Environmental Engineering Reference
In-Depth Information
(1 633 birds recovered) and horned larks (597 birds recovered). Investigators also identifi ed 12 spar-
rows (species unspecifi ed), fi ve western meadowlarks (
Sturnella neglecta
), fi ve common grackles,
fi ve red-winged blackbirds, one American robin, and one American kestrel (
Falco sparverius
). They
also found 150 partially scavenged carcasses that could not be identifi ed as well as dead kangaroo
rats (Genus
Dipodomys
).
The farmer had planted the fi eld to wheat the year before (2005). Previously, he had planted
red millet (a component of commercial bird seed) in the fi eld and had produced a good harvest. A
hail storm severely damaged the wheat crop in July 2005 and may have resulted in a substantial
amount of wheat grain being present on the soil surface. The farmer then planted sunfl owers in the
spring of 2006 but cutworm and wireworm damage destroyed about two thirds of the fi eld. On
13 June 2006 the farmer did a 'burndown' broadcast treatment of 2,4-D and glyphosate to rid the
fi eld of sunfl owers and weeds. He also added fl owable carbofuran to the tank mix application.
The investigators from the US FWS observed grains of both wheat and red millet in the fi eld
at the time of the bird kill. It is likely that the presence and availability of this waste grain resulted
in the kill being so large. Although the courts found the farmer guilty of some minor violations, the
use itself was deemed a legal one. The investigators concluded that most of the birds had likely died
after consuming the surface seed contaminated with the spray.
8.4.4.3 Incidents from carbofuran used in chemigation
Chemigation is the introduction of a pesticide into irrigation water. This can prove extremely
hazardous to wildlife, especially in arid areas, where wildlife is drawn to any source of water.
In 1990, bird losses were reported in coastal wine growing counties in California. By early 1992,
investigators had documented almost 2 000 bird deaths from exposure to carbofuran used on grapes
(CDFG 1990b; CDFG 1990e-j; CDFG 1990l; CDFG 1990m; CDFG 1991a-w; CDFG 1992a; CDFG
1992b; CDFG 1992d). These losses were from applications of fl owable carbofuran (Furadan 4F)
through drip irrigation systems during the day. A drought in California during this time likely exac-
erbated the situation by drawing large numbers of birds to available water in vineyards. Investigators
also documented secondary poisoning of predatory birds preying on songbirds.
In order to prevent further bird loss, State authorities cancelled the use of Furadan 4F in Napa,
Sonoma, and Mendocino counties and changed label directions in other counties to prohibit use
of carbofuran during daylight hours. In Monterey County, government regulators implemented an
intensive post-application fi eld monitoring programme in the autumn of 1992. Carcasses of more
than 400 animals (birds, mammals, reptiles, and amphibians) were recovered from vineyards in
the monitoring programme and carbofuran was detected in each carcass that was analyzed (CDFG
1992e-h; CDFG 1993a-f; CDFG 1993h-p). Most of the carcasses recovered were diurnal passerines,
indicating that prohibiting diurnal applications did not offer suffi cient protection to these species.
Analysis revealed that grapes, weed seeds, and leaf litter on the soil surface surrounding the drip
emitters had been coated with carbofuran as a result of splashing from the drip puddles. It is inter-
esting to note that no other losses were reported in the county, indicating that, without a directed
post-application monitoring programme, important wildlife losses would not have been detected or
reported (Finlayson, McMillin and Hosea, unpublished report).
In response to the monitoring results, alternative methods of application including subsurface drip
emitters and tubing connecting above ground emitters directly to the soil surface were developed and
tested. The new methods revealed up to a 90% reduction in detectable wildlife losses. Indeed, only
one wildlife loss (in grapes) has been reported state-wide since 1993 (CDFG 1995b). However, Fite,
Randall, Young et al. (2006) pointed out that limited information is available on the effectiveness of
these mitigation measures. Carbofuran use declined substantially after 1994, as did all monitoring
efforts to uncover any further problems.
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