stock drinking supplies, only four contained detectable 1080 residues at 0.1ppb (1 sample) and 0.2 ppb (3 samples) – all well below the ministry of health level of 2 ppb. in an experiment funded by the animal health board and conducted by niwa simulating the effects of rainfall on 1080 on a steep soil-covered hillside a few meters from a stream, it was found that 99.9% of the water containing 1080 leached straight into the soil (see 4.3 of) and did not flow over the ground to the stream as had been expected. the experiment also measured contamination of soil water, which was described as the water carried through the soil underground at short horizontal distances (0.5-3m), downhill toward the stream. the experiment did not measure contamination of deeper soil and ground water immediately beneath the site of application. soil the fate of 1080 in the soil has been established by research defining the degradation of naturally occurring fluoroacetate (oliver, 1977). sodium fluoroacetate is water-soluble, and residues from uneaten baits leach into the soil where they are degraded to non-toxic metabolites by soil microorganisms, including bacteria (pseudomonas) and the common soil fungus (fusarium solani) (david and gardiner, 1966; bong, cole and walker, 1979; walker and bong, 1981). birds although it is now infrequent, individual aerial 1080 operations can still sometimes affect local bird populations if not carried out with sufficient care. in new zealand, individuals from 19 species of native birds and 13 species of introduced birds have been found dead after aerial 1080 drops. most of these recorded bird deaths were associated with only four operations in the 1970s that used poor-quality carrot baits with many small fragments. on the other hand, many native new zealand bird populations have been successfully protected by reducing predator numbers through aerial 1080 operations. kokako, blue duck, new zealand pigeon, kiwi, kaka, new zealand falcon, tomtit, south island robin, north island robin, new zealand parakeets (kakariki), and yellowhead have all responded well to pest control programmes using aerial 1080 operations, with increased chick and adult survival, and increases in population size. in contrast, seven of 38 tagged kea, the endemic alpine parrot, were killed during an aerial possum control operation in okarito forest conducted by doc and ahb in august 2011. because of their omnivorous feeding habits and inquisitive behaviour, kea are known to be particularly susceptible to 1080 poison baits, as well as other environmental poisons like the zinc and lead used in the flashings of backcountry huts and farm buildings. recent research found that proximity to human-occupied sites where kea scrounge human food is inversely related to survival; the odds of survival increased by a factor of 6.9 for remote kea compared to those that lived near scrounging sites. high survival in remote areas is explained by innate neophobia and a short field-life of prefeed baits, which together preclude acceptance of poison baits as familiar food. reptiles and amphibians reptiles and amphibians are susceptible to 1080, although much less sensitive than mammals. amphibian and reptile species that have been tested in australia are generally more tolerant to 1080 poison than are most other animals. mcilroy (1992) calculated that even if lizards fed entirely on insects or other animals poisoned with 1080, they could never ingest enough poison to receive a lethal dose. laboratory trials in new zealand simulating worst-case scenarios indicate that both leiopelma archeyi (archey's frog) and l. hochstetteri (hochstetter's frog) can absorb 1080 from contaminated water, substrate, or prey. the chance of this occurring in the wild is ameliorated by a variety of factors, including frog ecology. captive maintenance and contamination problems rendered parts of this study inconclusive. further population monitoring is recommended to provide more conclusive evidence than provided by this single study. in new zealand, the secondary poisoning of feral cats and stoats following 1080 operations is likely to have a positive effect on the recovery of native skink and gecko populations.: 257 killing rabbits and possums, which compete for food with skinks and geckos, may also have benefits. fish fish generally have very low sensitivity to 1080. toxicity tests have been conducted in the us on bluegill sunfish, rainbow trout, and the freshwater invertebrate daphnia magna. tests at different 1080 concentrations on sunfish (for four days) and daphnia (two days) showed that 1080 is "practically non-toxic" (a us epa classification) to both these species. rainbow trout were also tested over four days at four concentrations ranging from 39 to 170 mg 1080 per litre. from these results an lc50 (the concentration of 1080 per litre of water which theoretically kills 50% of the test fish) can be calculated. the lc50 for rainbow trout was calculated to be 54 mg 1080/litre – far in excess of any known concentration of 1080 found in water samples following 1080 aerial operations. thus 1080 is unlikely to cause mortality in freshwater fish. invertebrates insects are susceptible to 1080 poisoning. some field trials in new zealand have shown that insect numbers can be temporarily reduced within 20 cm of toxic baits, but numbers return to normal levels within six days of the bait being removed. other trials have found no evidence that insect communities are negatively affected. another new zealand study showed that wētā, native ants, and freshwater crayfish excrete 1080 within one to two weeks. there is also evidence that 1080 aerial operations in new zealand can benefit invertebrate species. both possums and rats are a serious threat to endemic invertebrates in new zealand, where around 90 per cent of spiders and insects are endemic and have evolved without predatory mammals. in a study on the diet of brushtail possums, 47.5 per cent of possum faeces examined between january 1979 and june 1983 contained invertebrates, mostly insects. one possum can eat up to 60 endangered native land snails (powelliphanta spp.) in one night.