Refined Avian Risk Assessment for Chlorpyrifos in the United States - Reviews of Environmental Contamination and Toxicology - page 180

Fig. 5 Components of GranPARAM

Each time a bird feeding in a treated fi eld ingests a particle, the particle is either
a granule or a piece of natural grit. The default assumption of the model is that birds
forage for particles within each spatial zone randomly, and therefore the probability,
p, of selecting a pesticide granule is equal to the relative availability of granules in
comparison to natural grit particles of the same size. However, birds may select
particles non-randomly and show preference for some types of particles over others
(Best and Gionfriddo 1994 ; Best et al. 1996 ). In GranPARAM, the user has the
option to input the relative preference birds have for selecting pesticide granules in
comparison to natural grit. If this factor is used, as was the case with CPY,
GranPARAM modifi es the estimate of p accordingly. Birds prefer sand for grit con-
sumption and thus strongly avoid Lorsban 15G granules because of its clay-based
formulation (see SI Appendix 3, Sect. 2.1 for additional details). Once p is defi ned,
the number of Lorsban 15G granules ingested during the day following application