Environmental Engineering Reference
In-Depth Information
3.3.4 Discussion
A signifi cant proportion of mortality was observed in birds that visited plots where pesticide-laced
baits were placed; 36% of all birds that visited the plots in which pesticide-laced baits were left in
the irrigation scheme were killed. As such, it is entirely fair to say that the populations of a number
of intra-Africa and palaearctic species are currently being decimated. The black-tailed godwit, for
example, was listed in 2010 as Near Threatened by the IUCN (http://www.iucnredlist.org/apps/
redlist/details/143984/0).
The Bunyala Rice Irrigation Scheme is located on a major migratory fl yway, which means that
unless the poisoning is addressed, populations will continue to decline. Wetland birds, including
storks, egrets and waders, are the primary victims of deliberate poisoning. Grassland birds and birds
of prey are attracted by the concentration of food resources at the rice irrigation plantation, and their
numbers suffer accordingly. Only frugivorous birds were not affected at this study site.
Flocking birds were the primary target of pesticide hunting of all the species poisoned (i.e.,
87.5%, or 28 of 32). Jointly, four species of raptors and non-fl ocking birds were also casualties of
poisoning: long-crested eagle (
Lophaetus occipitalis
), black kite (
Milvus migrans
), yellow-throated
longclaw (
Macronyx croceus
) and grassland pipit (
Anthus cinnamomeus
). The African openbill,
doves/pigeons (see Figure 3.12), black-tailed godwit and wood sandpipers (see Figure 3.13) were
the most frequently killed species.
Occurrence (seasonality) also determined the intensity of poaching, and therefore, the level of
mortality. Overall, resident species suffered higher mortality rates. The African openbill endured the
heaviest mortality because it is a fl ocking species and is also present year round at the site. Hunting
this species is enhanced using decoy methods of baiting leading to a very high mortality of the spe-
cies. These factors likely made the openbill the bird of choice amongst poachers and consumers over
time. Considering its size, the openbill stork is sold at a very low price and as a result, it is preferred
Figure 3.12
Mixed species of doves being gathered from the poisoning fi eld
Photo taken by Martin Odino
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