Dormice were trapped at an average height of 136 ± 64 cm, which was significantly higher than the average height at which traps were set (99 ± 75 cm). Bonferroni Z tests indicated that dormice positively selected areas with high canopy cover and connectivity, possibly to decrease predation risk. Generalized Linear Models showed that trap use and numbers of visits and different animals caught were positively associated with a high arboreal connectivity, hence supporting the hypothesis that woodland dormice may depend on wooden “corridors” for their movements.
- Full Text:
Diet of the yellow mongoose (Cynictis penicillata) in the Albany Thicket Biome of South Africa
- Authors: Bizani, Mfundo
- Date: 2014
- Language: English
- Type: Thesis , Masters , MSc (Zoology)
- Identifier: vital:11796 , http://hdl.handle.net/10353/d1019840
- Description: The dietary habits of the yellow mongoose Cynictis penicillata were studied in the Albany Thicket Biome of South Africa (Great Fish River Reserve, Eastern Cape). The diet was investigated through the analysis of 1,056 scats that were sampled over a period of 7 years (2005−2009 and 2011−2012) mainly in three similar sites (Kelarny, Grasslands and Junction 10) that were used by at least three families or groups of yellow mongooses. Scats were collected near latrine sites, labelled and stored in a freezer. In the laboratory, scats were oven dried for a period of 24 hours at 50 C. Diet was determined by identifying undigested food remains in the scats. Hair samples were examined under the compound microscope to identify which mammals were ingested. In the field, both arthropod and small mammal abundance were determined in order to evaluate whether yellow mongooses are opportunistic or specialist feeders. Furthermore, inter-annual (2006–2008) and inter-group/inter-site variations in the diet were assessed. Based on faecal analysis, arthropods were the principal prey, while small mammals acted as supplementary food item. Other food categories like vegetation, reptiles and birds were only ingested or preyed upon infrequently. Intermediate dietary diversity, and low standardised diet breadth indices were obtained for all seasons, as well as for the whole sampling period. The diet overlaps calculated for pairs of seasons were very high and did not differ substantially. However, the diet of the yellow mongoose varied seasonally, yearly and between groups (sites), mostly due to variations in arthropod and small mammal consumption. Food availability displayed an increase in biomass of both small mammals and arthropods in summer and autumn. Results obtained in this study could suggest that the yellow mongoose at the GFRR is insectivorous by preferring to feed on insects (and arthropods in general) when both insects and rodents are abundant. However the fact that its diet varies both seasonally, yearly and locally, as well as the presence of remains of other food categories in the scats, indicates that this species is rather an opportunistic, generalist feeder than an insect specialist.
- Full Text:
- Authors: Bizani, Mfundo
- Date: 2014
- Language: English
- Type: Thesis , Masters , MSc (Zoology)
- Identifier: vital:11796 , http://hdl.handle.net/10353/d1019840
- Description: The dietary habits of the yellow mongoose Cynictis penicillata were studied in the Albany Thicket Biome of South Africa (Great Fish River Reserve, Eastern Cape). The diet was investigated through the analysis of 1,056 scats that were sampled over a period of 7 years (2005−2009 and 2011−2012) mainly in three similar sites (Kelarny, Grasslands and Junction 10) that were used by at least three families or groups of yellow mongooses. Scats were collected near latrine sites, labelled and stored in a freezer. In the laboratory, scats were oven dried for a period of 24 hours at 50 C. Diet was determined by identifying undigested food remains in the scats. Hair samples were examined under the compound microscope to identify which mammals were ingested. In the field, both arthropod and small mammal abundance were determined in order to evaluate whether yellow mongooses are opportunistic or specialist feeders. Furthermore, inter-annual (2006–2008) and inter-group/inter-site variations in the diet were assessed. Based on faecal analysis, arthropods were the principal prey, while small mammals acted as supplementary food item. Other food categories like vegetation, reptiles and birds were only ingested or preyed upon infrequently. Intermediate dietary diversity, and low standardised diet breadth indices were obtained for all seasons, as well as for the whole sampling period. The diet overlaps calculated for pairs of seasons were very high and did not differ substantially. However, the diet of the yellow mongoose varied seasonally, yearly and between groups (sites), mostly due to variations in arthropod and small mammal consumption. Food availability displayed an increase in biomass of both small mammals and arthropods in summer and autumn. Results obtained in this study could suggest that the yellow mongoose at the GFRR is insectivorous by preferring to feed on insects (and arthropods in general) when both insects and rodents are abundant. However the fact that its diet varies both seasonally, yearly and locally, as well as the presence of remains of other food categories in the scats, indicates that this species is rather an opportunistic, generalist feeder than an insect specialist.
