200 D. O. Manoa et al.
TABLE 1 The number of predator-proof bomas suffering damage, as reported by boma owners at evaluation, by types and combinations of components.
Fence post type
Extent of damage No damage
Damage to one component Gates only
Chain-link fences only Posts only
Damage to two components
FIG. 2 Number of livestock at construction of predator-proof bomas in April 2010–July 2018 and at evaluation in August 2018.
255.5 (n = 88) at the time of evaluation (Fig. 2). The number of livestock was significantly lower at the time of evaluation
(related-samples Wilcoxon signed rank test: Z =−4.893; P,0.0001). At the time of evaluation, 55 bomas (63%) held #200 heads of livestock, whereas at the time of con- struction only 23 bomas (26%) held#200 heads of livestock and 39 bomas (44%) held 201–400 heads of livestock. The bomas measured on average 223 ± SD 95.8 min
circumference (n = 88). There were significantly positive relationships between livestock numbers and boma cir- cumference at both construction and evaluation (Kendall’s τb= 0.280,P = 0.00013, and 0.207,P = 0.0049, respectively). Bomas were on average 1.93 ± SD 3.99 km (n = 88) from the nearest predator-proof boma and on average 17.68 ± SD 11.21 km from the nearest protected area (n = 88).
Damage to boma components
Of all evaluated bomas, 57 (64.8%) exhibited some damage, of which 14 (15.9%) had some damage to all three compo- nents (gates, chain-link fences and posts; Table 1). Of the sampled bomas, 78.4%(n = 88) had recycled plastic posts. Bomas with wooden posts exhibited a higher mean level of damage to posts, gates and chain-link fences than those with recycled plastic posts (Fig. 3; Supplementary Table 2). All 19 bomas with wooden posts exhibited some damage, whereas only 55%of the 69 with recycled plastic posts exhib- ited damage. Furthermore, of the bomas with wooden posts, only one exhibited no post damage. Boma owners identified cattle or other livestock to be the
most common reason for damage overall and for chain-link damage and loose posts to be the main reason for gate dam- age, and termites to be the main reason for post damage (Table 2). However, for chain-link fences, gates and posts, differences in the proportions of damage from different causes were not significant (χ2 goodness-of-fit tests: χ2 = 5.516, 0.077 and 5.723, respectively; P = 0.138, 0.962 and 0.334, respectively). Nevertheless, analyses conducted with all data combined (total number of reports of damage)
FIG. 3 Number of predator-proof bomas exhibiting damage to three elements (gates, chain-link fences and posts), by predator- proof bomas with wooden posts (n = 19) and with plastic posts (n = 69).
revealed statistically significant differences in the propor- tions of damage from different causes (χ2 goodness-of-fit tests: χ2 = 59.904;P,0.0001).
Drivers of boma disrepair
Damage to bomas was driven largely by livestock density (r =−0.037,P= 0.028), boma post type (r =−2.941, P,0.001) and distance to nearest predator-proof boma
(r,0.001,P = 0.033). Specifically, the proportion of da- maged components and damaged posts decreased in bomas with greater livestock densities; plastic posts were less likely to be damaged compared to wooden posts; and greater proportions of damaged chain-link fences were noted for bomas located far from others (Table 3; Supplementary Table 2a,c,d). Using the subset of data for 47 bomas in the Mbirikani and Olgulului group ranches, bomas located far away from others had greater proportions
Oryx, 2023, 57(2), 196–204 © Born Free Foundation and the Author(s), 2022. Published by Cambridge University Press on behalf of Fauna & Flora International doi:10.1017/ S0030605321001642
Wooden Plastic 0
5 0 0 5 8
Gates & chain-link fences only 1 Gates & posts only
3
Chain-link fences & posts only 4 Damage to all three components 6 Total
19
31 19 2 5
12 11 2 4 5 8
69
Total 31
24 2 5
17 19 3 7 9
14 88
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