Herd size of Common Wildebeest (Connochaetes taurinus) in Relation to Cover Type in Northern Tanzania
Emily Chudek
University of Washington, School of Environmental and Forest Sciences, Spring 2014
Results
The common wildebeest (connochaetes taurinus) is a highly gregarious species, with herds that can contain more than 500 individuals. This study focused on herd size in relation to the amount of cover available. Two habitat types were analyzed: low cover and cover. Grassland is low cover, and a habitat type with cover is forest or shrubland. Grasslands tend to have more food available, thus, I hypothesize that herd size will be larger in low cover areas. Habitat Effect: Fail to reject the null hypothesis that there is no significant effect of amount of cover on herd size.
Park Effect: There is a significant effect of park (site) on group size.
Lake Manyara National Park
5
4
3
2
1
0
Cover
No Cover
Natural Log of Herd Size
Whole Study Area
6
6
4
3
2
1
0
Cover
Habitat Type
5
4
3
2
1
0
Cover
No Cover
6
Manyara Ranch
4
3
2
1
0
Habitat Type
Figure 1: All data across entire study area.
The median is the line between the purple and green blocks.
No Cover
Habitat Type
5
Cover
Tarangire National Park
5
No Cover
Habitat Type
Natural Log of Herd Size
6
MS
F obs P‐Value
3.067 1.249
0.2667
9.404 3.83
0.0124
2.456
Natural Log of Herd Size
Natural Log of Herd Size
Source df
SS
Habitat 1
3.07
Park (Site)
3 28.21
Error
91 223.46
Natural Log of Herd Size
Introduction
6
Ngorongoro Conservation Area
5
4
3
2
1
0
No Cover
Habitat Type
Figure 2: Data separated by the four different sites. The median is the line between the purple and green blocks. Discussion
Methods
Study Area: Four areas throughout Northern Tanzania, Africa.
Field Methods: Observations in both habitat types in each park, along roads. Observations were taken from a vehicle using binoculars. Date, time, habitat type, and herd size were noted. Statistical analysis: An ANOVA was performed with herd size as the response and habitat type and site (i.e. the park) as factors. The natural log of herd size was taken in order to normalize the data.
When looking at the whole study area (Fig. 1), there seemed to be a slight trend towards larger herd size in areas of low cover, but the individual study areas did not follow this pattern (Fig. 2). Although there was not a significant effect of habitat type on herd size, it is of interest to note the significant effect of the sites. This site effect may be for a variety of reasons including differing predator densities and/or availability of food resources distributed within each park. Acknowledgements: Thank you to Aaron Wirsing for his help and guidance, Lindsay Fulton for the use of her pictures, and the School for Field Studies for giving me the opportunity to study wildebeest in Tanzania.