- Full Text:
Resting site ecology and microhabitat use of the Mozambique thicket rat (Grammomys cometes) in a riverine Combretum forest
- Authors: Gebe, Zimkhitha
- Date: 2014
- Language: English
- Type: Thesis , Masters , MSc (Zoology)
- Identifier: vital:11794 , http://hdl.handle.net/10353/d1019768
- Description: Very little is known about the resting and spatial ecology of the Mozambique thicket rat, Grammomys cometes, a rodent species distributed in two disjoint populations in South Africa and Mozambique. The present study focused on determining the characteristics and usage patterns of resting sites, as well as the microhabitat use and selection of this species during its activity period. Broadly, I predicted that resting ecology and space use would be affected by environmental, climatic, social and sexual factors. I also hypothesized that predatory risk could affect thicket rat behaviour. Field work took place in the Great Fish River Reserve complex (Eastern Cape Province, South Africa), in a stretch of riverine Combretum forest (length × breadth: ca. 500 × 100 m) located in the western section of the conservation area. Overall, 38 different rats (22 males and 16 females) were trapped and radio-tracked for varying periods between July 2011 and November 2012. Individual rats used a mean of 2.54 1.89 different resting sites (range: 1–9) during each tracking session and resting-site fidelity averaged 85 17%. Overall, 27% of the 131 resting sites identified were artificial wooden nestboxes, 45% were inside branches, 21% were inside trunks, 3% were located on the ground, 2% in bushes, 1% inside dead logs, with one uncertain location (1%). Cape bushwillows Combretum caffrum were the predominant trees (60.32%) used for the resting sites, probably due to their abundance in the forest, and their propension to rot from the inside and provide natural cavities. The mean height of resting sites used by thicket rats was 217 119 cm, and the mean circumference of branches and trunks was 79 35 cm, with no seasonal and sexual variation. In contrast, males exhibited an overall lower percentage usage of individual resting sites than females, probably due to their increased movements during the long mating season. Percentage usage was significantly higher during the cold season, likely for thermoregulatory seasons. Nearly 50% of the resting sites were shared with an average ( SD) of 3.20 1.25 individuals (range: 2–6). However, simultaneous use of resting sites only took place in about 8% of locations. Sharing involved 2–3 males in 90% of the cases. It is suggested that females are solitary but not territorial, while at least some males are more social or tolerant towards each other, and have overlapping ‘home ranges’. These observations could be indicative of a promiscuous mating system. v Microhabitat use and selection were determined by conducting a 5-day trapping session during each season between June 2011 and May 2012. A grid of 96 stations (16 rows 6 lines) was set at the study site, with pairs of traps per station placed at 10-m intervals, at different heights and on different types of vegetative stands. Several variables describing microhabitat structure were recorded seasonally at each station. Thicket rats (38 individuals captured 91 times) were captured mostly at night, with an overall trapping success of 2.16 0.27% over the year. The average height at which rats were trapped (140 65 cm) was significantly higher than the height of traps set in the field (99 ± 75 cm). A large proportion of traps (31.3%) where rats were caught were placed on Combretum caffrum trees, and majoritarily on trunks (46%), tree canopy (19%) and woody lace (19%). Bonferroni Z tests indicated that thicket rats actively avoided trap stations with less than 50% canopy cover as well as areas that had arboreal connections in less than 50% of the directions. Rats also significantly avoided traps that were set in bushes and on the ground, irrespective of whether these were situated in open terrain or surrounded by some vegetation. Generalized Linear Models confirmed that two main predictors (Cover >150 cm and height) had a significant positive effect on the use of traps and on the numbers of visits to, and different animals caught at, trapping stations. All other variables, including connectivity with the surrounding vegetation, tree species, vegetation type and position in which the traps were placed, and tree trunk/branch circumference at trap height, did not have any significant effects. This study confirms that thicket rats are essentially nocturnal, arboreal and prefer dense canopy cover, possibly because this decreases predation risk at the microhabitat level.
