CHAPTER 1 INTRODUCTION
5. FAUNA
3.1 Overall results
During the 120 days of the study (40 days per season), a total of 18,000 km were driven. A total of 522 hours were driven with a daily average of 180 minutes (range 132 – 278 minutes) on the 100 km paved road and 33 minutes (range 22 – 66 minutes) on the 20 km unpaved road.
A total of 991 roadkill were observed on the 100 km paved road transect and 36 roadkill on the unpaved road. These comprised 162 species from 24 orders and 65 families and 93 individual roadkill that could not be identified to species level. These roadkill were classified to genus (25), family (12), order (19) or class (29) depending on the state of the remains. Only eight roadkill were completely unidentifiable and could not be classified further than Vertebrata (Appendix B).
3.1.1 Roadkill rates
With all the data pooled for each road type, the number of roadkill differed significantly between road type and season (χ2 = 11.40; df = 2; p <0.05). On both road types the proportion of roadkill was greatest in the hot/wet season and lowest in the cold/dry season (Table 4.9). On the paved road, numbers of roadkill in the two hot seasons were similar (Table 4.9).
Table 4.9: Number of roadkill detected per season on the 100 km paved road and the 20 km unpaved road in the GMTFCA, South Africa.
Season Number of roadkill detected (100 km paved road)
Number of roadkill detected (20 km unpaved road)
Season totals
Hot/dry 376 9 385
Hot/wet 416 25 441
Cold/dry 199 2 201
Total 991 36 1027
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When these data were further stratified by vertebrate class, the highest roadkill rates on both road types in the hot/dry and hot/wet seasons were for birds, while in the cold/dry season, it was for mammals (Table 4.10). Roadkill rates were highest for all classes except mammals in the hot/wet season, lower in the hot/dry season and very low in the cold/dry season (Table 4.10). Across all three seasons, roadkill rates were highest for birds, lower but similar for reptiles and mammals and lowest for amphibians (Table 4.10).
3.1.2 The effect of animal activity pattern and season on roadkill
All of the amphibian species and 62% of all mammalian species were nocturnal (Appendix B). The reptiles were more evenly balanced, with 47% of roadkill species being diurnal and 41% nocturnal (Appendix B). By contrast, the majority of the birds (80%) were diurnal (Appendix B).
In this analysis, data from the 20 km sub-transect of the paved road that was driven pre-dawn (n=26 roadkill), post-dawn (n=61 roadkill) and post-dusk (n= 27 roadkill) was used to analyse the effect of animal activity pattern and season on roadkill. In a two way ANOVA with activity pattern and season as predictor variables and roadkill rate per km as the dependent variable, there was a significant effect of activity pattern (F4,15 = 9.29; p <0.05: Figure 4.11) with significantly more nocturnal species killed than species in any other animal activity category. This trend was similar in each of the three seasons and there was no effect of season (F2,15 = 0.18; p = 0.83).
There was no significant interaction between animal activity and season (F4,15 = 1.06, p = 0.44).
Both crepuscular diurnal nocturnal unknown Animal activity period
-0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0
Daily rate of roadkill detected per km
Figure 4.11: The rate of roadkill (all species combined) detected per km for diurnal and nocturnal species (data are means ± 95% CI) along a 100 km section of paved road and 20 km section of unpaved road in the GMTFCA, South Africa during the three ecological seasons.
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Table 4.10: Roadkill rates for each class detected across three ecological seasons on the GMTFCA, South Africa (a) paved road, (b) unpaved road. (For identified species only.) The highest rate per season is highlighted in bold.
(a) Paved Hot/dry Hot/wet Cold/dry All 3 seasons
Taxa
Rate per km
Rate per day
Number of species
Rate per km
Rate per day
Number of species
Rate per km
Rate per day
Number of species
Rate per km
Rate per day
Number of species
Amphibia 0.4 1.0 2 0.1 0.2 2 0.0 0.0 0 0.2 0.4 3
Reptilia 0.9 2.3 22 1.3 3.6 27 0.1 0.2 7 0.8 2.0 34
Aves 1.4 3.4 49 2.2 5.6 52 0.8 2.0 21 1.5 3.7 81
Mammalia 1.0 2.6 28 0.7 1.8 24 1.0 2.8 19 1.0 2.4 44
Total 3.7 9.3 101 4.3 11.2 105 2 5 47 3.4 8.5 162
(b) Unpaved Hot/dry Hot/wet Cold/dry All 3 seasons
Taxa
Rate per km
Rate per day
Number of species
Rate per km
Rate per day
Number of species
Rate per km
Rate per day
Number of species
Rate per km
Rate per day
Number of species
Amphibia 0.0 0.0 0 0.0 0.0 0 0.0 0.0 0 0.0 0.0 0
Reptilia 0.0 0.0 0 0.1 0.1 2 0.0 0.0 0 0.1 0.0 2
Aves 0.3 0.1 4 0.9 0.4 11 0.0 0.0 0 0.2 0.2 16
Mammalia 0.2 0.1 2 0.3 0.2 2 0.1 0.1 2 0.2 0.1 3
Total 0.5 0.2 9 1.3 0.7 25 0.1 0.1 2 0.5 0.3 36
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Five hundred and eighty eight live animals (Appendix D) were observed either crossing the road or feeding on the road verge on the 100 km paved road transect over a period of 120 days. Of these, 13% occurred during the hot/dry season, 35%
during the hot/wet, and 52% during the cold/dry. This was despite there being less roadkill during the cold/dry season. Mammals were the most visible class accounting for 67% of the sightings during the hot/dry season, and 70% during the cold/dry season with the two most common species being Warthog (Phacochoerus africanus) and Chacma baboon (Papio hamadryas). Reptiles were most visible during the hot/wet season (48%) with the Flap-neck Chameleon (Chamaeleo dilepsis) being the most sighted. Individual bird species were not counted unless it was a bird of prey or they were in flocks (such as Helmeted Guineafowl Numida meleagris).
3.1.3 The effects of time of day and season on the occurrence of roadkill The 20 km sub-transects of the paved road (pre-dawn, post-dawn and post-dusk) was used to test if time of day and season affected the occurrence of roadkill. In a two way ANOVA with roadkill/km as the dependent variable and time of day and season as predictor variables, there was a significant effect of time of the day (F2,291
= 18.67, p <0.05; Figure 4.12) and significantly more roadkill was detected 1.5 hours after sunrise than in the pre-dawn (1.5 hours before sunrise) and post-dusk (1.5 hours after sunset) periods (Figure 4.12). There was a significant effect of season (F2,291 = 3.84 p = 0.02; Figure 4.12) with more roadkill/km in the hot/dry season than any other season. There was no significant interaction between season and the time of day when roadkill was detected (F4.291 = 1.5, p = 0.2; Figure 4.12).
Hot/dry season Hot/wet season Cold/dry season
DAWN DAY DUSK
Time of day -0.02
-0.010.000.010.020.030.040.050.060.070.080.09 Daily rate of roadkill detected per km
Figure 4.12: The rate of roadkill detected per km at three different times of day within a 24 hour period and the three ecological seasons along a 20 km section of paved road in the GMTFCA, South Africa species (data are means ± 95% CI).
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3.2 The effects of biophysical factors on the occurrence of roadkill on paved