A chronicling of long-standing carbofuran use and its menace to wildlife in Kenya - Carbofuran and Wildlife Poisoning: Global Perspectives and Forensic Approaches - page 77

3.6 Forensic analysis of carbofuran in vultures and environmental
samples collected from Laikipia and Isiolo Districts
Peter Otieno, 1 Joseph O. Lalah, 2 Munir Z. Virani 3, 4
1

Institute of Ecological Chemistry, Helmholtz Zentrum München, Ingolstädter
Landstraße 1, D-85764 Neuherberg, Germany

Department of Chemical Sciences and Technology, Kenya Polytechnic University
College, P.O. Box 52428, 00200 City Square, Nairobi, Kenya

2

The Peregrine Fund, 5668 West Flying Hawk Lane, Boise, Idaho 83709, USA
4

3

Ornithology Section, Department of Zoology, National Museums of Kenya, P.O.
Box 40658-00100, Nairobi, Kenya

From the 1990s onwards, an increasing number of lion and vulture poisonings, purportedly with
Furadan, have been reported in Laikipia and Isiolo District. Granular Furadan was known to be
widely used in agricultural areas around Lewa and Ol Ar Nyiro wildlife conservancies in Isiolo and
Laikipia Districts, respectively, to control agricultural pests (Otieno, Lalaha and Virani 2010a,b).
In response, Dr Munir Virani, an ornithologist with The Peregrine Fund and National Museums of
Kenya, initiated an investigation in August 2007 to more rigorously evaluate Furadan involvement
in the high vulture mortality cases that were reported and to carry out an assessment of carbofuran
use and exposure in the districts of Laikipia and Isiolo. The project was funded by The Peregrine
Fund, through the Africa project, and the research was conducted by Peter Otieno as part of post-
graduate studies in environmental chemistry at Maseno University, Kenya. This section summarises
the study and its results. For further details, including sampling method and analytical parameters,
the reader is referred to Otieno (2009 thesis) and to Otieno, Lalah and Virani (2010a,b).
First, the a) amount of Furadan applied locally for agricultural purposes, b) formulations and
application methods used, c) application rates, d) potential non-target organisms exposed, and e)
characteristics of catchments on farms and potential environmental contamination of soil and water
bodies such as rivers, canals and ponds within the two districts were all carefully documented.
Samples of soil, water, plants and vultures (talons and beaks) were collected and analysed for res-
idues of carbofuran and metabolites, to evaluate levels in the environment/wildlife and identify
potential routes of exposure. The Ngare-Ndare and Ngare-Sirgoi rivers in Isiolo, the Kinamba dam
and a dam inside the Gallman Memorial Wildlife Conservancy were chosen for this study. Apart
from being adjacent to the conservancies, they are located within the catchments of agricultural sec-
tors likely to contribute to residue contamination. Prior to this, few studies had evaluated secondary
poisoning (non-point sources) such as exposure to carbofuran-contaminated water in Kenya (Lalah
and Wandiga 1996a, b).
Vultures were selected for this study because initial reports indicated they were dying in large
numbers at baited carcasses in the study area. Vultures are at the top of the scavenger food chain,
are communal feeders and are extremely vulnerable to eradication from poisoning (as previously
discussed in Section 3.5). Their absence constitutes a clear indication that the environment has been
compromised. The threat to species such as Gyps africanus and Gyps ruppellii, which are obligate
scavengers, is further exacerbated by the fact that they are a long-lived species and have a very low
reproductive rate (i.e., they lay one egg at a time) so their populations are sensitive to even small
declines in the number of breeding adults (Slotta-Bachmayr, Bogel and Camiña 2004). Under natu-
ral circumstances, vultures have high adult survival rates, which can compensate for low annual
offspring production. However, incidents of mass mortality such as the death of over 20 vultures