- Full Text:
- Authors: Gebe, Zimkhitha
- Date: 2014
- Language: English
- Type: Thesis , Masters , MSc (Zoology)
- Identifier: vital:11794 , http://hdl.handle.net/10353/d1019768
- Description: Very little is known about the resting and spatial ecology of the Mozambique thicket rat, Grammomys cometes, a rodent species distributed in two disjoint populations in South Africa and Mozambique. The present study focused on determining the characteristics and usage patterns of resting sites, as well as the microhabitat use and selection of this species during its activity period. Broadly, I predicted that resting ecology and space use would be affected by environmental, climatic, social and sexual factors. I also hypothesized that predatory risk could affect thicket rat behaviour. Field work took place in the Great Fish River Reserve complex (Eastern Cape Province, South Africa), in a stretch of riverine Combretum forest (length × breadth: ca. 500 × 100 m) located in the western section of the conservation area. Overall, 38 different rats (22 males and 16 females) were trapped and radio-tracked for varying periods between July 2011 and November 2012. Individual rats used a mean of 2.54 1.89 different resting sites (range: 1–9) during each tracking session and resting-site fidelity averaged 85 17%. Overall, 27% of the 131 resting sites identified were artificial wooden nestboxes, 45% were inside branches, 21% were inside trunks, 3% were located on the ground, 2% in bushes, 1% inside dead logs, with one uncertain location (1%). Cape bushwillows Combretum caffrum were the predominant trees (60.32%) used for the resting sites, probably due to their abundance in the forest, and their propension to rot from the inside and provide natural cavities. The mean height of resting sites used by thicket rats was 217 119 cm, and the mean circumference of branches and trunks was 79 35 cm, with no seasonal and sexual variation. In contrast, males exhibited an overall lower percentage usage of individual resting sites than females, probably due to their increased movements during the long mating season. Percentage usage was significantly higher during the cold season, likely for thermoregulatory seasons. Nearly 50% of the resting sites were shared with an average ( SD) of 3.20 1.25 individuals (range: 2–6). However, simultaneous use of resting sites only took place in about 8% of locations. Sharing involved 2–3 males in 90% of the cases. It is suggested that females are solitary but not territorial, while at least some males are more social or tolerant towards each other, and have overlapping ‘home ranges’. These observations could be indicative of a promiscuous mating system. v Microhabitat use and selection were determined by conducting a 5-day trapping session during each season between June 2011 and May 2012. A grid of 96 stations (16 rows 6 lines) was set at the study site, with pairs of traps per station placed at 10-m intervals, at different heights and on different types of vegetative stands. Several variables describing microhabitat structure were recorded seasonally at each station. Thicket rats (38 individuals captured 91 times) were captured mostly at night, with an overall trapping success of 2.16 0.27% over the year. The average height at which rats were trapped (140 65 cm) was significantly higher than the height of traps set in the field (99 ± 75 cm). A large proportion of traps (31.3%) where rats were caught were placed on Combretum caffrum trees, and majoritarily on trunks (46%), tree canopy (19%) and woody lace (19%). Bonferroni Z tests indicated that thicket rats actively avoided trap stations with less than 50% canopy cover as well as areas that had arboreal connections in less than 50% of the directions. Rats also significantly avoided traps that were set in bushes and on the ground, irrespective of whether these were situated in open terrain or surrounded by some vegetation. Generalized Linear Models confirmed that two main predictors (Cover >150 cm and height) had a significant positive effect on the use of traps and on the numbers of visits to, and different animals caught at, trapping stations. All other variables, including connectivity with the surrounding vegetation, tree species, vegetation type and position in which the traps were placed, and tree trunk/branch circumference at trap height, did not have any significant effects. This study confirms that thicket rats are essentially nocturnal, arboreal and prefer dense canopy cover, possibly because this decreases predation risk at the microhabitat level.
- Full Text:
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